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Re: [Amps] Alpha 77 start up

To: Paul Christensen <>,
Subject: Re: [Amps] Alpha 77 start up
From: Jan Ditzian <>
Date: Mon, 28 Feb 2011 15:05:07 -0500
List-post: <">>
On 02/28/2011 09:49 AM, Paul Christensen wrote:
>>   6. *On the top of K5, no two pins are connected.*  AHA!  It seems to
>>      me that the pins on top are the contact pins, and that two of
>>      these should be connected at all times.
> Jan,
> I think your reasoning is good.  I'm not sure how the amp ever worked 
> with the configuration you've described.  K5 has all terminals 
> populated.  Two on the bottom for the coil and three on the top for 
> the SPDT operation.  Coil resistance is about 300 ohms.
> There should be DC continuity between RF IN and RF OUT when the amp is 
> powered off and the RF AUX ANT switch is in the THRU position.  When 
> the slide switch is placed in the AUX position, you should measure DC 
> continuity between RX AUX ANT and RF OUT.
> I'm not sure the vacuum relay is actually bad  -- or that it's simply 
> not wired correctly.   Check for continuity on the relay terminals and 
> if possible, apply 26V from an external bench supply to activate the 
> relay for DC resistance measurements.  If it's still bad, I would go 
> for a new 26.5V Gigavac GH-1 from MaxGain.
>> "The tuned/untuned switch does not appear to work.
> I think it's correct based on your description.  If you look at the 
> schematic, the tuned network is a switched shunt leg to ground.  The 
> tuned/untuned INPUT switch only has two terminals connected.
> Paul, W9AC

Perhaps I was not clear in my description.  I did not actually figure 
out what went where.  There were three connections to the relay, and a 
continuity test showed that nothing was connected to anything.  Since 
this looks like a SPDT relay, it looks like the center paddle is burned 
off, or something like that.  I think that I may have a 12 volt or 
higher wall wart that I will use to excite the relay, with the 
continuity tester attached.

Jan, KX2A

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