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Len Over 21 wrote:
In the case of the mixing-by-crystal-banks plus VFO (or "PTO" for most Collins radios), there was a dependency on the quartz crystals being correct. Those were typically in the 30 to 50 PPM (plus-minus) accuracy by themselves. That was GOOD accuracy for the 50s to 60s time frame...but one band might be off on the low side while another band might be off on the high side. That "off on the low side while another band might be off on the high side" stuff might be correct if not for the individual band trimmers featured in all such equipment. R.L. Drake and Ten-Tec also used PTOs in their equipment. With TCXOs or VTCXOs (Temperature Compensated Crystal Oscillators, fixed or Voltage-controlled), the drift on modern "all band" (HF that is) transceivers can be within 1 PPM after calibration. The old Collins "PTO" (Permeability Tuned Oscillator) achieved stability of 50 to 100 PPM over a full military temperature environment (-55 C to +85 C) but they were not inexpensive. Collins amateur equipment was often at the top of the money line when they were marketing for the hams. Ten-Tec and Drake equipment achieved similar accuracy and were sold at much lower prices than comparable Collins gear. Besides, "real hams" don't use any FM on HF...they hardly ever go above 30 MHz. :-) Is this just another things you've heard from someone else, Leonard? While I use 2m FM, most of my operation on 6m, 2m and 70cm is on SSB or CW. I have the latitude to choose a band I like and to operate there. I can do this from my home or from my car. The subject has gotten out of hand in here with all the PCTA extras eager to beat on any NCTA by taking a phrase out of logical context. :-) It surely does get out of hand but not because of anything being taken out of "logical context". It happened because you spouted off about something you weren't up on. You compounded things by not admitting to your lack of knowledge. You tried to fine tune your original statements and were snagged yet again. Those all have expensive ready-builts in their "shack" and - naturally - those rigs are the closest thing to perfection as anything. Jim's isn't ready built. Mine is. They're both as close to perfection as anything. Why would that bother you? They don't seem to know squat about the inner technology involved in frequency synthesizers so they want to "get even" with anyone who does. Sigh. "Tney" seemed to know enough to chew you up and spit you out on your synthesizer spur and phase noise gaffes. You'd better bring yourself up to date, old fellow. Dave K8MN |
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