RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

damaging transmitter modules

Reply

Old 10-12-2004, 10:42 PM
  #1  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default damaging transmitter modules

i have a transmitter module that is about a year old and i have been doing a lot of setting up with the antenna completely collapsed. i recently heard a rumor that doing so for extended periods of time will head up certain internal components and cause damage to the module. is this true?
Spaceclam is offline  
Reply With Quote
Old 10-12-2004, 11:16 PM
  #2  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

It is not a rumour, but a fact. When you're doing setup work, extend at least 3 lower segments of your antenna. The final RF output amp is prone to overheating and damage if the antenna is collapsed for too long. This is exaggerated by the circuit board density in some modules. Do a range check with your module and it falls below the normal range, send it in for service or replacement. Good luck !
rajul is offline  
Reply With Quote
Old 10-12-2004, 11:53 PM
  #3  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

what kind of time are we talking about when we say "for too long"? also, you say that circuit board density plays a role as well. what about the modules used in the futaba 8u-9c systems? i had also heard that they had rectified the problem in the newer systems, but i was not sure if that was true or not. have they actually fixed the problem?
Spaceclam is offline  
Reply With Quote
Old 10-13-2004, 12:05 AM
  #4  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

The "rule of thumb" of extending a few segments of the antenna applies to any radio make, with or without module.
rajul is offline  
Reply With Quote
Old 10-13-2004, 08:41 AM
  #5  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

so what kind of time are we talking about here? have they fixed the problem or will that happen to all radios and stuff
Spaceclam is offline  
Reply With Quote
Old 10-13-2004, 08:56 AM
  #6  
Rodney
Senior Member
 
Join Date: Dec 2001
Location: FL
Posts: 7,769
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Any time you operate a transmitter with the antenna not matched for impedance, the standing wave ratio (SWR) goes up which causes the energy normally radiated as RF to be reflected back into the output stage and converted to heat. Yes, running with the antenna not fully extended will heat up the output stage and reduce "Mean time to failure" and can possibly cause immediate failure sooner or later. Even a partially extended antenna causes excess heat to build up in the output stage so, for best transmitter life, always keep the antenna FULLY extended except for very brief (1 to 2 minutes) range tests. The more dense or compact the transmitter final components are, the more of a problem this is. The only way to correct it is to make the heat sink on the final very large with good ventlation which detracts from size, balance and weight desires, i.e. marketing appeal, so all manufacturers do a compromise in this area in order to maintain sales.
Rodney is offline  
Reply With Quote
Old 10-13-2004, 08:57 AM
  #7  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

See here http://www.futaba-rc.com/faq/faq-9c-q516.html
rajul is offline  
Reply With Quote
Old 10-13-2004, 09:19 AM
  #8  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Spaceclam, do a range check http://www.futabarc.com/faq/faq-q331.html If it passes the criteria, then go fly. Just remember to do a range check before each flight session. You'll be OK
rajul is offline  
Reply With Quote
Old 10-13-2004, 09:28 AM
  #9  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

considering that i spend about 2 hours several days ago setting up two planes with the tx on and the antenna fully collapsed, i am glad i sent it in yesterday for service...
i know how to range check and it came out as it always had but i did have a series of lockouts in flight that almost took my plane.
Spaceclam is offline  
Reply With Quote
Old 10-13-2004, 09:31 AM
  #10  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

You did the right thing by sending it in for service. Hope that the damage is minimal. Good luck !
rajul is offline  
Reply With Quote
Old 10-13-2004, 11:55 AM
  #11  
smokingcrater
Senior Member
 
Join Date: Sep 2002
Location: Up north, ND
Posts: 2,353
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

I've accidently left my 9c on twice till it was completely dead, antenna all the way down... it still works fine, but it may have shortened the life of the module. (i'm planning on getting the synth when that comes out anyway, whenever that might be!)

as far as fixing the 'problem', there isn't really anything viable to do. as someone else mentioned, heat sink it, but you are still left with the high swr condition. You could also have the tx shut down output if a high swr connection is detected. (common among ham radio stuff, I know my icom 2800 will do that, but that puts out 60+ watts also) the third option is to have a built in antenna tuner, but not practical for a tx...


Ryan
kc0lmo
smokingcrater is offline  
Reply With Quote
Old 10-13-2004, 05:59 PM
  #12  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

and you would not be able to range check it...
Spaceclam is offline  
Reply With Quote
Old 10-13-2004, 06:28 PM
  #13  
Lynx
Senior Member
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Your topic says module, if you're setting up just remove the module...
Lynx is offline  
Reply With Quote
Old 10-13-2004, 06:48 PM
  #14  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

the module is the component in which all the broadcasting electronics are housed. some radios such as mine have removable modules so that you can change channels without having to send it in, so the radio would not work without it.
Spaceclam is offline  
Reply With Quote
Old 10-14-2004, 12:01 AM
  #15  
smokingcrater
Senior Member
 
Join Date: Sep 2002
Location: Up north, ND
Posts: 2,353
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

so the radio would not work without it.
the radio doesn't work, but the rest of the tx does. i take my module out all the time for programming and fms sim use. batteries last MUCH longer without a signal going out!
smokingcrater is offline  
Reply With Quote
Old 10-14-2004, 06:45 PM
  #16  
GJr.
Senior Member
My Feedback: (3)
 
Join Date: May 2003
Location: Nashville, TN
Posts: 310
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

If your radio has DSC capabilities, use it while setting up your plane. That will save your module and reduce TX battery consumption.
GJr. is offline  
Reply With Quote
Old 10-14-2004, 07:39 PM
  #17  
Spaceclam
Senior Member
Thread Starter
 
