[Hallicrafters] More S-40 questions

[Mike Everette]

Hi Gene,

The S-40 is one of the "standard" designs that carried
Hallicrafters along for many years.

The S-20R begat the S-40 -- same circuit, with a few
tube changes such as the 76 BFO being replaced by a
6J5; and a "new" cabinet.  It's real interesting to
look at the 1946 ads for the S-40, which seem to put
more emphasis on the cabinet styling -- perhaps to
keep one from noticing that it's "same-ol'-same-ol"
inside...?

The S-40 begat the S-85; again, a few cosmetic circuit
changes such as lowering the upper band limit from 43
MHz to 34, and a new cabinet (here we go again).

The S-85 begat the S-108, exact same circuit in
(again) a new cabinet.

Similarly, the SX-24 was similar to the S-20R but with
a crystal filter and S-meter.  The SX-24 begat the
SX-99; there was no comparable "update" to the SX-24
to compare with the S-40.  One may have been planned,
but it wasn't produced.  The SX-99 begat the SX-110,
exact same circuit as the 99 (and the SX-99 Sams
underchassis map works for the 110, believe it or
not), exact same circuit as the 99 but in a new box.

All this being said, it means the design was pretty
darn good.

I like the sound of SSB audio on the S-40; with thw
wide IF, it really sounds good.  The downside of
course is that the selectivity leaves a lot to be
desired on a crowded band; but when one understands
the operation of the radio and how to get the most out
of it, the results are excellent.  

A fine accessory for the S-20R/S-40/S-85/S-108 etc is
the Heathkit QF-1 Q Multiplier.  You can get the power
directly from the 5-pin accessory socket and the IF
connection can easily be made to a pin on one of the
IF tubes.  A crystal calibrator is a necessity. 
Again, you can take the power from the accessory
socket.  With those weapons added to the arsenal
you'll have a lot of fun.  

Don't forget to periodically clean the band switch,
the front end tube pins and sockets (ALL the tubes and
sockets need it of course) and the wipers on the
variable caps; that will exterminate a lot of the
"halli-bugs" that make the receiver (and many others)
appear unstable.

73

Mike
WA4DLF




      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs