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Which models had 4kv on the plate?? A Triode is only going to give 10 to 12 DB of gain.??

Man, I have worked on and rebuilt pretty much all of these amps and even the later 3KA with its HD supply won't do 2kw.? It does not have 4KV on plate.? I was curious which ones did.? It's rated at 3k input and the efficiency is pretty poor.??

Henry used horrible small Fil chokes in series.? These things need to be tossed in the trash.? They get super-hot and after years of use the permeability changes.? they get harder and harder to drive.

Its so bad that the Tubes won't have the same fil voltage on them. Thats why these things always have one bright tube.? One of the tubes can be a half to a full volt off!?

The last one I rebuilt made 1800W out on low bands but needed a 200W radio to get there. It really works hard there.? ?I put a fil transformer in with a proper Fil choke.? Now each tube is spot on for voltage.? The amp runs so much better.? The blower is way too small.? I put a Dayton ball bearing blower it. Half the noise and twice the air.?

C

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From: [email protected] <[email protected]> on behalf of Louis Parascondola via <Gudguyham=[email protected]>
Sent: Friday, February 14, 2025 3:41 PM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Drake L-7

?

It’s a well known fact that the Ameritron AL80b can obtain 1kw output ?pep?with a single 3-500. They only run 3000 volts anode voltage.? The old Henry amps made prior to the power rule change were used in some Embassies.? For that use they were running the same amps sold to hams.? The Henry amps had choke input filers and 4000 volts anode and the?plate voltage was rock steady.? Easily capable of 2kw pep output.? Naturally the ham manuals didn’t necessarily boast that sort of power and tune up instructions were geared towards legal limits.? Hence the CW/SSB change in voltage.? Load to 1 kwdc input on CW Carrier) switch to SSB and talk and get 2kw pep input, but dare not let down in the SSB voltage!!! You’ll break the law.? When the 1500 pep putput came in, away went the cw/SSB switches, not need for them anymore!!

On Friday, February 14, 2025, 12:51 PM, W7WRX <clark@...> wrote:

Which henry amps were rated at 2kw out Jim???

C

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From: [email protected] <[email protected]> on behalf of Jim VE7RF via <jim.thom=[email protected]>
Sent: Friday, February 14, 2025 3:29 AM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Drake L-7

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Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?

To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the tank circuit off resonance...such that both tubes show some colour.?