K7ITM wrote:

Yeah, saw that. Trouble is that I need EVEN harmonics


Huh? I thought you wanted to multiply by 18. 18 = 3 * 3 * 2.
Quite right. 18 is an even harmonic of course but I forgot about the
3*3*2 bit


If you were specific about what you want to do with the output, I
missed it.

It's to test a 1296 down-converter basically but will try a CW
transmitter later so a bit of grunt wouldn't go astray.

..... There might already be enough 18th harmonic in the oscillator
output to do what you need.

Could be. AT the moment I have a 2N5485 as the osc and a 2N918 as a
doubler but the 2N918 runs out of puff well before 1296MHz. I have some
BFR91s so I might put them into use.

Cheers,
Tom
73 de Alan

On Fri, 23 May 2008, Alan Peake wrote:



K7ITM wrote:

Yeah, saw that. Trouble is that I need EVEN harmonics


Huh? I thought you wanted to multiply by 18. 18 = 3 * 3 * 2.
Quite right. 18 is an even harmonic of course but I forgot about the 3*3*2
bit


If you were specific about what you want to do with the output, I
missed it.

It's to test a 1296 down-converter basically but will try a CW transmitter
later so a bit of grunt wouldn't go astray.

But unless you need a signal to tune the converter to the right frequency,
this is quite a bit simpler. So long as the converter is tuned to the
right general frequency, merely something with good harmonics will do.
The fact that they will be attenuated at the desired frequency is not
a bad thing, since you won't want a strong signal for tuning the converter
anyway.

Your original post didn't give an end use, but it was easy to assume
you needed a clean signal for a transmitter of local oscillator injection
in a converter. You don't want unwanted signals there.

But for a signal generator, having extra harmonics isn't really a problem
(unless you can't be sure that your converter is tuned to the right
frequency). The extra harmonics will just be ignored by the converter's
tuned circuits.

There was a time when a lot of cheap signal generators actually used
harmonics for their upper ranges.

Michael VE2BVW