Sometimes the answer to a question is staring you right in the face.
Yesterday I unboxed the Hallicrafter SX-117 I got from eBay recently. The price was right and in the past month I picked up the matching HT-44 transmitter. My goal of course was to put together a complete SX-117/HT-44 station; the only thing I’m missing is the matching power supply — well, I’m not actually “missing” it, I have two of them paired with Halli SR-150/160 transmitters already. My plan is to use one of those with the new station.
Anyway, the SX-117 was fairly grimy on the exterior of the case; not true dirt or barn dirt, but looks mostly like nicotine from heavy smoking. The interior looks really nice. The seller said the radio turned on but no sound. Something was working with the rig, at least it wasn’t completely dead.
On the bench, the radio turned on and seemed to operate normally — but without audio out. The electronics looked unmolested. I didn’t have much time to spend on it, but decided to do some troubleshooting at a later time, staring with voltage and resistance checks.
Late last night while doing something else, a nagging thought kept bugging me. I have owned and operated this station years ago and enjoyed it, but I remember hooking up the E.F. Johnson electronic T/R switch — didn’t some wiring connect to the rear of the receiver to mute it?
I pulled up the operating manual, and there it was — there are two terminals on the rear of the radio to mute it in transceive operation. The terminals are normally open, which means a jumper is required across them in order for the receiver to work! Doh!
Earlier today when I had time, I put the receiver back on the bench, this time WITH a jumper installed. Viola! The receiver came to life!
I took time tonight to check the receiver — at least on 75 meters — and it seems to be close to the same sensitivity as my Yaesu FTDX-3000 … “close” I said, not perfect!
It was like taking a trip back in time about 20 years, when I had the SX-117/HT-44 station operating … actually, just smelling the tubes getting up to operating temperature was quite a kick. Burning the dust off the tubes (or at least heating up the dust, lol). My 22-year-old son, a ham who has no appreciation for pre-transistor electronics, asked me if something was wrong with the receiver.
Why do you ask, son?
“Because of that awful smell!”
Kids! Sheesh!
The switches all need cleaning on the rig; I had to cycle through the AM/USB/LSB mode switch about a dozen times before I got LSB working. But that’s to be expected. I’m just tickled to death the receiver works. I could peak white noise on 40 through 10, so my guess is that if the band conditions ever improve I will hear signals on those bands, too.
The Yaesu has more preamps and attenuator options that the SX-117, but to its credit, the Hallicrafters has variable crystal filtering (5 Mhz / 2.5 MHz and 500 Hz) and an effective notch filter. As noted by others, the notch filter has an “off” setting, but actually the notch is never truly “off” — it just moves the notch outside the receiver’s bandpass so you don’t notice it.
The receiver is missing the correct knob for the noise limiter / calibrate switch, but I’m not going to complain. For safety’s sake, I’m going to wind up replacing the original line cord, which is terribly brittle. It appears to have been tied up in a bundle for a decade or more, and my fear is that flexing the cord much will mean its going to begin to shed the insulation.
The receiver needs a good cleaning, and once cleaned the case needs repainting. Before I do any painting, I would want to match the paint to the HT-44 transmitter case, which is in nice condition, but that will remain to be seen.
Now here’s hoping my luck with the matching transmitter is as good as it was with the receiver!
73 es CUL de KY4Z SK … SK … dit dit ….