[Hallicrafters] Re: SX-100 update

[David L. Thompson]

Been out of town for a few days.  Thanks for all the replies.

I have the antennas (all unbalanced) to ant 1 and 2 through a balun.  The
two terminals are set for 300 ohm balanced.  This seems to work much better
than hooking the coax center to to ant 1 and jusing a jumper between ant 2
and ground.  The coax shield can then be hooked to either ant 2 or ground.
If you use a coax connector installed in the knock out slot on the chassis
rear you need a balun inside to better match to the 300 ohm input.

As to the S meter, yes it does read backward so when the receiver is off its
all the way to the right.  I got some good ideas as how to check it out and
will get to those (carefully as it reads
RF voltage) tomorrow.   So far the only test I have used is to switch the
toggle switch between receive and transmit and the meter jumps backward
slightly.  The leads to the meter look good but that too will be checked.

As to the actual model, the reference material says the original SX-100 used
a second IF at 50 kcs.  The Mark I A switched to 50.5 kcs and the Mark II
changed that to 50.75 kcs.  The IF transformer in my SX-100 is 50.5.   I am
still looking for the serial number and if anyone has additional differences
in model types I would like to hear it.

I did use the 100 kcs calibrator and on mots bands its not very loud.  I
have to switch to the dummy load to be able to hear it.  I have an outboard
calibrator that puts out a fairly loud signal on each band.  So I will look
into wht the output is so weak.  I have an old HQ-120 with built in
calibrator that had the same ptoblem and I found the lead from the
calibrator tube to the antenna
circuit had a cold solder joint.  The signal pins the S meter on 80 now and
is S9 on 10.

Oh I forgot,yes I do set the band spread to full right end of scale to then
look at the main dial.  As I said before once I find the place where to put
the main dial (7500 kcs on 40) the band spread lines up very well on 40 and
20.  I don;t have a Signal Generator that goes below 100 kcs right now so
except for getting the main dial to line up I won't be able to do a full
alignment.  A friend has a function generator taht puts out a signal
anywhere from nearly zero to 100 mcs (as I remember) both modulated and
unmodulated.   I used that for a HQ 170 but he has a NC-300 that he is
working on right now so I have to wait until he finishes.

73 Dave K4JRB