The TX and RX pin diodes have been remarkably reliable with infrequent
failure. The best explanation for pin diode failure is the system setup -
see the following link several years ago by John, W0UN which still holds
true today. Read the final paragraph which I can confirm personally as
well. Also, Verical (Arrow) is selling the TX pin diodes for only $45 and
still had hundreds in stock.
http://lists.contesting.com/_amps/2003-01/msg00004.html\
73 Jerry NY2KW
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Robert Arenella
Sent: Monday, June 13, 2016 10:10 AM
To: amps@contesting.com
Subject: Re: [Amps] Alpha 87a Low receive
My Alpha 86 had an Rx fuse and pin diode T/R switching. If that fuse
popped, my amp had exactly the same symptoms exhibited by your 87A.
I had a pin diode failure that took out the PA's in my flex 5000. I finally
had enough......sent the amp off to Dick Byrd, N4UQ. He mods the T/R board
and eliminates the pin diodes & Rx fuse. T/R switching is now handled
seamlessly with a vacuum relay. No more trips or faults, the amp just works.
Those pin diodes are the Achilles Heel of every Alpha amp that uses them
The pin diodes are still available, but they are very expensive.
73 de Bob
N2OAM
PS I have no connection to Dick Byrd, just a very happy customer.
On 6/11/2016 12:13 PM, 'DGB' wrote:
> I recently acquired a 87A and after keying it up, the receive goes to
> low until I hit the STBY key.
>
> It was reported to be fresh back from Alpha.
>
> What could be causing this?
>
> thanks 73 Dwight NS9I
>
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> http://lists.contesting.com/mailman/listinfo/amps
>
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