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Press the PLAY button to hear the description in morse code.
SX-111 Mark1 is a ham band only receiver with a dual conversion IF. The Mark1
has a product detector tube added for SSB detection otherwise it is the same as
the SX111. It has fourteen tubes including the voltage regulator and rectifier.
This was by far the most complex radio that I had bought when I took up the
challenge of bringing it back to life. The only good thing I could see about it
when the shipping box was opened was that the dial glass was intact. The rest
was, let us say, awful. The case had what appeared to be house paint put on
with a six-inch brush. Later I found at least six layers of brushed on oil base
paint when it was stripped. The chassis was literally green. The cadmium
plating had corroded and made the chassis look like a cheese gone bad. But the
radio worked! Not well, but noise came out of the speaker. There was hope!
I started stripping the case by using a stripper from Ace Hardware. I don't
recall the brand but it was very strong and had lots of warnings on the can. It
took a half-day to strip it down to what was left of the original baked on
paint. The stripper would not remove the original paint so I began sanding and
took it down to bare metal. Rustoleum auto body primer was used as a base coat.
I sanded the primer several times to remove all traces of dings and scratches.
Luckily there were no major dents. Rustoleum Hammertone gray was the top
coating. I put on three coats lightly sanding with 600 grit sandpaper between
corroded chassis was the next challenge. I found through Internet searching
that the cadmium could be poisonous so I did not sand or otherwise disturb the
greenish stuff. I wiped the chassis down with mineral spirits until the
cleaning cloth (or cue tip) came away clean. A cue tip was then used to spread
a very thin coat of aluminum paint on the chassis. I did not like the result.
It looked rough. I then masked everything that should not be painted and
sprayed quality metal protective bright aluminum paint. I know it was heresy
but the result looks great to me and certainly did not affect the performance
of the radio.
I then turned to
the electronic restoration. All of the capacitors were
replaced including the electrolytics in the power supply. There were lots of
"bumblebees" which have a notorious reputation for going bad. The
capacitors attached to the selectivity switch were the biggest challenge. I was
able to remove the switch leaving the wires attached and rotate it as needed to
replace the capacitors.
There was a candohm resistor riveted to the band switch assembly that was
burned open. It is used to warm the band switch assembly and reduce moisture
absorption in the coils, I assume. Also it may have been intended to reduce
drift. I replaced it with a sand resistor mounted in the same place with a
homemade mount. It looks like it belongs there. The original resistor was rated
eight watts and the actual power was about the same. That is the reason it
burned, I think. I replaced it with a twenty-five watt resistor. It is
connected across the incoming line voltage before the switch so it is energized
whenever the receiver is plugged in.
All of the tubes tested good on my TV2 emission tester but that test is a
primitive test at best. Since the radio played when received, I assumed none of
the tubes were basket cases.
I used the alignment procedure in the Hallicrafters manual and carefully
aligned the set. The 50.75 KHz second IF could have been a stumbling block had
it not been for my Heathkit sine/square wave generator that I had just restored.
The sine generator along with a frequency meter made aligning the 50.75 kHz IFs
I made three modifications to the radio all of which are meant to prolong the
life of the radio and reduce heat damage to the case paint. I added a line voltage-reducing transformer in series with the power transformer input that drops the
line voltage from 121 volts to about 115 volts. I also used 1N4007 silicon
diodes to replace the 5Y3 rectifier function but left the 5Y3 in place with the
filament disconnected for esthetics. A fuse was added on the input also.
This is an
excellent radio! It is very sensitive and as selective as it needs to be. All
functions work perfectly. Any ham of the early sixties would have done well to
have one of these receivers. It would have sold for around $285.00 in 1960
taking a month’s wages for most workers of the era. Click here to view an ad from the 1960 Radio Amateurs Handbook announcing the new
I was never able to find a matching speaker for this radio that was affordable.
Apparently very few receivers were purchased with the matching speaker which
makes the speaker a rare collectable and thus expensive. I made a speaker box
using a Hallicrafters speaker removed from a S77A. At least it is a
Hallicrafters speaker if not a match!
I have sold this
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