Futaba 9CHP RF module PPM output?

[village_idiot]

I'm looking to put a Plantraco 900Mhz Monolith module on the connection for the "normal" Futaba RF module, but I think some thing is odd. When I put a scope on the PPM pin (#1) where the module goes, there is no signal unless I have the Futaba RF module installed. Is this PPM signal generated when the RF module pulls this line up to X volts and something pulls the line down to ground to make the pulse (open collector)?

It does transmit, so I know it is working, and of course as I said when I put the module into place, then I can measure a good clean PPM pulse train.

Now if it is running open collector does a 1K resistor to a +5 volt regulator sound about right to pull that line up?

And yes the trainer port has a good strong PPM signal on it all the time, so I may just have to connect the Monolith to that port, but it is my second choice.

Thanks

[TheSteve]

The PPM output on Futaba radios require a pullup. I am using a 5.6K resistor to 3.3 volts myself(the voltage my 2.4ghz transmitter is using) If the transmitter you're using has 5 volts that should be fine as thats what most Futaba modules use.

The transmitter should work fine without the RF sense line pulled low but you can tie it to ground through a resistor while you're at it, again I am using 5.6K as its what I had around.

[village_idiot]

I just measured the module with the radio pin bent out of the way and it is pulling up to 2.5 volts, so I think that is probably what I better use. Guess I'll have to see what I have for voltage regulators in stock, think I might have a variable hanging around ro I can probably salvage a 3.3v from a computer supply.