[Hallicrafters] SX-32 and (vs.) NC-183 was: SX-42 Pedestal?

[Carl]

> Very interesting comments, Carl, especially from someone who knows the
> equipment so well.  You hit resonance for me on the SX-32 and NC-183. The
> SX-32 is awaiting rehabilitation.  The NC-183 is working.

You will enjoy the 32 Chris.


> A couple of weeks ago, I was participating in an evening AM roundtable on
> 160.  The noise level was unusually high - peaking S-9 (emanating from
> mysterious and off property electrical sources - no unusual atmospheric
> noises here in the Sacramento area).   Four receivers were simultaneously
> tuned to the frequency: S-76 (one of my favs), HQ-180, NC-183, and 75A-4.
> Three antennas were being utilized (one shared via RF splitter between two
> receivers) - no antenna is higher than 35 feet: 295' long wire, Carolina
> Windom with isolators, G5RV.


Never had a S-76, the rest are here also.


>
> The So. California stations (S-9 or below) were not readable through the
> noise.  Between the S-76, HQ-180, and 75A-4, the best any of these could 
> do
> on the SoCal stations, with or without the noise limiters, was R-1 to R-2
> (unreadable to barely readable, with occasional words distinguishable).
> There was also no audible difference between any of the antennas with any 
> of
> the receivers. OTOH, much to my amazement, the NC-183 which is a "new -
> recent acquisition" receiver to me, while not immune to the noise, allowed
> me to copy the LA stations with considerable difficulty to with almost no
> difficulty. The NC-183 circuit magic bumped up the readability by 2 "R"
> units. Again, no antenna showed any audible advantage on the 183, either.
>
> I don't understand this because the noise level was not being generated by
> internal receiver noise but external noise (disconnected the antennas to
> each receiver as part of this non-scientific comparison). While the noise
> limiters had some effect, the relative R advantage/disadvantage was still
> the same between these receivers.  Is there something about the design of
> the 183 that explains what I heard?


Two things come to mind. The 183 uses a new  series gate noise limiter with 
a dual diode and is faster acting on noise spikes that go above the audio, 
and its adjustable as with the earlier ones. I dont know if its a result of 
WW2 development in one of their several specialized radios or just something 
they decided to try.

The 183, 183D, HRO-50 and 60 also have measured among the best for audio 
recovery.

Id say its a combination of both. As the old saying goes: "If you want a 
frequency meter buy a Collins but if you want to hear them buy a National". 
Since that came out after WW2 Id say they already knew something!!

I have a NBS-1 which is a 183 variant with 3 IF stages and selectable IF 
selectivity plus the standard xtal filter. Performance is downright amazing, 
they are very low production but I know of 8 other owners. They go cheap on 
Ebay since its an unknown to most plus its a rack mount.


  Would the SX-32 enjoy the same
> advantage?


Its still basically a SX-28. Its advantage is the lack of the 6L7 IF which 
is part of the Lamb silencer. It is about the noisest tube built and 
overloads if you look at it wrong AND it is always in the circuit. The 32 
uses a standard single diode limiter that is not adjustable; the same 
circuit Halli used earlier.


Or is this the effect of too many years listening to Rush
> Limbaugh rants :-O !!


I enjoyed his comments the other day when he told the governor of NY to 
stuff it after his condo on Park Ave finally sold for 11.5Mil


> Any and all comments on how your SX-32's do in this regard will be
> appreciated.


I have several radios that cycle thru the 2 operating positions. The 32 gets 
it chance on a rotating basis and is a keeper. Its nothing spectacular; just 
a nice performing slightly updated SX-17 which is another of my favorites.


>
> 73,
> Chris
> W7JPG
>
> Carl: I would be pleased if you came back direct to me if you could help
> with some history on this NC-183; SN 202 0441; large print ink stamp near
> SN: 650 (there might be a much smaller "w" in front of the 650 but I may 
> be
> imagining it.
> Two small stickers on the bottom of the underside cabinet cover;  one is
> white National form (about 2" sq.) with a small 1946 ink stamped on it, 
> one
> is a faded off white color. It is also a National form about (2 3/4" sq)
> entitled: Standard Form Warranty" . "Repaired", "Aligned" both checked in
> the boxes; date is 10-4-Arrrrggggghhhh (illegible, the paper is there but
> it's like someone peeled off half the thickness of the paper.  Where is
> Miami CSI when you need 'em? *They* could raise the ink from the lower 
> paper
> strata!  My 10X Loupe couldn't make out any readable indentations.


Its from Production Run (aka Engineering Release or ER on the back cover of 
most all National manuals)202 and Serial 0441.

Cant help with the rest but I used to place a sticker with date and ham call 
on that plate if I worked on it. I was there in one job or another and 
sometimes 2-3 at once from 63-69.....Service Tech, Service Mgr, Sr Engr 
Aide, Acting Sales Mgr. It was fun while it lasted.

Funny thing is that I didnt care for any boatanchors when I was there, I was 
already into SSB and my favorite was CW DXing. Tried a Drake 2B which I 
quickly dumped, a SX-101 on loan from a friend, and then bought a 75A4 from 
one of the engineers who went to S Line. Spent a fair amount of time 
considerably reworking it (serious Collins nuts hate that but in 65 it was 
just an old radio) to survive in serious DXing and contesting and still use 
it paired to one of the TS-940's. For serious digging on 80/160 CW it cant 
be beat. It also hears much better on 10-15M unless I use a HB low NF preamp 
on the 940.

Carl
KM1H




>
> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Carl
> Sent: Wednesday, July 14, 2010 7:02 AM
> To: kirklandb at sympatico.ca; hallicrafters at mailman.qth.net
> Subject: Re: [Hallicrafters] SX-42 Pedestal?
>
> --------------- edited------------------
> I love my SX-28's and SX-32 but performance wise under battle conditions 
> or
> 10-15M it has a few flaws unless mods are made. For overload distortion 
> the
> SX-32 is better.
>
>
> The 1946 NC-183 is also a better performer, especially above 20M. This was
> Nationals first high end conventially switched radio and they went to
> extremes to minimize losses and ensure stability.
>
>
> Carl
> KM1H
>
>
>