[Hallicrafters] Restoring My SX-111 Rcvr

[Jerome Wysocki]

Hello everyone,

I've learned a lot over the years just by reading about the various topics on restorations here. Thanks to all who added to my knowledge on these topics.

 I am currently restoring a Hallicrafters SX-111, Mark 1, that many would probably have considered suitable only as a donor, or parts rig. It had considerable corrosion damage. This included control shafts that were corroded stiff. I remedied these. I recapped the receiver, and checked resistors and voltages. They were all close enough to spec. Controls, switches and tube sockets were carefully DeOxed. The set powered up, and actually received signals on most bands.

Sensitivity was somewhat low. Tube swapping with ones known to be good did not help. Then I noticed all of the exterior slug seals on the IF transformers were broken. Someone with a "golden screwdriver" apparently got to them.

First question concerns alignment of the 50.75 KHz IF transformers. Both of my signal generators bottom out at 100 KHz, so I can't use them here. Actually, I haven't seen pictures of any signal generators that go down to 50 KHz. Do many of these exist? So I guess I'm wondering how anyone else faced this issue. Is there an alternate way to generate a 50.75 KHz signal to appropriately feed into the receiver to align this section?

Meanwhile, I carefully re-adjusted the IF transformer slugs and noticed an improvement in sensitivity. To do this is normally considered a "no -no" so I documented how many turns on each slug I made, so that I could return them back, if necessary. What was obvious, however, was that who ever worked on this set before, did mess up the IF alignment, so no harm was done, here, by me. The IF section must still be properly re-aligned.

My second question concerns slugs in the RF coils that are stuck. All of mine were, and I VERY CAREFULLY loosened them with an Allen wrench. (Is there a better, safer way to do this?) I was able to pretty well complete the RF alignment. The sensitivity and signal strengths improved dramatically but the slugs froze up again. I'm afraid of permanent damage to these coils by again using a wrench, yet I still need to fine tune these coils a bit more.

Any help would be very much appreciated!

Regards,

Jerry Wysocki, KC9JXE


Sent from my iPad