I'm nearing the end of building a 4*40 and am installing the radio receiver/battery etc. I am using the old 72 Mhz system and am on channel 37 so when I purchased the reciever combo (Futaba) I got the crystal for channel 37. I installed the crystal last night, hooked everything up and turned it on. The servos twitch a little as you'd expect but my transmitter does not control anything. Nothing happens when I turn my transmitter on or off. The frequencies match (72.530) so I'm kind of at a loss. Am I missing something here?

Thanks!

What brand transmitter are you using?

Bruce

Futaba 6EXA.

Are both batteries charged ?

What Rx ? try bypassing the switch ?


Bob

http://www.advantagehobby.com/produc...roductid=60141
http://www.advantagehobby.com/produc...roductid=42814

This is the receiver and crystal. The transmitter was getting low on battery and I was using the charge the receiver came with. I assumed it was at least partially charged due to the movement in the servos when turned on.

Is your transmitter set to transmit in PCM mode? If so, switch it to PPM mode. The receiver you have is most likely a PPM receiver.

Bruce

Both are FM, transmitter and reciever. Could it be that the battery power was just too low to pick up and respond?

Best thing to do would be to charge them both back up and try again. If your transmitter batteries were real low or dead the servos would start twitching all over the place.

Yup. They ship the battery without a charge.

Alright. I'll charge both up and see what happens. Thanks!

Both PPM and PCM are FM transmissions. But it sounds like the battery charge is the most likely cause.

Bruce

check for pcm and ppm modulation on the transmitter. ppm is an analog signal and pcm is a computer signal neither will work on a reciever that is not capable of recieving the right format of the signal but fortuneatly the transmitter can easily change between pcm or ppm

Success! Charged both for about 2 hours and it came to life! Of course my elevator and rudder controls were switched but that's an easy fix.

Great !


If using a wall wart charger, you'll need to charge
overnight or longer.


Bob

Just an FYI, not all TXs can be changed over from PCM and PPM, if you have the wrong RX there is often nothing you can do about it. Too many people don't know this when buying used gear. Glad it was just the battery charge for the OP.