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THE AM BULLETIN BOARD => Technical Forum => Topic started by: KB2WIG on November 25, 2017, 11:21:15 AM



Title: Fun and games with the NC-183D
Post by: KB2WIG on November 25, 2017, 11:21:15 AM
I recently picked up a National 184d that had been sitting in an attic since the early '90s. I used my incandescent variac and fired her up. Very little noise from the speaker, but the installed dual electrolytic seemed to be OK. So I started to replace parts, particularly wax paper caps as a online search returned tales of woe.

As of Wed night, most of the paper caps and almost all of the electrolytics were replaced. The static levels came up to a nice level, but no signals......  So, I grabbed my trusty GDO, and went searching for  its signal on 75m. MY scope knob(s) broke, and then the fun began. While moving the GDO dial around, I was able to 'find' the signal. So things are looking goodish, but with my 80m dipole connected, nothing off the air. Then .......   rocking GDO knob, out pops some CW. Tuning the GDO tunes the receiver !             Amazing!

 D'oh ! !  I've just replaced the LO.  With out the GDO, nothing.

I'm waiting for a tube shipment to shotgun the radio. I bought a  tube for the Converter and one tube for the IF locally, and continue to play around with this beast. ( Yeah, I can buy tubes from a real lectronics store ! Stewart W. Smith, here in Syracuse) Today, more parts to stuff inside.

If it snot one thing its another.

klc


Title: Re: Fun and games with the NC-183D
Post by: K4CCW on November 25, 2017, 11:32:04 AM
Restoring these oldies is always a fun education or, sometimes for me, a re-education. :D

The 183-D is still on my wish list, mainly 'cause it's such a good looker.

I'll be following your adventures with interest.


Title: Re: Fun and games with the NC-183D
Post by: KA2DZT on November 25, 2017, 12:28:06 PM
Check all the screen resistors throughout the RF and IF stages.  The 6BE6s converter tubes can be a problem.


Title: Re: Fun and games with the NC-183D
Post by: WD8BIL on November 25, 2017, 01:01:24 PM
Quote
Check all the screen resistors throughout the RF and IF stages.  The 6BE6s converter tubes can be a problem.
Yup...... what he said.
My R390A had a very low sensitivity problem when I got it. Turned out to be open screen resistors in IF amps 2 and 3!



Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on November 25, 2017, 01:33:54 PM


well, I'll not have to go boldly as someone else replaced the 47K screen resistors. These are a "known" problem area...... I've got 3 more 'problem' caps to replace.

This thing is complicated, so I am trying to get it going on the single conversion side. I wish I had got 2 of the 6be6 tubes,  the 183d is a dual conversion; so I don't have to trace out which Converter is only used for the 455 IF..... 

And its 1:30 PM, my 160m el is somewhat strung - I'm threading it between the trees and scrub.  SO its outside in the next few minutes and get the arrow out of the sky.

thanks,

klc


Title: Re: Fun and games with the NC-183D
Post by: WD4DMZ on November 25, 2017, 02:34:04 PM
The NC183D is one of the last receivers on my wish list. Next Frostfest in Richmond might bring me some luck. I will be watching your progress to find out where the big issues might lie should I acquire one.

The toughest receiver I have dealt with was a Hallicrafters SX42. What a chore as some paper caps in the RF amp sections are just not accessible. Once working it took a prominent place in my boat anchor station as it sounds great.

I learned what tubes need to be on hand for these kind of projects so am now rarely caught empty handed. However, every so often I need an odd one so I usually buy 2 of each when ordering tubes.

Keep posting.

Rich


Title: Re: Fun and games with the NC-183D
Post by: Jim, W5JO on November 25, 2017, 03:35:58 PM
I think you may find that the majority of resistors in the set have wandered off the reservation and  should be replaced.  Be sure to clean that switch that changes the conversion scheme well along with all the oscillator and mixer stage switch wafers.  If the IF transformers do not peak properly then you may have to go inside of the cans and replace the little mica caps.  I have seen several sets that required replacement in one or two of the transformers. 

If it has been in an attic and subjected to temperature changes then  switch contacts are probably covered with a difficult to remove film that prevents them from making good contact.  I suggest you not use Deoxit on them, I saw a 183D that someone used it and the stuff helped continuity between contacts.  Then after a good cleaning of the switch it came back to life.

Actually it is a very straightforward receiver and a very hot one once it is playing correctly. 


