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Re: [Amps] Alpha 77SX forward & reverse W not working

To: "MU 4CX250B" <>, <>
Subject: Re: [Amps] Alpha 77SX forward & reverse W not working
From: "Carl" <>
Date: Sun, 31 Mar 2019 12:01:48 -0400
List-post: <>
Yes the tank is the same and with the stock transformer there is not that much of a difference in output so the operation is adequate. There is nothing magic about the ARRL Q=12 and a wide variation is still tuneable.

Does even the stock DX harmonic suppression meet current FCC rules? I doubt it but it appears to not bother anyone.


----- Original Message ----- From: "MU 4CX250B" <>
To: <>
Cc: <>
Sent: Saturday, March 30, 2019 10:40 AM
Subject: Re: [Amps] Alpha 77SX forward & reverse W not working

As I recall (and maybe I don’t!),the 77SX has the same tank circuit as
the 77DX, which means the plate load Z is too low for the tank
components. The amp tunes to resonance, except on 10m, but not certain
how good the harmonic suppression is.
Jim W8ZR

Sent from my iPhone

On Mar 28, 2019, at 8:34 PM, Gary Smith <> wrote:

Another hiccup in getting this old girl
back into shape. I rarely use the watt
meter in the amp, I use the one in the P3
and on top of the amp is a LP-100A, those
always handle my needs. As a general rule
I leave the multimeter in the Grid setting
and always use that.

When I had a look see in the amp to see
what was what was going on with the
padding caps, all seemed to go well, no
unexpecteds happened but with reassembly I
tried using the watt meter and found it's
barely working; the meter moves but very
little. The last time I used it 4-5 months
ago, it worked well.

No telling if I somehow bumped something
but is there a likely first thing to look
at? The meter movement is fine, works
seamlessly with grid current.



P.S. I received all the new  High Energy
7.5KV 9A doorknobs to replace the old
Jennings and Centralab 1A variety. Waiting
for the Ameritron choke and some silver
plated flat wire to come in and I'll get
them installed. It'll be nice to have the
tank upgraded.
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