[Hallicrafters] Antenna Trimmer Alignment - SX-111

[Bill Gerhold]

I was performing a final alignment on my SX-111.  This involved checking or
tuning
the antenna inductors for each band.  The usual method of doing this is to
inject a
signal from a standard signal generator and look for a peak either at the
speaker 
leads or some other voltage level that will indicate proper tuning with the
radio
on.

I suddenly realized I could do this alignment or peaking without having the
radio
on at all.  This may not be new to some of you but it occurred to me that
using an
antenna analyzer (not available in the 50's & 60's), one should be able to
connect the
analyzer to the antenna input of the receiver and measure the SWR to the
trimmer
circuits directly.

Using a short piece of coax connected to the MFJ-259B analyzer, I switched
the band
switch to 80 meters, I measured an outrageous SWR.  Something was wrong
here.  Then I
pulled the schematic and of course, the front panel trimmer is in the
circuit and also
the main tuning capacitor.  Turning the front panel trimmer brought the SWR
down to a
very acceptable 1:1 SWR.  It was amazing to watch the SWR change as I
rotated the main
tuning dial.  No adjustments necessary internally and no high voltages to
worry about.

At this point I went to each band and using the front panel trimmer control,
all bands 
except 15 meters came in with low SWR.  For some reason, I am unable to
bring 15 to what
I believe to be an acceptable SWR.  3:1 is the best I can get and the
inductor will not
turn.  I believe epoxy is holding it tight so, I will live with it.

Anyway, I thought I might pass this along to others out there as a safe and
accurate
method for checking the input circuits of a receiver that should work with
all old
and I would imagine even new receivers.  It probably would work feeding a
transmitters
output circuits to find out if the output tuning will resonate at certain
frequencies.

         Bill Gerhold, K2WH 
Hallicrafters, The Radio Mans Radio
            http://www.w9wze.org/
  http://groups.yahoo.com/group/The19Group/