[Spitball]

Does anyone know where I could find a Ch.#22 (72,230Mhz) crystal for an Airtronics/Sanwa/Cox Tx? It's a conventional looking crystal and would be marked 36,115Mhz, half the operating frequency. Thanks.
Have a nice Tx standing idle but for this crystal!

[g-manz35]

check this out. I've swapped several crystals withh them and if you want you can buy new/used crystals from them.

http://www.radicalrc.com/rrcxtalexchange.html



George

[Spitball]

Thanks George, ja I've done quite a few exchanges with Dave Thacker, mostly Futaba and the odd J-R but thought I'd give RCC guys a chance first - it's for quite and old Airtronics/Sanwa/Cox AM transmitter and I have a couple of AM receivers on Ch.#22 so thought I'd put out a feeler.
I must check RadicalRC tonight.

[Madman]

Is this an FM or AM transmitter? I don't know about the AMs but the FMs have a white tag on them.

Stephen

[Madman]

The reason I am asking is I probably don't have a ch 22 Tx crystal but may have a few Rxs and a matching Tx crystal on another channel. I have some spare FM Tx crystals with matching FM dual conversion Rx crystals. I need to know how many Rxs you need as well as the original Tx frequency. If the original frequency is not close to 22 you will have to get the transmitter re-tuned to match the new frequency. I know of a guy in Dundas and Flightcraft in KW who can do this if you don't have anyone local. If the Rxs are dual conversion and the crystals are OK I would be willing to trade 1 for 1 on them. All are Airtronics brand.

Stephen

[Spitball]

Thanks Stephen - as I said this is an older AM transmitter and someone has whipped the crystal out at sometime. I have a couple of AM receivers I could use if I could get the Tx x-tal. It's not even really worth what it would cost to re-tune but I am familiar with Flitecraft. K-W is no too far from us here. Thanks.

[NEW222]

Hi there. Just reading your post, look also for a Futaba AM crystals. I am using an old Cox/Sanwa crystal in a Futaba Rx with no problems.

[Spitball]

g-manz35's post on the 12th made me realize I could swap any channel older Sanwa/Cox/Airtronics Transmitter crystal for a Ch.#22 at RadicalRC, as they say they have most channels so any suitable crystal would be welcome. They don't sell them outright though. I very much like my two Ch.#22 receivers.
Anybody out there got such an animal - dbmac ol' friend, did you find anything?
Thanks for reminding me George, and hi NEW222. Would the older Futaba Tx crystals work too?
Cheers and thanks for looking.

[NEW222]

Never tried the older Tx crystal swapping. Only Rx. But me thinks that if the Rx works, why wouldn't the Tx?

[Spitball]

Unfortunately, Tx and Rx x-tals generally differ. The Rx crystal generally comes up on the 3rd or 5th overtone at the local oscillator frequency, whereas Tx crystals oscillate at half the Tx output generally and the output stage doubles that to the final output frequency. This is particularly the case in FM Txs as a crystal at half the operating frequency better exhibits the 'pullability' needed for the frequency shift of the FMed output. I think most Tx crystals are marked and operate at half the frequency.
PS The overtones of a crystal are not exact multiples of the fundamental cut, whereas an harmonic is, and the Tx puts out at the second harmonic or double the crystal frequency - there I've certainly talked myself into a corner now!! Phew! Not all manufacturers follow the same techniques though.
Sorry; badly expressed there, but I know what I mean fortunately!!
I may have some luck at the Kitchener-Waterloo Scale bash next weekend, hi denmac!? CU-there.