Some People...

[w5hro]

I have a grip about an item I just sold via eBay. I sold my near mint NC-183D receiver just recently for $949 on eBay. It might seem like a very high price, but that is was it was worth to me and I wanted it to go to a good home. I did not want to see it get shipped overseas like much of the American made equipment has ended up. I knew that if someone was willing to pay that high price it would be someone who really wanted it and they would take care of it because they would not be able to make any profit.
 
Here is my grip; the A-hole in New York who bought it just sent me an email today complaining that it didn't work very well. He said it had low sensitivity, the resistor tolerances were way out and the audio sounded distorted, etc. Well, I used the receiver all last winter for SW listening because of the great high powered audio quality via the two 6V6GT’s in push-pull and it never sounded distorted. Anyway, the NC-183D’s are known for having very low sensitivity on the higher bands and the receiver was all-original. It had all of the original tubes; resistors and capacitors except for maybe the electrolytics in the AF final section. I think I did replaced those years ago, but I can’t remember for certain.
 
Its common sense that when you have a receiver made back in the 1950’s such as the 183D the components are going to have drifted. Nevertheless, none of the caps in the receiver were shorted and everything was working and nothing was missing. The receiver was in excellent cosmetic condition with only a few (3 or 4) very light scratches on the sides.

Its obvious this idiot must be a newbie and is probably using the receiver with the AVC turned off which is why he is getting the audio distortion. He probably has no experience with the old antique gear and just assumed it should work like a modern ricebox. I already received the money via PayPal minus the eBay and PayPal fees, but if anyone knows who this A-hole is please purchase the receiver from him so it will have a good home.

[k4kyv]

90% of the carbon composition resistors of that age will have drifted off the original values, even new old stock that have never had a soldering iron touch their leads.

But over 90% of the ones in a circuit that have drifted in value will have no discernible effect on operation.  I change them out only when they actually cause degradation in performance, which is very seldom.  I suppose the drop off in performance could be cumulative, but I have never seen any improvement in anything that I have "repaired" by replacing drifted resistors.  Mine usually increase in value, sometimes by as much as 50%.

If it's a drastic change, which happens sometimes, that is a different story, and usually fixes the problem.

Also, I have found the drifted values of old resistors to be just about as stable as they ever were.  The change seems to take place over an extended period of time.  I have several boxes full of composition  resistors.  For handling any significant amount of power, I prefer them over film resistors  - films seem to be about as delicate as solid state devices, and are not always guaranteed to be non-inductive.  If I am building something and can't find one that is still in tolerance, but I run across a different value one that has drifted within range, I use it, and this has never given me any problem.

In restoring antique equipment, I have been known to re-paint old body-tip-dot resistors to represent the measured value of replacements.

[Tom WA3KLR]

My dad's NC-183D developed weak reception a few years ago.  The main culprit was the rf and if amplifier screen grid dropping resistors going up in value.  Every resistor of that value and appearance in the set was bad.  (There appeared to be 2 distinct vendors of that value.) There was one weak tube replaced but not a problem.  The radio was never worked on since new.

I found ALL of the audio section capacitors and resistors bad - first audio, phase inverter, audio output stage and even the output feedback components. 

Also the audio output transformer looks like it has a design problem.  I could only get 3 1/2 watts out.  Many many troubleshooting test were done. The transformer is not shorted or something like this.  I came to the conclusion that there was another transformer vendor (or lot) and that the turns ratio is not correct.  Some units do put out 10 watts of audio I believe.  The one other ham that did check his NC-183D audio output power for me also came up with 3 1/2 watts out.

[K3ZS]

I have a 1947 NC-183 (not D), that I have had since 1958.   When I was a young ham I thought it had great sensitivity, that it seemed to have lost over the years.  As Don has noted, most of the resistors had changed in value.    I replaced mainly the screen dropping resistors and all of the ones in the audio stages.   Also had some leaky paper capacitors, which were all replaced along with a power transformer that burned up because of some leaky caps.    The receiver then worked as I had remembered it.   The NC-183D does not have low sensitivity on the higher bands if it is aligned correctly and working correctly.  I believe it has two tuned RF stages like the NC-183 has.   I don't believe there is any obligation for sellers on ebay to replace resistors on old equipment unless it is claimed that it has been done recently.

[WQ9E]

As an ebay buyer, all I really want is an honest description and it sounds like you certainly provided that to him.  With this older gear you can have all original with generally less than perfect performance, restored properly with good performance, or (unfortunately too common) a hack job restore and poor performance.  For his $900 it sounds like he got a very nice looking NC-183D that could be restored, if he wishes, to pristine electrical performance.  Probably a bit of buyer's remorse or as commonly referred to in marketing, cognitive dissonance which is very common after buying something "pricey".

