Justin,
For 2m you may find the phase noise fairly high.? Just listening to it bare
with my?2M system suggests that.
For 222 and higher its not what you want to use the harmonics sound bad!
For 432 the third harmonics sound like FM modulated with white noise.
The problem as you go up is so route the signals you need traces and the
traces are transmission lines and likely low impedance at VHF and up so
your going to source current no matter what.? 1pf loading? at 10mhz is?
not significant, at 144 it multiplied by 144 and is significant.
For a quadrature case crosstalk is not an issue they are the same frequency.
I do not think, subject to testing, you can get a 90 degree quadrature at 144
as the divisors are getting small.
FYI a hybrid at 144mhz will give you plenty of bandwidth easily 1% for
amplitude and phase is rarely an issue for wider.? ( I do IQ)? A hybrid
is easy at 144 and a clean lo is all that's needed (everything has to
be well shielded).? I presume you really don't want to do FM with IQ rx.
The alternate is use a fixed LO (crystal) split into I/Q and up convert both
to whatever.? The up convert can be then anything that decent at HF
and not harmonically related.?and a 5351 one channel might do that
well.? I did that with SI570 but that is a cleaner part.
Basically what is fine at 10M does not fly at 2M.? ?I build for 2m for very
low target NF.? I want to hear signals below -144dbm.? The quality of
the LO is critical as at 2M and up you will hear it!? ?Look at KK7Bs work.??
For easy build a good 10M (one that can tune 28 to 30mhz) IQ RX and
put a well done down converter using a 116mhz LO.? Then get a
11 element beam minimum (more like 15 or more would be better).
Allison
