A KOA RK73B to Walsin Technology (Walsin) cross-reference breaks at the 2 W 2512 size. Walsin’s general purpose 2 W rows stop at 10 ohm, 140 parts. Above 10 ohm only the High Power series reaches 2 W, with 690 plain rows. None of the 6,249 Walsin 2 W 2512 rows is on our shelf.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin chip resistor export of 234,815 rows, 234,401 of them distinct part numbers once embedded spaces are removed, and a stock list dated 23 September 2026. This post is for a procurement or design engineer at a Thai electronics or appliance maker whose bill of materials names a KOA RK73B resistor. Every Walsin part number is real and every count is ours. Statements from the press and from KOA’s datasheet name their source and the day we read it, 23 October 2026.
What do Thailand’s August export figures tell a resistor buyer?
That industrial demand is strong. The Nation Thailand reported on 25 September 2026 that exports were 34.62 billion US dollars in August 2026, up 24.3% on a year earlier and the fastest growth in 56 months, with industrial exports up 27.1% for a 29th straight month of growth. The same report puts January to August exports at 266.15 billion US dollars, up 18.9%, and names computers and components and integrated circuits among the strong performers.
We draw one conclusion, and it is ours: a buyer on a line shipping this much is more likely to be asked to hold a second source on commodity resistors, and a cross-reference is where that starts. We have no information on any maker’s KOA volumes and say nothing about KOA’s supply.
How do you read a KOA RK73B part number, field by field?
In six fields. KOA’s RK73B datasheet, whose footer carries a revision date of 26 October 2025, prints the example RK73B2BTTD102J: series, a size code, a termination letter, a taping code, a resistance code of two significant figures plus a multiplier, and a tolerance letter. The datasheet’s own field list orders the items differently from its example, so we followed the example.
| KOA field | In RK73B2BTTD102J |
Walsin field in WR12X102 JTL |
Match / mismatch |
|---|---|---|---|
| Series | RK73B |
WR |
Match in function (general purpose thick film) |
| Size code | 2B (1206) |
12 |
Match on body; the code differs |
| Termination | T (Sn) |
T (Sn base, lead free) |
Match |
| Taping code | TD (4 mm pitch punched paper) |
L |
Mismatch or unknown: the export prints 7 inch reel taping with no pitch |
| Resistance | 102 (1 kohm) |
102 with a trailing blank |
Match on value; Walsin pads a plus or minus 5% number with a blank |
| Tolerance | J (plus or minus 5%) |
J |
Match |
The datasheet lists tolerance letters G (plus or minus 2%) and J (plus or minus 5%) for RK73B. We counted 1,249 general purpose rows in 1206 in the Walsin export, and the plus or minus 5% form WR12X102 JTL is one of them, with the blank in position 9. That blank is why a pasted KOA value fails to find the Walsin part, and our post on why Walsin part numbers do not paste into your BOM explains it.
Which Walsin code does each KOA size code point to?
Each KOA code has a Walsin partner, but none shares the characters. KOA’s datasheet lists 10 type codes (1F, 1H, 1E, 1J, 2A, 2B, 2E, W2H, W3A and W3A2) over 9 bodies, and none of the 10 equals the two-digit size code Walsin puts in its number. We checked the Walsin side against the Size column of the export.
| KOA code | Body | Walsin size code | Walsin general purpose rows in the export | Match / mismatch |
|---|---|---|---|---|
1F |
01005 | 01 |
755 | Match after translation |
1H |
0201 | 02 |
5,814 | Match after translation |
1E |
0402 | 04 |
969 | Match after translation |
1J |
0603 | 06 |
969 | Match after translation |
2A |
0805 | 08 |
969 | Match after translation |
2B |
1206 | 12 |
1,249 | Match after translation |
2E |
1210 | 10 |
855 | Match after translation. Trap: Walsin 10 is 1210 and Walsin 20 is 2010 |
W2H |
2010 | 20 |
1,249 | Match after translation |
W3A |
2512, 1 W | 25 |
1,249 | Match after translation |
W3A2 |
2512, 2 W | 25 |
1,249 | Match on body; mismatch on power unless a 2 W row is chosen |
Our post on imperial and metric case sizes covers the translation, and the last row is the one this post follows.
Where does the Walsin 2 W 2512 row stop, and what takes over?
At 10 ohm. KOA’s sheet rates the W3A2 at 2.0 W against 1.0 W for the W3A, with a rated terminal-part temperature of 95 degrees Celsius for the W3A2. In the Walsin export, the general purpose series has 140 rows rated 2 W in 2512, out of 1,249, and all 140 fall between 1.0 and 10.0 ohm.
Above 10 ohm the general purpose 2512 is rated 1 W. The 2 W rating comes back in a different series: we counted 4,140 rows in 2512 rated 2 W above 10 ohm, in four series, of which 690 are the plain, commercial High Power series and 3,450 carry an automotive or anti-sulfuration label. The 2 W tier of the general purpose line is a small corner of that size, and a KOA W3A2 line at, say, 47 ohm cannot be crossed inside it.
Which Walsin parts answer a KOA W3A2 brief at 4.7 and 47 ohm?
