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FM Tuner alignment generator?..
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>I am not aware of HP units that can be as good at this specific work as some of?
>the Panasonic models I know. The Panasonic, Meguro, and some of the other? >makes mentioned cater very specifically and with the right set of features to? >the FM tuner techs. I don't think you should be focusing on HP for this duty.? >I am a hardcore fan of HP instrumentation and I use a Panasonic for this work.? >There may be HP units I am not aware of, but once I got this, I never looked back.? I have looked at the distortion specifications of the HP FM generators in this tread. They state distortion between 3 % to 1 % so far. The Sound Technology 1020 that I use has a stated distortion of 0.01 % at 100% modulation, +-75 kHz. My Yamaha CT7000 FM tuner has a measured distortion of 0.011 % at 100 % modulation in wide mode using the ST1020 generator. This tells me that the FM tuner can be better than 0.011 % distortion since we are very close to? the generator stated 0.01 % distortion. Now there are many FM tuners available with a stated thd at 100 % modulation below 0.02 % distortion. How can you properly adjust an FM tuner with that low distrtion if the FM generator, HP, generates 1 % distortion ? -------- Best regards, Goran Finnberg The Mastering Room AB Goteborg Sweden E-mail: mastering@... Learn from the mistakes of others, you can never live long enough to make them all yourself.??? -?? John Luther (\__/) (='.'=) (")_(") Ranglet, Aron, VovVov, Nero & Smurfen:RIP |
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With an HP generator with that stated distortion value, I can't imagine you can - though in my experience HP instrumentation often far exceeds its stated spec. But I never used an HP generator for alignment, so I can't really speak of that.? With a Panasonic (and other similar, newer units), you absolutely can. Even if the stated distortion may be higher, in practice their actual performance allows for much finer adjustment. Which is why I feel these instruments are of the same breed as those made by an HP (orTek, AP, and a few others in the same class), which is to say they may exceed their spec'd performance by a good bit.? I am speaking here of actual measured performance. If an instrument allows me to adjust the?DUT to a certain level, I don't care what its spec is (I'll simply conclude it exceeds it, which is simply to believe my empirical data).? On Sat, Feb 12, 2022 at 11:58 AM Goran Finnberg via <mastering=[email protected]> wrote: >I am not aware of HP units that can be as good at this specific work as some of? |
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Spec for the old 8656A is 0.5% THD, but is normally much better for the internal oscillator.? You can use a low distortion external oscillator of course, and even an MPX generator.? I don't know what you are looking at.? The 8657x may be better or the same, I don't know.
Spec for the Sencore SG80 is 0.01% and is typically better, also provision for an external signal source. I have an SMG1 which measures very low measured modulated THD, but the manual states 0.1% THD. The fact is that many instruments perform much better than the stated specifications.? So comparing measured distortion to manual specs is not a level playing field at all.? I do remember running all mine through an HP 8901A and also a Boonton? AD82 modulation meter.? I check my equipment with these on occasion and always use them to set actual modulation levels using an external source. I was authorized warranty for Revox, McIntosh, Yamaha and others who all make excellent tuners.? I do have to say that when you get close to equipment residuals you cannot assume anything.? You can get cancellation and noise becomes an issue too.? When things get that low I am looking at output spectrum as well as a meter needle (HP 339A and ShibaSoku AD725C).? Besides, transmitted FM signals have higher distortion than 0.011%, typically a lot more. The average tuner distortion does sit in the 0.15% to 0.25% range.? While you couldn't measure the level of distortion using a generator with 0.5% THD, you can still align it for minimum distortion.? The OP was questioning a single, non-remarkable instrument.? This is only suitable for setting up mid-range tuners while having good training and experience.?? -Chris |
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