Hi All, Well, this morning I essentially duplicated my previous stability tests with the Drake T-4X here, only with a minor change: as was suggested to me earlier, this time I let the "umpire" rig---my ICOM 751A transceiver---warm-up, alone, for a full hour...
Before getting to the results, I should add here that the T-4X has a small cooling fan mounted above the amplifier cage, extracting air from inside it to the outside: it ran continuously whenever the rig was on during the course of both evaluations. Ambient room temperature in my basement was 59F, as before. Again, I measured the frequency a total of SIX times, i.e. (1) immediately at the start of the test, (2) 3 minutes into the test, (3) 15 minutes into the test, (4) 30 minutes into the test, (5) 1 hour into the test, and finally (6) two hours into the test. The actual PTO frequency itself was monitored with the 751A in general coverage mode... Here are the results this time: (1) 5455.0-KHz (cold start); (2) 5454.8-KHz (downward drift of 200-Hz from cold start); (3) 5454..4-KHz (downward drift of 600-Hz from cold start); (4) 5454.0 KHz (downward drift of 1-KHz from cold start); (5) 5453.7-KHz (downward drift of 1.3-KHz from cold start), and, (6) 5453.7-KHz (unchanged). The end result in terms of drift was actually 100-Hz MORE than was observed the first time, i.e. 1.2-KHz with both rigs running from cold starts, to 1.3-KHz with the ICOM warmed-up for an hour! No matter---after an hour's warm-up the signal remains essentially unchanged, and I'm happy with that. I'm especially pleased to note that the warbble effect / jumpiness previously afflicting my PTO has apparently disappeared, in the aftermath of all of my resistor swapping in it...and the dial correction that I have to do on the T-4X after the resistor swaps is pretty much in line with what I had to do before the re-build. My conclusions after all this stuff? Well, #1, it was most interesting & gratifying, both...and #2, if I take the quoted manual "warm-up" period time to be, in fact, one full hour minimum, then my transmitter actually EXCEEDS the quoted Drake specs for drift of ":...less than 100 cycles after warm up" considerably: in fact, mine doesn't drift at all after that time...! And THAT, as Martha Stewart is wont to say, "...Is a GOOD thing." Hi Hi Now---how about all those other T-4X rigs that are out there in general circulation...? Are the results of YOUR stability tests similar to mine here...? ~73~ de Eddy VE3CUI - VE3XZ _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
