In Reply to: Does anyone know what the difference are between the Heathkit W4AM and the Heathkit W4B posted by steveaaa on November 10, 2004 at 15:39:49:
Electrical differences are very minor. W4B added a pair of 10K resistors between each side of the filament tap and ground, and has an on/off switch. Also the fuse was moved so that it just fuses the power transformer on the W4B, where on the W4A it also fused the AC outlet. I have schematics here for both, and a full manual for the W-4B version.There is also an AA-71 which is even a later version of the same basic design.
Reducing the bias just involves increasing the value of the 360 ohm resistor on the cathode bias.
A lot of W4's didn't make it thru their first 45 years, so I wouldn't hold my breath on 50 more. Then again, we may not be here to find out :)
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Follow Ups
- Re: Does anyone know what the difference are between the Heathkit W4AM and the Heathkit W4B - Gary Kaufman 11/10/0417:13:27 11/10/04 (4)
- From back then to eternity, ebay and a question... - j rodney 17:48:48 11/10/04 (3)
- Re: From back then to eternity, ebay and a question... - Gary Kaufman 08:05:25 11/11/04 (2)
- Big wax caps? - j rodney 12:21:25 11/11/04 (1)
- Re: Big wax caps? - Gary Kaufman 09:49:16 11/13/04 (0)