The first real piece of vintage gear I bought was an NC-183D back in 1983.  It looked great but performance was pretty weak and at that time vintage gear wasn't collectible so it cost me all of $10.  That receiver had more WAY out of spec resistors than anything I have seen since.  I remember in particular the 47K screen dropping resistors, of which there were many, were all consistently within 10K of 270K and I wondered at the time if a receiver could have been built and gotten through National quality control with mis-marked resistors.  There is a note in the owner's manual from the original purchaser noting poor gain and he changed all of the band switched gain adjust resistors so that it ran full gain on all ranges.  Once I went through and changed all of the out-of-spec resistors it really came to life except for the top frequency range.  I finally traced that to inadequate oscillator injection on that range due to a damaged coil. 

I don't recall ever measuring the sensitivity on my 183D but I do know that peaking the trimmer causes a definite increase in background noise on all ranges so in my fairly quiet rural location it has all of the sensitivity and gain it needs.  I am still amazed how well the calibration holds across the bands on my NC-173, 183, and 183D receivers.

Rodger WQ9E

[WA1GFZ]

only a moron will pay almost $1K for that radio.

[wb1ead]

Aft all..wow $949!..have my eye set on an NC 173 w/spkr unrestored..noticed that E-Bay has one now for $62 with a day left..last one sold for $76..did not realize the huge differences in prices between these 2 models..can anyone enlighten me as to why..the 183 has an extra RF sect and dual output on the AF but is that about it?..Sorry Brian didn't mean to go off on another tangent but ur experience with the buyer we all can relate at one time or another..I usually STRESS "as is"..several times   73 de DAVE

[W7SOE]

I might try to explain to him how the radios age etc etc.  For that kind of dough he might expect at least some verbal customer support...........

[W1RKW]

Some people prefer cupcakes.....  I for one care less for them.
Frank Zappa

[k4kyv]

My first real "communications" receiver was an NC-173.  I used it to replace the converted AM broadcast receiver with SW and LW bands with homebrew add-on BFO.

I used the 173 for several years until I acquired a 1935 vintage HRO in the late 60's.  The HRO was so much better that I ended up giving away the 173 to a friend, just to get it out of my way.  But the HRO didn't perform well on 10m, and was made before the advent of 15m, so I had no bandspread coil for that band, and besides, it used the same coil for 15 as it  did for 10.  The HRO was superb for 160-20, but it was built before the technical design for 10m reception had been perfected. 

The 173 was sensitive enough on 15 and 10, fairly selective, but its frequency stability and image rejection SUCKED.

[K3ZS]

They added the extra RF stage in the NC-183 to improve image rejection.   The 183 image rejection still sucked.   Didn't they use the NC-173 on the Kon-Tiki expedition.   Maybe that's why they had trouble with communications.

[WQ9E]

They added the extra RF stage in the NC-183 to improve image rejection.   The 183 image rejection still sucked.   Didn't they use the NC-173 on the Kon-Tiki expedition.   Maybe that's why they had trouble with communications.

There was a nice article in an early ER about the NC-173 used on the Kon Tiki and it got a salt water bath but did come back to life; not too shabby.

The image rejection on the NC-183D is pretty good since it operates with dual conversion (1720 Kc first IF) on the higher bands.  One of my NC-183 receivers would make an awful crackling sound after a few minutes of warmup; it turned out to be an air dielectric temperature compensating cap across the oscillator section of main tuning cap was shorting.  I guess this cap was an attempt to address the drift issue but it sure had me searching for awhile to find the problem.  It appeared to be factory given the mount for it was integrated with the main variable cap frame.  It looked a lot like an old style neutralizing cap.

Rodger WQ9E

[K1JJ]

only a moron will pay almost $1K for that radio.

You're killing me Frank - right to the point...    (choke-choke-gag)

T

[Opcom]

"a-hole from NY".. there are a few there. I guess that was one of them. Maybe it's a perception due to the different culture.

If someone wants it or thinks it's the best, the willing buyer is the key and they have a right to complain -only- if they did their research and were mislead. Not radio related, but I'm about to lay out the bucks for a pair of Wesco "boss" boots made to measure. Sure there are way cheaper engineers' boots out there, but there's no guarantee they'll fit well or be tolerable to wear all day. (I'm an engineer, I should have the boots right?)

High-dollar stuff is a long term item, like that radio will be for that New York gentleman. Same as the person who lays out $20K for a restored car, or $3000 for a sweet-looking Zenith shutter-dial console that "plays well". It's not necessary, but it's what they want. People have spent more on stupider stuff, like $5K worth of 24" rims for the proverbial $300 chevy caprice. His money..

The guy probably felt the same about the particular radio, was in love with it or really needed it somehow, but he didn't take the time to ask about it and discovered its design imperfections after receiving it due to his own ignorance of the model itself and is trying to blame the seller.

[W3RSW]

Fun boots.
Ya gotta take care of your feet.

-and just about everyone knows the difference between engineers' boots and cowboy boots. 

[K1JJ]

Give me a pair of EEE wide engineer boots anytime.  Have a set and love 'em!    No pointy, tight shoes or boots here.

(I'm NOT known for my trend setting styles, however... )


T

[c. mac neill w8znx]

ive bought and sold on e bay

calling a buyer
that is not here to defend them self
idiot newbie a-hole
is poor taste

the NC-183D is one of Nationals better
band set band spread general coverage receivers

dit dit
mac

[Opcom]

I never try to be Mr. Style. Huge useless drain on the funds. Hate the pointy and the silly/weird too. It's like the designers of so-called fashion are trying to see who can con the sheeple into buying the most outlandish stuff.

