NC183D color and other information

[ke7trp]

I picked up an NC183D recently cheap.  It was a in need of alot of cleaning and work. The radio had a bad china 6v6 so audio was shotty.  New RCA 6v6s, caps, cord, and dial lamps the radio came back to life. I will do the full alingment next, its off as stations sound very dull when tuned spot on.   It also has a breadboard Xtal Calibrator using an IC chip.  This is wired to the phono switch. It works with a nice signal.  Considered ripping this mod out.

The question here is about the color of the rig. This one is a very light grey/ light blue.  It does not match the NC300, the HRO 50t, HRO 60, at all.  Its much lighter.  I was told this is a rare color by a fellow ham.  I cant find any of them painted like this on the web.  It is factory paint and not a repaint. 

I dont see much on the web other then specs.  I guess I will have a heck of a time trying to find the correct speaker for this odd ball.

This one has the same transformer as the one you have Frank.  It runs warm. Real warm.  All Caps replaced EXCEPT the 25UF near the audio section and one up under the edge.  I will replace them tomorrow.

Anything sore spots on the old 183D that need attention?

[KA2DZT]

My 183-D is the color of the speaker in the pic.  Never saw one with the light gray color.  Maybe it was a special order color.  I sure someone will know.

Fred

[ke7trp]

Yep. Thats what I am finding on the web.  Kinda odd.  It matches the T3 and the T368 dummy load/watt meter to a T.  I mean its exactly the same military color.

C

[Jim, W5JO]

Clark, the NC 183D is the same color as the speaker in the picture.  Someone repainted that one either because it was the color available or wanted it to match something.  Duplicolor makes a Truck/Pickup paint that is close and has the same sheen.  I don't recall the number but check your auto parts store if you are a mind to change it.

[ke7trp]

Its not a repaint. Its factory.  I have been all inside this thing and removed brackets under the chassis. Its also silk screened.

C

[w3jn]

I've never seen a NC183* variant with a silk screened panel either.  Either engraved (like my NBS-1) or stamped/recessed lettering like the 183, 183D, etc.

[ke7trp]

I just walked out to the radio and looked.  Its silk screened right over the top.  No engraving or stamping.  Very odd.  I cant find a serial number anywhere on this thing. Where would the serial number be?

C

[N3WWL]

I have one that is the same light gray color.  I purchased it around 15 years ago.  It was certainly repainted and the lettering was silkscreened too.  I also have the speaker that was restored the same light gray color.  I have never seen another one the same color until the one posted here.  I just assumed the restorer liked the lighter gray color.

[Jim, W5JO]

What type of tubes does that receiver have in the RF and IF sections?  If they are Loctal you have a NC 183 not the D version.  They were that color and had silk screened panels.

[KB5MD]

Maybe it's a prototype, if it doesn't have a serial number.
  I have a Collins 75A-3 that does not have a serial number and it also has some little details that are different than other 75A-3's.  Maybe it's a prototype also.

[K3ZS]

What type of tubes does that receiver have in the RF and IF sections?  If they are Loctal you have a NC 183 not the D version.  They were that color and had silk screened panels.

The NC-183 (not D) has mostly metal octal tubes if they are original.    They did not have the black dial or knobs.

[W7TFO]

I had a 183 rackmount a few years ago. 

It was black wrinkle on the panel, all octal layout. 

Also it had a GSA tag, so it was at some time in gov't employ.

73DG

[ke7trp]

Who knows, I got it cheap and its working fairly well.  Going to finish it tonight/tomorrow.  The S meter might need replacement. It is not going through its whole range of motion.  I am hoping an alignment will fix this.  I need to go through the AGC section of the radio.  With the AGC on, BC stations distort the front end, I have to back down the gain to clear it up.  It is working, just not correctly. 

C

[AC0TX]

"""""I have a Collins 75A-3 that does not have a serial number """""

Workers at the Collins factory could BUILD their own radios. Just pay for the schematics and parts.

[KM1H]

I suspect it is a first run set and using NC-173/183 colors. Does it have a 6J5 or 6SN7 as the phase inverter?

The serial is in the right rear inside, get your head all the way in and look straight down. What is the #?

Carl

[ke7trp]

372-1006.   I missed it before. The chassis is kind of corroded.  It has 6SN7, 6ba6, 6be6 ect. 

I spent some time with it today.  I cleaned the switches, Replaced the remaining caps and did the 455,1720 alignment. This thing was way way off.  I also did the AVC alignment. Some monkey turned that as well. 

This thing is HOT HOT HOT.  The AVC works but not enough.  BC stations require me to back down the RF gain to 8 on the dial.  I checked the resistors, tubes, caps ect.  I think its just strong stations blasting the thing.  Some of my other RXers do the same thing.  Some dont.

What I need is an S meter.  Its lowest point is S9.  It will read over that, But never below S9.   If anyone has an S meter, I would be greatfull.

C

[AB3FL]

I had started a thread about 2 weeks ago about it running hot.  I have a NC-183D also.  The best thing that I did was go to RatShack and get a 3A 6.3V transformer and buck the line.  It lowered the voltage down to around 110V and it runs MUCH cooler.  As for the AVC, I have to back the RF Gain down on mine when I am tuned into a really strong station such as a local.  I have a 1KW AM about 1.5 miles from my QTH.


Tom - AB3FL

[w3jn]

What I need is an S meter.  Its lowest point is S9.  It will read over that, But never below S9.   If anyone has an S meter, I would be greatfull.

C

First verify that the problem is mechanical, not electrical.  Try a battery in series with a 1 meg or so pot and see if it moves OK throughout its range that way.

