Hammond PWDM13037 Collins KW-1 Modulation Transformer, 500VA
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224-955-1644Key Features
- Modulation transformer for Collins KW-1 and Johnson Desk KW
- PP 810 modulators to parallel 4-250A's
- Primary 2400VCT (18000 ohms CT) and 1800VCT (11600 ohms CT)
- Secondary 1768 VAC at 283 mA CCS, 6250 ohms RFPA
- 500VA total output
- EI-175 EE-stack core, approx. 35 lbs
- Made in Canada; REACH and RoHS compliant
The PWDM13037 is a modulation transformer for the Collins KW-1, and the Dahl ordering table also lists it for the Johnson Desk Kilowatt. In both cases it couples push-pull 810 modulators to parallel 4-250A RF amplifiers, making it a key part for anyone restoring one of these kilowatt-class AM transmitters.
The primary is 1800/2400 VCT at 18000/11600 ohms plate-to-plate. The drawing details the taps: terminals 1 to 5 give 18000 ohms CT at 2400VCT, terminals 2 to 4 give 11600 ohms CT at 1800VCT, and terminal 3 is the center tap. The secondary, terminals 6 to 7, is 1768 VAC at 283 mA CCS into a 6250 ohm RFPA load. Total output is rated 500VA.
The unit uses an EI-175 EE-stack core. The Collins KW-1 listing gives Style 10 and the Johnson Desk KW listing gives Style 8. The approximate weight is 35 lbs, with a shipping weight of 35 lbs (15.88 kg). The drawing label marks it Made in Canada. It is REACH and RoHS compliant, with UPC 623980240275 and UNSPSC 39121301.
Dahl magnetics are usually built to order one at a time; confirm availability by phone or e-mail. Stock units can usually be shipped next business day.
Ideal For
- Collins KW-1 transmitter restoration
- Johnson Desk Kilowatt modulator repair
- High-level plate modulation of 4-250A finals
- Vintage AM broadcast-style amateur stations
Overview
| Series | Peter W Dahl Transformers (PWDAHL Series) |
| Part Number | PWDM13037 |
| Product Type | Modulation Transformer |
| Series Focus | Magnetics for Amateur Radio Products |
| Drawing Title | COLLINS/JOHNSON DESK KILOWATT MODULATION TRANSFORMER |
| Country Of Origin | Made in Canada (per drawing label) |
| Short Description | COLLINS KW-1 MODULATION TRANS |
| Ordering Table Description (Collins) | COLLINS KW-1 MODULATION XFMR PP 810 MODULATORS TO PARALLEL 4-250A'S |
| Ordering Table Description (Johnson) | JOHNSON DESK KW MOD PP 810 MODULATORS TO PARALLEL 4-250A'S |
Electrical
| Primary | 1800/2400 VCT, 18000/11600 OHMS PP |
| Total Output | 500VA |
| Primary Ter 3 | Center Tap |
| Modulator / RF Tubes | PP 810 modulators to parallel 4-250A's |
| Primary Ter 1 To Ter 5 | 18000 OHMS CT, 2400VCT |
| Primary Ter 2 To Ter 4 | 11600 OHMS CT, 1800VCT |
| Secondary (Ter 6 To Ter 7) | 1768 VAC @ 283 MA CCS (6250 OHMS RFPA) |
Identifiers
| UPC | 623980240275 |
| UNSPSC | 39121301 |
Packaging & Shipping
| Shipping Weight | 35 lbs (15.88 kg) |
| Approx. Weight (Ordering Table) | 35 lbs |
Construction & Finish
| Core | EI-175 EE-STACK |
| Style (Collins KW-1 Listing) | 10 |
| Style (Johnson Desk KW Listing) | 8 |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
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Frequently Asked Questions
Does PWDM13037 fit the Johnson Desk Kilowatt as well as the Collins KW-1?▾
Yes. The ordering table lists PWDM13037 for both the Collins KW-1 and the Johnson Desk KW, each as PP 810 modulators to parallel 4-250A's.
What primary impedances are available?▾
18000 ohms CT at 2400VCT (terminals 1 to 5) and 11600 ohms CT at 1800VCT (terminals 2 to 4), with terminal 3 as the center tap.
What is the secondary rating?▾
1768 VAC at 283 mA CCS into 6250 ohms RFPA, terminals 6 to 7, with 500VA total output.
How heavy is it?▾
About 35 lbs; shipping weight 35 lbs (15.88 kg).
Is this transformer kept in stock?▾
The series notes that these transformers are usually built to order one at a time, and that stock units can usually be shipped next business day. Confirming availability by phone or e-mail is recommended.
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