[R-390] R390A Popping

Sun, 28 Sep 2003 08:04:56 -0700

 GM Chuck.  I have had a similar problem but, its been a few years and I
 don't remember if the "pop" occurred at regular intervals.  If u have use
of
 an o-scope and tube extenders look at the trace around the tubes and see if
 that gives u any clues.  What I have had on two 390 non "a" radios is a
 failure of the coil just after the final mixer.  I think its t-207 on the
 390 non "a" and it might be t-208  on the 390a.  One of my coils was in the
 process of failing open and was causing the same popping sound.  The 390
 manuals give a dc resistance for the winding of each coil so pop the coil
 cover and check.  Incidentally for those who are interested I sub'ed a 390a
 mixer coil into the 390 non"a" and it works fine to this day.

 Dave
> ----- Original Message -----
> From: Chuck <[email protected]>
> To: <[email protected]>
> Sent: Saturday, September 27, 2003 8:51 PM
> Subject: [R-390] R390A Popping
>
>
> > Guys,
> > My R390A has recently developed a problem.
> > During ordinary listening conditions in either AM or SSB, it pops at
> > regular intervals. The signal strength meter jumps when this occurs.
> > But, the pops are not always the same amplitude on the meter. The
> > popping seems to respond to a change in agc settings.
> > At first I thought it was external interference as it quits when the
> > antenna was disconnected. However, after comparing other receivers in
> > the shack and hearing nothing, I came to the conclusion it is internal.
> > Before tearing into the radio I thought I would ask the group for ideas
> > and suggestions
> > TIA
> > Chuck
> > [email protected]
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> > R-390 mailing list
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> > http://mailman.qth.net/mailman/listinfo/r-390
> >
>