From: "Netgeek" on Sun, Mar 13 2005 4:42 pm

I'd like to build some homebrew VHF-AM receivers - specifically a
receiver
for
the VHF 108-118 Mhz band. I've found lots of great ideas and
reference
designs
out there but they're all constructed of parts made from "unobtainium"
(e.g.
old
MC13135/6, MC1350, etc., etc.)...

Can anyone on this group point me to some designs/ideas for how to
construct
something made from "actually available" components???

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.

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 got 18 of them just before
Christmas along with some other good parts. Good
service from Kitsandparts, great source of toroid
cores.

There's still lots of legacy ICs available out there
but you may have to search for sources.

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.

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.

Lots of inexpensive "all-band" radios off the shelf
include the aviation band, those in addition to all
the available VHF scanner receivers. Those all work
better and more reliably than simple regens and
super-regens in my observation.