On Fri, Nov 22, 2024 at 05:39 PM, waltcates wrote:

Yes. The entire SR series of transceivers has receiver incremental tuning, RIT. Hallicrafters had the original patten on the RIT concept and was the first?to go into production with it.

Wow - everyone has missed the point entirely.? Guess there aren't many folks using Hallicrafters gear in CW mode, particularly in contests.? I will go into greater detail and hope I don't offend anyone.??

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Note: all of the following applies to the HT-44 with the rear slide switch in XCVE (transceive) mode.? The goal here is: when you tune in a CW station on the SX-117 (with the HT44 slide switch in XCVE mode), you want the HT-44 to be tuned TO THE SAME FREQUENCY AS THAT OF THE STATION YOU'RE HEARING.? That way, the station you're calling will hear you at a reasonable pitch.? But, when setting up the SX-117 and HT-44 for receive mode, you adjust C1 for zero beat, putting the transmitter and receiver on exactly the same frequency.? For SSB, that's exactly what you want and it works perfectly.? But, for transceiving in CW mode, you want the two to be offset by the frequency of the CW tone you like to hear - say, 600 to 700 Hz.? On my HT-44, the range of adjustment of C1 can provide an offset of around 200 Hz, not enough.? Many early manufacturers of transceive capable gear got this offset thing wrong - notably Collins.? If you wanted to transceive in CW mode on the S Line, you ended up with an offset of 1.5 Khz in some cases and that's simply not usable.? Drake got this right in their 4 Line with a fixed offset of around 700 Hz.? In SSB mode, the offset is zero, but switching to CW changes it to 700 Hz.??

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So, what I'm after is being able to shift the frequency of the HT-44 carrier oscillator by 600-700 Hz in an adjustable fashion so that I can still put it back to 1650 Khz for SSB operation.? Not something I'd often do, so a screwdriver adjustment is entirely acceptable.? In the HT-44, the crystal frequency is varied by adjusting C1, a capacitor in parallel with the crystal.? You can also adjust the frequency of a crystal oscillator using a capacitor in series with the crystal.? A good way to do that in the HT-44 might be to use varicap diodes.? But, pulling a crystal frequency has limitations and in this case, I have no idea how far we could actually pull the crystal frequency without some negative effects.? Hence my original question: has anyone actually done this and how did it work out?? ?Some academic papers I've read on the subject of pulling a crystal frequency indicate that 50 ppm might be the limit, but it depends upon the crystal cut and a lot of other factors.??

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And, yes, an RIT function would satisfy my requirement but that doesn't exist on the SX-117.? Fiddling with the BFO frequency does NOT solve the problem and no need to explain that here.? For now, I continue to use the SX-117/HT-44 for CW in the NORM mode, having to switch the Operation switch to CAL and turning the HT-44 VFO to the desired frequency.??

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73, Floyd - K8AC

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