Vintage Hallicrafters SX-100 Mark 1B Shortwave Receiver Restoration: Complete and Ready for Testing

[@RestoreOldRadios]

Al, great to hear it playing. Another very successful project. Best, Don

[@i82996]

Thank you

[@jerdobi]

I see a thermistor on the bottom. Can you show how you wired in this and being safe for AC

[@i82996]

It is an inrush current limiter I found on Mouser.com. by Intherm, maybe MS80 (not at home right now) - larger size. About 150 ohms at cold start and 1.5 ohms operating. Preserves tubes and current inrush on B+ at cold start and reduces nominal AC voltage input to 118.3 VAC. Installed between switch and primary on power xformer. AC wiring hot from wall first to fuse then switch then thermister then xformer. Other primary side of xformer direct to AC neutral. Type XY safety Caps .01 uf at fuse to switch connection to ground and at xformer to neutral to ground.

[@charleslauter5035]

What is the Make and model or part number of the programmable frequency counter? CAL

[@i82996]

PLJ-6LED-A programmable Frequency Counter only available on Ebay. Expect 4-6 weeks delivery but cheap and easy to adapt. I order the minute I start a project.

[@charleslauter5035]

Good job, Looks good too. Thanks! CAL

[@i82996]

Thanks 👍

[@terrybotts7530]

What would be the best antenna for this unit? I have one but I don’t get too good of reception with the 15 ft single wire antenna. I just got it and I don’t know very much about shortwave radio. I have been able to hear local am radio stations so far, no Morse code or anything outside of the US yet

[@i82996]

Terry, the antenna and ground is as important to the radio itself for performance. I dont know your situation, but in my experience, for general coverage receivers like this one, I work hard to have a long wire antenna at least 20 feet off the ground, and I install a 9:1 balun to a coax leading to the lightning protection at the entrance to the house. Then I bring the coax into the shack in the house to a receiver antenna tuner which tunes the antenna. For grounding, I have an 8 foot rod in the ground bonded to the lightning protection at the house, and at the antenna itself out near the woods with another rod there. This is still not best practice, but my setup is pretty noise free and gives excellent reception on all bands. If you go for an Amateur Radio License, you will find that any antenna built well for a transmitter will work well on the amateur bands but may not be best on shortwave bands in all cases. The ground is so important for noise free reception. Now the kicker: my long wire is an inverted L, proceeding up from the balun at the ground to a 20 foot high turn to horizontal where it continues another 100 feet. The receiving pattern is fairly omnidirectional at most frequencies with a few dbs favoring the axis of the horizontal portion of the antenna. I know the manual for the SX-100 talks about a dipole, but for shortwave reception only you want omnidirectional reception as much as possible and dipoles are highly directional. In fact a bad long wire antenna should work better overall for shortwave listening than a dipole. 15 feet is way too short a length to receiver much, and an antenna tuner such as a MFJ-956 or 959c is essential to hear anything with any length of antenna. Blessings, Albert KR3HAB

[@i82996]

Your comment tells me I need to do a video tailored to the shortwave listener for antenna designs. If your backyard is not easily converted to antennas there are alternatives. Albert