Hi Steve, Be that as it may, I'm still gonna re-run my test here, but only AFTER allowing the ICOM to warm-up for an hour---could be interesting...
~73~ de Eddy VE3CUI - VE3XZ ************************************************************************* On 2011-11-26, at 5:45 PM, Steve Wedge wrote: > I should have commented that what Eddy reported doesn't seem unusual given > the temperatures involved. The fact that everything seems to have settled > down after an hour obviously empirically shows what time was needed for the > 59F ambient warmup from cold. > > Even an "ovenized" counter will drift when turned on from cold. If you've > left the oven running, you just won't get any drift from the crystal. > > 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: Eddy Swynar > Sent: Saturday, November 26, 2011 8:13 AM > To: captc...@flash.net > Cc: drakelist@zerobeat.net > Subject: Re: [Drakelist] T-4X Stability > > Hi Curt, > > Wow...! > > What I really wanted to do here, primarily, was to validate my "fix" of the > Drake PTO that's been practically driving me to drink here lo these past many > months! Hi Hi. > > What I'll do, then, is warm-up the 751A separately for one full hour, before > initiating a repeat of the test that I did the other day. Any major > divurgence in the "apparent" drifting of the PTO in the new test (as compared > to yesterday's) can then be reasonably assumed to be the fault of the ICOM > rather than the T-4X, all things remaining the same... > > Stay tuned---this just gets more & more interesting all the time, I must > say... > > ~73!~ de Eddy VE3CUI - VE3XZ > > > ************************************************************************************************************************* > > > On 2011-11-26, at 8:02 AM, Curt Nixon wrote: > >> GM Eddy: >> >> Even the 100Kc calibrator is going to suffer from start-up drift. At the >> very least--and surely acceptable for a tens-of-Hz startup measurement, just >> leaving the 751A on for some period of time before doing the start-up test >> on the Drake should suffice. >> >> I settled my 751 down an amazing amount by simply surrounding the primary >> crystal with an improvised styrofoam "box" and some cotton. >> >> Its all as stable as a crystal can be without some PLL or temp compensation >> done on it. I guess the main thing is to use a standard that is already >> settled in and warmed up when making the turn-on drift measurement. >> >> If you haven't been involved in an FMT, (Frequency Measurement Test) the >> level of effort will shock you!. But we're talking a few hundredths (yes, >> .01) Hz. Small enough so the variations seen in the over-the-air WWV >> broadcasts become non-useable when multi-path is present. >> >> What you find out real fast is that if you can control the temperature, the >> frequency of most equipment follows along. >> >> Current state of the art is GPS-disciplined rubidium reference oscillators. >> It makes my military oven-ized HP reference osc seem flaky! >> >> Any way, thanks for sharing your results. I will be interested to see how >> much different they are with a pre-stabilized 751A as the reference. >> >> BTW, if you use a PC in the shack, a program like FlDigi, or Spectran, (or >> Spectrum Lab if you are really into it) can help you plot very good >> reference information using WWV at 2.5, 5, or the CHU frequency infor. They >> plot using an audio reference from your rig. pretty simple really and easy >> millihertz accuracy right out of the gate. >> >> Have fun. >> >> Curt >> KU8L >> >> On 11/26/2011 7:37 AM, Eddy Swynar wrote: >>> Hi Curt, >>> >>> When I get the chance this weekend I'm gonna run some stability tests on >>> the 751A here, using a 100-KHz crystal calibrator / oscillator as its >>> "umpire"... >>> >>> You've got me thinking: maybe there really WAS a reason that ICOM offered >>> for sale an optional "high-standard / ultra-stable" crystal oscillator as >>> option for the 751A back-in-the-day...! >>> >>> ~73~ de Eddy VE3CUI - VE3XZ >>> >>> >>> >>> *************************************************************************************** >>> >>> >>> >>> On 2011-11-25, at 9:05 PM, Curt Nixon wrote: >>> >>>> Not sure anyone asked this, and I didn't see it in your initial post, but >>>> was the 751A already warmed up when you tested the drake? >>>> >>>> What is the frequency reference in the 751A? >>>> >>>> I recently used a 751 which