The AM Forum

I was using AM a few years ago. I sold my Collins 51J-4 receiver for a huge sum of money compared to what i paid for it. The Collins is even more expensive now.
Getting back into AM I bought an affordable Hallicrafters Guy rebuilt Hallicrafters SX-100. Looking for a Johnson Ranger. Anyways, how does the affordable SX-100 perform compared to the very expensive Collins 51J-4?

You said you had a Collins 51J-4; now you have a Hallicrafters SX-100. I would think you would know how they compared performance wise.

Benn too many years, I would like an opinion.

I've not owned either receiver, but I'll offer my likes and dislikes based on experience with similar receivers (bandspread tuning vs. PTO tuning).

In the class of PTO receivers I currently own a 75A-4, and have owned a 75A-3 and various other PTO-type receivers in the past like Drake B- and C-Line radios. Properly working and aligned, the frequency readout resolution and accuracy of PTO radios can't be beat in vintage tube-type radios. Accurately reading frequency to the nearest kc is probably the most important receiver feature to me. Collins and Drake radios, and those of similar quality will be solid performers in other areas as well, like selectivity and stability for instance. Out of the box they're not hi-fi radios, but hi-fi ham radio isn't a thing for me.

Hallicrafters, Hammarlund, some National, and other bandspread radios are at the bottom of my list because of the coarseness of the frequency readout and accuracy that's dependent on precise setting of the main tuning dial. Sure, a crystal calibrator will get you close, but you're not going to read down to the kc level. Again, that's what's most important to me. Many of them do provide better audio quality than Collins and some Drake radios, if that's your thing.

If you're cost-conscious, don't want or need kc-level readout accuracy, and want smoother audio, then the SX-100 would probably suit you. Another choice that's a pretty nice sounding radio is the HQ-129-X, and they can be had for relatively cheap.

The SX-100 was calibrated from Hallicrafters Guy. The bandspread does not have kHz markings, but the 1/4" in-between say 3850 and 3900 makes it easy to find any Ham frequency. Radio has a crystal calibrator get exact frequency on dial too.

Who is Hallicrafter Guy? I can't find any reference to that name on the web.

On the Bandspread dial of the SX-100 using the 80 meter section as an example,  3800 and 3900 have major tick marks. Smaller tick marks appear at 3820, 3840, 3860, and 3880. However bandspread dial accuracy is totally dependent on the setting of the main tuning dial. If that's a hair off, if will throw the bandspread dial accuracy way off. Likewise to maintain dial accuracy of the main tuning dial, the bandspread control has to be positioned accurately.

I have a 51J-3 and had a SX-100. I considered the Collins to be a solid design, great dial accuracy, and has excellent performance all the way to 30 MHz. I view the SX-100, as well as a number of other Hallicrafters receivers during that same time frame, as consumer grade equipment. They were OK but I wouldn't put any of them in the same class as the 51J receivers. Hallicrafters couldn't seem to finalize on the SX-100 design during it's entire life cycle. There were at least 6 design variations (Mark I A/B/C, Mark II A/B/C). Several of the Mark versions had a 50.5 KHz IF, others had 50.75 KHz IF.

I still have the 51J-3 receiver. The SX-100 is long gone and I don't miss it. And I prefer the 51J-3 even over the SX-88. I never considered the SX-88 to be a great receiver, but for $40, not a bad investment.

The Hallicrafters Guy was likely the best Hallicrafters rebuilder in his day. He passed in 2015. He replaced every capacitor in the SX-100 including the silver mica caps and 97% of the resistors per his rebuild statement paper. He used higher wattage metal film resistors. Then aligned the SX-100.

I know this. At the time I got the Collins 51J-4 I owned a Hallicrafters SX-71. The Collins way outperformed the Hallicrafters.
I have not seen a Collins 51J-4 under $1K lately.

The SX-100 is very nice for ham AM because it operates as a selectable sideband receiver for AM.  So if interference appears above or below your operating frequency, switch to the other sideband.

Collins makes some good stuff, I have Collins gear ranging from the 75A-1 and R-388 through the 75A-4, 51J-4, R-389, 390, 391, 65S-1, HF-380 etc. and they are far from infallible.

For typical ham AM operation, I would take a SX-100 over a 51J series without question.  If I were contesting in the 1970s, it would be with my Drake C line twins and not the Collins S-3 twins.

51J series needs the 4:1 tuning knob for a reasonable tuning rate.

Rodger WQ9E