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Single or dual conversion?

Old 02-16-2007, 11:09 PM
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trevormatney
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Default Single or dual conversion?

Hi everyone! I have what I think is a dumb question, but all the same I need an answer to. OK, I have a futaba skysport transmitter, a Hitec 05s micro reciever, and futaba micro servos. I plug everything in correctly trying to center the servos, using a receiver pack. The servos jump a bit when I plug the battery in, but there is no response to stick input. If it matters the channel is !3. All I can figure is that this being a single conversiion receiver, I need a dual conversion to operate with this transmitter. I don't know, but sure do need to figure it out! Anyone able to help me track down my problem? Thanks a bunch!
Trevor
Old 02-17-2007, 12:05 AM
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Crazy4Flight
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Default RE: Single or dual conversion?


ORIGINAL: trevormatney

.....All I can figure is that this being a single conversiion receiver, I need a dual conversion to operate with this transmitter. I don't know, but sure do need to figure it out! Anyone able to help me track down my problem? Thanks a bunch!
Trevor
What you need is a Hitec SINGLE Conversion FM crystal.

If you are useing a Hitec or Futaba dual conversion crystal, It will not work.
Old 02-17-2007, 08:39 AM
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Default RE: Single or dual conversion?

Yep. A transmitter is just a transmitter, dual or single conversion is purely a function of how a receiver handles an incoming signal. Single coversion recievers use less parts so they are lighter and are often used in small micro receivers. So you need a single conversion crystal, on the same channel as your transmitter, thats made by your receiver manufacturer.
Old 02-17-2007, 09:21 AM
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trevormatney
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Default RE: Single or dual conversion?

Ok, so I double checked my crystal, and frequency, and everything is the way it should be. I'm using a hitec single conversion crystal 72.050 MHz. This particular receiver is auto shift, and the directions state " If you need to match the shift type (negative to positive), between Tx and micro 05s, with power OFF and ON of micro 05s, youcan easily synchronize shift type (Tx is still power on status)". After trying this I'm still getting no response. Could it be that I have a bad receiver, or crystal? All servos and battery are plugged in with the black wire toward the bottom of the receiver. Any other thoughts? I appreciate your help!
Trevor
Old 02-18-2007, 09:03 AM
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BillyGoat
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Default RE: Single or dual conversion?

To answer your question about the possibility of a bad Rx or a bad crystal, yes to both. I’m not familiar with that Rx to know if your plugging in the servos right.

Your problem may not be on the receiving end, lets check the Tx side of the equation.

First pull the crystal (right on the front, lower left) to make sure it also says. 72.050. Can’t always believe external stickers on the Tx. I know that first hand. Double check to make sure the antenna is screwed in tight. One last thing I can think of is make sure both batteries have a good charge.
Old 02-18-2007, 01:39 PM
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Rcpilot
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Default RE: Single or dual conversion?

I'm not familiar with your TX--so pardon me if this is way off:

Is the TX set to run in SPCM mode?

I've had that problem before. I use regular FM PPM RXs in all my planes. But, my TX can transmit in SPCM or PPM (FM). If I forget to turn the radio to PPM when I first set up a plane, it will act exactly as you describe. Everything jumps for a second and then I got nothing.

As soon as I remember--I switch the TX to PPM and then it all works perfectly.
Old 02-18-2007, 07:31 PM
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BillyGoat
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Default RE: Single or dual conversion?

Rcpilet, I’ll answer that question for Trevor. The Skysport is Futaba’s 4ch basic entry level system. It's just PPM using a crystal.

Good call though, that little detail has derailed many a modeler and left them wondering what the heck was going on.
Old 02-19-2007, 03:18 PM
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trevormatney
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Default RE: Single or dual conversion?

Thanks for the replies! My transmitter is definitely on 72.050 MHz, as Ive used it with other receivers with no problems. Batteries are fully charged, and Tx antenna is tight. I guess I should just call Hitec. I would like to thank all who replied. Have a good one.
Trevor
Old 03-19-2007, 01:50 PM
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trevormatney
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Default RE: Single or dual conversion?

I figured I'd follow up on this post, since I have figured out what the problem was. I called Hitec, and they said send it in. I did, and about two weeks later they returned it to me with a service order that said no problem found. O.K. so what was the problem? Well I decided to reverse the servo and battery wires- putting the negative(black) wires toward the top. or label side of the Rx. Lo and behold no problem! I feel a little dumb, but I did'nt want to plug anything in backwards and have something short. On the two other Rx's I have, the negative wire faces toward the bottom, so I guess I learned something here. It's always the simple things that get me!!! Thanks and have a good day!
Trevor

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