RC Model Reviews

JMP_blackfoot wrote:Is the antenna connector making good contact to the case metal?

You know...I wasn't real happy with the antenna configuration. I removed the old antenna and the hole was too big for the new antenna connector. I used a 1/4" washer on each side of the hole and attached the new antenna. I really need to improve that and perhaps run a direct gnd lug from the antenna base to chassis gnd. You mentioned another possility of the RF getting into the encoder itself....that's a good thought...especially with the problem going away in reduced power mode. Will do something else with the antenna and go from there. Thanks for the help you provided....instead of poking around with the scope I was able to just verify the pinouts with the schematic and it was simple from there. Will keep you posted. If I get the thing working, do you want the old RF deck?

Whiteprop wrote:If I get the thing working, do you want the old RF deck?

Yes, I am interested in the old deck.
Hope you get it to work without the buzz.
It will be a nice transmitter.
I had some similar buzzing trouble some years back with a home-made single-stick transmitter.
I solved it by carefully grounding the coder PCB to the case. But, as they say, results may vary...

Whiteprop wrote:

JMP_blackfoot wrote:Is the antenna connector making good contact to the case metal?

You know...I wasn't real happy with the antenna configuration. I removed the old antenna and the hole was too big for the new antenna connector. I used a 1/4" washer on each side of the hole and attached the new antenna. I really need to improve that and perhaps run a direct gnd lug from the antenna base to chassis gnd. You mentioned another possility of the RF getting into the encoder itself....that's a good thought...especially with the problem going away in reduced power mode. Will do something else with the antenna and go from there. Thanks for the help you provided....instead of poking around with the scope I was able to just verify the pinouts with the schematic and it was simple from there. Will keep you posted. If I get the thing working, do you want the old RF deck?

Reconfigured the antenna and ran a dedicated gound lug from the antenna base to chassis ground. Same problem...servos dithering...only stopping in reduced range mode.....anybody else having this kind of issue....any ideas?

Just did an extended full power ground range test at full power. Although the range remained extreme (comunicated to my wife with the receiver and servos by phone. Went down the road...probably almost 1/2 mile...never lost control and the servo buzzing remained. Rules out any sort of receiver rf swamping possibility. As JMP_blackfoot suggested...maybe the RF is getting into the encoder...will try to perhaps shield the module from the encoder.

A little dissapointed with the amount of discourse about this. I thought this was somewhat a tech forum....haven't seen too much support yet.......

It does sound like RF getting into the encoder, perhaps a bypass cap on the power-leads may help.

Also try moving the DIY module's position inside the case so as to provide maximum physical separation.

Maybe also try to twist the wires to the module ?
And it is always a good idea to replace the electrolytic capacitors in old radios.

Played around with it this evening. Found approx. 300mV. of a modulated ripple riding on the +9.6 supply and the encoder PPM drive. Went to "Power Reduction" mode and the the ripple dropped off to less than 100mV. and again the buzzing stopped. Tried adding some bypass caps...no help. Unplug the DIY module and the +9.6Vdc supply and PPM signal is completely clean...no ripple. Obviously the module is generating the noise. Running out of stuff to try. Has anybody else played with these DIY modules?

The DIY module uses a switch-mode regulator so adding an inductive choke to the positive line may make a big difference. As many turns as you can fit around a ferrite core ought to do it.

RCModelReviews wrote:The DIY module uses a switch-mode regulator so adding an inductive choke to the positive line may make a big difference. As many turns as you can fit around a ferrite core ought to do it.

Thanks....I'll give that a try tomorrow. Was also considering trying my FrSky JR module to see it it did the same thing. Do you know the pinouts of the JR module? The JR module in my 10X was rock solid. Have you found power reduction (Ground Range Check mode) to produce extreme range?...I had in excess of 200 yards with both the JR and DIY modules!

It depends when you purchased your FrSky module as to what you can expect from a power-down range-test.

The latest ones have (from memory) about a 30dB power reduction but the earlier ones offered a somewhat higher power level in range-test mode. Testing with modules purchased 5 months or so ago, it's not uncommon to get 200m range in the power-down mode but I think the latest ones give somewhat less.