R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 01-05-2003, 10:20 PM   #1
Tech Apprentice
 
Join Date: Sep 2002
Location: Never Never Land
Posts: 53
Default Radio Glitch

Hi,

I'm having problems with my KO receivers, its the 297FZ small-sized FM receiver, and another Normal-sized KO FM receiver. Both receivers run on 29Mhz.

I got the TX/RX off a swap with a friend. I noticed the problem when I mounted the RXs on my TB EVO. As soon as the car gets 10 feet away from the TX (Mars EX1, antenna fully extended), the car starts glitching.

I tried putting the car on a stand, then retracted the antenna. Then with both TX/RX turned on, slowly stepped away from car while sweeping the steering wheel left and right. The glitch starts when I'm 4 feet away.

Figuring it might be my old LRP F1 Reverse ESC causing the glitch, I took my JR battery holder and plugged in 4 cells worth of power to the ESC. I also ripped the receiver from the car, along with the JR577 servo I'm using then just placed them on a small plastic tray. I still see the servo twitching even with the TX turned off. This is more noticeable when I placed the RX-Battery-Servo near a n Electric Fan (running 60Hz 220V).

I took away the KO receiver then swapped in my JR AM receiver (27). No glitches.

I don't get it. The FM should be cleaner than the AM receiver, right? What can I do to fix the glitch apart from buying a new 3rd party receiver? I'd also prefer not to buy a new RF module for the EX1 if possible.

Thanks.
TRF512 is offline   Reply With Quote
Old 01-05-2003, 11:33 PM   #2
Tech Elite
 
popsracer's Avatar
 
Join Date: Oct 2002
Location: "Hot, Sunny Southern California"
Posts: 3,120
Default Radio Glitch

TRF512;

OK, I gotta ask. Are you using the correct band crystals FM-RX with FM-TX both on 29Mhz? For FM the Transmitter crystal MUST be the SAME brand as the transmitter to work properly. The receivers don't care.
Next I'm going to say that it sounds like crash damage or that the Radio is badly out of tune. Other than that, I'm blank.
popsracer is offline   Reply With Quote
Old 01-05-2003, 11:52 PM   #3
Tech Elite
 
Diva's Avatar
 
Join Date: Aug 2001
Location: Delaware
Posts: 2,379
Trader Rating: 1 (100%+)
Send a message via Yahoo to Diva
Default Re: Radio Glitch

Quote:
Originally posted by popsracer
...For FM the Transmitter crystal MUST be the SAME brand as the transmitter to work properly. The receivers don't care...
I'm afraid that it's not totally correct. I tried crystals from the brand called "Central" on my Mars. Also FM 29Mhz. It worked perfectly.

TRF512, there are many possible reasons behind your problem. First of all, your antenna wire of the receiver might be broken inside the rubber wrap. 2nd, your transmitter module might be worn. It may be due to power-on long time or using high voltage (perhaps over charged) TX batteries. By this way, your module would be overheated.

I have broken my previous Mars with a freshly charged 9-cell pack which read 15.9V. haha. It seemed to be working but after a few packs, your problem occured.
Diva is offline   Reply With Quote
Old 01-06-2003, 12:36 AM   #4
Tech Regular
 
fasterdanu's Avatar
 
Join Date: Dec 2002
Location: the bat cave
Posts: 428
Default

if you have a tb evo i believe that they have woven carbon fibre of grafite or something like that for a chasis i am aware of people having problems because of interfearance from the chasis matireal try useing two layers of tabe between the chasis and the reciver and make sure as little as possible of the antenna is touching the chasis this might help.
fasterdanu is offline   Reply With Quote
Old 01-06-2003, 01:26 AM   #5
Tech Apprentice
 
Join Date: Sep 2002
Location: Never Never Land
Posts: 53
Default

Thanks for the reply guys,

PopsRacer: Yes, one of the things I checked immediately after noticing the glitch are the crystals. All share the same frequency. I tried moving the crystals between either receivers and the TX. Still no go.

As for the TX probably going bad:

I don't think RXs should start glitching in the absence of the TX? 'Cause If this is the case, then the TX should always be really strong to jam out all potential noise, right? I expect the receiver-servo-battery assembly to just sit there quietly and not go glitching wildly when I turn off teh transmitter.

The AM receiver was not glitching even when I turned off the AM TX. I had high hopes with the "double attenuation noise filter" printed on the RX label. Maybe I was wrong.

Diva: I'll go check the RXs tonight.
Fasterdanu: I also thought it might be the CF in the chassis. This is why I removed the receiver, esc and servo from the chassis. Sadly, the servo is still twitching like an epileptic.
TRF512 is offline   Reply With Quote
Old 01-06-2003, 10:03 AM   #6
Tech Apprentice
 
Join Date: Nov 2002
Location: Cypress, CA
Posts: 75
Default

Painful personal experience: Check the RX antenna wire carefully. It may be broken - can be checked w/a VOM or missing insulation. Either one will send you out of control, because of the very limited transmission distance I would suspect a broken antenna wire.
dalem is offline   Reply With Quote
Old 01-06-2003, 03:13 PM   #7
Tech Elite
 
popsracer's Avatar
 
Join Date: Oct 2002
Location: "Hot, Sunny Southern California"
Posts: 3,120
Default Radio Glitch

TRF512;

You know, are you testing where there are Fluorescent lights CLOSE by. These will cause glitching sometimes. I have problems in my garage with the lights on.

Diva;

I've never tried aftermarket Receiver crystals before, but have ALWAYS been told to use the same brand of xtals as the Transmitter when on 75mhz FM.
27mhz doesn't seem to mind either way.
popsracer is offline   Reply With Quote
Old 01-07-2003, 02:57 AM   #8
Tech Apprentice
 
Join Date: Sep 2002
Location: Never Never Land
Posts: 53
Default Guilty

Yes I'm using flourescent lamp in my room and on my desk lamp. Both were open when the receivers were going crazy.

What's puzzling me is that the JR AM receiver was quiet under the same condition even with no TX turned on. I expected the FM would be better since they're, well, FM. What turned out is that I need a strong TX to jam out all interferences just to quiet the RXs. I'm quite sure that out on the tracks, the glitches would be far greater as the distance between TX and RX increases...
TRF512 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
DX2.0 Glitch? monkeyracing Radio and Electronics 3 03-25-2008 11:51 AM
JRXR2 Radio 2 receivers JR Z650M Servo Batteries Glitch Buster Tires hardey R/C Items: For Sale/Trade 6 01-15-2007 02:19 PM
HELP! Electric motor twitching! Radio Glitch?? NSXTACY Rookie Zone 5 12-28-2006 05:45 PM
GLITCH.. zax Electric On-Road 18 09-25-2005 09:51 AM
MX-3 Glitch tridagger Electric On-Road 7 01-25-2004 06:55 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 06:39 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net