[time-nuts] HP 10811 Tuning Diode

Rick Karlquist richard at karlquist.com
Thu Oct 18 17:16:15 EDT 2012

Probably unobtainium.

0122-0244 is shown as Motorola SMV315-24 or MSI Electronics SQ529.
For whatever that's worth.  Reminds me of a popular audio amplifier
design that was in Popular Electronics using Motorola SS1122 diodes.
Some special non catalog diode.  Turns out Dan Myers, the designer,
just happened to have these in his junk box.  A gazillion other
diodes would also work.

In the 5071A, we used a 10811 with a different tuning diode that
gives a 10X larger range and is linear tuning (being hyperabrupt).
There is nothing magic about the 0122-0244.  Lots of diodes can work.

Rick Karlquist N6RK

Adrian wrote:
> 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
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