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HP8656A

Harold Kinley All Messages By This Member #156 I have a HP8656A signal generator. Works fine for FM and AM. However, when using it to test a SSB receiver there is a pronounced "warble" in the tone and it is serious enough to affect the measurements. Any clue as to where to look for the trouble? A friend of mine bought one at the same time and place as I did (used equipment dealer) and his does the same thing. Any ideas or suggestions on how to repair it? Thanks, Hal Kinley WA4GIB
John Miles #157 They all do that. The 8656A has a lot of close-in phase noise. Not clean enough for any SSB work that requires an extremely stable reference. -- john KE5FX toggle quoted message Show quoted text -----Original Message----- From: halkinley [mailto:halkinley@...] Sent: Monday, February 16, 2004 10:09 AM To: hp_agilent_equipment@... Subject: [hp_agilent_equipment] HP8656A I have a HP8656A signal generator. Works fine for FM and AM. However, when using it to test a SSB receiver there is a pronounced "warble" in the tone and it is serious enough to affect the measurements. Any clue as to where to look for the trouble? A friend of mine bought one at the same time and place as I did (used equipment dealer) and his does the same thing. Any ideas or suggestions on how to repair it? Thanks, Hal Kinley WA4GIB Yahoo! Groups Links
RICHARD W. MURRAY All Messages By This Member #158 开云体育 I found similar problems with my 8656A.? I replaced all electrolytic caps.? I also replaced the osc. I believe it's a FET,? try Sphere in B.C. they had some.? I still have one extra.? It's not as clean as my 8647A but 100% better. ? Regards ? Richard Murray
John Miles #159 开云体育 Which oscillator? ? -- jm toggle quoted message Show quoted text -----Original Message----- From: Richard W. Murray [mailto:inertial@...] Sent: Tuesday, February 17, 2004 8:48 PM To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] HP8656A I found similar problems with my 8656A.? I replaced all electrolytic caps.? I also replaced the osc. I believe it's a FET,? try Sphere in B.C. they had some.? I still have one extra.? It's not as clean as my 8647A but 100% better. ? Regards ? Richard Murray
RICHARD W. MURRAY All Messages By This Member #164 开云体育 JM ? If I recall there are two xtal oscillators.? They are both designed along the same lines.? Check the output on a good digital scope with at least 500 mhz bw.? You will see where the problems begin,? you will see noise & non linear waveforms.?If there is a problem here?it will only get worse as you move through the instrument.? ?I'd find a service manual somewhere before you start the process.? The attenuators will likley need cleaning as well.??After you clean them switch the?gold?plated finger?around,? this will sometimes help. ? Richard ???

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