[R-390] Broadcast Band On Other Bands

Tue, 23 Apr 2002 14:28:41 +0200

I have had this when an RF stage goes into oscillation - the pop is when
it starts to take off. Usually accompanied by noisy signals on the band
you want to hear. Would start with bypass caps in RF stage.

>>> "Tom M." <[email protected]> 04/23/02 02:19PM >>>
Sounds like you either had a component failure in the RF section, or
the RF is
out of alignment.

The RF section has to track with the PTO and variable IF.  You can tell
if you
can benefit from an RF alignment by slightly turning the MCS knob.

If you turn it half way to the adjacent band, it will move the slug
rack a tad
prior to changing xtal position.  Try this and see if you get an
increase on
the signal meter.  If you get an increase, then you need an RF
alignment (at
minimum).

73 Tom N5OFF
--- blw <[email protected]> wrote:
> 
> > My R-390A was operating normally on 3870 but after a fairly loud
audio
> click
> > overlapping local broadcast stations could be heard.  With some
tuning
> > around these "stations" occur at various places on several bands,
noteably
> > the 3, 13,14,15 Meg bands, maybe others.  It's hard to tell if the
selected
> > frequency is being received.  The 1 to 2 Meg band seems OK.
> > 
> > Ideas before the trouble shooting begins?
> > 
> > Mike VE7MMH
> 
> 
> Mike,
> 
> This makes me think of several things. First, I sometimes get a
sudden pop
> of louder audio especially if I've had the radio parked on a
frequency for a
> long time. Something seems to open up somewhere for full audio. It
has been
> going on for a few years now. Turning up the RF Gain usually gives me
full
> audio again, or turning the MC Change knob up or down a band will do
it. I'm
> pretty sure that the racks are moving loose enough to not bind like
they do
> on my other one. Sometimes I get the impression that crud on the
Local Gain
> and RF Gain pots is causing the problem.
> 
> Maybe some of these stations are harmonics?
> 
> 
> 
> Barry
> 
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