Re: [Drakelist] T-4X Stability: EPILOGUE
Nice work Eddy. I do my tests a little differently, I look at "overall" stability by zero beating WWV. Regardless, my early T-4X (5KHz markings) is also just about 1.2KHz. But my slightly newer R-4A (13 tube, but 25KHz markings and vernier Preselector) is worse at just about 1.5KHz. IIRC, there is a drift spec. somewhere of... 1.5KHz, if so, WE are in spec :) And, like you, after a GOOD warmup, they are pretty darn stable!! I have also noted that the drift seems worse at the high end of the dial. 73, Gary WB6OGD - Original Message - From: Eddy Swynar 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
Re: [Drakelist] T-4X Stability: EPILOGUE
Hi Eddy - Would you be up for one more test run?? I wonder what would happen WITHOUT the fan. Certainly the interior would warm up faster. A trade-off would 'perhaps' be a larger delta t from transmit to receive. Especially without an ambient air of 59F constantly being pulled through the cabinet. As this is a T-4X, it is a bipolar PTO. The T-4XB and C had a FET PTO, "for better stability". The receiver PTOs switched from bipolar to FET early in the 'B' series. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs Eddy Swynar wrote: Hi All, 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. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE
Hi Eddy: Excellent! Now, you might also learn something worthwhile by doing the same test, but measuring the drift of actual output after mixing at say 7 or 14Mhz. If the crystal Osc goes the other direction, it might get somewhat better...then again if it goes the other way...well...! :) I'll see if I can measure my B twins here but will not guarantee my room temp to start at 59.. It is usually about 62 upstairs in the AM now. Curt KU8L On 11/29/2011 8:30 AM, Eddy Swynar wrote: 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 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE
Hi Garey, An EXCELLENT idea...! I'm doing exactly that, even as I type this... Stay tuned! ~73~ de Eddy VE3CUI - VE3XZ ** On 2011-11-29, at 9:26 AM, Garey Barrell wrote: > Hi Eddy - > > Would you be up for one more test run?? > > I wonder what would happen WITHOUT the fan. Certainly the interior would > warm up faster. A trade-off would 'perhaps' be a larger delta t from > transmit to receive. Especially without an ambient air of 59F constantly > being pulled through the cabinet. > > As this is a T-4X, it is a bipolar PTO. The T-4XB and C had a FET PTO, "for > better stability". The receiver PTOs switched from bipolar to FET early in > the 'B' series. > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line > and TR-4/C Service Supplement CDs > > > > Eddy Swynar wrote: >> Hi All, >> >> 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. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE
Hi Curt, A sort of an elaborate "...temperature-compensating-oscillator-heterodyning" scheme...! Hi Hi We could call it "The Rube Golberg" method of frequency stabilization!: >) ~73~ de Eddy VE3CUI - VE3XZ ** On 2011-11-29, at 9:42 AM, Curt wrote: > Now, you might also learn something worthwhile by doing the same test, but > measuring the drift of actual output after mixing at say 7 or 14Mhz. If the > crystal Osc goes the other direction, it might get somewhat better...then > again if it goes the other way...well...! :) > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE
Which brings us to an interesting point: isn't the spec for the stability of the rig overall? I don't have the manual with me, so I'm just asking. Steve, W1ES/4 PS - nice work, Eddy! -Original Message- From: Eddy Swynar Sent: Nov 29, 2011 10:57 AM To: Curt Cc: drakelist@zerobeat.net Subject: Re: [Drakelist] T-4X Stability: EPILOGUE Hi Curt, A sort of an elaborate "...temperature-compensating-oscillator-heterodyning" scheme...! Hi Hi We could call it "The Rube Golberg" method of frequency stabilization! : >) ~73~ de Eddy VE3CUI - VE3XZ ** On 2011-11-29, at 9:42 AM, Curt wrote: Now, you might also learn something worthwhile by doing the same test, but measuring the drift of actual output after mixing at say 7 or 14Mhz. If the crystal Osc goes the other direction, it might get somewhat better...then again if it goes the other way...well...! :) ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE
Yes it is for output or input frequency. The other oscillator is crystal controlled, so not likely
to move even 10 Hz over this restricted range.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
Steve Wedge wrote:
Which brings us to an interesting point: isn't the spec for the stability of the rig overall? I
don't have the manual with me, so I'm just asking.
Steve, W1ES/4
PS - nice work, Eddy!
-Original Message-
From: Eddy Swynar
Sent: Nov 29, 2011 10:57 AM
To: Curt
Cc: drakelist@zerobeat.net
Subject: Re: [Drakelist] T-4X Stability: EPILOGUE
*/Hi Curt,/*
A sort of an elaborate
".../temperature-compensating-oscillator-heterodyning/" scheme...! Hi Hi
We could call it "*/The Rube Golberg/*" method of frequency stabilization! * :
>)*
*/~73~ de Eddy VE3CUI - VE3XZ/*
___
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Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!)
