Evidently I didn't send my reply to the list.
1, I have used the Heathkit Shop rebuild kit with success and have to AC4s with them. Not hard to install.

2, I do not have the Hayseed Hamfest kit but have bought lots of other capacitors from Tom and am very satisfied.

3, I mentioned a third kit but couldn't remember details. Its at:


I have no experience with this but its gotten good reviews on the Drake lists. Also Harbach is a reputable firm.

I will reiterate the warning about the bias supply. If it fails the tubes burn up. They have become quite expensive.

Richard Knoppow
Los Angeles
----- Original Message ----- From: <choward...@aol.com>
To: <drakelist@zerobeat.net>
Sent: Thursday, May 29, 2014 6:36 PM
Subject: [Drakelist] TR-4 Audio Hum Question

Thanks to Gary and John for their response to my audio hum question. I plan to accomplish the easy one first; cleaning the pins on the AC-4 power
If that does not work, I will go to #2: re-cap the power supply. In fact, I may that in any case. But, I would like some advice. I am 74 years old and the only real electronic work I have done was to build a Viking Adventurer transmitter when I was 14. It worked the first time.
I have found 2 different products for the AC-4.
The first is from "Hayseed Hamfest". It is a kit that replaces all five
electrolytic capacitors with new ones. It is $72.00.
The second is from "The Heathkit Shop". The Drake AC-4R kit includes a new PCB that replaces the old Caps and diodes. Only the transformer and the bias adjusting pot from the old power supply are used. It also requires a
voltmeter capable of 1000 volts to be used in the testing.
My question is to anyone who has knowledge of these products and which
they recommend for someone with limited electronic skills.
As usual, Thanks for any help you folks can provide. You have helped in a couple of previous situations, which turned out just as you suggested.
Howard - N0KOE


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