Quick answer: The JST EH is a 2.5mm pitch, single-row, low-profile wire-to-board crimp connector with a friction lock, a 3.8mm body thickness and an 8.1mm assembled height. It is rated 3A AC/DC with AWG #22 wire at 250V AC/DC, carries a 1,000MΩ insulation resistance, and its withstanding voltage is 800 VAC for one minute — deliberately lower than the 1,000 VAC of the JST XH next to it on the same pitch. The KONNRA KR2504 is the cross-reference equivalent, and it is the most faithful electrical cross-reference of the 2.5mm family: the 800V withstand matches on both documents, the 3A is referenced to AWG #22 exactly as the original does, and the DIP-only mounting and 8.1mm height both carry across. The wire window is where it does not match. JST accepts AWG #32 to #22 — six sizes; the KR2504 documents 22# to 24# — two of them. And the insulation window is published as 1.9mm maximum with no lower bound, against JST’s φ0.5mm to φ1.9mm.
The low-profile member of the 2.5mm family
Three JST families sit at a 2.5mm pitch, and the EH is the one that trades electrical margin for height. JST positions it exactly that way: “a 2.5mm pitch low-profile, wire-to-board connector that meets the needs of high density PCB requirements”, with “the top entry type … 3.8mm in thickness and 8.1mm in height”, and “the low profile design helps to save space”.
That single design decision explains every difference between the EH and the XH:
| Attribute | JST EH | JST XH |
|---|---|---|
| Pitch | 2.5mm | 2.5mm |
| Assembled height | 8.1mm (3.8mm body) | 9.8mm |
| Withstanding voltage | 800 VAC for one minute | 1,000 VAC for one minute |
| Conductor size | AWG #32 to #22 (0.032–0.33mm²) | AWG #30 to #22 (0.05–0.33mm²) |
| Insulation O.D. | φ0.5mm to φ1.9mm | φ0.9mm to φ1.9mm |
| Current rating | 3A AC/DC (AWG #22) | 3A AC/DC (AWG #22) |
| Voltage rating | 250V AC/DC | 250V AC/DC |
| Temperature range | −25℃ to +85℃ | −25℃ to +85℃ |
| Insulation resistance | 1,000MΩ min. | 1,000MΩ min. |
| Circuits | 2 to 15 | 1 to 16, and 20 |
| Mounting | Through-hole only | Through-hole and SMT |
| Lock | Friction lock | Friction lock |
| Standards | CSA, TÜV, UL | CSA, TÜV, UL |
| KONNRA equivalent | KR2504 | KR2501 |
Read the table as a trade, not a ranking. The EH gives up 200V of dielectric withstand and 1.7mm of height, and in exchange it reaches two wire sizes finer than the XH can — AWG #32 and #30 — and it goes lower at the insulation end too, φ0.5mm against φ0.9mm. If your harness is built on #32 or #30, or if the enclosure has 8.2mm of clearance where 9.8mm will not fit, the EH is the choice and the XH is not. If you need dielectric margin, the XH is the choice.
That difference is why the EH/KR2504 comparison reads differently from the XH/KR2501 one. The two originals are not the same product with a different name. They are two different answers to the same pitch, and the wire window is where the answers diverge most.
What the JST EH 2.5 Connector Is
KONNRA KR2504 series EH 2.5 DIP wire-to-board connector with lock, the cross-reference for the JST EH 2.5
JST’s own catalogue describes the family in four lines, and each one is a design decision worth knowing:
- “Low profile, space-saving design” — the 8.1mm assembled height, which is the family’s reason to exist
- “High reliability contacts” — JST does not name a contact geometry for the EH the way it names the “original double-leaf contact” for the XH
- “Shaped top to prevent misinsertion” — the housing is polarised so it seats one way only, and JST describes the header as having a shaped top rather than calling it a shroud
- “Excellent workability in the wire harness assembly and mating process” — the family is positioned for harness shops as much as for designers
Two further details from JST’s published material:
The contact is a shaped mating style, and the catalogue describes the family as “Crimp Style and Mating Style”. JST’s specification tables list a contact resistance with a separate initial value and a value after environmental tests — the same two-limit structure the XH uses.
The Type A header exists for mating workability. JST’s note on the Type A header states that it has a post length designed to improve mating workability — a longer post, so the housing starts to align before the contacts engage. That is the same design intent that makes the EH easier to mate than its height alone would suggest, and it is the detail to quote if you are choosing between the -A and one of the taped variants.
And one caution that belongs in any harness standard. JST’s note on the low-insertion-force contact reads, in its own words:
“SEH-001T-P0.6L is a low insertion force type contact for easier insertion [and with]drawal operation. Please take the application and environment into consideration as the low insertion force type contact is less resistant to vibration. Please note that the crimp height is different from the standard EH contact.”
So the low-insertion-force option is a genuine trade with a documented vibration penalty and a different crimp setting — which means the applicator setting has to change with the terminal. Do not specify it by default because it mates more easily.
The Four Terminals, and Why the Count Matters
JST splits the EH across four crimp terminals, and they are not interchangeable:
| JST terminal | Role |
|---|---|
SEH-001T-P0.6 |
The standard contact |
SEH-001T-P0.6L |
The low insertion force type — JST states it is less resistant to vibration and that its crimp height differs from the standard contact |
SEH-002T-P0.6L |
A further low-insertion-force variant, covering a different wire segment |
SEH-003T-P0.6L |
A further low-insertion-force variant, covering a different wire segment |
JST publishes the conductor and insulation window for each terminal in that terminal’s own drawing, and the series figures — AWG #32 to #22 and φ0.5mm to φ1.9mm — are the union of the four.
On the KONNRA side, the KR2504 documents two terminals — T25040PT0101B and T25040PT0102B — against a single wire window of 22# to 24#. Which of the two covers which wire is not stated in the specification.
The engineering consequence is the central point of this guide. With the JST part, “what wire can I use” has four answers and the series range is the union of them. With the KR2504 as documented there is one answer, and it covers two of the six conductor sizes JST publishes. A harness drawing that names a JST terminal and a wire does not translate by copying the wire across.
The KONNRA KR2504 Part Numbers
PS-KR2504-01 §2.0 lists five production part numbers for this series:
| Component | KONNRA part number |
|---|---|
| Housing | H25040***0101A |
| Terminal 1 | T25040PT0101B |
| Terminal 2 | T25040PT0102B |
| Straight wafer (DIP 180°) | C2504VD***01T0101PA |
| Right-angle wafer (DIP 90°) | C2504RD***01T0101PA |
Note what is not in that list. There is no SMT wafer — and there should not be. JST catalogues the EH as through-hole only, and KONNRA’s KR2504 offers two wafers, both DIP. That is a genuine, deliberate match rather than an omission, and it is the right answer for this family: an 8.1mm low-profile part is chosen for a through-hole design.
