Am 2023-05-12 20:52, schrieb Richard (Rick) Karlquist via time-nuts: > a considerable amount of knowledge about them. The idea > that a simple frequency divider could replace the > traditional harmonic sampler architecture used in microwave > counters is way too simplistic. Especially if that divider > is the dynamic variety, which is the only kind available > on the open market, AFAIK. What is dynamic in this context? Like the dynamic HP n-mos process I had to use in the 80s? There are now real FlipFlops. Like 7474, only 30 GHz. > Trying to take the entire LF to > 18 GHz spectrum, and somehow process it as a single > broadband signal without filtering, and then trigger a > flip flop is not realistic, as a general purpose piece of > test equipment, when there is noise and spurs that have > to be tolerated. The HP 5340, circa 1970, actually > achieved a single coaxial input that could measure > any frequency from 10 Hz to 18 GHz, automatically. > I would venture to say that this 50+ year old technology > could still handily beat any prescaler IC today. Actually, the HMC363 triggers quite nicely on nasty signals like this ADF5356 frequency synthesizer output whose frequency doubler cannot make up its mind if it should pass the 5 GHz fundamental or the wanted 10 GHz out. I admit that the input gain block peters out below 1 GHz, but there is nothing anyway. When I don't care about missed / suppressed zero crossings, then I can just as well have the spectrum analyzer crawl behind the wanted signal. Then I can see what dirt is there in addition. The old W&G SNA-33 does that to 1 Hz resolution from 20 Hz to as far as 3.5 mm connectors go. Gerhard Oh, in the previous post I forgot: www.dubus.org And my provider tags timenuts as spam now.

Bob, I see your point about questioning whether the real failure was a short or an open (fuse). I believe from the OP, it was an "apparent" short because the SMPS supplying the Z3801A unit would not start it up. This can be for a number of reasons, including a short, or a part failure as voltage goes up, or the inability of the PS to deliver enough startup surge current (even though it did before). I don't think the conversation evolved to diagnosing the actual problem, but jumped from considering some possible causes, to outright re-doing of the whole PS design - which I believe is unnecessary, and risky. Some more testing should show the real deal. Then the options emerge. Ed

All, Thanks again for your inputs, when I get back from my vacation (and replace the now-inop AC power transfer switch in my RV) I’ll look into this further. Still looking for confirmation of what I found as the internal power supply schematic, and experience on replacing the VP receiver with a UT+. Best regards Mahlon - N4ZK > On May 24, 2023, at 7:35 AM, ed breya via time-nuts <time-nuts@lists.febo.com> wrote: > > Bob, I see your point about questioning whether the real failure was a short or an open (fuse). I believe from the OP, it was an "apparent" short because the SMPS supplying the Z3801A unit would not start it up. This can be for a number of reasons, including a short, or a part failure as voltage goes up, or the inability of the PS to deliver enough startup surge current (even though it did before). > > I don't think the conversation evolved to diagnosing the actual problem, but jumped from considering some possible causes, to outright re-doing of the whole PS design - which I believe is unnecessary, and risky. > > Some more testing should show the real deal. Then the options emerge. > > Ed > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com