If it's mechanical, you might have a piece of crap stuck in the meter armature.  Those meters come apart easily.  Inspect it and see what the problem is - bent needle, iron filings in the armature, the armature is off its bearing, the bearing is adjusted too tightly, etc.

If there's stuff in the armature, you can often remove it by CAREFULLY drawing a small piece of masking tape thru it.  With luck the filings will stick to the tape and be pulled out.  This takes some patience and a steady hand.

[MikeKE0ZUinkcmo]

I really liked the color of the NC-183D, and it was fairly close to the color of the HRO-60.

[Jim, W5JO]

You guys having trouble with the AGC must have something wrong.  Try a new 6AH6 first then if that doesn't fix it try alignment.  If that doesn't fix it check the voltage out of the transformer associated with the tube.  I have seen as much as
-20 volts on the grid of the first RF amp.  That knocked down the signal level of a 50 KW station located not much more than 10 miles from me.   Something is wrong.

[KM1H]

The 6BA6 has a history of H-K leakage when run hot as from leaky caps killing the AGC voltage for a few decades and there are 5 of them involved. The 6BE6 can also suffer leakage when run hot for other reasons.

Check the individual grid voltages and I'll bet at least one is well out of spec with or without a signal.

National did a lot of repaints when coming thru the service department so dont expect a perfect match across the models. Ive also seen HRO-50/60 and 183D cabinets also go thru the same day.

That set is ER372 which is fairly early, maybe 1954, and one of the first with the 6SN7. Its also possible it got a factory or outside full repaint at some point; National did it completely and not like Earl Scheib.

[ke7trp]

I will have some time today to check the Grid volts.  It distorts badly on a local 1kW AM station. I have some tubes to swap in, I have already tested them on the Tv7 and they dont show leak and show strong but you never know.

I think I will complete this one and pass it on to someone that needs/wants it.  That picture Mike put up of his Spotless Grey NC183D keeps flashing in my head. I would rather have that color and condition so it can sit next to the 60 and 50.

C

[ke7trp]

Ok. I spent a few hours with the rig today.

1.  The S meter is not broken. Its the rig.  The S meter wont go below about 10 DB over 9.

What caused me to believe the S meter was bad was this video:

http://youtu.be/iH8MOJ6nOLc

It seems that SOME NC183Ds have the meter resting at 0 when off and some rest at full scale when off!!!    In that video, that mans reciver is clearly OFF and its at 0.  I googled searched NC183D and started looking at photos and found some at ) and some at 60DB when off.  WTF???l  MINE reads full scale when oFF and when you turn it on, the needle Drops down towards 0 or trys.

I found that the S meter pot was 1K.  Its listed at 2 meg.  I got a 1 meg out of the junk Drawer and put that in. No change.  Zeros to the same spot. I then put my Resistor sub box in line and tried different resistors.  No change. The meter wont read below 10DB.  The meter WILL read above this with a strong station as normal.

2.  I have - 2.8 volts on the Grid of the first Tube after the AVC.  If I rotate the RF gain control this goes to -24 volts. 

If I Flip the AVC OFF, the volts go to -1.2 and distorts badly.  I checked ALL the caps and resistors one by one and found nothing bad.  The rig was already recapped at some point. B+ voltages are very close to the chart on all tubes.

So what ever causes the AVC to CLAMP down harder, Is not doing its job. The 6ah6v tube that is in there tests strong on the TV7. I do not have another. I can order some tomorrow.  I did pull the tube and the audio is full on distorted.  So the tube is working but not as strong as it should. I have to back the RF gain down to 7 or 8 to get it to clear up.

I did find that someone installed those yellow tubular style capacitors in this section and I cant get a reading on TWO of them with the cap checker. They show 047 on the label but measure .15 on the new cap checker.  I lost interest before clipping them out.  Maybe tomorrow. They look brand new and are marked 630 volt.  They seem to be polarized.  I am going to clip them out and wire in some new 047 Orange Drops for good measure They are not polarized so it wont matter which way I put them in.

My last effort will be those caps and to order new 6ba6s and a new 6ah6 tube in the morning.  Past that I am lost.  Anyone have any suggestions?

What is the deal with teh S meter?  Is this S meter the wrong one?

C

[Jim, W5JO]

The meter is right provided you have the 6SN7 phase inverter and meter driver.  If you have the 6C5 phase inverter the meter works differently and rests at 0 when the set if off.

You don't say where the caps are that don't read right on your checker or what kind of checker it is.  You may be on to something if they are bad.  The 6C5 phase inverter version has the 2 meg pot the 6SN7 has a 1K.  Check to see which version you have and follow that diagram.  I have the 6C5 version and setting the pot doesn't work like the other.

When it works right, that is a fine receiver.  I wouldn't get rid of it too fast, but that is a personal opinion.  They work very well when everything is right and they are as sensitive as one can find.  Be very careful around C48 the coupling cap from the last IF to the AGC amp.  In the wrong place it can cause you grief. 

Also be certain you follow the alignment instructions for the AGC transformer.  From the voltage reading you mention, it sounds like it is ok but check other stages for a similar voltage change without a signal and with one.

[ke7trp]

Thanks Jim.

I have the 6sn7 and I think I have some spares. So I will go swap one in and see if the meter starts to work.  The Schematic shows 2000 on the Pot for the meter.  Either way, I have plenty of pot there.

I did the AVC transformer alignment when I aligned the rest of the rig. It was way off. Someone tried to adjust it. I tried again today and I will now have to go back and align it again. I did get a sharp nul when adjusting it the first time around so I know it is working.

I will now redo the alignment for the AVC, Swap in an another 6sn7 and then check all the caps/resistors around the 6sn7.  The meter thing really annoys me.  I can back off the RF gain an bit, thats not a deal breaker.

C