Key Specifications at a Glance
| Attribute | JST EH (manufacturer) | KONNRA KR2504 | Verdict |
|---|---|---|---|
| Pitch | 2.5mm | 2.50mm | Match |
| Assembled height | 8.1mm (3.8mm body, top entry) | 8.1mm after mounting | Match |
| Current rating | 3A AC/DC (AWG #22) | 3A (22AWG) | Match — including the reference conductor |
| Voltage rating | 250V AC/DC | 250V | Match |
| Withstanding voltage | 800 VAC for one minute | 800V AC/minute (page and specification §5.3) | Match on both documents |
| Insulation resistance | 1,000MΩ min. | 1000MΩ Min | Match |
| Conductor size | AWG #32, #30, #28, #26, #24, #22 | AWG 22# to 24# | Two of six sizes — the gap |
| Insulation O.D. | φ0.5mm to φ1.9mm | 1.9mm Max | Upper bound matches; no lower bound |
| Contact resistance | Not on the series page; the catalogue gives a separate initial limit and post-environmental-test limit | 20mΩ Max (specification and all pages) — “below 10mΩ at the initial stage” in the product-page prose | Internal conflict on the page |
| Temperature range | −25℃ to +85℃ (including temperature rise under load) | −40℃ to +105℃ | Wider by 20℃ / 15℃ |
| Circuits | 2 to 15 | 2 to 16 | One more than the original |
| Mounting | Through-hole only | DIP only (two wafers, no SMT) | Match |
| Row count | Single row | Single row | Match |
| Lock | Friction lock | Friction lock / “anti-wrong-insertion design” | Match |
| Housing material | PA, natural (white) | PA66 UL94 V-0, White | Same polymer class |
| Post / contact plating | Brass, copper-undercoated, tin-plated | Brass, tin over nickel | Tin finish on both; different under-plate |
| Terminal base metal | Phosphor bronze | Phosphor bronze | Match |
| Terminals published | 4 (SEH-001T-P0.6, -001T-P0.6L, -002T-P0.6L, -003T-P0.6L) |
2 (T25040PT0101B, T25040PT0102B) |
Fewer |
| IDC / HR compatibility | Yes — JST documents the header as compatible with an IDC-style connector and with the HR crimp connector | Not documented | Original only |
| Colours | Around 10 documented colours | White | Fewer |
| Crimp tooling published | Crimp machines AP-K2N and MKS-L, with applicators named per contact | Crimp dimensions only; no applicator part numbers | Original only |
| Agency | CSA, TÜV, UL | UL E482542 | Partial |
Both columns come from manufacturer documents. Sources are listed at the end.
Where the Electrical Sheet Actually Agrees
This is the part of the comparison that deserves to be stated plainly, because it is stronger than in any of the neighbouring 2.5mm cross-references.
The 800V withstanding voltage agrees on all three documents. JST publishes 800 VAC for one minute, no breakdown or flashover. KONNRA’s specification §5.3 requires 800V AC for 1 minute between adjacent terminals or to ground, based on EIA-364-20A. And — unlike the KR2501, whose product page puts the rated voltage into the withstand row — the KR2504’s product page states 800V AC/minute as well.
| Source | Withstanding voltage |
|---|---|
| JST EH series page | 800 VAC for one minute, no breakdown or flashover |
KONNRA PS-KR2504-01 §5.3 |
800V AC for 1 minute, EIA-364-20A |
| KONNRA KR2504 product page | 800V AC/ minute |
| KONNRA KR2504 component pages | (not stated; the electrical rows give voltage, current, contact and insulation resistance) |
Three documents, one number, and the number is lower than the neighbouring series’ 1,000V. That is the opposite of a defect: it is a cross-reference that has correctly carried across the original’s least favourable headline figure. A supplier optimising for a datasheet would have written 1,000V.
The current rating agrees on its basis too. JST rates 3A AC/DC with AWG #22, and the KR2504’s specification says 3A(22AWG) — the same reference conductor. That matters more than it looks. In the JST XH and Yeonho 2.5 comparisons, KONNRA rated 3A against 24 AWG, so the number was the same but the statement was not. Here it is the same statement.
The mounting technology and the assembled height both carry across — through-hole only against DIP only, and 8.1mm against 8.1mm. Enclosure clearance and board layout do not change when you cross-reference this family.
And the insulation resistance matches at 1,000MΩ min.
That is five agreements on rows where a cross-reference most often drifts, including the two that are hardest to get right. Which makes the wire window stand out.
The Wire Window: Two Sizes Out of Six
This is the finding that decides whether a given harness transfers, and it is the one place where this cross-reference is materially narrower than the original.
| Conductor size | JST EH | KONNRA KR2504 |
|---|---|---|
| AWG #32 | ✅ Accepted (0.032mm²) | ❌ Not documented |
| AWG #30 | ✅ Accepted (0.05mm²) | ❌ Not documented |
| AWG #28 | ✅ Accepted | ❌ Not documented |
| AWG #26 | ✅ Accepted | ❌ Not documented |
| AWG #24 | ✅ Accepted | ✅ 22# to 24# |
| AWG #22 | ✅ Accepted (0.33mm²) | ✅ 22# to 24# |
JST accepts six conductor sizes; the KR2504 documents two. Four of the six have no documented home on the cross-reference: #32, #30, #28 and #26.
And the four that are missing are not arbitrary. They are the entire fine-wire half of the EH’s range — and the fine-wire half is why the EH exists. Set the two JST 2.5mm families against each other and the EH’s exclusive capability over the XH is precisely:
- AWG #32 — the XH stops at #30
- insulation O.D. from φ0.5mm — the XH stops at φ0.9mm
Everything else in the EH’s conductor range, the XH also covers. So an engineer who chose the EH over the XH usually chose it for one of those two things. And those are the two things the KR2504 does not document.
Look at it from the other end and the picture is the same: the KR2504’s 22# to 24# window is a subset of both originals’ ranges. It does not reach the fine end of either.
For context inside the KR2504’s own product family, the neighbouring KR2501 — the JST XH cross-reference, on the same 2.50mm pitch — documents 22# to 28#. So within KONNRA’s own 2.5mm range, the XH cross-reference reaches two sizes further into fine wire than the EH cross-reference does. If your harness is on #26 or #28 and you are looking for a fine-wire 2.5mm solution, that is worth knowing before you choose a series.
What to do about it. Three options, in order of preference:
- If your harness is on #26, #28, #30 or #32, ask before you design. Send the wire specification and we will tell you in writing whether the KR2504 is supplied against it. The specification’s window is what it documents today, not necessarily the limit of what can be supplied — but that has to be answered by us, not assumed.
- If your harness is on #22 or #24, the documented window covers you, and the rest of this guide applies.
- If you need the fine end and the 8.1mm height is not negotiable, say so. The height and the fine wire are the two reasons to be on this pattern at all, and a cross-reference that loses one of them is a design change rather than a part substitution.
The Insulation Window Has No Lower Bound
| Source | Applicable wire insulation O.D. |
|---|---|
| JST EH series page | φ0.5mm to φ1.9mm |
KONNRA PS-KR2504-01 §4.0 |
Insulation O.D. 1.9mm (Max.) |
| KONNRA product page | Insulation O.D 1.9mm Max |
| KONNRA terminal component page | Insulation Diameter 1.90mm (MAX) |
The upper bound is an exact match — 1.9mm on both sides. That is a genuine agreement, and it is the number that matters if you are running heavy insulation.
The lower bound is absent. JST states a φ0.5mm floor; every KONNRA document states only a ceiling. So the window is published as open downwards, which reads as permissive but functions as unspecified: nothing in the KR2504 documentation tells you the smallest insulation the insulation barrel will grip.
And the missing floor sits exactly where this family is used. Insulation O.D. scales with conductor size, so the finest wire the EH accepts — AWG #32 — is also the wire with the smallest insulation, in JST’s stated range somewhere between φ0.5mm and roughly φ0.8mm. “1.9mm Max” describes the ceiling of a window whose floor is the part of the range the EH was designed to reach.
This is the parameter that fails quietly. An insulation barrel that is too tight for the wire closes on the insulation instead of gripping the conductor; the joint passes a continuity check, ships, and fails in the field. At a 2.5mm pitch the insulation barrel has to sit inside the housing cavity, which makes the insulation diameter a design input, not a manufacturing detail.
What to do: measure the actual insulation O.D. of the wire on your harness drawing — not the nominal — and confirm it in writing against the terminal you are quoting. Because one end of the published window is missing, the datasheet cannot be your safety net for this parameter.
One crimp-table boundary worth knowing
The KR2504’s crimp table covers 22 AWG and 24 AWG only, and its insulation crimp heights are:
| Wire | Insulation crimp height |
|---|---|
| 22 AWG | 1.80 ±0.10mm (band 1.70 – 1.90) |
| 24 AWG | 1.70 ~ 1.85mm |
At 22 AWG the top of the accepted band, 1.90mm, is exactly the 1.9mm insulation ceiling stated in section 4.0 of the same document. That is a boundary, not a contradiction — the two numbers meet rather than overlap, and the 24 AWG band sits clear below it. It is worth stating because it is the kind of thing that gets misread in both directions.
