[Elecraft] Hang-up on Relay Using QSK

[Guy Olinger K2AV]

A LOT of the 86's, 87A's and 89's have had the pin diodes removed
because of the usual problems with pin diodes and replaced with a
relay board. This has been done just because the owner is tired of the
expense of the TX pin diodes, or living in circumstances that
frequently present pin diode blow up events.

Some folks I know had that mod done right away after they bought one
used. Real QSK afficionados sometimes just deal with the diodes, which
would put the problem somewhere other than the K3 and the amp, as in
Vic's post.  86's, 87A's and 89's are legend for pin diode problems
which is why so many have been converted to relays and need to be
checked on intermittent RX problems just like any relay t/r amplifier.

Such comments as this one in an eHam evaluation on an Alpha 86 are common:

"I use the Alpha 86 for CW, RTTY contests and DXing. Since I had RF
Concepts put in the vacuum relays, the reliability has been
excellent."

I know replacing the pin diodes is what I would do immediately on
purchase of one of those. These days such things as W7RY's QSK boards
for various amps make that relatively easy and result in an an
outstanding amp for QSK. At some point I will have an SB-220, an
AL1200, a homebrew 3-1000Z, and an HL-1K all modified with a W7RY
board.

73, Guy.

On Tue, Dec 1, 2015 at 12:45 PM, Vic Rosenthal 4X6GP/K2VCO
<k2vco.vic at gmail.com> wrote:
> Lee,
>
> The Alpha 87A uses PIN diodes for t/r switching, so unless someone modified
> it, it's not the amp t/r relay, which is the usual culprit for this problem.
>
> It could also be a poor connection somewhere in the antenna circuit.
> Sometimes a coax plug or socket is oxidized (or whatever) and it has high
> resistance for small voltages such as received signals; a shot of RF cleans
> it up.
>
> I had a problem like this which drove me nuts for months. It turned out to
> be a corroded solder joint in a balun (at the antenna feedpoint, of course).
>
> 73,
> Vic, 4X6GP/K2VCO
> Rehovot, Israel
> http://www.qsl.net/k2vco/
>
>
> On 1 Dec 2015 19:06, KY7M wrote:
>>
>> Towards the end of CQWW CW, I was having issues with the K3 not getting
>> back
>> to receive when I stopped transmitting.  This was an intermittent problem
>> -
>> if I keyed the radio again with a dit or two, I could get back to full
>> receive.  I could still hear signals, but greatly attenuated when the
>> relay
>> would hang up.  I was using QSK with the K3 and my Alpha 87A.  I am not
>> seeing any fault indication on the 87A and I am trying to figure out if
>> the
>> problem is in the K3.  I also have a KPA500 but have not used it in a
>> contest lately to know if the problem would repeat with another amplifier
>> or
>> barefoot.  It seems to happen only after heavy use.  I think I experienced
>> it a week earlier in the WAE RTTY contest as well, but did not do as much
>> operating as in CQWW.
>>
>>
>>
>> 73,
>>
>>
>>
>> Lee, KY7M
>
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