Modify Tx frequency

[loyn]

Guys like to find out is there anyway to modify the operating frequency of a Tx? I have an old JR 7 channel radio on 27 mHz and no micro Rx is available in the market is in this frequency. Thinking is it possible to modify the Tx to work in other frequency. Just do not want to wast the system.

Any electronic expert out there can help or any idea which LHS is capable of doing the modification?

All advise are welcome, thanks

[Super-Hornet]

Hi Loyn

I no Telecommunication Expert, this is what I think is possible:

If your frequency different is not that high, (Like Changing 35MHz to 40MHz) I believe u can just change the crystal to the frequency u want. U might lost the Transmission range due to its TX and RX variable inductor and variable capacitor (or its IF Tuner) is possible tune to the frequency of 35MHz.

Note: Some RX uses different frequency crystal clock like in my case, my TX uses 35.250MHz where its RX crystal is lower that 35.250MHz. But this maybe the reason my RX sensitivity sux!

Super-Hornet

[Jcho]

Try Jet hobby, they have a type of Rx which does not require a crytal. It is a programmable Rx. Please check spec before buying; look at the freq range. BTW this is a FM Rx.

Cheers

[plasma]

well, isit possible to get a crystal in sim lim tower and plug into the tx and reciever? will it work?

[Super-Hornet]

OK... this is what I experimented before on my GWS RX and TX.

Those crystal clock (2 pins) for PPM (or FM) only should be compatible to those u get from Sim Lim Tower except u have to find those Crystal Clock that has bigger diameter pins. Maybe u can solder those wire wrapping pins on it.

As for changing from 35MHz to 40MHz, I haven't try on RX side yet but if u change your TX crystal clock from 35MHz to 40MHz, your Transmission signal/wattage drop dramatically. This is due to the internal Resistor, Capacitor, Inductor (R, C, L) are already tune to 35MHz. To really modify it, u need to retune those RLC.

If u own Futaba 9CHP, (I believe 9X or 9Z or 7C also true) u can change to different frequency (Let say from 25MHz to 40MHz to 72MHz) by changing the Transmitter Module and the Crystal Clock.

Super-Hornet