The practical reading is still worth a question: a 22 AWG wire whose insulation measures at the very top of the range leaves the insulation crimp no closure to work with. If your 22 AWG wire is at the top of its tolerance band, ask for the intended insulation crimp height for that wire rather than taking the 1.80 ±0.10 at face value.
And one thing worth noticing by contrast. In the two neighbouring 2.5mm specifications, the insulation crimp band’s top overshoots the stated insulation ceiling by 0.1mm. Here it does not. That is a small point in this document’s favour, and it is why this guide reports a boundary rather than a conflict.
The One Internal Conflict: 10mΩ or 20mΩ
Every cross-reference in this family has a place where two of the supplier’s own documents disagree. For the KR2504 there is exactly one, and it is a contact-resistance figure.
| Document | Contact resistance |
|---|---|
| Product page, General Specification table | 20mΩ Max |
| Product page, Advantages prose | “contact resistance below 10mΩ at the initial stage” |
| All four component pages (housing, terminal, both wafers) | 20mΩ Max |
| Specification, section 5.1 | 20 milliohms Max. (dry circuit, 20mV max, 100mA max, EIA-364-23C) |
| JST EH series page | Not published — the EH catalogue gives a separate initial limit and post-environmental-test limit |
The controlling figure is 20mΩ. It is the one in the specification, in the General Specification table and on all four component pages. The 10mΩ claim appears once, in marketing prose, and nowhere in any specification.
Two things follow, and the second is the important one.
First, use 20mΩ. It is what a first-article test will be measured against, and it is what the specification obliges us to deliver.
Second, the unsupported number is the optimistic one. “Below 10mΩ at the initial stage” is a claim half the documented limit, with no test clause behind it. That is the same failure mode as the previous series in this range, where the documentation claimed a better contact resistance than the original published. A number that beats the specification is the number a purchase order should not rely on — and in this case it is our own prose contradicting our own specification rather than an original.
What to ask for: if your circuit is sensitive enough that 10mΩ against 20mΩ decides whether you can use the part, ask for the measured contact-resistance distribution from a production lot under the §5.1 dry-circuit condition, with a maximum and a sample size. Do not design to the prose.
Circuit Counts: One More Than the Original
| Source | Circuits |
|---|---|
| JST EH series page | 2, 3, 4, … 15 |
| JST EH housings | EHR-2 through EHR-15 |
| KONNRA KR2504 product page | 2-16pin |
| KONNRA housing component page | 2P~16P |
| KONNRA straight wafer page | 2P~16P |
| KONNRA right-angle wafer page | 2P~16P |
| The specification, §8.0 force table | 2 to 16 |
This one is internally consistent, and it is worth saying so. The product page, all four component pages and the specification’s own force table all say 16 — four documents agreeing.
The only question is the original’s ceiling. JST catalogues the EH from 2 to 15 circuits; the KR2504 documents 2 to 16, one position beyond what the original publishes. Unlike the neighbouring cross-references, where the circuit claim was not even consistent between the supplier’s own pages, here the extension is supported end to end — including force data at 16 circuits, which the specification’s §8.0 table provides.
So treat this as a question, not a defect. If you need exactly 16 positions, the documentation carries it. Ask for the drawing for a 16-way and confirm the housing and wafer are supplied at that count; if you are at 15 or below, the question does not arise.
And note the edge case at the other end. There is no 1-circuit EH and no 1-circuit KR2504 — both start at 2. If a design uses a single-position connector as a mechanical key, this is not the family for it.
The Mechanical Clauses in PS-KR2504-01
| Clause | What is measured | Test condition | Requirement |
|---|---|---|---|
| §6.1 | Insertion and withdrawal force | At 25.4 ±3mm/minute, excluding plastic detents, EIA-364-13D | Refer to §8.0 |
| §6.2 | Terminal insertion force | Insert the crimped terminal into the housing | 1.5 kgf (14.7 N) max |
| §6.3 | Terminal / housing retention force | Apply axial pull out force at 25.4 ±3mm/minute on the terminal assembled in the housing | 2.0 kgf (19.6 N) min |
| §6.4 | Pin–pin retention force | Apply axial push force at 25.4 ±3mm/minute | 1.5 kgf (14.7 N) min |
§6.2 is stiffer than in the neighbouring series. The KR2504 allows 1.5 kgf (14.7 N) max to click a crimped terminal into its housing, where the KR2501 and KR2502 specifications both allow 1.0 kgf (9.8 N). A higher permitted insertion force means a firmer lance engagement — but it also means more effort per position for the operator, and it is worth checking on a multi-way assembly whether that is comfortable. Different series, different value; this is not an error, it is a design choice.
§6.3 is the clause to design against. A terminal-to-housing retention of 2.0 kgf (19.6 N) minimum means the wire can take a 2kg axial pull before the terminal leaves the housing. Set that against §8.0, where the minimum withdrawal force for the whole 2-circuit connector is 0.40 kgf — that is 0.20 kgf per contact, because that figure is for the complete 2-way assembly and not per position. The ratio between the terminal’s grip inside the housing (2.0 kgf) and the housing’s grip on the wafer (0.20 kgf per contact) is 10:1.
Why 10:1 is the right shape. The wire should be much harder to detach from the housing than the housing is to detach from the board. If it were the other way round, a tug on the cable would pull a terminal out of the housing — leaving bare contacts on the board, and a repair instead of a re-plug. The larger this ratio, the more forgiving the connector is to a technician working by feel.
§6.4 states a retention test that cannot be run as written. A retention force is the force required to separate two parts, so the test is a pull. §6.4 calls for a push while requiring a minimum — and a push in the mating direction is limited by how hard the parts can be pressed together, not by how well they hold. Read literally, the clause is not a retention test.
This is now the third series in which the same wording appears. The KR2500, KR2501 and KR2502 specifications all carry “Apply axial push force” in §6.4, while all of them correctly say “pull out” in the terminal-retention clause immediately above. It is house wording carried across specifications rather than a missing requirement — but when you write a test procedure against any KONNRA specification, read §6.4 and write the pull you require rather than transcribing the clause.
And do not cross-read §6.2 with §8.0. §6.2’s 1.5 kgf maximum is the force to click a crimped terminal into its housing cavity, which is a lance-engagement force. §8.0’s insertion figure is the contact-spring force when mating the two halves. They measure different things, and a review that treats the 1.5 kgf cap as the mating limit will conclude the connector fails its own specification.
The insertion and withdrawal force table
PS-KR2504-01 §8.0 publishes a per-circuit-count force table in kgf for 2 to 16 circuits. This is the complete table.
| Circuits | Insertion force max | Withdrawal force min, initial | Withdrawal force min, after 30 cycles | Circuits | Insertion force max | Withdrawal force min, initial | Withdrawal force min, after 30 cycles |
|---|---|---|---|---|---|---|---|
| 2 | 2.50 | 0.40 | 0.20 | 10 | 6.50 | 1.20 | 1.00 |
| 3 | 3.00 | 0.50 | 0.30 | 11 | 7.00 | 1.30 | 1.10 |
| 4 | 3.50 | 0.60 | 0.40 | 12 | 7.50 | 1.40 | 1.20 |
| 5 | 4.00 | 0.70 | 0.50 | 13 | 8.00 | 1.50 | 1.30 |
| 6 | 4.50 | 0.80 | 0.60 | 14 | 8.50 | 1.60 | 1.40 |
| 7 | 5.00 | 0.90 | 0.70 | 15 | 9.00 | 1.70 | 1.50 |
| 8 | 5.50 | 1.00 | 0.80 | 16 | 9.50 | 1.80 | 1.60 |
| 9 | 6.00 | 1.10 | 0.90 |
The table is internally consistent to two decimal places, which is the most useful thing that can be said about a force table, because it means the numbers were generated from a model rather than transcribed:
- Insertion force maximum = 1.50 + 0.50 × N kgf — 2 circuits gives 2.50, 16 circuits gives 9.50
- Withdrawal force minimum (initial) = 0.20 + 0.10 × N kgf — 2 circuits gives 0.40, 16 circuits gives 1.80
- Withdrawal force minimum (after 30 cycles) = 0.10 × N kgf — 2 circuits gives 0.20, 16 circuits gives 1.60
All 45 figures in the table reproduce from those three expressions, and every circuit count shows the same 0.20 kgf drop after 30 mating cycles. That is a genuine point in the specification’s favour.