Spaceclam's Avatar
 
Join Date: Apr 2003
Location: chatsworth, CA
Posts: 4,643
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

what is dsc? i am assuming i dont have it because i have never heard of it before
Spaceclam is offline  
Reply With Quote
Old 10-14-2004, 07:55 PM
  #18  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

DSC=direct servo connection. This is where the Tx is linked directly to the Rx via a cable. Not all Tx and Rx in the market have this feature.
rajul is offline  
Reply With Quote
Old 10-14-2004, 09:06 PM
  #19  
Flying Geezer
My Feedback: (14)
 
Flying Geezer's Avatar
 
Join Date: Apr 2003
Location: Bowling Green, KY
Posts: 1,326
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

DSC cord can be used with 9C provided your receiver is a R149DP or R309DPS. I believe the latter has been discontinued.

Hope this helps.
Flying Geezer is offline  
Reply With Quote
Old 10-16-2004, 10:51 AM
  #20  
dirtybird
My Feedback: (5)
 
Join Date: Jan 2002
Location: San Tan Valley, AZ
Posts: 5,768
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Solid state electronics have no wear out problems. So if you leave it on and it survives you have not reduced its life span any.
I think any RF designer worth his salt would anticipate the radio would be operated for a span with the antenna down if it has an antenna that can be collapsed and choose components that will withstand it. I think this falls in those rules we used to live by in the '50s and the equipment was ameteur built. Since I am an old person and have a tendancy to forget things I have left my transmitter on to run down several times. It never seems to bother it. I think I wrecked the battery though.
dirtybird is offline  
Reply With Quote
Old 10-16-2004, 12:06 PM
  #21  
Rodney
Senior Member
 
Join Date: Dec 2001
Location: FL
Posts: 7,769
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Sorry Dirtybird, solid state items do wear out. The controlled impurities ( the dopeing done that is necessary for them to work) do migrate and degrade operation, this degredation roughly doubles for every 10 degrees C that the temperature increases thus the higher failure rate at higher temperatures. This is worse in geranium than in silicon bases but the 10 degree steps still apply. Heat is the major cause of failures in electronics as long as voltages are held within design limits.
Rodney is offline  
Reply With Quote
Old 10-16-2004, 12:19 PM
  #22  
rajul
Moderator
My Feedback: (58)
 
rajul's Avatar
 
Join Date: Jun 2002
Location: Missouri City, TX
Posts: 8,167
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

Here are some semiconductor wearout mechanisms that can accelerate under higher operating temperatures - electromigration, hot electron injection, diffusion, corrosion, brittle intermetallics, purple plaque, etc
rajul is offline  
Reply With Quote
Old 10-16-2004, 10:10 PM
  #23  
dirtybird
My Feedback: (5)
 
Join Date: Jan 2002
Location: San Tan Valley, AZ
Posts: 5,768
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

OK I'm not a solid state expert. But I've done a bit of RF design and I still think a good designer would take into account the heat dissipation of the module with a high VSWR and size it to keep the temperature below the critical point. Otherwise the first time the unit is operated with the antenna down the module would burn out.
One of my favorite tricks is to reset the time on my transmitter then forget to turn it off. So it sets inside a metal case with foam insulation around it and with the antenna down until the battery runs down. As I say it never seems to bother it. One of the modules I have is more than ten years old.
dirtybird is offline  
Reply With Quote
Old 10-16-2004, 10:41 PM
  #24  
Flying Geezer
My Feedback: (14)
 
Flying Geezer's Avatar
 
Join Date: Apr 2003
Location: Bowling Green, KY
Posts: 1,326
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

I think the instructions not to leave the transmitter on with the antenna not extended is to avoid damage as the result of a possibility, not a probability, of damage. These instructions are well worth following because no two modules or rf circuits are of equal quality.

Prolonged on-time without the antenna extended might damage one, and not another. As for degradation of components, the extent is anybody's guess. I too, have forgotten to turn my tx off and let the pack run down. Haven't hurt my rf circuits, but it sure in hard on battery packs. I took one out the first time.

Best to follow the instructions (to the best of your memory), but if you have left it on, and it is still range checking properly, there is no need to send it off for service because the technican will find the same thing you did. It works!

Some of us older flyers are more prone to leave our transmitters on, because there are three things that go with aging. One is memory, and I can't remember the other two.
Flying Geezer is offline  
Reply With Quote
Old 10-17-2004, 01:31 PM
  #25  
dirtybird
My Feedback: (5)
 
Join Date: Jan 2002
Location: San Tan Valley, AZ
Posts: 5,768
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: damaging transmitter modules

ORIGINAL: Flying Geezer

I think the instructions not to leave the transmitter on with the antenna not extended is to avoid damage as the result of a possibility, not a probability, of damage. These instructions are well worth following because no two modules or rf circuits are of equal quality.

Prolonged on-time without the antenna extended might damage one, and not another. As for degradation of components, the extent is anybody's guess. I too, have forgotten to turn my tx off and let the pack run down. Haven't hurt my rf circuits, but it sure in hard on battery packs. I took one out the first time.

Best to follow the instructions (to the best of your memory), but if you have left it on, and it is still range checking properly, there is no need to send it off for service because the technican will find the same thing you did. It works!

Some of us older flyers are more prone to leave our transmitters on, because there are three things that go with aging. One is memory, and I can't remember the other two.
Yes it does make sense to follow the instructions that come with the radio. But as you say the most likely casualty is the battery.
BTW they tell me the memory is usually the second thing to go. If you can't remember the first one there is no hope.
dirtybird is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service