[HBR] Mixer questions and other tech questions..

[Ian Wilson]

Very interesting topic; I'd been considering using beam deflection
mixers for a while, and I stumbled upon Andy G4OEP's site with
a neat design (the Retro and Retro II): http://g4oep.atspace.com/

The 6JH8 and similar want 15v peak or so to the deflection plates.
This makes a multiband solution quite a challenge unless you are
prepared to make the deflectors part of a tuned circuit. I've spent
some time recently trying to come up with a wideband amplifier
with the ability to swing 15v peak into a 12pF load. This is not
easy.

I have also wondered whether the large signal handling capacity
of the deflectors might be better applied to handling the signal,
as opposed to the LO. This would seem to me to give the best
linearity and large signal handling capability. I suppose that the
conversion gain becomes much lower (hence worse noise figure?)
and you lose the advantage of balancing out the LO signal in
the outputs.

Very interested in others' approaches here. Using a device with
good linearity, good large-signal capability, with filtering immediately
at the mixer output and with no RF stage seems like the basis
of a receiver with outstanding performance.

73, ian K3IMW