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-   -   Testing Receiver (https://www.rcuniverse.com/forum/questions-answers-154/4147464-testing-receiver.html)

crebulus 04-10-2006 11:24 AM

Testing Receiver
I was given a box of "stuff". In this box was a Circus Hobbies(i think, don't have it in front of me) receiver by jr. It said hi-band, so I tried to test it out with a 60 crystal. I couldn't get anything to work. Is there a method for testing to see if it is bad, other than what I've done? Did I use the wrong crystal?

Thanks for the help,


agexpert 04-10-2006 05:38 PM

RE: Testing Receiver
Are you sure it's FM and not AM?

I have some old stuff from circus hobbies that is all AM. I don't use it.

crebulus 04-11-2006 08:14 AM

RE: Testing Receiver
I'm pretty sure it's FM. It had a 72.630 crystal in it. That is channel 42 if I looked it up correctly. Any other ideas, or am I just out of luck?

agexpert 04-11-2006 06:12 PM

RE: Testing Receiver
I think it still could be AM.

I know I may be corrected on this, but I think the frequencies are the same for 72 mhz in AM and FM. The difference is the type of modulation. I'm thinking you have a RX on 72mhz channel 42 AM. Both AM and FM frequencies are reserved for RC use within a specified range of the 72mhz band.

If it turns out to be an AM rx, you can still use it, but I wouldn't if it were mine. I have some AM stuff, but I don't know why I keep it.

flyinryan2 04-12-2006 04:04 PM

RE: Testing Receiver
Why not use the Am, I've(and 1000's of others) have used it for years. It actual works quite well. I dosn't have the interference that you maybe thinking of, like your car radio when you drive under a bridge. Just because its AM doesn't make it bad.

crebulus 04-12-2006 04:36 PM

RE: Testing Receiver
it's FM says it right on the label, I just looked at it. I've tried it numerous times. I guess it's just bad.

agexpert 04-12-2006 07:49 PM

RE: Testing Receiver
You're right about AM being usable and legal and just plain fine. I don't use it because all, (both), of my computer radios are FM/PCM only I still have an analog AM tx that works fine, (got it in college for my Gentle Lady, RIP). I just think that someone who is beginning the hobby would be better-off going with something that can be used with newer, more common radio equipment.


This information would have been more useful in your first response:

"it's FM says it right on the label, I just looked at it. I've tried it numerous times. I guess it's just bad. "

Good Luck!!

impactiq 04-12-2006 10:03 PM

RE: Testing Receiver


it's FM says it right on the label, I just looked at it. I've tried it numerous times. I guess it's just bad.
What brand TX are you using to test this? There is + and - shift modulations depending on brand. JR uses Negative shift modulation to send the signal. Is the receiver PPM or PCM? This will also determine if your "test" TX will be able to communicate with the RX.

crebulus 04-13-2006 09:18 AM

RE: Testing Receiver
I would've put that info in if I had the receiver in front of me at the time. Sorry about that.

I'm using a jr 6102 to test, and i've tried PCM, PPM. I don't know of any other way to test it. No big deal, I'll just get another one, I was just trying to use the stuff in a trainer I was setting up to teach my neices to fly.

agexpert 04-13-2006 03:26 PM

RE: Testing Receiver
Yup Darrin...at this point I wouldn't risk it even if I could find a way to make it work. Hitec makes some low-cost shift selectable receivers. Get an 8 channel or more and your nieces can use it forever in different planes.

Good luck!!

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