[time-nuts] Dead 5065A - Some comments - Some questions... (III)

[Poul-Henning Kamp]

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Bob kb8tq writes:

> Common wisdom is that there is a filter in the cavity match that
> is specific to 60 MHz.  Putting in 120 MHz apparently does not work
> well. I haven’t tried it so I’m just passing on what I’ve heard.

Driving step-diodes is a bit of an art, and the relationship between
driving frequency, AC power and DC bias is very far from trivial,
as the "real" parameter, if I have understood it right, is the
slew-rate through the "magic" voltage.

> The “other” signal (normally 5.3x MHz) is mixed with the multiplied 60 MHz.

As far as I have been able to make out, both the 137Hz and 5.3x MHz
are "mixed" through their amplitude modulation of the DC-bias.

My Personal DDS plan is to simply drive the step diode at 59.953... MHz
+/- the modulation pattern, and forget entirely about the 5.3x MHz and
137 Hz.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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