From: "RST Engineering" Mon, Mar 14 2005 8:11
pm

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.

Firstly, the tower does NOT repeat voice comms over a VOR. The local
Flight
Service Station MIGHT, but in the days of crystal controlled navcoms,
the
amount of voice traffic on a VOR is next to nothing.

Now, now, Jim. They do.

My residence is a mile and a half from BUR, roughly
eight miles from VNY here in the San Fernando Valley
area of Los Angeles.

Agreed, tower operators SELDOM repeat their transmissions
over the VOR but it is there in case it is needed. I've
heard them often enough.

VOR has an almost enormous bandwidth between 30 Hz and
the 9.96 KHz subcarrier phase reference...which was
INTENDED to carry voice as a conventience to the tower.

BUR, now the Bob Hope Airport, USED to carry the taped
weather broadcasts over their VOR but stopped several
years ago.

Secondly, the tower/FSS will never in HELL repeat something on a
localizer
frequency.

Calm down. I may still vote for you next election,
but not if you act like Arnie... :-)

Hokay, I may have spoken hastily on the voice over
Localizer. Color me "probably wrong" there.

You are correct; the civilian aviation voice band is 118.000 to
136.975 MHz.

Thank you. Sigh, I was only in the business of making
civil avionics and their test sets once. :-)

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.

The 145151 is OK if you don't mind spurs every 25 kHz. from dc to
daylight.

Sorry, I don't agree there. "Spurs" with an ordinary
PLL happen when the loop filter component values are
incorrect...and/or a higher frequency pole is used
(via an extra R and C in loop filter)to reduce higher
frequency components out of the PFD.

I've made a few PLLs with that MC145151 for homebrew
projects and not had any spurs from "DC to daylight"
or within the band of interest.

The 145152 is a much better dual-modulo prescaler that gets rid of a
lot of
trash and garbage from single modulo prescaling that you probably
don't
want.

I've not tried the 145152 but, back a number of years
before On Semi split from Motorola Semi, a Motorola
factory person said the 152 is essentially the same as
the 151 except for the serial data interface. I can't
vouch for that but that's what I remember.

Single modulus prescaling (putting a simple divide by
8 or divide by 10 in series with the VCO and PLL IC
signal input) doesn't produce any more #$%^&!!! stuff
than going direct into the PLL IC signal input. That
is said PROVIDED the loop filter output line to the
VCO it is controlling is "clean" and doesn't pick up
other circuit signals. Such garbage pickup is the
common cause of "spurs" and is layout dependent, NOT
dependent on whether or not any prescaling is done.
There's some dependency on proper supply rail decoupling
for the phase-frequency detector and any active op-amps
used between the loop filter and VCO control input.

By the way, I've used the MC1350 down to 10 V supply
rails with no problem although I do agree with it
running optimally (for gain and noise figure) at 12 V
supply. There's a lot of internal constant current
sources on that IC and that causes the dependency on
supply voltage. The same with the MC1349 which I'm
working with now as both gain blocks and as mixers.
I've worked with the MC1590 metal can original 34
years ago and the plastic package 1350 since 31 years
ago. I like it as a little block of gain which has
low distortion when running balanced input to balanced
output...on up to 70 MHz with hardly any gain rolloff.