On Fri, 4 Jul 2014, Rob wrote:

Eric Weaver wrote:

Wondering if there are any plans or commercial kits available (aside
from the part-15 3-meter broadcast stuff) with the MC145151 PLL. Also
what VCO people use with it. Seems it would be handy for tunable
beacons on 2M or such.

Is this one of those articles reposted from the "usenet 30 years ago"
system?

No, but it is like a flashback.

I think I made a synthesizer using that chip, but that is long ago
and I don't think I would use that today.

I was going to say, it's well in the past. The IC just makes it simpler,
there's nothing magical about the phase detector that can't be had other
wasy, and the rest is just a a crystal oscillator and and divider chain,
and a programmable divider chain. There may be more recent ICs, though a
lot of that has gone out of availability. The problem is, things used in
TV sets and AM/FM radios don't have the versatility of the general purpose
ICs, and the spacing will be too wide. But synthesizer ICs for TV likely
are for being controlled over a serial bus, like that I2C, and in this day
and age that likely is an easier process, saves having find bcd switches
at the very least.

There was a lot of tedious wiring forty years ago for those people making
sythesizers and frequency counters, but what worked then often still works
now, so long as you can get the logic ICs in packages that are not surface
mount. Later ICs became denser, so a 74390 (or schottky variant) has two
decade counters, and an 8bit latch intended for computers is twice as wide
as the 7475 latch so common decades ago in frequency counters.

SOmetimes the longer route along is actually faster than the short route.

Michael