Two readings that matter for this family specifically.
The insertion force maximum reaches 9.50 kgf — about 93N — at 16 circuits, slightly below the 10.00 kgf of the neighbouring specification, which is what you would want from the family designed to be the easier one to mate.
The withdrawal force is materially lower than the neighbouring 2.50mm series’, and the slope is the reason. Compare the two published models:
| Model | Insertion force max | Withdrawal force min (initial) | After 30 cycles |
|---|---|---|---|
| KR2504 (EH pattern) | 1.50 + 0.50 × N | 0.20 + 0.10 × N | 0.10 × N |
| Neighbouring 2.50mm series (XH pattern) | 2.00 + 0.50 × N | 0.20 + 0.20 × N | 0.20 × N |
The insertion slopes are identical at 0.50 kgf per way — the difference is only the 0.50 kgf lower intercept. But the withdrawal slope is halved, from 0.20 to 0.10 kgf per way, so at 16 circuits the documented minimum withdrawal is 1.80 kgf against 3.40 kgf. Both models are internally consistent; they simply describe two different retention designs.
That is not a defect in either document — but it is a number to know, because withdrawal force is felt by whoever unplugs the connector, and halving it changes how a serviceable module behaves after a few hundred cycles in the field.
One honest limitation. JST does not publish a series-level insertion and withdrawal force table for the EH — the series page lists no force figures, and the catalogue’s tables give current, voltage, resistance and wire data rather than a force-versus-circuit-count ladder. So these figures cannot be reconciled against the original — only checked against themselves, which is what the three expressions above do. If your qualification plan depends on a specific withdrawal force, measure a first article.
Crimp and Termination
KONNRA KR2504 2.50mm pitch crimp terminal for the JST EH 2.5 wire-to-board system
PS-KR2504-01 §6.5 publishes crimp geometry for two wire sizes — all the specification documents.
| Parameter | 22 AWG | 24 AWG |
|---|---|---|
| Conductor crimp width | 1.35 ±0.10mm | 1.35 ±0.10mm |
| Conductor crimp height | 0.85 ±0.05mm | 0.60 ~ 0.75mm |
| Insulation crimp width | 1.55 ±0.10mm | 1.55 ±0.10mm |
| Insulation crimp height | 1.80 ±0.10mm | 1.70 ~ 1.85mm |
| Crimp strength | 4.54 kgf min | 3.63 kgf min |
| Stripping length | 1.9 ~ 2.7mm | 1.9 ~ 2.7mm |
Four observations.
The conductor crimp heights run the right way. 0.85mm at 22 AWG down to a 0.60–0.75mm band at 24 AWG — decreasing as the conductor gets thinner, which is the correct direction. So do the insulation crimp heights. This is worth checking on any crimp table you are handed, because the direction carries the whole meaning.
The 24 AWG rows are given as ranges rather than tolerances — 0.60 ~ 0.75 for the conductor height and 1.70 ~ 1.85 for the insulation height — where the 22 AWG rows are given as centre-plus-tolerance. Both are usable in a setup sheet; just do not read the 24 AWG band as ± anything.
Stripping length is longer than in the neighbouring series: 1.9 to 2.7mm here against 1.6 to 2.1mm in the KR2501 and KR2502 specifications. That is a real change to the setup sheet, and a harness shop moving a wire from one series to the other will need to change the strip dimension as well as the die.
And there is a gap. The KR2504 documents two terminal part numbers — T25040PT0101B and T25040PT0102B — but the crimp table covers one wire window. Which terminal serves which wire is not stated. With JST the split is explicit, because JST publishes four terminals with per-terminal windows and states outright that the low-insertion-force contact has a crimp height different from the standard contact. Ask which KONNRA terminal is quoted against your wire before the setup sheet is written.
Tooling. KONNRA publishes crimp geometry but no applicator or crimp-machine part numbers. JST does publish them — the crimp machines AP-K2N and MKS-L, with applicators named per contact family. If you crimp in house, the applicator data is a document to request with the quote rather than after the first build.
Environmental and Durability Programme
PS-KR2504-01 §7 publishes eleven environmental and durability tests, each with a stated requirement.
| Clause | Test | Condition | Requirement |
|---|---|---|---|
| §7.1 | Durability | Mated up to 30 cycles at 10 cycles per minute, EIA-364-09C | Contact resistance 40mΩ max |
| §7.2 | Temperature rise | Carrying rated current load, EIA-364-70B | Temperature rise 30℃ max |
| §7.3 | Vibration | Amplitude 1.5mm P-P; sweep 10~55~10 Hz in 1 minute; 2 hours in each X, Y and Z axis, EIA-364-28B | No damage; contact resistance 40mΩ max; discontinuity 1 microsecond max |
| §7.4 | Shock | 490 m/s² (50g), 3 strokes in each X, Y and Z axis, EIA-364-27B | No damage; contact resistance 40mΩ max; discontinuity 1 microsecond max |
| §7.5 | Heat resistance | 105 ±2℃ for 96 hours, EIA-364-17B | No damage; contact resistance 40mΩ max |
| §7.6 | Cold resistance | −40 ±2℃ for 96 hours, EIA-364-59 | No damage; contact resistance 40mΩ max |
| §7.7 | Humidity | 40 ±2℃, 90–95% RH, 96 hours, EIA-364-31B | No damage; contact resistance 40mΩ max; dielectric strength must meet §5.3; insulation resistance 100MΩ min |
| §7.8 | Thermal shock | 5 cycles of −40℃ for 30 min, room temperature 5 min, +105℃ for 30 min, room temperature 5 min, EIA-364-32B | No damage; contact resistance 40mΩ max |
| §7.9 | Salt spray | 16 hours exposure at 35 ±2℃ from a 5 ±1% solution, EIA-364-26B | No damage; contact resistance 40mΩ max |
| §7.10 | Solderability | 3 ±0.5 seconds at 245 ±5℃, EIA-364-52 | 95% of the immersed area must show no voids or pin holes |
| §7.11 | Solder resistance | DIP type products, able to withstand the solder heat-resistance range, EIA-364-71B | No damage |
Four things are worth a designer’s attention.
§7.11 is written for this product and only this product. It says “DIP type products” and cites EIA-364-71B — the through-hole solder-heat standard. There is no SMT row. That is exactly right for a family JST catalogues as through-hole only, and it is the kind of consistency that tells you the specification was written against the real product rather than cloned.
Vibration is specified for 2 hours in each of three axes, with a 1 microsecond maximum discontinuity — a demanding requirement rather than a nominal one, and the same test condition the neighbouring KONNRA specifications use.
The contact-resistance limit doubles after every test. Section 5.1 sets 20mΩ max on a dry-circuit measurement; section 7 then allows 40mΩ max after heat, cold, humidity, thermal shock, salt spray, vibration, shock and 30 mating cycles. A relaxation after conditioning is normal and correct — the surfaces have oxide on them by then — but the size of the step is the number to know. If your application budgets 20mΩ for the whole service life rather than for the first article, this specification permits twice that after conditioning.
Humidity is the only test that tightens the insulation-resistance requirement — §7.7 requires 100MΩ min, against the 1000MΩ min set in §5.2 for a dry part. That is a sensible allowance for absorbed moisture, and it is also the mechanism behind the change in insertion and withdrawal force that shows up on a humid production floor.