Not sure about being in it? deep, I just want to try the best for once and the choice is conservative. I don't like cupcakes either. Leave them for the ladies. I like pi.

I had a 183D for a while so I can opine that whatever version, it was a great SWL radio for fun back in the day, but it is not the best model if performance expectations are high. The HRO Sixty is a much better radio and the only reason I do not have it any more is it was traded for an R390A. I eventually traded the 183 for an SX-28 and I am more pleased with that. Maybe it's subjective. Either one can make good use of a 10dB preamp for the high end if a bandpass/BC filter is placed before it.

[Tom WA3KLR]

I'm surprised of the comments about this double-conversion receiver with 2 r.f. stages being insensitive and having poor image rejection.

When I overhauled my dad's NC-183D I did a full re-alignment including the optional plug-in FM adapter.  I don't recall a sensitivity problem.  I did use my r.f. swizzle stick (brass tip one end and ferrite tip on the other end) to prove that the coils were perfectly aligned and tracking perfectly.

In a couple days I will be visiting my dad’s QTH  and will dig into that receiver's file folder to see if I recorded any sensitivity and image rejection numbers.  He has a HP-606A signal generator so maybe we will make some new measurements.  I will report back.

[Opcom]

well, I can't say I had any decent test gear back when I had mine, and I didn't know how to fix radios back then. Maybe it was out of alignment. It came from a ham, it should have been in order.. or so I believed back in them ancient days. haha I know better now! But at the time I thought it was a very fine radio, and that changed only when I got the chance to try one that worked alot better.

Isn't there a website that compares old comms receivers specs? That could provide some answers about it.

[Tom WA3KLR]

I was at my dad’s QTH today and read through his NC-183D file folder – no notes on the  sensitivity or image rejection from when I overhauled and re-aligned the receiver a few years ago.  So I fired up his HP-606A rf generator and did some testing.

The receiver has plenty of overall gain and is capable of driving the speaker with noise to a loud level without an input signal on all bands.  I recorded the level at which you could begin to hear (but not straining) the 1000 Hertz 30 % modulated signal AM signal. 

For image rejection I used the S-meter at S-4 or S-5 for reference.

Results:

Frequency   Audible signal  image rejection
3850          <0.1 uV             75 dB                      single conversion
7200           0.2 uV           118 dB (compression?) double conversion     
14200         0.35 uV             93 dB                    double conversion     
29000         0.35 uV             58 dB                    double conversion     
51000         0.5 uV               40 dB                    double conversion 

The performance looks o.k. to me.

[Tom WA3KLR]

Hi Brian,

My sensitivity numbers are not 6 or 10 dB S/N AM sensitivity numbers where the modulation is turned on and off to see the S/N ratio, they are just to hear the modulation 1000 Hertz tone being recovered in the noise.  I do trust the HP-606A calibration.

[Steve - WB3HUZ]

No sensitivity measurement I've ever seen was for 20 dB SNR.

[Tom WA3KLR]

Brian,

Sorry to hear about the -606 transformer.  I will look at my manual to see what would be the specs.  I don't know off the top of my head of sources for exact replacement except to canabalize. 

I have been looking at NC-183D ads in the old ARRL handbooks.  My NC-183D manual had no specs!  However it did state that the input impedance is an average of 300 Ohms.  The input is a balanced link input.  I have a 50-to-300 Ohms balun and may try that next time I am at my dad's QTH.  That should give a voltage step-up and may improve upon the numbers.  I will do the proper 6 dB S/N measurement.

The late 1950's ads quote 2 different specs for AM sensitivity:
1. "3.5 uV for 10 dB S/N"
2. "1.5 uV for 6 dB S/N, entire range".

[Tom WA3KLR]

Brian,

I have my HP606B manual out here.  The power transformer has three secondaries with no center taps.  Each secondary runs a bridge rectifier.  

I feel that those early silicon diodes were unreliable then and especially now.  Shorted bridge diodes is probably what took out the transformer; was the fuse size proper?  Replace all of the diodes at any rate (if you get a transformer) by putting in (2) 1N4007's in series in each leg of the 3 bridges.  No matter how high the PIV rating of replacement diodes, if you just use one per leg and they short, things will cook.

The 3 windings are 315 V, 220 V, and 31 V.  Remember this is my 606B manual.  There are 3 series regulators then giving +300 Vdc, -200Vdc and +25.6 Vdc.  I don't know the currents, but there is a fuse in the +300 V supply bridge from the
 (-) output to ground - F2 1/4 Amp.
Gives you an ideas on the 315 v winding current.

The bridge for the -200 V supply (220V winding) has a fuse from the
 (-) output to ground - F3 1/8 Amp.

No fuse in the +25 V volt supply.

Unfortunately an odd combination of secondary windings.  Well there should be junker 606s around.  The part number for the transformer in the HP-606B is 9100-0375, manufacturer coded as HP.