National NC-183D HELP
 

Hi
I just got a National NC-183D Receiver
It was sitting for a few years.
I turned it on and it seems the RF gain is low.
As you turn up the RF gain nothing is heard til you
get up to to the number 8 on dial.
So no receive until you turn dial up to 8 and I turn it up to 10,
I hear signals on AM SSB fine. But need to get the RF gain higher
so signals come in stronger.
The glass tubes seem to be on.
Can it be the tubes or something else?
It seems to receive all bands but 40 Meters.
Thanks for reading
Rich NJ

National NC-183D HELP
 

Rich,
Having restored both an NC-183 and a "D", I found that re-capping was
mandatory in both cases. Its not a bad task, given that these receivers
are fairly open and accessible, below the chassis. I found that the
electrolytics in the power supply and the audio stages were either
totally shot or leaking badly. I'd also suggest checking all the tubes.
One or two weak ones can certainly degrade the whole receiver. If an
alignment is found to be necessary, note that the front-end inductors in
these rigs are not easily tuned; they use mechanically repositioned
loops (the book explains all). Finally, I highly recommend running the
set on 110v rather than a higher line voltage. The power xformers in
both my 183's get (I think)abnormally hot above 120v. In fact, I run
the entire collection of boatanchor rigs via one of two 15A variacs
installed in the ops room. Its quite amazing the drop in temp rise of
all the equipment and I'm convinced that their longevity has been increased.

National NC-183D HELP
 

Check your RF gain control. Sounds like you might be using an audio taper
pot where a linear taper pot is required. If you've got the correct taper
maybe the pot has gone out of its design curve. I have experienced this on a
couple of vintage receivers. I had one that responded just like yours...no
gain till "8" or "9" then lots of gain. I also had one going the other way,
near full volume by "2" or "3" then little increase. Replacing with a fresh
proper taper pot corrected both.

Another pot anomaly is where the increases normally as your rotate the pot
then you hear a little "pop" and the volume goes high or low. Pot problem
that (often) contact cleaner will not fix. It's mechanical and often
dependent on the taper that was designed or has developed over the years due
to wear, age, dirt etc etc.
Good luck.

Smokey

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wrote in message
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Hi
I just got a National NC-183D Receiver
It was sitting for a few years.
I turned it on and it seems the RF gain is low.
As you turn up the RF gain nothing is heard til you
get up to to the number 8 on dial.
So no receive until you turn dial up to 8 and I turn it up to 10,
I hear signals on AM SSB fine. But need to get the RF gain higher
so signals come in stronger.
The glass tubes seem to be on.
Can it be the tubes or something else?
It seems to receive all bands but 40 Meters.
Thanks for reading
Rich NJ