9 replies to this topic

[robmitch]

I have been having issues with bad glitches with my old JR X-347 radio. I have used it to tune servo movements and other PPM projects, while it has been turned on with antenna collapsed, which I now believe is bad for the RF circuitry. I am sure the radio is outputting a solid PPM stream, but the RF module is probably out-of-whack. What needs to be done to tune the circuit in the module?
Cheers,
Rob

[Terry]

I dont think a re-tune will help if it's down to you using it with the aerial down. It is possable there is damage to the output transistor but you will need the correct equipment to check this propperly. It may also need a new aerial, I have had a couple in the past that were intermittant. A service centre is your best bet if you don't have the gear.

Good luck, Terry

[W3FJW-Ron]

An alternative may be to use an X8 hack module & convert to 2.4ghz. Probably be much cheaper than having it fixed.

Edited by W3FJW-Ron, 09 November 2009 - 12:46 AM.

[robmitch]

Thanks Terry, Ron, I thought as much, but asked on the off chance... I suppose I can go and get a 2.4module, but then I need to change all my receivers and video freq...

Ron, What is an X8 module?
Terry, new aerial... What could go wrong with an aerial?

Appreciate the replies. Cheers, Rob.

[Terry]

I understand your reaction but Ive seen the telescopic aerials cause problems a few times, the sections have little copper springs and when they get dirty you effectivly have a shorter aerial. One in a magazine was reported to be so bad that a check with a multimeter showed there was no connection what so ever beteen the top and the bottom.

Terry

[W3FJW-Ron]

An X8 module is an Assan product sold by Hobbyking. There have been consistantly good reviews of their products.

http://www.hobbyking...odule_(PPM_Only)

http://www.hobbyking...6&ParentCat=190

As Terry said, check your antenna first. If you go 2.4ghz for airborne equipment, then you would have to change your vid Tx & Rx to 900mhz, 1.2 ghz, or 5.8ghz.

[Mr.RC-Cam]

I think you will find that the cost of replacing your JR plug-in RF module is less than the cost of a tuneup/repair. Plus, a lot of hobbyists have moved to 2.4Ghz R/C, so used modules (and entire R/C Tx's) are often sold at bargain prices.

[robmitch]

I think you will find that the cost of replacing your JR plug-in RF module is less than the cost of a tuneup/repair. Plus, a lot of hobbyists have moved to 2.4Ghz R/C, so used modules (and entire R/C Tx's) are often sold at bargain prices.

Thanks guys. I am thinking about getting a Futaba 9C instead, although, a second hand one. We use 36MHz in Aus. Does anyone know if the 72MHz US radio's antenna is that same as the 36MHz version used in AUS. That is, if I buy a radio from the US and buy a 36MHz module, will the antenna be as well tuned as if I bought a set locally?
Also, what is the difference between a 9C and a 9Z?
I take it these radios are able to easily physically change btw mode1/2
Cheers,
Rob

Edited by robmitch, 10 November 2009 - 07:32 PM.

[Kilrah]

Usually R/C transmitter manufacturers only ship one antenna length regardless of frequency.

9C: http://www.allproduc...00673116617.jpg
9Z: http://www.futaba-rc...d/futj9000a.jpg

9C is easy to change mode, 9Z isn't at all.

[robmitch]

Well, I havent been able to get a 9C yet... In the meantime I had ordered a new antenna for my JR radio.

Well, I would never have believed it, but I think it may have been the antenna !!!

I have had no glitches since. Having said that, I havent had too many flights. There is also one other big factor: In the time it took for the new antenna to get here, I have changed to 2.4GHz Vtx. I will retry with my 900MHz Vtx (10mW and 500mW) soon and report back. Hopefully everything will be apples.

As a matter of interest, I have great Video reception (2.4GHz) where I live (rural), but nearer to suburban areas, the reception is REALLY bad. I have only tried the one channel (Airwave 633module on ch4). Is changing channels likely to help much with that?