Michael Black wrote:

I don't know, and one thing to remember is that what was done years ago
may no longer be the solution because other things have come along.

Yes, as others have pointed out, a VCO and PLL is a better solution.

A single stage of multiplication is of course simplest. But, if you
do it in one step, the signal may be so weak that you need stages of
amplification at the ultimate frequency. Once upon a time, frequency
limits may have made that unfeasible.
I have a supply of MAR-1s that should do the trick there.


Also, if you have one stage that basically generates harmonics, and
then you expect to pick off the desired frequency, that filtering
may need to be much better than multiple stages. If you start
with a low enough crystal frequency, the next harmonic may be too close
and some of it will get through the filter on the ultimate frequency.
If you have a string of multipliers, each does filtering so the next
stage only has to deal with filtering out a relatively high frequency.

I wouldn't try a diode to go from 72 to 1296 but will double or triple
the oscillator and perhaps try the diode from there.

Note that your two examples aren't comparable. The first example you
say multiplies by 17, while the second only multiplies by 6. Even in
the old days, it wasn't uncommon to see a jump like 6, but something
like 17 was less common.
Sorry, it was a factor of 9, not 17. I just found the circuit The xtal
was 17 MHz.


The real trick seems to be to start with as high a frequency as possible.
Then the multiplication needed is limited, and it's far easier to filter
out harmonics from a higher frequency crystal than a lower one.



Michael VE2BVW
Thanks for your thoughts.
Alan