John 2 with the same type of issue that is bad luck or simply age. Oh my do I for see this in my future? I would be willing to bet it exactly looks like your description. I like the fact that for $1.23 you can get something from digikey. I do tend to trust them and mouser. Regards Paul.
On Tue, Dec 18, 2012 at 4:42 PM, John Miles <[email protected]> wrote: > > I was recently repairing a noisy A3 module for an HP 5065A. > > > > > > The phase modulator has 4 varactor diodes in parallel. > > > > > > Since I suspected a diode, I removed them one at a time. > > > > > > Of course it was the last one! Must be a universal rule there! > > > > > > Anyway here is a PIX of the noise with the diode reverse biased at 20 > > > volts. > > > > > > Anybody know where to get an MV840 ??? > > > > www.octopart.com identifies 23 of them in stock at a reseller called 4 > Star > Electronics. Bob's idea of trying a power-supply rectifier sounds > interesting, though. Failing that, an NTE replacement part for AM radio > tuning might work, perhaps in a different series/parallel combination. > > > > Just curious, what was the 5065A acting like with the bad diode? Mine > seems > to run quietly for days at a time, but then occasionally it generates > excess > low-level random noise for a period of hours to days (see image). Every > time I've tried to get serious about tracking the problem down, it stops > misbehaving. Did yours look like this? > > > > > > It's especially annoying now that I finally sprung for a second 5065A, > which > seems to behave almost identically... > > > > -- john > > Miles Design LLC > > > > > _______________________________________________ > 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.
