[R-390] R-390 IF: Looking for 20-pin socket and plug

[Glenn Little WB4UIV]

Look at the back of the connector.
The pins may be held in with a small clip.
If so you can replace the bad pin from a donor without changing the 
entire connector.

73
Glenn
WB4UIV

On 6/12/2026 1:52 PM, n4buq via R-390 wrote:
> Here’s a picture.
>
> Thanks,
> Barry
>
>
>> On Jun 12, 2026, at 12:48 PM, Barry via R-390<r-390 at mailman.qth.net>  wrote:
>>
>> I have a 20-pin female connector that I believe was for an R390A.  I presume that's the same as for the R390 but I don't know that for sure.  Unfortunately, I don't have the male chassis mount part.
>>
>> Let me know if you think you can use it.
>>
>> 73,
>> Barry - N4BUQ
>>
>>> Everything has been going well on restoring my R-390, until I noticed no AGC
>>> voltage.  Then I unplugged the 20-pin connector.  Lo and behold, pin 15 had
>>> corroded right off (the AGC line)!  The mating plug has severe pitting and a
>>> thick black oxide replaced what was once gold plating.  But underneath,
>>> everything is pristine.  I am going to have to replace the pair.
>>>
>>> A parts radio might yield them.  I would happily buy them.  An extender cable
>>> would have this pair.
>>>
>>> Interestingly, the Antenna Box BNC jacks were destroyed by pitting, but I
>>> re-built that without thinking beyond it.  This reminded my of the circuit
>>> breakers in a plant that made sulfuric acid.  Not only did the breakers fail
>>> every few months, but the panels would grow long silver whiskers.  So there
>>> was something in the environment of that radio... ?
>>>
>>> Thank you,
>>> WN9i Fred
>>>
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-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4uiv at arrl.net     AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"