Hi Varactors are typically biased through very large decoupling resistors. The amazing part isn't that they get noisy, it's that they ever are quiet :).. In most circuits if they ever leaked at the rated "max leakage" spec, you would see all sorts of trouble.
Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Miles Sent: Thursday, October 18, 2012 11:55 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] HP 10811 Tuning Diode That's extremely interesting, Adrian. I've never heard of a noisy varactor, but then I've never looked for one, either. It'd be great if some of the problems that have been blamed on jumping crystals were in fact caused by the tuning diode. What steps did you take to rule out the crystal and narrow down the problem to the diode? -- john, KE5FX Miles Design LLC > -----Original Message----- > From: [email protected] [mailto:time-nuts- > [email protected]] On Behalf Of Adrian > Sent: Thursday, October 18, 2012 12:19 PM > To: Discussion of precise time and frequency measurement > Subject: [time-nuts] HP 10811 Tuning Diode > > Hello, > > I found the 10811 in my 8662A to be quite noisy and was able to trace > the problem down to the tuning diode. > Actually, the phase noise started to jump when the oven heated up. As a > quick solution, I replaced it with a SMD type that I had at hands. > > I would appreciate any hint where to find an original diode (even though > I could leave it as is). > > As by the manual, the original is a '0122-0244 DIODE-VVC 100PF 5% > C4/C25-MIN=2 BVR-30V Mfr. 28480' > Mfr. 28480 is listed as HP, but the diode is marked 'M' for Motorola and > '0244' and '312'. > > Adrian > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi- > bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
