On a sunny day (Sat, 21 Feb 2004 19:22:15 +0000) it happened Paul Burridge
wrote in
:

On Sat, 21 Feb 2004 18:22:44 +0000, Leon Heller
wrote:



Paul Burridge wrote:
Anyone care to nominate an RF mixer chip for 100Mhz that's readily
available in the UK?

What sort of performance is required?

"Good." :-)

Diode mixers are easy to obtain
and have good IMD characteristics. The impedances on the ports need to
be properly matched.

What - the sort of crossed diode config one often sees in the ham
design books? Do you think I might as well just make one up from
discretes? I'm basically just trying to combine 60Mhz with 20Mhz to
end up with the difference frequency in this case. JJ suggested a
chip, but looking at the data sheet, it seemed to be designed more as
a modulator than a mixer. Let's not get into an argument over
semantics but y'all know what I mean, I'm sure.

BTW, thanks for a good steer with the Pulsonix suggestion, Leon. I'm
making good progress getting to grips with it.
I do this with a dual gate MOSFET, osc on second gate, signal on first.
A voltage divider on gate 2 to set it in teh non-linear part.
This works very well, is not critical, very cheap and extremely reliable.
Also the noise figure is good.
So tuned 40MHz in drain
I did one some weeks agao, but cant remember what that was for?
Anyway that sceme works up to a GHz , from kHz up.
If you need diagram and part example I could draw up one here.
Copyright Jan Panteltje 2004 All Right Reserved
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