[Amps] Henry hum on transmitted signal

[Mark Bitterlich]

Steve Katz mentioned:"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."It is also key in determining if you're experiencing voltage drop at the wall outlet where the amp is plugged in. IMHO you need to somehow listen to your own signal, so as to listen to it with a pure carrier versus listening to it with modulation. Yes, a bad filter cap in the power supply can cause this, but so can a florescent light near the microphone wiring, or even a radio sitting directly on top of a 12 volt power supply. Dive bombing a problem like this can become expensive relying on others to reply to: "Can you hear it now?"  Beg/borrow/build another was to see (scope) or listen to your transmitted signal. This will eminate a lot of "possibilities", and give you a path forward, while learning in the process. De wa3jpy-------- Original message --------From: Steven Katz <stevek at jmr.com> Date: 9/3/23  4:47 PM  (GMT-05:00) To: r-emails at n5ot.com, amps at contesting.com Subject: Re: [Amps] Henry hum on transmitted signal 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.comSent: Sunday, September 3, 2023 3:38 PMTo: amps at contesting.comSubject: [Amps] Henry hum on transmitted signalI 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 a2K-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 N5OT