[Hallicrafters] HT-37 saga epilogue

[Al Parker]

Hi all,
    I have recd several comments and questions after my HT-37 saga notes,
basically in 2 areas, "how's the comparison to the HT-32?", and, "what
about the SS'ing of the p.s.?   This is a response to the list, for the
benefit (?) of all.
    1.  How do they compare?  On the audio quality, I'll just say that's
it's in the ear of the beholder.  The operator can't hear what's going out,
only the receiving operator can.  I haven't operated the 2 xmtrs side by
side so I could put them both on the air at the same time, with the same
microphone.  That would be the best way, if the rcvg op had good ears (I
don't).  I have gotten good reports on both rigs.  The phasing system of
the HT-37 is "supposed" to be better, many op's know that, and if they know
that's what they're hearing, their opinion may be tainted.  Nobody's said
the HT-37 didn't sound good, similarly, I get good reports for my CE 20A,
also a phasing rig.  Maybe some day I can put both on the air at the same
time and get some real comparative opinions, particularly if I don't say
which is on at which time ;-)
    Physically and electrically?  There are very few electrical differences
beyond the SB generation.  Even mechanically the chassis layout is pretty
much the same, it might even be possible to swap SB generators from one to
the other without too much trouble (neglecting the panel controls).  But
the external cabinetry, panel, & knobs of the HT-37 show the cost saving
that was a main feature of the HT-37.  It is definitely less solid, more
flexible, and to me not as attractive.  When my daughter, married, not
living with us, first saw my refurbished HT-32/SX-101 station, her
immediate reaction was, "aren't those beautiful radios?"  I doubt that
she'd have the same reaction to the HT-37, it is definitely a boatanchor,
and attractive, but ---?  I think the SX-101 is the prettiest receiver
made.
    Some HT-37, and I think HT-32, vfo's take a long time to stabilize.  My
HT-32 doesn't, it doesn't move any more than about 150cy from 1 min. after
turn-on for as long as you care to wait.  I can't say the same for the
HT-37, tho' I haven't put a freq. ctr on it like I have the HT-32.  The
HT-37 does drift some for at least an hour.  I don't think there is any
difference in the construction or components, but haven't examined closely,
maybe some one else can fill us in.
    2. SS'ing the pwr supply?   The HT-32/37 pwr xfmr is a "high failure
rate" item, and the extra line voltage and the resultant extra internal
heat are probably the main reason, made worse by moisture, if the unit's
not been used for a long time.  They usually develop leakage or shorts,
between the HV winding, a 5v winding, and ground.  It's happened in 2 HT-3x
xmtrs, an SX-28, SX-101, and SX-42 of mine.  Replacement of the rectifiers
with solid state items is one way of reducing the heat.  That will raise
the DC voltage a bit, but that's not too much of a concern in these
transmitters, tho' isn't a good idea in some rcvrs unless some means of
reducing the B+ voltage is used.
    A 6v fil. xfmr is often used as a bucking xfmr in the 120vac input to
reduce the input voltage to closer to the original than what we get
nowadays.  This could be done for most of our boatanchors, with or without
the SS'ing of the p.s. to provide protection from general overheating &
over voltage in the B+ areas.
    I don't know of any problem going SS on the rectifiers in a
transmitter.  It reduces transformer & general heat, which is a great help
in the HT-32/37.  Disconnect the 2 5v fil. windings completely.  I haven't
done it in the HT-32 that I have with the Peter Dahl xfmr, but have in the
HT-37.  I use 2 1000piv diodes in series for the LV section, and 3 in
series for the HV section.  I have used surge protection resistors of 5 to
20 ohms in the series strings, but this may be overkill.
    I hope this answers some questions, and it may promote some more
opinions.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
anchor at ec.rr.com
http://www.thecompendium.net/radio/
http://www.hammarlund.info/

And remember; "-They don´t make tubes nowadays like they used to..."