On May 15, 12:32*am, raypsi wrote:
Hey OM:

Back that far they been using PLL for FM demod. Only because they
needed to demod stereo phase, at 15 some Khz. Find the slope in that
PLL and it'll detect AM. But most osc's in those things are only good
to 110Mhz, with 10.7 Mhz IF, *that'll get you to 120.7Mhz You just
can't make the capacitance of the circuit go away with a coil.
If you are lucky the airport your near will be within 108 to 120.7 Mhz

You might as well just build a converter, like back in the day when FM
first came out they used a converter to take 88 to 108 MHz and put it
on the AM *band. All you did was plug the box into the antenna of your
AM car radio and viola' FM and with a reverb you could even simulate
stereo. That was b4 8 track tape decks.

Heck I made a living making and selling a converter for police band
453Mhz to AM radio band you could actually tune 4 police channels in
the Detroit, MI USA area with the converter and any AM radio. We used
a CB crystal for the oscillator multiplied it up to 452 Mhz and viola'
police band on any AM radio. the converter was the size of a pack of
cigarettes.

This link will give you an idea now a days things are a lot easier:http://tinyurl.com/qwk9pw

73 OM

de n8zu

On May 14, 8:41*pm, JIMMIE wrote:



On May 14, 8:24*pm, (Dave Platt) wrote:

In article ,
Bill M wrote:

Also, if I remember correctly, aircraft use AM in the 108-136 MHz range. *
So modifying the 88-108 MHz FM portion of the receiver wouldn't work. *
Doesn't really matter much since you can slope tune it.

IIRC, slope tuning can be used to allow an AM receiver to demodulate
FM (albeit somewhat crudely).

Does it work in reverse? *Can you offset-tune an FM receiver, and get
its discriminator to demodulate an AM carrier-and-sidebands?

Seems to me that this wouldn't necessarily work... the
huge-amounts-of-gain-and-then-clip-the-result architecture of an FM's
IF strip is going to equalize out the amplitude variations in the AM
signal pretty effectively, won't it?

--
Dave Platt * * * * * * * * * * * * * * * * * AE6EO
Friends of Jade Warrior home page: *http://www.radagast.org/jade-warrior
* I do _not_ wish to receive unsolicited commercial email, and I will
* * *boycott any company which has the gall to send me such ads!

If an FM radio has a decent amount of limiting forget about receiving
FM but if the limiting can be removed or it doesnt have too much you
can receive AM on an FM receiver thought it may be fairly distored but
it most likely will be copyable. For example I have an ICOM two meter
FM *transceiver that *will tune the VHF aircraft frequencies. Sorry
but I forget the model # at present I bought it about 15 years ago and
havent tused it in 10 years.

Jimmie- Hide quoted text -

- Show quoted text -

I remember when those things were around. There was a group of my
friends who like to do a little street racing so we used it to keep up
with where the police were. We also used CB radio to talk to each
other. When we found out the police were on to us planing races on CB
we got where we would pass the mike around and pretend like we were
having a race and watch them run all over town. The things we had to
do back then to keep intertained.


Jimmie