Len,

Thanks for the input and observations! Comments follow:

wrote in message
oups.com...
Firstly, 108 to 118 MHz is the international civil
aviation radionavigation band. It's not all that
interesting to listen to unless a local tower is
also repeating voice comms over a VOR or Localizer
radionav transmitter nearby on the ground. The
civil aviation voice band is 118 to 137 MHz.

Agreed - not that interesting to listen to, but the NAV
channels are exactly what I'm interested in - (both VOR
and LOC). The "experiment" I have in mind is a processor
controlled scanner of sorts that tracks multiple VORs
and performs as a backup to GPS. Hence the need for
fast/agile tuning (either PLL or DDS). As you may have
gathered - I'm not an "RF guy" by any stretch - but I'm
attempting to learn (out of sheer necessity 8-).....

Secondly, the MC1350 gain block is available from
Jameco (it is still made after buying all the masking
and stuff from Motorola). You can get MC1349s, a
slightly higher gain version from Dieter Gentzow at
Kitsandparts.com

I'm not locked in to the MC1350 - it just happens to be
what's used in the "ultra-cheap" kit I ordered. As it turns
out, there's a company (Lansdale.com) that seems to be
forming a business model around buying "obsolete" IP
from Motorola et.al. and keeping the parts available.
Interesting idea. As it happens, NTE has a drop-in
replacement part for the MC1350 in their "NTE746" -
available from Mouser. May be of interest to some on
this group???

If you are trying to build something at VHF, you
will need some reasonably accurate signal sources
to check out the receiver. That's not a trivial
task unless all you want is to carbon-copy some
regen or super-regen tuned-by-a-single-variable
sort of receiver.

Well, even though (as I said) I'm not an RF-type I do
have quite a bit of test equipment laying around that I've
collected over the years. Among that stuff is an HP8654A
good to about 520 MHz that I've never used (and for the
life of me can't figure why I bought 8-)........

Jameco sells the MC145151 PLL IC (On Semiconductor
the Motorola spin-off still makes them) which, with
a prescaler, can make a good, stable LO that is
channelized at 50 KHz increments for precise tuning.
MC145151 is parallel-load for division, no extra
IC needed to get the right division ratio as in
some serial-input PLL or DDS chips.

Thanks for the tip - I'm concerned about how long
such a thing might be available though. For now the
safest bet seems to be the National LMX series (or
the Analog Devices equivalents) - and adding a
processor for control is not a problem.

Thanks again for your input - it is appreciated!!!
Regards,
Bill