SB401 Problem Help Please

[Fred Wittman]

Are the relay contacts possibly oxydized?

Fred W.  --  KG6NYK
----- Original Message -----
From: "Dan Pividal N4VET" <OTAKEBI at AOL.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Sunday, December 01, 2002 2:13 PM
Subject: SB401 Problem Help Please


> Have an SB401 that has an intermittent problem.
> The problem seems to take place if the SB401 is not used every day.
> If I use the rig everyday it will not malfunction.
> If I do not use the rig for two or three weeks problem gets very bad.
> Seems that I get only the RF output that the final bias of 50ma would give
> me.
> I get no grid and only 50ma on the meter.
> I can hear the relay kick in but I hear no load on the transformer.
> The only way I can get RF output is to tap ever so gently on the carrier
> generator board or the mixer-bandpass board.
> And, when I say it only takes a gentle tap I mean it.
> Once I get radio to work it puts out full power and no more problems.
> If it sits for more than a day I have to do the tap again or if no longer
> than a day the pushing of the mike several times to activate vibrations
from
> the relay causes the unit to come to life.
> If I turn up the driver control all the way when I click the mike on and
off
> makes this fix work faster.
> I do not think this could be a resistor or capacitor problem since the
> symptoms go away completely once the unit works.
> I have checked for bad solder joints and have found non.
> I have replaced tubes and problem pops up again.
> Can anyone come up with any ideas?
> Thanks,
> Dan
>
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