summerkc

Hi all, I have a Futaba 4 channel high band 72mhz Tx with a Ch.46 dual conversion crystal (I also have the matching Rx crystal). I want to use this in a park flyer that is also a 72mhz high band but uses a single conversion crystal. If I buy a Ch.46 single conversion crystal for the Rx will it work with my Tx? Also, what is single or dual conversion anyways?

dirtybird

My Feedback: (5)

Single or dual conversion is concerned with the receiver only. It has nothing to do with the transmitter. A dual conversion receiver is less prone to interferrence than a single conversion receiver. You only have to make sure the crystal installed in your receiver is the type required for the receiver for that frequency. (Single or dual)
If you want to know more I would suggest you go to the library and check out some books that cover superhetrodyne receivers and read up on it. Its a bit more to explain than is normal here

Scar

My Feedback: (3)

What brand crystal do you have?

Futaba sells their receivers in two types, one to cover channels 11 through 35, and another one to cover channels 36 through 60. They designate the receivers "High" and "Low". You can buy a "High" one for your channel 46 crystal.

Or, you can buy a HiTec receiver and crystal, works the same with your Futaba.

I'm doubting that you can drive that parkflyer receiver with your Futaba transmitter, because the parkflyer is probably an AM receiver, while your Futaba radio probably broadcasts an FM signal.

But then, I'm guessing.
Dave Olson

summerkc

Ummm...no thanks! I just wanted to know if it would work mixing the two types of crystals, thanks.

AirBearMA

My Feedback: (1)

Single and Dual Conversion apply to the receiver crystal. In a single conversion receiver operating on channel 46 (72.71 MHZ) usually the conversion frequency is 455 khz which means that (depending on your receiver manufacturer) to receive the signal at 72.71 Mhz, you would need a crystal cut for either 72710k - 455k or 72710k + 455k. (72.255Mhz or 73.165Mhz). A dual conversion radio would usually have it's first conversion at 10.7Mhz. Therefore the two potential crystals are 62.010Mhz or 83.410Mhz depending on whether they mix high or low. As you can see depending on whether your receiver is single or double conversion and whether the manufacturer mixes high or low in the receiver would determine which of 4 different frequency crystals would be used.

Unless you know exactly the frequency crystal required for a receiver, always find out from the Receiver Manufacturer what crystal you should use for it to work properly on any model channel. Otherwise you could run into problems with that receiver. If you have the correct crystal in your Channel 46 receiver AND the receiver is a model compatible with your model of transmitter, it will work.

NOTE: On standard PPM receivers, there are two different "shift" types. One is Positive shift used primarily for JR/Airtronic radios and the other is Negative Shift used primarily for Futaba/Hitec radios. Make sure that the receiver you buy will have Negative shift capability to work with your Futaba transmitter.