In message , Alan Peake
writes


amdx wrote:

Here's an interesting simple circuit to generate odd harmonics.
"New Topology Multiplier Generates Odd Harmonics"
http://www.wenzel.com/pdffiles1/pdfs/RFDesign2.pdf
Mike
Yeah, saw that. Trouble is that I need EVEN harmonics

If you want EVEN harmonics, then use the 'fullwave rectifier' circuit.
This is essentially identical to what you use to rectify the mains, but
it works at RF. One version is the simple bi-phase circuit, consisting
of a ferrite input transformer (ratio 1 : 1+1) and two rectifying
diodes. An alternative is the fullwave bridge version.

I have used the former with great success to multiply by 2, 4 and even 6
but, of course, you get a lot less with the higher order harmonics.
Also, the relative suppression of the even harmonics is less.

Anyway, there was some interesting info on snap diodes etc. Makes me
think that the diode used in the gear I have, aren't SRDs as these seem
to be mainly for microwave use.

I did get involved with a comb generator which used a single step
recovery diode, driven at 6, 7 or 8MHz, to generate fairly equal
amplitude harmonics (both odds and evens) to around 600MHz.

The other info I gleaned was that it's easier to get low phase noise
with straight multiplication than it is with PLLs. Not that I have an
urgent need for low phase noise - but it's interesting nonetheless.
Alan

I didn't know that the "New Topology Multiplier Generates Odd Harmonics"
circuit existed. It's every bit as simple as the fullwave rectifier
circuit for generating even harmonic!
--
Ian