is essentially the same frequency determining >>>> set-up for a freq measurement test and I can tell you, it isn't all that >>>> stable either...and, it goes up and down with small temperature >>>> differences over a span of only several minutes. Even when it had been >>>> running in Rx only for over 24 hours. >>>> >>>> So..keep in mind that the data you recorded is the net difference from a >>>> moving reference. >>>> >>>> After warm-up, I'm not so sure that the 751A is any better than the Drake. >>>> >>>> They are a lot better if they have the TCXO module added, but I didn't see >>>> that mentioned. >>>> >>>> Anyway, just curious what the reference conditions were. >>>> >>>> Thanks >>>> >>>> Curt >>>> KU8L >>>> >>>> On 11/25/2011 5:57 PM, Garey Barrell wrote: >>>>> Steve - >>>>> >>>>> I think 30 minutes is a reasonable 'warm-up' time. IF the radio is in a >>>>> controlled environment.!! Take one out of the garage in winter >>>>> and plug it in, it's gonna take considerably longer before everything >>>>> reaches equilibrium. You have some sizable chunks of iron and steel in >>>>> there that can absorb quite a bit of heat. From 60 degrees to a >>>>> 'nominal' 75 degree ambient on top of normal internal heating would take >>>>> a while, perhaps an hour?!? :-) >>>>> >>>>> Plus as Evan said there will be a delta from transmitting as well. A fan >>>>> makes a BIG difference in this if you are into long transmissions or TTY, >>>>> etc. This is one reason why the TR-7 fan is used to exhaust hot air from >>>>> the PA right out the back rather than blow it in all over the radio, >>>>> including the PTO, with each transmission. >>>>> >>>>> 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 >>>>> <www.k4oah.com> >>>>> >>>>> >>>>> Steve Wedge wrote: >>>>>> I always assumed it was a 30 minute warmup, because I seem to remember >>>>>> the alignment procedures spec 30 minutes warmup before doing an >>>>>> alignment. >>>>>> >>>>>> Steve Wedge, W1ES/4 >>>>>> >>>>>> "I can't complain, but sometimes I still do." >>>>>> - Joe Walsh >>>>>> >>>>>> If the above message appears, it came from Steve's Son of Laptop! >>>>>> ----- Original Message ----- From: "Eddy Swynar"<deswy...@xplornet.ca> >>>>>> To:<drakelist@zerobeat.net> >>>>>> Sent: Friday, November 25, 2011 2:32 PM >>>>>> Subject: [Drakelist] T-4X Stability >>>>>> >>>>>> >>>>>>> Hi All, >>>>>>> >>>>>>> The manual for my T-4X states that stability is "LESS THAN 100 CYCLES >>>>>>> AFTER WARM-UP". My question is simply this: how long, exactly, is an >>>>>>> accepted period of "....warm-up"...? >>>>>>> >>>>>>> After all of the hoops that I've jumped through in stabilizing the PTO >>>>>>> in my rig (re-buiding it almost, actually!), I decided this morning to >>>>>>> actually measure its drift. I used my ICOM 751A transceiver (in general >>>>>>> coverage mode) as the frequency "umpire", and tuned it directly to the >>>>>>> Drake PTO's output frequency of 5454.0-KHz. Both rigs were in the >>>>>>> basement overnight, where the ambient room temperature was 59F. 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... >>>>>>> >>>>>>> Here are my results: >>>>>>> >>>>>>> (1) 5454.0-KHz (cold start); >>>>>>> >>>>>>> (2) 5454.0-KHz (unchanged from cold start); >>>>>>> >>>>>>> (3) 5453.5-KHz (downward drift of 500-Hz from cold start); >>>>>>> >>>>>>> (4) 5453.0 KHz (downward drift of 1-KHz from cold start); >>>>>>> >>>>>>> (5) 5452.8-KHz (downward drift of 1.2-KHz from cold start), and, >>>>>>> >>>>>>> (6) 5452.8-KHz (unchanged). >>>>>>> >>>>>>> So---it looks like the rascal that I have here stabilizes after a good >>>>>>> hour of steady warm-up, which leads me to suspect that maybe "warm-up" >>>>>>> to the writer of the manual was, in fact, just that, i.e. one hour...? >>>>>>> >>>>>>> No matter, it was a most interesting exercise---and I sure would be >>>>>>> curious if my rig's performance might match that of some of the other >>>>>>> T-4Xs that are out there...although I dare say, probably not everyone >>>>>>> has as thick a hide as I do in being able to withstand a 59F ambient >>>>>>> room temperature...! Hi Hi. >>>>>>> >>>>>>> ~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 >>>>> >>>> _______________________________________________ >>>> 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 > > > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist
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