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Old Jul 15, 2007, 08:52 AM
wamanning@email.com
Guest
n/a Posts
noob question: FM radios going from 27mhz to 72mhz possible?

is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
with a simple crystal swap in one of the units? both are FM and the
RX supports both +/- shift.

for some reason i'm thinking it's not that simple, but want to be
sure...

walter

Old Jul 15, 2007, 10:27 AM
Ed Cregger
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?


<wamanning@email.com> wrote in message
news:1184507548.995403.116030@22g2000hsm.googlegro ups.com...
> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
> with a simple crystal swap in one of the units? both are FM and the
> RX supports both +/- shift.
>
> for some reason i'm thinking it's not that simple, but want to be
> sure...
>
> walter
>


-----------------------


You can swap crystals within a band (27 MHz OR 72 MHz), but you cannot swap
bands unless the transmitter utilizes a module system that includes the
circuitry necessary to change bands.

Ed Cregger


Old Jul 15, 2007, 10:39 AM
Vance Howard
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?

On Sun, 15 Jul 2007 06:52:28 -0700, wamanning wrote:

> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
> with a simple crystal swap in one of the units? both are FM and the
> RX supports both +/- shift.
>
> for some reason i'm thinking it's not that simple, but want to be
> sure...
>
> walter


That would be too far of a jump for just a crystal swap. It would need to
have a few other parts adjusted by a qualified technician.
Old Jul 15, 2007, 11:20 AM
Tim Wescott
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?

On Sun, 15 Jul 2007 06:52:28 -0700, wamanning wrote:

> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
> with a simple crystal swap in one of the units? both are FM and the
> RX supports both +/- shift.
>
> for some reason i'm thinking it's not that simple, but want to be
> sure...
>
> walter


No can do.

Both the transmitter and receiver contain tuned circuits that
can only be adjusted over a relatively small range of frequencies. To
make the nearly 3:1 step you need at least component changes, and will
often see different circuits used.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
Old Jul 15, 2007, 11:40 AM
42etus
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?

You are correct it's not that simple. It could be done, but it would take
much more than simply changing crystals.
42

<wamanning@email.com> wrote in message
news:1184507548.995403.116030@22g2000hsm.googlegro ups.com...
> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
> with a simple crystal swap in one of the units? both are FM and the
> RX supports both +/- shift.
>
> for some reason i'm thinking it's not that simple, but want to be
> sure...
>
> walter
>




--
Posted via a free Usenet account from http://www.teranews.com

Old Jul 15, 2007, 11:53 AM
Red Scholefield
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?

An cost more than a new radio transmitter on 72 mHz. You can buy good 4
channel name brands on e-bay for little to nothing. I've got several that
I'll let go for $25 plus shipping ($8.95 Fixed rate box).

Red S.

"42etus" <paulinlapine@msn.com> wrote in message
news:469a41e2$0$16357$88260bb3@free.teranews.com.. .
> You are correct it's not that simple. It could be done, but it would take
> much more than simply changing crystals.
> 42
>
> <wamanning@email.com> wrote in message
> news:1184507548.995403.116030@22g2000hsm.googlegro ups.com...
>> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
>> with a simple crystal swap in one of the units? both are FM and the
>> RX supports both +/- shift.
>>
>> for some reason i'm thinking it's not that simple, but want to be
>> sure...
>>
>> walter
>>

>
>
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>



Old Jul 16, 2007, 09:13 AM
Ed Cregger
Guest
n/a Posts
Re: noob question: FM radios going from 27mhz to 72mhz possible?


"Red Scholefield" <redscho@bellsouth.net> wrote in message
news:fismi.58014$Fo1.38676@bignews7.bellsouth.net. ..
> An cost more than a new radio transmitter on 72 mHz. You can buy good 4
> channel name brands on e-bay for little to nothing. I've got several that
> I'll let go for $25 plus shipping ($8.95 Fixed rate box).
>
> Red S.
>
> "42etus" <paulinlapine@msn.com> wrote in message
> news:469a41e2$0$16357$88260bb3@free.teranews.com.. .
>> You are correct it's not that simple. It could be done, but it would take
>> much more than simply changing crystals.
>> 42
>>
>> <wamanning@email.com> wrote in message
>> news:1184507548.995403.116030@22g2000hsm.googlegro ups.com...
>>> is it possible to get a 27mhz TX to work with a 72mhz RX (both are FM)
>>> with a simple crystal swap in one of the units? both are FM and the
>>> RX supports both +/- shift.
>>>
>>> for some reason i'm thinking it's not that simple, but want to be
>>> sure...
>>>
>>> walter
>>>



I have a few RTF electric models. The transmitters that come with two of
them, are simply amazing in their feel and utility. It wasn't long ago that
just a transmitter of similar apparent quality and feel would have cost more
than I paid for the whole RTF set up.

Today, with Tiger Direct selling rechargable batteries and chargers (4 AA
cells) for around $25 USD, fitting one of these transmitters with
rechargable batteries is a piece of cake and cheap. Not only that, but you
can use the rechargable batteries for other purposes when not in the
transmitter. Such as my Olympus C5050A digital camera.

Ed Cregger


 


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