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