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on November 25, 2017, 05:19:50 PM
Rich, good points r/e the tubes. MY policy is to always have a replacement... or 5.   I was hoping the tubes would be OK. They all may be, but I ordered a replacement set anyway.  Like having 2 scopes in case one craps out.  Well  my Tek RM45 and 453 are kaput. the backup for  the '45  was the 453, which craped out yesterday ( I'm using a vise-grip to turn the TIME/ switch, so it works). Too lazy to fix things up, so now I suffer.

Jim, yes the switch contacts all seemed to be oil coated. I used C3H8O to clean things up a bit.  The ganged slide switch was very dirty, and still needs some work.My can of DeOxIt is at least 14+ years old. I use it, with tooth picks or Q-tips, very little. It's got Heptane, and we all know about that.

I'll keep all posted.

klc

P.S. I got the arrow back, and replaced the fishing line with #14 AWG THHN. 2?3  of the way there, so I'll pollute 160m this winter.


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on November 25, 2017, 05:48:30 PM
The 183 is one of the prettiest radios ever, I think.   I had one several years ago and sold it for some reason, so I had to buy another here a year or so ago.

(https://photos.smugmug.com/NATIONAL/183/i-3GdHMcW/0/7743bb99/L/DSC_2059-L.jpg) (https://mikeharrison.smugmug.com/NATIONAL/183/)

They're easy to work on, and the size of capacitors today make replacing the oldies a snap.   I used a piece of Vector board to mount the replacement PS caps on.  

Just remember, the positive end of C-65 goes to ground, and negative goes to B-, along with the negative of both sections of C-64.   None of those two cap's negatives go to ground.
  
(https://photos.smugmug.com/NATIONAL/183/i-6xqc878/0/6f96bd73/XL/FltrsCloseUp%202-XL.jpg) (https://mikeharrison.smugmug.com/NATIONAL/183/)


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on November 25, 2017, 06:58:24 PM


M, have no fear, the caps are safely " above gnd ".


KLC


More to follow.


Title: Re: Fun and games with the NC-183D
Post by: K4CCW on November 25, 2017, 09:15:16 PM
The 183 is one of the prettiest radio ever, I think.

Indeed! And yours is a great specimen, Mike.

Quote
They're easy to work on, and the size of capacitors today make replacing the oldies a snap.   I used a piece of Vector board to mount the replacement PS caps on.  

I like that method, Mike. I hope it's not patented. :D


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on November 26, 2017, 08:23:31 AM


Quote
I like that method, Mike. I hope it's not patented. Cheesy
If it is, I guess we'll both be getting a letter!!


Title: Re: Fun and games with the NC-183D
Post by: WA4WAX on November 26, 2017, 04:55:09 PM
Terry of D-Labs is a good resource.  Here is one of several videos on the 183D.

Matt

https://www.youtube.com/watch?v=JJMhDsX7ixM


Title: Re: Fun and games with the NC-183D
Post by: WA2SQQ on November 27, 2017, 09:08:01 AM
About 45 years ago I had a one of these. I did a real stupid thing - I repainted the case to a wrinkle finish black. Beautiful job, buy looking back I can now appreciate what the original paint is worth. I often wondered what ever happened to it. It would be a real easy one to spot!


Title: Re: Fun and games with the NC-183D
Post by: W7NGA on November 27, 2017, 09:28:56 AM
The NC-183 restoration was fun. Same with the HRO-50T1 until I found the big slab of asbestos shielding the power supply!

W7NGA dan
Seaside, Oregon


Title: Re: Fun and games with the NC-183D
Post by: WA4WAX on November 27, 2017, 12:01:45 PM
Another D Lab video.

https://www.youtube.com/watch?v=EatZT8shpJA


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on November 29, 2017, 06:28:48 AM
Quote
...same with the HRO-50T1 until I found the big slab of asbestos shielding the power supply!
So long as you don't mess with it it's fine. 

Its when you start messing with it, trying to remove it, or otherwise creating dust, and inhaling the stuff, that you start putting yourself in danger.  As the saying goes, "leave sleeping dog lay".   

If you feel you MUST to do SOMETHING, brush, don't spray, a liberal coat of clear polyurethane on it, being sure to cover the edges.


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on November 29, 2017, 10:23:46 AM

Well, after replacing almost all the no mica caps, and nothing inside the IF cans, I exhibited due diligence and recorded voltages.  all the 6v filament voltages were 6.35 volts, so that's not much of a problem. The most disturbing results are in the IF stages. The first grid of  the 6BA6 IF's are supposed to be 2.3 V; I'm getting  - 3.14 V.   It looks like I'm going to have to go in the IF cans themselves and see if something is amiss.

( the anode(s) of the 2nd detector are both off...  pin1 1.4 V is 3.23 V, pin7 -2.6V is -4.07 V).

