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

[Chris Kepus]

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.

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.

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?  Would the SX-32 enjoy the same
advantage? Or is this the effect of too many years listening to Rush
Limbaugh rants :-O !! 

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

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.
  

-----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