One comparison that this guide cannot make. JST does not publish an environmental test programme for the EH at series level — no durability cycle count, no salt-spray duration, no thermal-shock cycle count on the series page or in the specification tables reviewed here. So the KR2504’s eleven tests cannot be reconciled against the original; they can only be read on their own terms. 30 mating cycles and 16 hours of salt spray are the two figures to weigh against your application, because a low-profile connector is often used in a compact enclosure that is opened for service.
Soldering
PS-KR2504-01 §9 publishes one temperature profile, and the fact that it publishes only one is the point.
§9.0 — Wave soldering profile
- Peak temperature: 250℃ maximum, held for 3 to 5 seconds
- A 60 to 150 second band at a minimum of 217℃
- A 60 to 180 second total band
- Pre-heat: 150 to 180℃
The specification adds: “Please check the [soldering] condition by your own devices beforehand. Because the condition changes by the soldering devices, P.C. boards, and so on.”
Two notes, one of which is a documentation residue.
There is no SMT reflow profile in this document at all — which is correct, because the KR2504 has no SMT products and JST has none either. The neighbouring KONNRA specifications each carry two profiles (reflow for SMT, wave for DIP); this one carries one. That is the specification matching the product.
The section is titled “Wave soldering profile”, but the note inside it says “check the _reflow_ soldering condition”. That is wording left over from a specification that covers SMT products, and it should read “wave”. It does not change any value in the profile — the numbers are a wave profile — but it is the kind of loose end that makes a reviewer wonder whether the profile itself was adapted rather than written. Take the profile from the drawing, not from the caption.
And one practical note on the material split. The wafer base is documented as PA66 in both the specification §3.0 and the component pages — a wave-solder material, consistent with a through-hole-only product. There is no LCP or PA9T anywhere in this product’s documentation, and there should not be.
Materials and Plating
This is the section where the KR2504 documentation is the tidiest of the family, and it is worth saying so.
| Item | PS-KR2504-01 §3.0 |
KONNRA component / product pages | JST EH |
|---|---|---|---|
| Housing resin | PA66 UL94 V-0 | PA66 UL94 V-0 | PA, natural (white) |
| Wafer base (both DIP types) | PA66 UL94 V-0 | PA66 UL94 V-0 | PA, natural (white) |
| Terminal base metal | Phosphor bronze | (not stated on the page) | Phosphor bronze |
| Terminal plating | Tin plated over nickel | Tin over Nickel | Tin plated |
| Wafer contact | Brass, tin plated over nickel | Brass, Tin over Nickel | Brass, copper-undercoated, tin-plated |
| Solder tab | None | — | — |
| Colour | — | White | Natural (white), plus around 10 documented colours |
The resin callouts agree with each other here. Specification §3.0 says PA66 UL94 V-0 for the housing and for both wafer bases, and every component page says the same. That is a straight answer to the question “what polymer is this part made of” — and it is not something every specification in this range manages. Two of the neighbouring series publish two or three different resin callouts for one part; this one publishes one.
The base metal matches the original on the terminal. JST specifies phosphor bronze for the EH contact and the KR2504 specification says the same. That is the callout that governs contact spring behaviour, and it is the one that matters most.
The solder tab is correctly “None”. On a through-hole wafer the posts are the termination, so there is no separate solder tab — and the specification says so explicitly rather than leaving the row blank.
One difference worth noting on the wafer contact. JST’s EH post is brass with a copper undercoat and a tin plate; the KR2504’s is brass with tin over nickel. Both finish in tin, both are brass underneath, and the difference is the barrier layer — copper against nickel. Nickel is the harder barrier and the more usual choice for a tin finish today; copper is JST’s long-standing practice. The practical difference is small, and it is not a reliability claim in either direction. What matters is that neither is bare brass under tin, because that is the combination that grows a diffusion layer at temperature.
KONNRA KR2504 EH 2.5 housing, white PA66 UL94 V-0
And one gap worth raising at quotation rather than at drawing release. JST documents the EH housing and headers in around ten colours — the family’s colour list runs Black, Natural (White), Red, Blue, Yellow, Green, Orange, Brown, Purple, Pink and Gray, with additional entries on some header types. KONNRA documents White only. If colour coding is part of your assembly’s error-proofing — keeping a 4-way signal cable from being plugged into a 4-way power header — that is a conversation to have before the drawing is released, not after.
Documentation and Change Control
PS-KR2504-01 is a 7-page document, Edition A1, carrying the same date in its “Date Issued” and “Date Revised” fields — 2022/2/26 — and no revision history table. Its section 10.0 reads, in full:
“Any change or revision for the product specification will not be announced in advance. Please contact our sales representative for the latest information.”
The signature block reads “Written: Arvin · Checked: / · Approved: Min xinhao”, with the checking field left empty.
Both drawings are graphics-only.
| Document | Size | Extractable text |
|---|---|---|
| KR2504 series drawing | 561 KB | 4 bytes |
| KR2504 package specification | 314 KB | 3 bytes |
PS-KR2504-01 specification |
299 KB | 7,908 bytes |
The series drawing and the package specification contain no machine-readable text at all — they are drawn, not typed. That means no dimension in either can be found by searching it, and neither can be diffed against an earlier revision by any automated means. For a footprint check, that is the whole difference between a five-second search and a drawing review.
Against that, here is what the original publishes for the EH:
- Downloadable per-part data for every housing and every header — JST’s product tables carry four download links per part number, the 3D and 2D formats JST publishes across its crimp range
- Crimp machine and applicator identifications (the machines AP-K2N and MKS-L, with applicators named per contact)
- A packaging specification with tape dimensions and quantities, stated as conforming to IEC 60286-2 / JIS C 0806 for tape packaging of components with unidirectional leads
- Handling precautions for terminals and connectors, referenced from the catalogue
- RoHS compliance stated on the catalogue
Two practical consequences.
Quote the revision, not just the series. Section 10.0’s wording is a statement that you will not be told when the document changes, which is common in this industry and is exactly the reason to pin what you designed to. If your qualification file cites the KR2504, cite PS-KR2504-01 Edition A1 and the section number, and ask for written confirmation that it is still current at the point you release.
Get the drawing; do not try to search it. The series drawing is graphics-only, and the supplier’s own pages disagree with each other on one figure (the contact resistance prose). For this product the specification is the document that bounds the performance, and the drawing is the document that settles a geometry question. Ask for both, for your circuit count and mounting type, and for the part-specific wafer drawing rather than only the series drawing.
DIP Only: Why This Product Has No SMT Option
| Through-hole (DIP) | Surface mount (SMT) | |
|---|---|---|
| KR2504 components | DIP straight 180° and DIP right-angle 90° | None |
| JST EH | Through-hole only | None |
| Solder profile in the specification | Wave only — 250℃ peak max for 3–5 seconds, 217℃ minimum for 60–150 seconds | No reflow profile published |
| Wafer base material | PA66 | — |
| Solder tab | None — the posts are the termination | — |
| Solder-resistance clause | §7.11, DIP type products, EIA-364-71B | No SMT row |
This is a match, and it is worth stating as one. In the two neighbouring 2.5mm cross-references, KONNRA offers SMT wafers where the original offers none, or fewer. Here the product line matches the original exactly: through-hole only, on both sides. For the EH that is the right answer — an 8.1mm low-profile part is chosen for a through-hole design, and a reflow-capable version would need a different resin and a different height.
Figure 1 — KONNRA KR2504 DIP straight 180 degree wafer, through-hole top entry
Figure 2 — KONNRA KR2504 DIP right-angle 90 degree wafer, through-hole side entry
What that means for a layout. A through-hole header needs a hole pattern and clearance behind the PCB. In a stacked assembly that clearance may not exist, and if it does not, the EH pattern is the wrong choice regardless of how well the electrical sheet matches — there is no SMT fallback in this family on either side. If a surface-mount 2.5mm wire-to-board connection is the requirement, the answer is the JST XH pattern and the KR2501, which does offer SMT — but note that the XH is 9.8mm assembled, 1.7mm taller than this family.