Eddy - Great info. Actually this confirms what I would expect to happen. What you do with the fan is provide a constant temperature, whatever it is, much better for short-term stability. The other oscillators involved in the output frequency are the Carrier Oscillator and the Band Oscillator. Both are crystal controlled, and probably stay within 10 Hz or less over the limited temperature range involved. One more run on 40M?? Transmitter keyed, minimum GAIN control. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs Eddy Swynar wrote: Hi Again All, At the specific suggestion of Garey, I went ahead& completed a 3rd stability test on my Drake T-4X transmitter PTO... I essentially repeated everything that I did in the very first test, i.e. I used the ICOM 751A as an umpire, both it and the T-4X were started at the same time (i.e. "cold"), and the ambient basement temperature was 59F---but this time I LEFT THE AIR EXTRACTING COOLING FAN ATOP THE FINAL AMPLIFIER OF THE T-4X CAGE TURNED OFF. 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... The results with this third (and final---I promise!) test were most interesting (NOTE: for comparative purposes, I have square-bracketed---[ ]---the changes observed at the very same time intervals in the FIRST test, at the end of each observation line). Here goes: (1) 5455.0-KHz (cold start)---[0.0-Khz]; (2) 5455.0-KHz (unchanged)---[0.0-KHz]; (3) 5454.3-KHz (downward drift of 700-Hz from cold start)---[500-Hz]; (4) 5453.7 KHz (downward drift of 1.3-KHz from cold start)---[1.0-KHz]; (5) 5453.2-KHz (downward drift of 1.8-KHz from cold start)---[1.2-KHz], and, (6) 5453.2-KHz (unchanged)---[0.0-KHz0 The end result in terms of PTO drift with the fan off was 1.8-KHz, versus 1.2-KHz with the fan on. Interesting! That's a difference of 600-Hz, or HALF of the drift experienced with the fan running! It's obvious that proponents of utilizing cooling fans for their Drake transmitters are on to something, alright---but the benefits are NOT restricted merely to prolonged tube life: PTO drift is reduced by one third, as well. My guess is that the cooler environment afforded by the fan to the entire "works" of the transmitter hastens the PTO in achieving its "ambient operating temperature." Because its environment is more directly controlled with the fan, the PTO has less opportunity to diverge in as great a frequency swing as it normally might, as may be evidenced by the results when no fan is used. Anyway, I'm still attempting to wrap my head around all of this, and I certainly do welcome any& all feedback& comments from the readership. One final point that bears repeating, as was mentioned to me by no less than two subscribers to the Reflector: the Drake manual specs for stability are quoted for THE TRANSMITTER AS AN OPERATING WHOLE, and NOT just for the PTO alone. The final transmitted frequency is a mix of many different frequencies, from self-excited oscillators,& from crystal control. As the TV advertisements state, "RESULTS AT HOME MAY VARY," Hi Hi. This has all been a most interesting exercise, nonetheless---I only hope that my ramblings herein have NOT inspired readers to unsubscribe from the list..! ~73~ de Eddy VE3CUI - VE3XZ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!)
" This has all been a most interesting exercise, nonetheless---I only hope that my ramblings herein have NOT inspired readers to unsubscribe from the list..! " On the contrary, Eddy. I find this stuff fascinating. The most productive learning environments always have people who say things like, "I wonder what would happen if we.?" I hope you keep sharing the results of your experiments with us. 73, Bob K6GGO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!)
I'll second that... it's epics like these that make this and other lists worth riding along with. Thanks for taking the time, and thanks for the info. I always knew fans were a good idea :-) John K5MO At 01:47 PM 11/29/2011, Robert Fish wrote: " This has all been a most interesting exercise, nonetheless---I only hope that my ramblings herein have NOT inspired readers to unsubscribe from the list..! " On the contrary, Eddy. I find this stuff fascinating. The most productive learning environments always have people who say things like, "I wonder what would happen if we.?" I hope you keep sharing the results of your experiments with us. 73, Bob K6GGO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!)
Absolutely - love reading these escapades! Since I author a few of them myself, I happen to find those of others equally interesting. 73, Steve Wedge, W1ES/4 I swear by my life, and my love of it, that I will never live for the sake of another man, nor ask another man to live for mine. -Ayn Rand. All my computers have my signature with various pearls of wisdom appended thereto. -- From: "john" Sent: Tuesday, November 29, 2011 9:30 PM To: "Robert Fish" ; Subject: Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!) I'll second that... it's epics like these that make this and other lists worth riding along with. Thanks for taking the time, and thanks for the info. I always knew fans were a good idea :-) John K5MO At 01:47 PM 11/29/2011, Robert Fish wrote: " This has all been a most interesting exercise, nonetheless---I only hope that my ramblings herein have NOT inspired readers to unsubscribe from the list..! " On the contrary, Eddy. I find this stuff fascinating. The most productive learning environments always have people who say things like, "I wonder what would happen if we.?" I hope you keep sharing the results of your experiments with us. 73, Bob K6GGO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4X Stability: EPILOGUE (Almost!)
On Tue, 29 Nov 2011 13:25:27 -0500, Eddy Swynar wrote: > >It's obvious that proponents of utilizing cooling fans for their Drake >transmitters are on to something, alright---but the benefits are NOT >restricted merely to prolonged tube life: PTO drift is reduced by one third, >as well. This, I have been saying :) 73 -Jim NU0C -- Questionable management practices at the 146760.net web site? http://radiojim.exofire.net/pages/Questions.html ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
