[Amps] Henry hum on transmitted signal

[Steven Katz]

What does the HV indicate in standby, transmit (no drive, just idling) and key-down at full power?

This is key to determining if it's actually a power supply problem.

-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of r-emails at n5ot.com
Sent: Sunday, September 3, 2023 3:38 PM
To: amps at contesting.com
Subject: [Amps] Henry hum on transmitted signal

I see there was no content in my messages the first time around.  I'm not sure what the problem is, but the workaround is to use a different email program.  Here's what I wrote:
- - - - - - - - - - - - - - - - -
Greetings,

I have a Henry 2K-4A console, and when I use it on the air, a few people have told me my signal is not pure.  One described AC hum on both sides of my signal frequency.  Another friend said I had "sidecars."

My conclusion is I need to replace the big (oil-filled) capacitor in the power supply.  I have a friend with an older Henry, I think it was a
2K-3 console, who had a similar-sounding issue, and he says he changed his big capacitor in the power supply, but it didn't really fix the problem.  He sold the amp and I got the capacitor that didn't fix his problem.

Two questions:

1. Am I looking in the right direction or the wrong direction?  Any other PS due diligence I need to do?  Any Henry 2K-4A-specific anecdotes in the brain trust?

2. My Henry has the factory capacitor from the 1970s, which is 20uf @
5000 volts.  The replacement I have says "replacement for Henry capacitor" but the values are 16uf @ 7500 volts.  It's close to the same physical size but not exactly the same size.  It has a 2019 date stamp.

Guidance appreciated.

73 - Mark N5OT
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