And check the PCB hole diameter. JST’s catalogue notes for the EH that the tolerance for the PC board hole pitch shall not accumulate, that hole dimensions differ depending on the type of PCB and the PCB drilling method, and that a larger hole diameter should be considered for PCBs made of hard material such as fibre glass cloth. None of that is in the KONNRA documentation, and it is the sort of guidance that saves a first-article failure.
The 2.5mm Class: Where the EH Sits
Because three connector families share a 2.5mm pitch, and two of them are KONNRA’s own 2.5mm cross-references, this table is the one to keep.
| Attribute | JST EH → KR2504 | JST XH → KR2501 | Yeonho 2.5 → KR2502 |
|---|---|---|---|
| Pitch | 2.5mm | 2.5mm | 2.50mm |
| Assembled height | 8.1mm | 9.8mm | not published |
| Current / voltage | 3A (AWG #22) / 250V | 3A (AWG #22) / 250V | 3A / 250V |
| Withstanding voltage | 800 VAC | 1,000 VAC | 1,000 VAC |
| Temperature range | −25℃ to +85℃ | −25℃ to +85℃ | −25℃ to +85℃ |
| Conductor size (original) | AWG #32 – #22 | AWG #30 – #22 | AWG #22 – #28 |
| Conductor size (KONNRA) | 22# – 24# | 22# – 28# | 22# – 28# |
| Insulation O.D. (original) | φ0.5 – φ1.9mm | φ0.9 – φ1.9mm | not published |
| Insulation O.D. (KONNRA) | 1.9mm Max | 1.2 – 1.8mm | 1.2 – 1.8mm |
| Circuits (original) | 2 to 15 | 1 to 16, and 20 | 2 to 15 / 16 |
| Circuits (KONNRA) | 2 to 16 | 2 to 16 | 2 to 20 |
| Mounting | Through-hole only | Through-hole and SMT | DIP and SMT |
| Terminal count (original) | 4 | 3 | 3 |
| Terminal count (KONNRA) | 2 | 1 | 1 |
Read the wire rows together, because they are the decision. Every one of the three originals accepts fine wire down to #28, #30 or #32, and every one of KONNRA’s three cross-references documents #24 as its lightest documented size — except the KR2501, which reaches #28. So if your harness is on fine wire, the KR2501 is the only one of the three that documents it, and even that one stops two sizes short of the EH.
And note what “800 VAC” means in context. It is the lowest withstanding voltage of the three 2.5mm families. That is not a weakness in the EH — it is the price of the 8.1mm height — but it does mean the EH/KR2504 pair is the one to choose when space is the constraint and the one to avoid when dielectric margin is.
Where the EH/KR2504 pair is the clear choice:
- The enclosure has clearance for 8.2mm but not 9.8mm
- The harness is built on AWG #22 or #24 and the design is settled
- A 250V-rated, 3A connection is required and 800V of withstand is ample — which it is for any low-voltage signal or control application
- The assembly needs a longer header post for easy mating, which is what JST’s Type A header provides
Where a different series is the answer:
- The harness is on #26, #28, #30 or #32 — ask us, and expect to move to the KR2501 or to a different outcome
- Surface mount is required — this family has none
- More than 16 circuits — move up in pitch
- The application needs 1,000V of dielectric withstand — that is the XH pattern
- Colour coding across several connectors is needed — the KR2504 is documented in white only
➡️ JST XH 2.5 Connector Complete Guide (KR2501) · Yeonho YH 2.5 Connector Complete Guide (KR2502) · Explore the full 2.5mm pitch range · JST connector types guide
Applications Where the EH Pattern Is Used
The EH’s combination — 8.1mm height, 3A, 250V, and wire down to AWG #32 — puts it in a specific place in a design: the connector you choose when the board is thin and the wire is fine.
| Application | Why the EH pattern fits |
|---|---|
| Compact home appliances | Control board to module wiring where the housing height is set by the enclosure, not the connector |
| Small consumer electronics | High-density internal wiring where 8.1mm clears a case wall that 9.8mm would not |
| LED lighting and drivers | Multi-way low-voltage distribution in a slim extrusion |
| Battery and balance leads | Fine-gauge connections to cells and protection boards, where AWG #26–#32 is normal |
| Instrumentation and metering | Dense internal harnesses in a shallow DIN enclosure |
| Security and access control | Sensor and reader wiring at low voltage in a compact housing |
| Portable and handheld devices | Where the harness has to pass a confined internal route |
The honest limits are the height you do not have, the wire you do have, and the current. This family exists to be short. 3A per contact is the ceiling, and above that the answer is a larger pitch rather than a different connector at 2.5mm. And the wire is the other limit — at a documented 22# to 24#, the KR2504 covers the heavy end of the EH’s range and none of its fine end.
Cable assembly options
KONNRA builds cable assemblies on the KR2504 system in the standard harness configurations:
| Cable type | Description | Typical use |
|---|---|---|
| Single-headed | Housing on one end, bare wire leads on the other | Pigtail to a wafer, panel wiring |
| Same-side-head | Housing on both ends, same orientation | Board-to-board extension, same-direction routing |
| Reverse-side-head | Housing on both ends, reversed orientation | Board-to-board extension, reversed routing |
| Adapter cables | KR2504 on one end, another series on the other — to JST XH/PH, to Yeonho 2.5, to 2.54mm DuPont | Interfacing this pattern to a board laid out for another 2.5mm or 2.0mm family |
Adapter and transition cables matter more at this pitch than at any other, because three families share 2.50mm and none of them mate. EH to XH, EH to Yeonho 2.5, XH to Yeonho 2.5 — every one of those combinations is a harness to order rather than a substitution, and every one of them looks like a match on a datasheet.
Connector lead time is typically 2–3 weeks; wiring harness lead time is typically 3–4 weeks.
➡️ Explore KONNRA wiring harness capabilities
Sourcing: What Procurement Teams Ask
Engineering decides that a connector will work. Procurement decides whether the supply chain around it is safe.
“Our drawing says EHR-6 or SEH-001T. Can you supply it?” Yes — send the full JST part number and we will map it to the KR2504 for your circuit count and mounting type, and tell you in writing what differs. The two things that will differ most often are the wire window and the terminal count, because JST splits the EH across four terminals and the KR2504 documents two.
“Can you be a second source without changing our design?” On the electrical sheet, yes — and this is the strongest case of the three 2.5mm cross-references: the 800V withstand matches on both our documents, the 3A is referenced to AWG #22, the voltage, insulation resistance, DIP-only mounting and 8.1mm height all carry across. The wire window is the caveat, and it is a real one: we document 22# to 24# against JST’s #32 to #22. Send us the wire and we will answer it in writing rather than by inference.
“What are your lead times?” Connector production lead time is typically 2–3 weeks; wiring harness lead time is typically 3–4 weeks. Key materials are prestocked to shorten cycles.
“How long for samples?” Complete connector set samples can be delivered within 45 days.
“What qualifications do you hold?” KONNRA holds ISO9001, ISO14001, IATF16949, ISO45001:2018 and ISO13485 among its quality systems, together with UL product and operational safety certification — the KR2504 components carry UL file E482542. Note that JST lists CSA, TÜV and UL for the EH. If a customer specification names CSA or TÜV as a requirement, raise it at enquiry stage — it is a document request rather than a redesign, but it has to be asked for.
“Does the header take an IDC connector?” For the JST EH, yes — JST documents the EH header as compatible with an IDC-style connector and with the HR crimp connector, so one EH footprint can carry crimp or insulation-displacement termination. KONNRA does not document an IDC or HR equivalent for the KR2504. If your design depends on that interchangeability, say so specifically; it is the kind of feature that does not show up in a specification table.
“Are you a manufacturer or a trader?” A manufacturer. Dongguan Konnra Electronics Co., Ltd., founded 2004, with in-house mould design, injection moulding, stamping, assembly and inspection — which is why the connector and the cable assembly can come from one quality system.
