| >Speaking of the problem, what is the problem? Jittering? Loss of
| >range? Something else?
| Loss of range. (60% reduction),
Hmm, not good. Any sort of strong RF intereference can desense a
receiver, even if it doesn't directly interfere.
How far are you trying to go anyways? I'd think that with good
directional antennas, pointed in the right direction, you could do 5
or so miles even with just one watt.
| >You might want to try a dual conversion receiver -- they might be
| >better able to reject the interference you're seeing.
| Who makes a good 6M dual conversion receiver? (See the end for why it
| gopt to be 6M)
| I'd gladly spend $500 for a receiver if it made the problem go away.
| 6M receivers are hard to come by, JR, Berg and FMA are the only ones
| I know of.
Futaba does too. I've got a few of them. They seem to work fine,
though I don't have the challenges that you do.
I don't think there's any shift issues with the 50 mhz equipment, so a
Futaba 50 mhz receiver should work fine with your JR transmitter.
Were you close, I'd let you try one of them, but you can order one
from Tower Hobbies easily enough for under $100.
You might be able to get some more range by properly tuning the
receiver antenna, making it the right length to be a 1/4 wave antenna?
Perhaps cracking open the antenna and finding the other lead, turning
it into a 1/2 wave dipole? (This all depends on your receiver
internals, of course -- there might be a coil inside to make the
antenna resonant even though it's less than 1/4 wavelength, especially
for 50 mhz. Maybe making a 5/8 wave antenna? (Of course, that would
be very long.) Sounds like you know what you're doing, so you can try
| I had some real bad problems with an FMA a while a go and I'm a bit
| gun shy.
I've had fine luck with FMA receivers, though I've not tried a 50 mhz one.
| >And you could try 72 mHz equipment ... maybe it would work better? In
| >theory it should work the same, but it's a possibility.
| One of the purposes of the airplane is to set some FAI records,
| I've built a 1W 6M amplifier and put it on a 4 element 6M yagi so I
| have positive control. I can't do that on 72Mhz.
Most R/C transmitters transmit at one watt, whatever the band. So why
would you need a one watt amplifier? Or was 1W a typo, and the actual
figure is higher?
The FCC regulations only permit one watt for R/C control on the ham
bands, so I don't see where they let you use more power than the 72
mhz band anyways.
And is there any reason you couldn't use a directional antenna on 72
mhz? I don't think the 72 mhz band would let you make your own
transmitter, but I don't think it would prevent you from making your
| My higher power rig also limits me to straight FM, not PCM as I
| drive my 1W transmitter with a trainer cord.
I'm not sure that's the case. PCM uses the same FM transmission mode
as FM (PPM) does, it's just that the signal being sent is different,
PCM vs PPM. Your transmitter should happily transmit the PCM signal
just like the FM signal.
... though some transmitters do send a PPM signal over the buddy box
cord, even when in PCM mode. But this would only be the high end
transmitters ... the lower end ones send the same signal as they
The Futaba 6XAS radio I have definately sends PCM both ways. But the
9C I have doesn't -- or, at least it has the option of not doing so.
If your radio has a module, you might be able to pull the PCM signal
from the wires going to the module if you need to.
Not that I think PCM will help -- it will have exactly the same range
problems as PPM.