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Re: [Amps] Alpha 77DX

To: Dan Hearn <n5ardxcc@gmail.com>, Amps@contesting.com
Subject: Re: [Amps] Alpha 77DX
From: George <at6c@bellsouth.net>
Date: Sun, 20 Oct 2013 19:33:55 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Hi Dan,
I have a 77SX and if you find a place to buy those switches let me know. I would not be comfortable using the amp without the switch unless I put a HV fuse in line with the B+ and probably a current limiting resistor in line with the B+. I had a failure of one of the doorknob capacitors in the RF section last spring and that solenoid trip the rig off and prevented serious damage. Best of luck finding replacement switches.
73, George
W2GS
On 10/20/2013 4:13 PM, Dan Hearn wrote:
After 17 years of reliable service the set of 4 push buttons on the right
front refuse to latch when pushed in. Of course the amp will not turn on
then.
   The manual says that there is a solenoid below, mechanically connected to
the switch, which will unlatch the switches if the plate current is
excessive, turning the amp off
   I used a piece of buss wire, formed into a hook, to lift up slightly on
the solenoid core and found that then the switches operate properly. I
believe there may be a spring in the switch  to counter the weight of the
solenoid core when it is not energized. I believe one could rig a small
spring slightly off vertical to help lift the solenoid core but I feel
comfortable without the safety feature.
   I am considering disconnecting the solenoid mechanical pull wire and
using the amp without the plate shutdown feature. Replacing the switch
would be a difficult job. I will probably order a spare switch since both
of the switches on the left and right sides may fail completely.
. Has anyone faced and solved this problem by this means or some other?

Dan, N5AR
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