How to Get a Cross-Reference Check on Your Part Number
Most 2.5mm sourcing enquiries stall on the same thing: the buyer is not sure what information the supplier needs, so the enquiry never gets sent. Here is the complete list.
Send us:
- The full JST part number, if you have it —
EHR-6,B6B-EH-A,S6B-EH,B6B-EH-TV4, or a terminal (SEH-001T-P0.6,SEH-001T-P0.6L,SEH-002T-P0.6L,SEH-003T-P0.6L). Quote the whole string, including the suffix — and if your terminal ends in L, say so, because JST documents a different crimp height for the low-insertion-force contact - Circuit count and row configuration
- Mounting type and entry direction — top entry (straight) or side entry (right-angle). There is no SMT option in this family
- Wire specification — AWG size and insulation outside diameter measured, because the KR2504 publishes no lower insulation bound and the value has to come from you
- Application and annual volume, so configuration, tooling and packaging can be matched
- A drawing or a photograph, if the part number is unreadable. At 2.5mm a photograph next to a ruler does not separate this family from JST XH or Yeonho 2.5 — all three are 2.50mm and none of them mate
- Any qualification requirements — automotive, medical, CSA, TÜV, or specific test standards
- Whether you need IDC or HR termination — if the answer is yes, we need to know at enquiry stage
What you get back: a mapped KONNRA part number with the relevant product and engineering drawings, a specification comparison against your original part including the wire and insulation windows, a statement of what the original publishes that we do not so you know which features cannot be validated by comparison, and a sample and quote plan.
Engineer’s Pre-Release Checklist
Run this before you release a drawing for a JST EH pattern connector.
- Wire size confirmed against the 22# to 24# window. If the harness is on #26, #28, #30 or #32, stop and ask — four of the six sizes JST accepts are not documented on the KR2504.
- Insulation outside diameter measured, not assumed. One end of the published window is missing: the KR2504 states 1.9mm Max with no lower bound, against JST’s φ0.5mm to φ1.9mm.
- 22 AWG wire at the top of its insulation range checked against the crimp table. The insulation crimp height band tops out at exactly the 1.9mm ceiling.
- Contact resistance budgeted at 20mΩ, not 10mΩ. The “below 10mΩ” figure in the product-page prose has no specification behind it.
- Terminal part number resolved. The KR2504 documents two terminals against one wire window; ask which one is quoted for your wire.
- Low-insertion-force terminal checked for the vibration caveat if you are substituting for a JST
…Lcontact — JST documents that type as less resistant to vibration with a different crimp height. - Temperature requirement checked. Above +85℃, ask for the heat-ageing evidence rather than inheriting the documented −40℃ to +105℃.
- Withstanding voltage confirmed as sufficient: 800V AC for one minute, on both the original’s and the KR2504’s documents.
- Height checked as 8.1mm assembled, and the enclosure clearance confirmed against it.
- Mounting confirmed as through-hole. There is no SMT fallback in this family on either side; check the far side of the board for clearance.
- PCB hole diameter and pitch tolerance checked — JST notes that hole dimensions vary with board material and drilling method, and that hard materials such as fibre glass cloth need a larger hole.
- Circuit count checked at both ends. No 1-circuit exists; the KR2504 documents 16 against the original’s 15, and our own force table carries 16.
- Stripping length set to 1.9–2.7mm — longer than the neighbouring 2.5mm series, so a setup sheet carried over from another series will be wrong.
- Crimp applicator data requested with the quote if you crimp in house.
- IDC or HR interchangeability confirmed if the design depends on it — JST documents it, KONNRA does not.
- Colour coding requirements raised at quotation — the KR2504 is documented in white.
- Approach to the retention clause in section 6.4 agreed with the supplier, so the test you write matches the test that will be run.
- The drawing requested separately from the specification. The series drawing and the package specification are graphics-only and contain no searchable text.
➡️ Send us your drawing. We will review it against the KR2504 specification and come back with any mismatch we find — before you commit tooling. Submit a drawing for review
Frequently Asked Questions
What is a JST EH 2.5 connector?
A 2.5mm pitch, single-row, low-profile wire-to-board crimp connector with a friction lock, a 3.8mm body thickness and an 8.1mm assembled height. JST rates it 3A AC/DC with AWG #22 wire at 250V AC/DC, with 1,000MΩ minimum insulation resistance and a 800 VAC for one minute withstanding voltage. It accepts AWG #32 to #22 (0.032–0.33mm²) with insulation O.D. from φ0.5mm to φ1.9mm, is through-hole only, and is catalogued in 2 to 15 circuits.
What is the KONNRA equivalent of the JST EH 2.5 connector?
The KONNRA KR2504 series — a 2.50mm pitch single-row wire-to-board connector offered as DIP straight 180° and DIP right-angle 90° wafers, plus a housing and two crimp terminals. Housing H25040***0101A, terminals T25040PT0101B and T25040PT0102B, wafers C2504VD***01T0101PA and C2504RD***01T0101PA. All four component pages carry Compatible: EH Series.
What is the difference between the JST EH and the JST XH?
Both are 2.5mm pitch, single row, friction lock, 3A and 250V AC/DC, −25℃ to +85℃, and 1,000MΩ. The differences that decide it: assembled height — 8.1mm for the EH against 9.8mm for the XH; withstanding voltage — 800 VAC against 1,000 VAC; wire range — the EH reaches AWG #32 and φ0.5mm insulation, where the XH stops at #30 and φ0.9mm; circuits — EH 2 to 15 against XH 1 to 16 and 20; and mounting — the EH is through-hole only, where the XH also offers SMT at 3, 4 and 6 circuits. They do not mate and do not share a footprint. The KONNRA equivalents are KR2504 for the EH and KR2501 for the XH.
What wire gauge does the JST EH accept?
AWG #32, #30, #28, #26, #24 and #22 — six sizes, from 0.032mm² to 0.33mm² — with insulation outside diameter from φ0.5mm to φ1.9mm. JST splits the range across four terminals and publishes the window for each in that terminal’s own drawing. The KR2504 documents AWG 22# to 24# — two of the six sizes — with insulation stated as 1.9mm Max and no lower bound. If your harness is on #26, #28, #30 or #32, ask before you design.
What is the contact resistance of the JST EH?
JST does not publish a contact-resistance figure on the EH series page — its catalogue gives a separate initial limit and a limit after environmental tests. The KR2504 specification §5.1 states 20 milliohms Max, measured by dry circuit at 20mV maximum and 100mA maximum, based on EIA-364-23C, and every KR2504 component page states the same. One place disagrees with all of them: the KR2504 product page’s Advantages prose says “contact resistance below 10mΩ at the initial stage”. That figure has no test clause behind it; use 20mΩ, and ask for lot data if 10mΩ against 20mΩ decides your design.
What is the withstanding voltage of the JST EH?
800 VAC applied for one minute, with no breakdown or flashover. That is lower than the JST XH’s 1,000 VAC on the same pitch, and it is the price of the 8.1mm low-profile body. The KONNRA KR2504 matches it on both its documents: specification §5.3 requires 800V AC for 1 minute between adjacent terminals or to ground (EIA-364-20A), and the product page states 800V AC/ minute.
Does the JST EH have a surface-mount version?
No — the EH is through-hole only, and the KONNRA KR2504 offers DIP straight 180° and DIP right-angle 90° wafers only. That is a deliberate match rather than an omission: an 8.1mm low-profile part is chosen for a through-hole design, and the KR2504 specification carries a wave soldering profile only, with its §7.11 solder-resistance clause written for DIP type products (EIA-364-71B). If you need a surface-mount 2.5mm wire-to-board connection, the answer is the JST XH pattern and the KR2501, which is 9.8mm assembled.
How many circuits does the JST EH come in?
2 to 15. JST’s housing range runs EHR-2 through EHR-15, and the header family runs from B2B-EH-A to B15B-EH-A. There is no 1-circuit EH. The KONNRA KR2504 documents 2 to 16 — one position beyond the original — and that figure is consistent across the product page, all four component pages and the specification’s own force table.
