[R-390] R390A antenna relay troubleshooting

[David Wise]

Check the selenium bridge rectifier that powers the relay coil.  This class of component is characterized by gradual failure.  The voltage drop increases.  Mine was weak twenty years ago when I bought the radio.  In my opinion, there are two reasonable actions.  You can replace selenium with silicon, or you can add a reservoir cap to raise the average voltage.  I never liked the idea of powering a DC relay with unfiltered rectified AC, especially in a spot where hum can be a problem, so I put in a cap.

Dave Wise
SWL in Hillsboro, Oregon
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From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> on behalf of Bob kb8tq <kb8tq at n1k.org>
Sent: Friday, March 16, 2018 6:25 AM
To: Larry H
Cc: peter murphy; r-390 at mailman.qth.net
Subject: Re: [R-390] R390A antenna relay troubleshooting

Hi

It’s also quite possible that Mr Spider has moved into the vicinity of
the relay and clogged things up. A good visual is the first step ….

Bob

> On Mar 16, 2018, at 7:00 AM, Larry H <dinlarh at att.net> wrote:
>
> Peter,  I've attached some pictures I have of the relay.  The 3rd one shows the 4 screws holding relay in place.  The 1st shows the armature that moves the contacts inside, 2 on 1 side and 1 on the other.  The 2nd shows the contacts that are operated with the cover plate off.
> There might be something preventing the free movement of the armature.  It's possible that the electromagnet core has become magnetized.  If so, it can be demagnetized by applying low voltage ac to it or reverse the dc to it for a short time.  If it only takes a slight pressure to release the armature, then perhaps the spring leave tension from the contact springs is not strong enough.
> Regards, Larry
>
>
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