DIY TX using MC2831/2833

[yctseng]

Does anyone try to use MC2831 or 2833 as the OSC and FM moduation for
TX PPM signal ? Does there any issue or problem for that ? Need advice, Thanks!

[yctseng]

I spend some times to do this kind of test. I found the Futaba's X'tal works
just fine for this MC2833. I also attach the PWM signal from my JR-347's
output pins using one small VR between them. That I can tune the VR to
set the modulation's level. It seem great and I can control the SERVOs
using JR-347's sticks. :)

[yctseng]

By the way, I also pick-up one of my DIY counter which built 20 years ago.
That's an terrible work compare with my skill today.. :D So I un-plug the ICs
and re-build that. This counter is using ICM7216D for count and display.
Cause that can just support up to 10MHz which is not enough for my project.
So I use HD10551 in front of ICM7216D. Then I can use this counter up to
100MHz.

[Mr.RC-CAM]

Looking good.

Just curious: Are you using Coilcraft brand tuneable inductors (L1/L2) or have you found another source? Did you omit the variable antenna matching cap or is it on the bottom of the board? Are you getting the full 10dBm (10mW) RF output?

What is the range with a practical size whip antenna? I'm guessing 100 to 200 meters should be possible with a good Rx.

[yctseng]

Looking good.

Just curious: Are you using Coilcraft brand tuneable inductors (L1/L2) or have you found another source? Did you omit the variable antenna matching cap or is it on the bottom of the board? Are you getting the full 10dBm (10mW) RF output?

What is the range with a practical size whip antenna? I'm guessing 100 to 200 meters should be possible with a good Rx.

Hi Mr.RC-CAM;
My coils are from Japan and labeled FCZ-50 which imported from some agent
here. Actually, I can wind them myself. These coils are not so expensive
and I just want to have a try this time. It cost about USD$ 0.75 for each.
About the cap, yes, I use SMD type and lay under the PC board. I do not
test the really output but just prove this IC can work in RC. I plan to add
two more stage transistors after that and put on my DIY TX rig as the transmitter module. Right now, I just considering about the matching voltage
between the PPM and MC2833 which will cause it's center fequency and
modulation percentage. Any idea or suggestion ? :)

[Mr.RC-CAM]

Right now, I just considering about the matching voltage between the PPM and MC2833 which will cause it's center frequency and modulation percentage. Any idea or suggestion ?It really depends on your country's RF spectrum rules. Here in the USA, it would involve two pots and some other components. One pot is for deviation (modulation gain/slope) and one for centering (modulation offset). If your RF rules are very relaxed, then you can simplify the signal conditioning to suit your needs.