What is the assembled height of the JST EH?
8.1mm, with the top-entry type 3.8mm thick. JST describes the family as low profile and space-saving, and it is 1.7mm shorter than the JST XH’s 9.8mm on the same pitch. KONNRA documents 8.1mm after mounting for the KR2504, so enclosure clearance does not change when you cross-reference.
What is the operating temperature range of the JST EH?
−25℃ to +85℃, which JST states as including the temperature rise under applied electrical current. KONNRA documents the KR2504 at −40℃ to +105℃ — 20℃ wider at the hot end and 15℃ wider at the cold end. The supporting tests are in the specification: heat resistance at 105±2℃ for 96 hours (§7.5), cold resistance at −40±2℃ for 96 hours (§7.6), and thermal shock over 5 cycles between −40℃ and +105℃ (§7.8). Above +85℃, ask for the heat-ageing report rather than inheriting the range.
Which terminal do I need — SEH-001T-P0.6 or one of the L types?
JST publishes four EH terminals: SEH-001T-P0.6 (the standard contact) and SEH-001T-P0.6L, SEH-002T-P0.6L, SEH-003T-P0.6L (low-insertion-force types covering different wire segments). JST’s own note states that the low-insertion-force contact is less resistant to vibration and that its crimp height is different from the standard EH contact — so the applicator setting changes with the terminal. Do not specify an L type by default because it mates more easily. The KR2504 documents two terminals, T25040PT0101B and T25040PT0102B, against one wire window; ask which is quoted for your wire.
Can the JST EH header take an IDC connector?
Yes. JST documents the EH header as compatible with an IDC-style connector and with the HR crimp connector, and lists “Compatible IDC connector available” and “Compatible crimp connector available” among the series’ connection variations. KONNRA does not document an IDC or HR equivalent for the KR2504, so if your design depends on that interchangeability, confirm it specifically at enquiry.
What standards does the JST EH meet?
JST lists CSA, TÜV and UL for the EH, and states RoHS compliance. KONNRA’s KR2504 components carry UL file E482542. If a customer specification names CSA or TÜV, raise it at enquiry stage.
How do I identify which 2.5mm connector I actually have?
Measure the centre-to-centre distance between adjacent contacts — 2.50mm is this class, 2.54mm is Molex KK or “DuPont”, 2.00mm is JST PH, 1.5mm is ZH. Then measure the assembled height, which is the fastest separator inside this pitch: around 8.1mm points at the EH pattern, around 9.8mm at the XH pattern. Measure the housing across the contact field, which for a 2.50mm single row is (N − 1) × 2.5mm, so a 4-way measures 7.5mm. Because EH, XH and Yeonho 2.5 all sit at 2.50mm with the same 3A/250V headline ratings, the pitch alone does not separate them — the part number and the height do. If the part number is unreadable, photograph the connector next to a ruler and send it to us.
How long does it take to get samples?
KONNRA can deliver complete connector set samples within 45 days. Connector production lead time is typically 2–3 weeks and wiring harness lead time typically 3–4 weeks.
Start Your Cross-Reference Check
KONNRA supplies the KR2504 series as individual components or as complete pre-crimped cable assemblies, in both DIP configurations, with customisation available for application-specific requirements.
- Request a quote — KR2504 pricing, MOQ and configuration options for your circuit count and mounting type
- Request a sample — complete connector set samples within 45 days
- Request cross-reference verification — confirm KR2504-to-JST-EH equivalence against your specific part number, including the wire and insulation windows, which is where this cross-reference differs
- Request a wire-window answer — send the AWG and the measured insulation O.D. and we will confirm in writing whether it is supplied
- Request the performance evidence — contact-resistance lot data against the §5.1 condition, and pull tests
- Request drawings — series engineering drawing, the part-specific wafer drawings, the product specification and the package specification
- Request the crimp applicator data — if you crimp in house
- Request a vendor qualification pack — certificates, test capability summary and quality documentation
- Request adapter and transition cable assemblies — EH to XH, EH to Yeonho 2.5, to JST PH, to 2.54mm DuPont
- Submit a drawing for review — we will flag any specification mismatch before you commit tooling
Contact KONNRA Electronics
- Phone: (86)-769-85449875
- Email: info@konnra.com
- Address: No.6 Nanchang South Road, Chijiao, Wangniudun, Dongguan, Guangdong, China
- Contact us
Sources and method. Every figure in this guide is taken from a manufacturer document, and where two manufacturers — or two documents from the same manufacturer — disagree, the difference is stated rather than averaged. JST EH figures are taken from JST’s published EH series page and the published EH catalogue: pitch (2.5mm), circuit counts (2 to 15), current rating (3A AC/DC with AWG #22), voltage rating (250V AC/DC), temperature range (−25℃ to +85℃, stated as including the temperature rise under applied electrical current), insulation resistance (1,000MΩ min.), withstanding voltage (800 VAC for one minute, no breakdown or flashover), conductor size (AWG #32, #30, #28, #26, #24 and #22; 0.032–0.33mm²), insulation O.D. (φ0.5–φ1.9mm), the top-entry body thickness of 3.8mm and installed height of 8.1mm, the through-hole-only PC board mounting, the friction lock, the single-row array, the top-entry and side-entry mating directions, the CSA / TÜV / UL standards listing, radial taping, the “Compatible IDC connector available” and “Compatible crimp connector available” (HR connector) notes, the catalogue’s “Low profile, space-saving design” / “High reliability contacts” / “Shaped top to prevent misinsertion” / “Excellent workability in the wire harness assembly and mating process” wording, the “Crimp Style and Mating Style” family description, the two-limit contact-resistance structure (initial value, and after environmental tests), the applicable PC board thickness row, RoHS compliance, the Type A header’s longer post note, the SEH-001T-P0.6L low-insertion-force note (less resistant to vibration; different crimp height), the crimp machines AP-K2N and MKS-L with applicators named per contact, the housing and post material and finish callouts (PA natural white; post brass, copper undercoated, tin plated), the documented colour lists, the packaging specification’s conformance to IEC 60286-2 / JIS C 0806, and the part-number families: terminals SEH-001T-P0.6, SEH-001T-P0.6L, SEH-002T-P0.6L, SEH-003T-P0.6L; housings EHR-2 to EHR-15; headers B2B-EH-A to B15B-EH-A, S2B-EH to S15B-EH, B2B-EH-TS to B8B-EH-TS, and B3B-EH-TV4 to B8B-EH-TV4. JST XH figures in the EH-versus-XH comparison are from JST’s published XH series page and XH catalogue, as set out in full in the JST XH 2.5 guide linked above. Yeonho 2.5 figures in the 2.5mm class table are from Yeonho Electronics’ own specification sheets, as set out in the Yeonho YH 2.5 guide linked above. KONNRA KR2504 figures are from PS-KR2504-01 (Edition A1, dated 2022/2/26, 7 pages) sections 2.0, 3.0, 4.0, 5.1–5.3, 6.1–6.5, 7.1–7.11, 8.0, 9.0 and 10.0, and from the KR2504 product page and the four KR2504 component pages. Three limitations are stated openly. First, JST does not publish a series-level environmental test programme, insertion-and-withdrawal force table or contact-resistance value for the EH, so the KR2504’s figures in those areas are checked against themselves — for example, all 45 entries of the section 8.0 force table reproduce from three arithmetic expressions — rather than reconciled against the original. Second, JST’s per-terminal conductor and insulation windows are published in each terminal’s own drawing, and the individual terminal drawings sit behind a registration wall on jst-mfg.com, so the terminal-level split of the AWG #32–#22 and φ0.5–φ1.9mm windows is not reproduced here as figures; this edition works from JST’s series-level window. Third, the KR2504’s wire window and the lower insulation bound are the two places where this cross-reference is narrower or less specified than the original, and both are stated in the body of the guide rather than left to the tables. If a figure here disagrees with the current revision of a manufacturer document, the manufacturer document is right.