New tubes arrive today.

klc


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on January 26, 2018, 09:18:31 AM
HELLO KEVIN!!   Did you fall off the edge of the earth?   

Last you said was "new tubes arrive today".   So whats happened since November??


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on January 26, 2018, 10:03:55 AM

Well, antenna weather arrived, the holidays, a few honeydews, and various crapouts....  i  replaced a few tubes, ill plug in the rest...


The 160m eL was strung up, and that entailed a lot of brush/limb cutting. I've only about 650' of radials on the ground. I picked up a 500' roll of #20 'electronic pet fence' at homely despot for $5.00. that's going in today. Got a antenna analyzer kit built, and that should speed things up.


More to follow


klc


Title: Re: Fun and games with the NC-183D
Post by: WD4DMZ on January 31, 2018, 09:14:03 PM
The Richmond FrostFest is this Saturday and if I see a clean 183D at a reasonable price I will bring it home. Then I can join the discussion.

Rich


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 18, 2019, 12:02:52 PM


ROUND TWO


(got a new scope)

After replacing all the RF/IF tubes, i get louder hiss from the speaker.

I' m just playing with the 2 lowest bands, single conversion, to make things easier.
My guess is the IF cans are screwed up, but usind a GDO for a signal source isnt the best way to go with this thing.....   the HP 8656B  is scheduled to show up Friday next week, but in the mean time, i'll see about brewing up a rf tracer.

KLC


Title: Re: Fun and games with the NC-183D
Post by: WA2SQQ on April 18, 2019, 02:20:18 PM
I had a 183 back in 1975. For reasons I'll never be able to justify I decided to repaint the entire case wrinkle finish black. The paint job came out excellent, and I often wondered where it is today. It would be very easy to identify! I bought it for $35 and sold it for $50.


Title: Re: Fun and games with the NC-183D
Post by: w9jsw on April 21, 2019, 09:17:24 AM
One of these for sale on QRZed. The fellow is in VA...


Title: Re: Fun and games with the NC-183D
Post by: Jim, W5JO on April 21, 2019, 03:17:30 PM


ROUND TWO




After replacing all the RF/IF tubes, i get louder hiss from the speaker.

My guess is the IF cans are screwed up, but usind a GDO for a signal source isnt the best way to go with this thing.....   the HP 8656B  is scheduled to show up Friday next week, but in the mean time, i'll see about brewing up a rf tracer.

KLC

If you are seeing a sharp peak when you adjust the cores, then the cans are probably fine. If the peak is broad, then suspect the caps in them.  This is not to say they will stay that way forever so monitor the operation after you get it going.

The big thing is have a calibrated source to check everything and do stage gain measurements as you go.  That will tell you which stage needs attention.  I had one in the past that lacked output of the crystal filter and it turned out to be the switch in the filter can.  A little cleaning of those contacts fixed the problem.



Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 21, 2019, 08:20:43 PM


J,

I'm a bit hesitant to diddle with the transformers yet; peaking to test is a FB idea.

When I get the 8656B this week things should go better..... the ePay seller had 5 or 6 pictures of the unit operating into a scope, so I guess it should work out OK. I considered buying a plastic Chinese generator, but HP ( or whatever its called now) has the name.

We'll find out this week.

klc


Title: Re: Fun and games with the NC-183D
Post by: Opcom on April 22, 2019, 08:41:37 PM
That;s a great radio set!
I had one before trading it for an SX-28 because the fellow said the SX28 was too heavy and had too many controls. Fact is the -28 had issues with which I was to be surprised later.


Title: Re: Fun and games with the NC-183D
Post by: WA1HZK on April 23, 2019, 09:40:53 PM
I have a copy of the manual.
You probably have it but just in case.
Keith
WA1HZK


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 24, 2019, 11:47:42 AM

K,,

Thanks for the offer... i've been using a BAMA manual thats not real good, and Mike, ke0zu has a flow chart of the beast......   curently waiting for a copy from Pete,  el manuel man.

KLC


Title: Re: Fun and games with the NC-183D
Post by: Jim, W5JO on April 24, 2019, 04:54:02 PM

Thanks for the offer... i've been using a BAMA manual thats not real good, and Mike, ke0zu has a flow chart of the beast......   curently waiting for a copy from Pete,  el manuel man.

KLC

I hope you discussed which version of the schematic you need.  There were several versions of the schematic and two different versions of the radio itself.  One has a 6SN7 for a phase inverter/S meter amp. and the other measures AGC for the S meter action and uses a 6J5 as the phase inverter.

If you run into trouble there are many here that can help.


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 24, 2019, 06:44:12 PM


J,

I've the 'old' one, the 6J5 phase inverter.


