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Hallicrafters SX-111 Mark1

Press the PLAY button to hear the description in morse code.

The Hallicrafters 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 coats.

Chassis Cosmetic Restoration

The green 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.

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Electronic Restoration

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 a breeze.

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.

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The Final Product

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 SX-111 receiver.

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!

Update 01/06/2005

I have sold this receiver.


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