norbe

My Feedback: (51)

Very easy question, I think I know the answer, can I use a TX crystal in a receiver?
Thanks

Imac Kiwi

No

norbe

My Feedback: (51)

Ok i thought the answer was yes, after all a crystal si a crystal what is the difference from a tx one and a Rx one technicaly speaking?

mr.rc-cam

There are many differences. For one, the Rx xtal will be at least 455Khz away from the Tx freq (and as much as 11Mhz different). Other differences include, but are not limited to, the overtone mode used, capacitance, and pullability.

RC-CAM

4 stroken ron

My Feedback: (29)

Well, we used to do that about 20 years ago.........when I was racing RC cars...........on 27.........AM. Occasionally we might run into a freq. conflict, and one of the competitors would announce he would use his "secret" freq.[X(][X(] Everyone turned there heads so they did not see and the racer would change his Xstals. It seemed to work then. I guess things are different now
Ron

norbe

My Feedback: (51)

If I don't recall wrong there is a place that exchanges the crystals what was it?

piper_chuck

My Feedback: (12)

The racer probably had a pair (tx and rx), and changed both. After all, it would do no good to just swap one of the two crystals.

4 stroken ron

My Feedback: (29)

http://members.aol.com/davthacker/ra...alexchange.htm


Ron

4 stroken ron

My Feedback: (29)

Ah no. What he was doing was putting the Rx Xtal in the Tx, and the Tx Xtal in the Rx. It worked way back them, on AM 27.
[sm=confused.gif][sm=confused.gif][sm=confused.gif]
Ron

dirtybird

My Feedback: (5)

It could work today if you are using a single conversion receiver. Only one problem: Its illegal- as it was on the 27MHZ systems. With a double conversion receiver the crystals are too far off frequency for the system tuning to work.

Rodney

Dirtybird, I doubt if it would work today even with single conversion as the transmitter crystals are usually approximately 1/3 the frequency of the final frequency (the transmitter operates on third overtone) while the receiver circuitry does not.

norbe

My Feedback: (51)

One thing I don't understand is how and why, technicaly, does the trasmitter have a third of offset. Shouldn't it be at the same frequency? Wouldn't it be better?

dirtybird

My Feedback: (5)

I think they are actually fifth overtone. Its hard to make a crystal of more than 15 mhz as they get too thin and fragile. For that reason the receiver also must be of the overtone type. Although they may not be the same type of cut which would make them incompatible

laryboy

My Feedback: (2)

most recievers are dual conversion type which means that the first xtal is 10.7mhz away from transmitter freq. the next conversion converts signal to 455kc. the reciever xtal is 455kc away fron the transmitter freq. therefore they are not interchangeable.

Rodney

Dirtybird, you are correct on most of them using 5th overtone, I am not sure what the receivers use but probably similar due to the frequencies involved.