The HP showed up at the door, so I'll skip out early from work tomorrow, grab some N connectors and and brew up some leads.  Syracuse has an actual electronics supplier, ( tubes in stock !) so I can get stuff locally.

more to follow,

klc


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on April 24, 2019, 10:37:55 PM
I have two flow charts for the 183, follow the link in the Sig line below, and the ER (engineering run) numbers are in the title blocks.  
My understanding is that each production run of radios, regardless of model were built to a particular Engineering Revision, with the appropriate printed owners manual, so you won't necessarily find the manual with the exact ER for your radio, simply  because there were so many issues of various manuals.


ERs are noted in the lower right hand corner of the rear cover.

(https://photos.smugmug.com/NATIONAL/NC240D/New-Rs-and-Cs/i-S96hNLn/0/382a38f8/L/Manual%20ER%20Cropped-L.jpg)  


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 25, 2019, 03:58:41 PM


M,

I've got your ER328 flow chart. ( I guess I can call it that??)

We'll be posting some updates either tonight or tomorrow r/e status of the IF.  Who wudda thought binary signal tracing would be so hard.

klc


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 26, 2019, 11:12:19 PM


The 1st converter has what appears to be a nice 71.4 Mc  signal........ 

This does not look good.

klc


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 29, 2019, 12:08:36 PM
  


V3  1st converter

71.4 Mc.signal.

Rcvr tuned to 2.2Mc, "D" band  1.55 to 4.4 Mc tuning range.. Single conversion on lower 2 bands, dual conversion on upper bands.


Any guesses as to why I 'm getting this???      《 《  I didn't post it up side down, the phone did it  》 》

KLC


Title: Re: Fun and games with the NC-183D
Post by: MikeKE0ZUinkcmo on April 29, 2019, 10:04:15 PM
Have you verified the BS knob is installed/oriented on the shaft correctly?

Have you checked the "single/double" converter switch for continuity, wiring?

DC Voltages OK?

Have you tried another tube?

Are the terminations, L-21 / L-39 OK?

Checked/replaced Bypass caps C22/23/61?

Have you cleaned the tube socket?

What probe are you using, X1, X10?

Where in the converter circuit are you looking?

AFN












Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 29, 2019, 11:25:24 PM


M,

A few quick answers before beddy-by. I'm trying to get this thing working 'single conversion' before I play around with the other bands.

I'm using 10X probes for the scope.

I've looked at pin1 for the LO and also at L19. The tube is a NOS 6BE6. I've replaced (3) 6BE6,(4) 6BA6, all NOS, and the 6AH6 with an unknown age. I have also swaped the 6AL5s, as I can't find any of my own.... I'll probably replace them with NOS ASAP.

I'll check the bypass caps, L-21 / L-39....

For voltages, V1,V2,V4,V7,V8 and V10 have some voltage values outside of published figures. I did take measurements per the Manual instructions.

No' I haven't cleaned the tube sockets. Most of the swaped tubes were 'tight' when replaced. Something to do.

The converter switch works O.K.. As far as the bandswitch, I think that's OK also -  doesn't look like anything has been moved.  I have not replaced any of the alleged SM caps or resistors in the coil/trimmer sections. I left the disc caps alone, but replaced almost all other resistors and caps in the radio.

Thanks for the input, now we'll see what I can do with it.

klc


Title: Re: Fun and games with the NC-183D
Post by: WZ1M on April 30, 2019, 02:37:29 AM
Food for thought, voltages will be off if your running 120 plus AC volts on the power transformer primary. I would run the 183 off a variac.
Just saying,
Gary


Title: Re: Fun and games with the NC-183D
Post by: KB2WIG on April 30, 2019, 12:07:56 PM
8

G,

Good idea. Future plans are to run the receivers off of a seperate, controllled ckt to keep things around 115.

As of now most of the voltage anomolies are of low voltages.

KLC


Title: Re: Fun and games with the NC-183D
Post by: Bob W8LXJ on April 30, 2019, 02:45:05 PM
  My 183D had sat in the heated room for 25  years, never plugged into 110 or turned on.
At 85 VAC, started to get high voltage DC on the tubes. A few Black by pass caps smoked and replaced them. Tube pins were tight in the sockets from oxidation, a lot of detox on tube pins, sockets, and rotary switches. Started to come to life, but tubes were gassy. After about 10 hours of 115VAC, started sounding better but not as good as the HRO 60 which is my main AM receiver. Have had the 183D since 1954, was my only receiver until  1970s when I went to SSB.

 Bob  W8LXJ,  Kw-1 and National and Collins receivers
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands