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Re: [Amps] issue with AL-1200 output

Subject: Re: [Amps] issue with AL-1200 output
Date: Thu, 22 Jun 2017 16:35:02 -0500
List-post: <>
bypass the output relay and retest.

Quoting Steve Bookout <>:

Hello all,

Need some input from the brain trust.

I recently acquired an AL-1200 amp from a non-ham third party, that got it from the estate of silent key. I think he was a relative, or at least a family friend.

Because this amp was new to me, I was taking it slow. All is fine and working as it should be up to about 300-400 watts.

At that point, the output suddenly and immediately dropped to about 12 watts, just like flipping a switch. The 'power output' function of the amp's meter confirms what my outboard meter showed.

Plate current remains unchanged at about 250 ma. Input from the K3 remains unchanged in power level and standing wave.

I can repeat it, over and over, with both CW and SSB bias. It takes a few seconds for this to happen, anywhere from 5 to 8 seconds, or so.

No vacuum relay in the output. No noises heard; no clicks, no snaps, no 'nothing'.

I recently had another amp given to me that had similar symptoms. Turned out, in that case, that the vacuum output relay was stuck in the N/C position and would not switch. Relay coil was fine and pulled current trying to switch the contacts.

Anyone with experiences similar to this.

73 de Steve, NR4M

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