[Amps] Starting up a NEW Henry amp

[Carl Braun]

I have some updates on the Henry amp(s) I picked up and thought some of you may find the results interesting.  Maybe some of you can help with some of the issues that remain.

I picked up Henry 3K Ultra head SN 65-171 and its mate, the SN 65-171 RF deck.  Along with those two pieces came an additional RF deck; Henry SN 65-104 that was still in the Henry crate.  I brought all three of these components back in my 2005 Honda pilot. Left Wisconsin on Sunday morning at 6 am then on to Prescott AZ and back home on weds at 3pm. Once home, I had two other guys help me up the steps with the 250# consoles to my ham shack where I would dig into the amps.

I did a visual inspection of the head and both RF decks.  The -171 RF deck had a damaged doorknob cap but looked ok other than that. Replaced 50pf doorknob.  Afterward,  I plugged the -171 head into the -171 RF console, put on my safety glasses and headphones in case there were any loud surprises. Fire extinguisher on standby.  I flipped the mains switch on the console and pushed the POWER button on...the amp jumped to life and a flurry of ceramic chunks started flying everywhere. Hmmmm.  I took the RF deck out of the console and found ceramic debris everywhere.  I found the culprit...it was toroid across the tube that was loose due to its damaged ceramic standoff insulator.  RF Parts came through on that and I was able to install the new ceramic standoff and resolder the toroid. All servo motors and tuning working well.

The only issues I have with this -171 RF console are:

  *   HV and Filament voltages are high.  Eimac says 5500V max at 6.3 on the filament.  Henry implies voltage on the plate at 3800 CW/4800V SSB or so and the filament voltage at 6.3.  Mine are at 5500V and 7.0V respectively. With 243VAC coming into the shack I will be re-tapping the plate transformer to 5000V and filament closer to 6.3v.
  *   When repaired, I put this amp on the air and noted a severe problem with the degradation of the incoming signal when the amp was ON.  With the amp idling, I can copy a strong, clear station and within seconds the signal begins to get scratchy and eventually gets so bad the signal is unreadable.  Eventually the band signals disappear on the scope.  A simple tap of a CW key brings everything back into clear reception for another 8-10 seconds before the signal degrades again.  This is happening on all bands.  Checked and cleaned input/output connections. Reseated tube as well as removed and inspected bird element connections.  Same problem.  It could be the crappy little guardian input relay Henry used to switch in the incoming RF? I have to pull the RF deck again and flip it over to see if I can pull and re-seat that relay. Suggestions?

After that exercise, I pulled the -104 RF console out of the crate and plugged it into the -171 control head.  I flipped on the wobbly AC mains switch and nothing... After some quick inspecting I found the mains circuit breaker broken.  It appears it was smashed when it was placed into the crate.  I found a replacement Heinmann 40A breaker and installed that.  Then I threw the switch and the amp came to life.  This amp had not seen voltage since 1994...that was the date on the shipping crate sent from Henry to General Dynamics in SoCal.  I saw 6.3 on the filament and 3800 CW/4900V SSB on the multimeter so I left the amp on to cook and walked away for 24 hours.  Returning to the shack all seemed well and I applied some RF to the amp.  Working like a champ.  70 watts in gets 1800 into the dummy load.

So, as it sits now I am in need of some advice as to why I see the signal degradation with the first RF console.  I plan on yanking the RF deck this weekend to flip it over to see if I can see anything obvious.

I also need to know a source for the small push in bulbs Henry used for their indicator lights.  No cross reference in my Ultra or 3KA manuals

Thanks in advance for any help you can provide.

More soon

Carl W9LF

From: Carl Braun
Sent: Saturday, October 21, 2023 3:49 PM
To: amps at contesting.com
Subject: Starting up a NEW Henry amp

I'm headed out tomorrow am on my way to save a Henry 3K Ultra amplifier. I'm in Wisconsin and the amp(s) is in Arizona. My buddy has gotten out of ham radio years ago and still has this Henry 3K Ultra. He also has a second RF console that came with it that has never been out of the crate. All of the hardware was originally sold to General Dynamics in southern California. The crates console still has the paper tag on it that shows delivery from Henry to Gen Dynamics.

My plan is to get the amp and extra console back home and get them back on the air. I don't see myself doing anything other than plugging them into 240vac, turn them on individually and letting the tube go thru a gettering process for a day or so. These are 3cx1200D7 tubes with a controller that displays plate and filament voltage so I can quickly see if anything is awry.

Any other suggestions from the group on starting these amps up?

Carl W9LF

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