NC-183DR

[N8LGU]

    I just snagged an NC-183DR with a flat front panel. Very fine condition. Anybody have any experience with this receiver? Two RF, three IF's and push pull audio. It should be great on AM. It has no case-looks like it was pulled from a rack.

[W1DAN]

I believe it is  a diversity reception model.

I have worked on an NC183, but not the diversity receiver.

Nice!

Dan

[Pete, WA2CWA]

It's the diversity version of the NC-183 done by Northern Radio. Had one a number of years ago but dumped it at a local flea market. Both my NC-173 and NC-183D outperformed it in sensitivity and AM audio quality. The one I had looked like it was dragged behind a truck for many miles.

[WQ9E]

Dave,

I have the table version of that (NC-183D, no R) and it is the first vintage receiver I bought back in 1982; a sign of things to come.  It uses 47K screen dropping resistors throughout the RF and IF section and all of mine measured within 5% of 220K so I have a feeling it was built with mis-marked resistors.  The original owner noted in the manual that sensitivity seemed low and he changed the gain adjustment resistors on the bandswitch so that it ran at maximum gain at all times.  Putting proper value resistors in the receiver brought it to life.

Before you do anything else, make sure that there is not a bypass capacitor from one side of the transformer HV secondary to ground (usually mounted at one of the rectifier plate socket connections).  This capacitor serves no useful purpose but when it shorts it takes out the transformer with it.  It may already have been removed in yours but if not remove it before you need to go transformer hunting.

It has great audio on AM and it is also a very good CW receiver.  Unlike the HRO-60 of the same era, the AVC can remain on for CW reception.  If the crystal filter doesn't seem to work properly it is common to find that the crystal element needs cleaning and the procedure for this can be found in the earlier HRO manuals.  Basically you disassemble the crystal holder and clean everything with good quality (low water content) alcohol and dry before reassembly.  It is easy to check the crystal if you have a signal generator and scope (or sensitive RF voltmeter available).  Connect the hot generator lead to one side of the crystal, the scope probe to the other, and connect the scope and generator grounds together.  You should see a pronounced peak on the scope as you tune through the crystal frequency and sometimes it is necessary to adjust the fasteners on some crystal cases to apply proper tension; just "tune" the hardware tightness for a peak if needed.

The 183D is a very good all around receiver, mine does receiving duty for a Viking 2.  There are a couple of different circuits used for the S meter circuit so you will need to make sure your schematic matches your receiver if you need to work in that area.

Enjoy your new find.

Rodger WQ9E

[N8LGU]

    I don't think this is a diversity model as it has the normal freq coverage of BC band thru 10M + 6 meters.  I'll have to improvise a case for it to keep out the cat.

[Pete, WA2CWA]

I think there was an article and/or a picture of the 183DR diversity model in Electric Radio. If I remember correctly, the diversity model had several extra front panel controls and a number of circuit changes.

[N8LGU]

    Thanks for the heads up, Dave. I know National used wax paper plate bypass caps on the NC 2-40D which slowly degraded into resistors over the years which kept increasing the load on the power transformer until it failed due to overheating. I'll be sure to check all that out. I haven't taken the bottom plate off, yet.

[K3ZS]

Ditto on what has been said.  I have a NC-183 (no D) that I bought in 1958.    Over the years I had the same problems and went through a couple of power transformers due to a shorted paper capacitor.     Replace all paper caps.    Check all resistors, most of the screen dropping ones go high and the sensitivity goes way down.   I found one a resistor that was originally wrong from its color code.
If you have a manual, the parts list identifies the paper capacitors.

[W3SLK]

Brian said:

Most people who find them quickly realize they are not as great as they were originally advertized to be. They are a huge letdown.

Your standards must be extremely higher than mine. I'm perfectly content with my -183D. I do have a HRO-50T that I resurrected and I find them both comparable to each other. The big minus I do have with the 183 is that there is no provision for a crystal calibrator. No big deal there either since I'm either running a pto or crystal in the transmitter. Zere beat works fine.

[WQ9E]

Brian,

The sensitivity drop off should be very little, my NC-183D easily copies a 1 uv signal from my HP generator on 15 meter CW.  You might want to check around the switching section, high IF,  and V-4 ( the 2'nd converter) since the D model switches to dual conversion for the A, B, and C ranges.  It sounds like your receiver is not performing as it should on the higher ranges.  Those 6BE6 converter tubes are always suspect; I bought a bunch of military equivalents (slightly taller with a 4 digit number which I can't recall right now) and I use those in most cases to replace weak 6BE6 tubes and they seem to work well and last for a long time.  Performance drop-off with increasing frequency is a common problem with some even near-new 6Be6's; I just don't like that tube.  I never found the 6 meter range to be very useful but it does cover it without needing a converter.

I would rate the selectivity as fine on CW (using the crystal filter) and OK on AM when there isn't much QRM.  The filter can be used on AM also but I don't like the performance as well as the selectivity available from a low frequency 2'nd IF as provided by some of the Hallicrafters and Hammarlund models; that is why I quit using an HRO-50 with my Desk KW.

Rodger WQ9E

[w3jn]

  Those 6BE6 converter tubes are always suspect; I bought a bunch of military equivalents (slightly taller with a 4 digit number which I can't recall right now) and I use those in most cases to replace weak 6BE6 tubes and they seem to work well and last for a long time. 

Rodger WQ9E

5750 is the mil equivalent of the 6BE6.

[WQ9E]

5750 is the mil equivalent of the 6BE6.

Thanks JN, 

That jogged my memory.  The ones I am using now are type 7036 tubes.  They are a little taller so in most cases the next taller shield is needed but they otherwise work great.  I bought a bunch of these tubes on ebay several years ago and I am very pleased with the performance.

Rodger WQ9E

[K3ZS]

My NC-183 was made in 1947 and is the single conversion one.    It drifts during warm up but is stable after about 1/2 hour on all bands including 10M.  It is not as selective as some of my other receivers, but it has the best sounding audio for AM.     The 10W push-pull audio stage can be appreciated best if you use a wide-range bookshelf speaker with it.  Maybe the newer ones had more problems but a restored original one works great.    The NC-173 was about the same with one less RF stage.    The two RF stages in the NC-183, when properly aligned helped with image rejection over other single conversion receivers.    Still would favor an HRO or 75A series receivers over it.