I have a basic Futaba 4 chan tx, and someone gave me a Futaba 6 chan rx. Assuming crystals match, should the rx respond to first 4 chans of my tx?

The only dumb question is the one not asked. Most of us use the futaba 127 receiver, which is the one supplied with all 4 and six channel radios. It is seven channels. If the receiver is one of the really old types, it may not work. The best bet is to plug it into a servo, power it up and test it out. It should work on all four lower channels. So check them all. If it does, you can have a friend help range check it hooked to servos, walk about 65 feet away with the antenna down and make sure all four channels are responsive in the correct directions with no jittering. If so, you should be good to go.
Hope this helps, good luck.

Actually its a FP-R107N 7 chan. Put a servo on and power up, and servos react, but wont respond to tx. I think its toast, but just want to check.

Double check the small print on the new reciever. With it being a FP it may be PCM. A PCM reciever would not work with your transmitter. And being it is a real oldie it may not even work wuth the new transmitters. A few years back PCM recievers were upgraded as to the decoding speed. And the old recievers won't work with the new transmitters. Double check the chrystal and be sure it is the same as your trans too. Good luck with it.

Mark Shuman

You can also go onto Futaba's website and see if it's compatible with newer TX's.

Andy

Also futaba splits their rec in the middle. If you fly on the low side and the one given you is on the high side, it will not work with your Tx.Dennis

It may be that your RX is just too old. I looked up your rx on http://www.futaba-rc.com/radioaccys/old-receivers.html. The R107M is listed near the bottom of the list (5th from the bottom) of "Wide Band" receivers.

It appears that your rx was discontinued in 1985. It won't play very well on today's Narrow Band TX's, and would most likely be susceptable to adjacent-channel interference.

I know that the older tx's could be modified to the narrow-band configuration of the early 90's, but don't know if the rx's could be, or if it would even be worth it. I'm assuming that your TX is one of the newer Narrow Band units.

Just being nosy and putting in my $.02

I hope that this helps in some way.

Bob

I appreciate the comments. Just going to toss it and move on.