[Hallicrafters] SX-73 VS: SP-600-JX Comparision question

[Carl]

Ive had both but never at the same time. A R-274 Halli has been in use here 
for almost 2 years and Im very pleased with it for general SWL band 
cruising. It replaced the HQ-180 when it developed SMD and has been sitting 
waiting its turn for an annoying repair job.

Its an extremely easy radio to overhaul as everything is out in the open 
unlike the SP-600 where its a major PITA to replace some paper caps.

The Halli has far less drift and with the single dial its a dream to tune 
with its excellent feel gear reduction. Neither has great audio as expected 
in a military radio but its far superior to a stock R-390A. No image 
problems as expected with dual conversion.

Sensitivity is more than can be used with an antenna attached and it 
compares well with my R-390A and souped up HRO-60. It has better audio than 
any Collins but nowhere close to the HRO-60 or any radio with PP audio. Both 
my R-388 and 51J4 dont hear as well above around 21 MHz. Thanks to the very 
low loss tuning turret the Halli is even quite good on 6M; removing and 
cleaning all the coils and turret contacts is important as are the catacomb 
Nationals. Id say that due to the difference in bandswitching that the Halli 
has the edge on sensitivity over the SP-600 on 6M and likely also on the 
high end of Band 5 where it wouldnt be noticed in the real world.

This is not your average Halli, it bears no resemblance to any and the 
transformer doesnt even get more than pleasantly warm. It looks more like 
something built by RCA or TMC.

SP-600's are everywhere while the Halli is somewhat scarce but not really 
rare; I dont know the production but the civilian SX-73 was very low 
production.

Carl
KM1H


----- Original Message ----- 
From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
To: <Hallicrafters at mailman.qth.net>
Sent: Wednesday, November 03, 2010 5:14 PM
Subject: [Hallicrafters] SX-73 VS: SP-600-JX Comparision question


>      I have long been curious about the relative
> performance of the SX-73 and SP-600-JX. The SX-73 was
> obviously built to meet the same military spec and bears the
> same military type number. It is not a clone but a unique
> design. I have seen very few and never actually used one. It
> has some features that look interesting such as regulated
> filament voltage for the oscillator. I've found that the
> SP-600-JX drifts with line voltage changes due to
> sensitivity of the filaments to the variation. It also
> appears to have a less delicate turret mechanism. I am
> curious to hear from those who actually have these receivers
> and can tell about their performance and how difficult or
> easy they are to work on. One merit of the Hammarlund RX is
> that its relatively easy to repair despite the complexity of
> some parts.
>     Also, does anyone have any idea of how many SX-73s were
> built and over what time period.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
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