At 4.7 ohm, two general purpose parts; at 47 ohm, none. A 4.7 ohm, plus or minus 5%, 2512 brief returns 19 rows once the current-sense series are set aside, and 7 of them are rated 2 W, among them WR25F4R7 JTL JN in the general purpose series, WF25P4R7 JTL in High Power and MF25E4R7 JTL in the automotive triple power surge series. At 47 ohm the general purpose 2 W row does not exist.
| Walsin part | Series, rating | Grade | Match / mismatch with a KOA W3A2 line | Your incumbent |
|---|---|---|---|---|
WR25F4R7 JTL JN |
General purpose, 2 W, up to plus or minus 100 ppm | Commercial | Match on size, value (4.7 ohm), tolerance and 2 W | A KOA W3A2 line is not in the export |
WR25F4R7 JTL |
General purpose, 1 W | Commercial | Mismatch: half the power, same stem as the 2 W part | |
WF25P470 JTL |
High Power, 2 W, up to plus or minus 100 ppm | Commercial | Match on size, tolerance and 2 W at 47 ohm. Mismatch: different series | |
WR25X470 JTL |
General purpose, 1 W | Commercial | Mismatch: half the power at 47 ohm | |
MF25E4R7 JTL |
Triple power surge, 2 W, up to plus or minus 200 ppm | Automotive | Mismatch: automotive series and a looser TCR bound |
The WR25F4R7 JTL and WR25F4R7 JTL JN pair differ only by the JN tail, and the JN is what carries the 2 W rating. A pasted number that drops the tail becomes a 1 W part. Our post on chip resistor power rating by case size covers the standard figures.
Our stock list as at 23 September 2026 holds 2 stocked general purpose 2512 lines, WR25X3301FTL and WR25X330 JTL, and both are 1 W. None of the 6,249 Walsin 2512 rows rated 2 W is on the list. The ready stock list is a dated snapshot and is never live-synced.
What will we not tell you about a KOA part?
Whether it is available, changing or constrained. We hold no KOA affected-part list, we make no statement about any KOA part number, and we hold no price or lead-time information on it. KOA and Walsin word qualification differently, and Walsin’s MR sheet says compliant; ask for the qualification report for the exact part. Venatech makes no qualification claim of its own.
We hold no ISO 9001 or IATF 16949 certificate. Our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation. We give no legal, customs or compliance advice; confirm with your compliance team.
How Venatech helps
Paste your KOA number into the free cross-reference tool, which decodes 18 manufacturers’ part numbers across 800,000+ crossable parts, and read the Walsin candidates with each field marked match or mismatch. Load a whole BOM, up to 500 part numbers or an Excel or CSV file, to run every line at once. The ready-stock list is a Hong Kong snapshot dated 23 September 2026, and our chip resistor range lists the families.
Worked example from our own export: the 2 W 2512 question above covers 6,249 rows rated 2 W in that size and none is on the shelf; the two stocked general purpose 2512 lines are 1 W. Walsin is the only line we are authorised for; Stackpole and Viking are lines we supply. We serve from Hong Kong in small lots, cross-reference your lines on request, and a quote is requested through the site.
The short version
For a Thai buyer holding a KOA RK73B number, the six fields map onto Walsin’s, the size codes need translating, and the 2 W 2512 line is the exception: the general purpose 2 W row stops at 10 ohm, and above it the High Power series is the commercial answer.
Send us one W3A2 line from your BOM, or paste it into the cross-reference tool, and we will return the Walsin candidates with power and series differences stated. Qualification stays with you; which KOA size do you run most?
Sources
Read 23 October 2026.
- The Nation Thailand, “Thai exports surge 24.3% in August as AI demand lifts electronics”, 25 September 2026: https://www.nationthailand.com/business/economy/40071468
- KOA Speer Electronics, “RK73B” general purpose thick film chip resistor datasheet, footer revision 26 October 2025: https://www.koaspeer.com/pdfs/RK73B.pdf
Frequently asked questions
How do I read a KOA RK73B part number?
RK73B2BTTD102J is the series RK73B, size 2B (1206), termination T, taping code TD, resistance 102 (1 kohm) and tolerance J (plus or minus 5%), as in KOA’s datasheet footer-dated 26 October 2025. G is plus or minus 2%. Confirm against the KOA datasheet.
Does Walsin have a 2 W 2512 chip resistor that crosses a KOA W3A2?
Yes, but the general purpose 2 W row covers only 1.0 to 10.0 ohm, 140 parts. Above 10 ohm the commercial answer is the High Power series, 690 plain rows rated 2 W in 2512. Confirm both datasheets and qualify in your own circuit.
Why does a pasted Walsin 5 percent part number fail?
Walsin pads the resistance field of a plus or minus 5% number with a trailing blank, so WR12X102 JTL has a space in position 9 and a pasted version without it finds nothing. Our cross-reference tool handles the spacing, and our post on pasting Walsin numbers explains the rule.
Is a 2 W Walsin 2512 resistor on your shelf?
No. None of the 6,249 Walsin 2512 rows rated 2 W appears on our stock list as at 23 September 2026. Two stocked general purpose 2512 lines are both 1 W. The list is a dated snapshot, not live stock, so ask us for the current position.
Do you say anything about KOA availability or lead times?
No. We hold no KOA affected-part list and make no statement about any KOA part number. We hold no price or lead-time guarantee on any part. The qualification decision, and any approval of a substitute, stay with you and your compliance team.
How do I start a KOA cross-reference with Venatech?
Paste the KOA number into the free cross-reference tool, or upload a BOM of up to 500 lines. You see Walsin candidates with each field marked match or mismatch. Request a quote through the site; we serve from Hong Kong in small lots.