Dalton,

The NC-183D is a solid National receiver. There are two distinct versions with the earlier using a 6J5 as the phase inverter for the output stage and the later version using a 6SN7 with one section as a phase inverter and the other as a S meter amp. Just make sure to use the correct schematic for the receiver that you have to avoid confusion.

Some National receivers of this era left the factory with a .1uf capacitor from one of the rectifier plate pins to ground. If your receiver has this, remove the capacitor because it isn't needed. If it fails shorted it WILL take out the transformer before the fuse can open and a lot of National receivers ended up with new power transformers because of this useless capacitor. It was left out in later production and probably cost National a bit in warranty dollars even back then.

Regardless of version, it is very common to find the 47K screen resistors used throughout the RF and IF sections to have drifted to many times their marked value. This is from a combination of less than stellar resistor quality combined with these resistors operating at near their rated dissipation in many of these positions. Check the screen voltage (or resistor value) on them but if you find any of them out I would just replace all of them. This was necessary on both NC-183D receivers I restored along with the NBS variant based upon the NC-183D. It is a known issue with this set.

Otherwise there will be a few paper type capacitors (primarily the larger value units) that should be replaced but even in the early production most of the capacitors are either mica or ceramic disc. The filter capacitors will likely need replacement, definitely replace the output stage cathode bypass cap because leakage or a short here will potentially take out the audio output transformer and possibly the power transformer. All of these that I have been around came from the factory with reliable ceramic discs in the coupling/DC blocking position for the output tube control grids but if by chance your radio was built with paper caps here then replace them for the same reason you replace the output stage bypass capacitor.

Unlike many receivers, several National sets of this era hold the B+ return slightly above ground to develop bias for the output stage and RF gain control network. It has a separate filter capacitor for this section which is 25 uf @ 50 volts. Some versions of the manual incorrectly list this as a 25 pf capacitor so ignore the manual and use the marked value on the schematic and existing capacitor when replacing. Observe proper polarity when replacing this bias supply capacitor remembering that the negative lead of an electrolytic capacitor goes to the most negative potential part of the circuit, in this case it is the bias bus and not ground.

Rodger WQ9E

You should enjoy this radio. It does not have a product detector but easily receives SSB. Mine was in terrible condition but was worth the effort to restore.

Norm

I'm glad you settled on a 183D. Besides the usual need to replace the paper and electrolytic caps, mine also suffered from out-of-tolerance resistors. The 470K units in the AGC circuit had gone way high or open. This led to several 6BA6 tubes developing grid emission which was a problem even after the resistors were replaced.

Properly restored and aligned, you will love this receiver especially its no-nonsense control layout and push-pull audio.

Dave

In my reading, I did come across mention of the .1uf capacitor problem. In that case, it was not fully open, but was operating at about half capacity, causing a problem with sensitivity.

Hi Dalton,

That Pic DOES NOT look good, it could well be the result of the capacitor Rodger mentioned, having failed, or some other transformer problem. I sure hope not.

National, as most other manufacturers, built radios in lots, and each chassis was marked with the Engineering Release number stamped as a 3 digit number as part of the complete serial number. Therefore, you can be sure you have the proper manual, assuming you are able to find one, based on the "ER" number as shown here. The ER number in this case is 372, and the actual serial number of the radio was 1,000.



Below is the chassis "ER" and serial for another of my National radios.




Manuals had the ER number stamped on the outside rear cover, showing this "Service Manual" number 3300, printed in August of 1946. Its the correct manual for the above radio.

I'm glad you settled on a 183D. Besides the usual need to replace the paper and electrolytic caps, mine also suffered from out-of-tolerance resistors. The 470K units in the AGC circuit had gone way high or open. This led to several 6BA6 tubes developing grid emission which was a problem even after the resistors were replaced.

Properly restored and aligned, you will love this receiver especially its no-nonsense control layout and push-pull audio.

Dave

Don't know why, but I seem to have a fondness for these two arched dial receivers, the National NC183D and the Hallicrafters SX-100, but I do think the NC-183D was probably the prettiest receiver ever built. ...

Looks in nice condition.

How can a guy with a beautifully restored NC-2-40D say such a thing??

...How can a guy with a beautifully restored NC-2-40D say such a thing??...

Oh, they're all nice, even the rat rods, for one reason or another, but now you're say'in I can't have more than one favorite?

Here's something I didn't know until now. According to Oxford Languages, "favorite" means No. 1, period, when used as an adjective:

Preferred before all others of the same kind.
"their favorite Italian restaurant"

But as a noun, it mean you just really, really like it:

A person or thing that is especially popular or particularly well liked by someone.
"the song is still a favorite after 20 years"

So I give you permission to have shelves full of favorites. No, no, it's okay. You don't have to thank me Happy Thanksgiving.

I looked at the other pictures of the radio that you bought on ebay. None of the original paper caps have been replaced and there are a ton of them including lots of bumblebees which you can re-sell and get some money back. I do see one replacement electrolytic and several overheated power resistors. But I don't see and nasty modifications made by a previous owner. I think this set will be an interesting restoration project. Mine certainly was and it is one of my favorite boatanchors. I found it locally at a hamfest without its cabinet but with a matching speaker. This was years ago before skyrocketing prices. Still don't have a cabinet.

Dave

I looked at the other pictures of the radio that you bought on ebay. None of the original paper caps have been replaced and there are a ton of them including lots of bumblebees which you can re-sell and get some money back. I do see one replacement electrolytic and several overheated power resistors. But I don't see and nasty modifications made by a previous owner. I think this set will be an interesting restoration project. Mine certainly was and it is one of my favorite boatanchors. I found it locally at a hamfest without its cabinet but with a matching speaker. This was years ago before skyrocketing prices. Still don't have a cabinet.

Dave