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Dual Comm Transmitter Problem

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noelloveys(at)yahoo.ca
Guest

Posted: Mon Jun 19, 2006 3:23 am Post subject: Dual Comm Transmitter Problem

If the hams in your area aren't listed under ARRL in the yellow pages try

asking at an electronics shop.  there may even be a shop in your area that

specializes in selling amateur radio equipment.  That would be another good

place to start.

 

 



Noel  V01 PL



--

noelloveys(at)yahoo.ca
Guest

Posted: Mon Jun 19, 2006 3:26 am Post subject: Dual Comm Transmitter Problem

You are right in suspecting the Lightspeed Aux input.  I did a bit of work

on a Bell 206 L that was having intermittent problems with it's HF

transmitter.  The problem was traced to a loose ground in a unit called a

Cellset.  This was basically a unit that allowed the cell phone to be wired

into the audio panel.  The surprising thing is that a few hours before the

Cellset had been returned form the repair depot where it had been repaired

of another problem.



The problem with the Cellset was internal.  Your problem may also be.



Noel



[quote] --

Hopperdhh(at)aol.com
Guest

Posted: Mon Jun 19, 2006 5:14 am Post subject: Dual Comm Transmitter Problem

To locate a local ham, look for a house with an "antenna farm"!  Many  hams 

these days have the MFJ-259B which is a very good tool for checking VSWR  

across the VHF band.  This is a very easy test to do.  One only needs  to plug the 

coax from the antenna into the unit and turn a knob.

 

I haven't read all of this thread, but my Lightspeed 20XLs will NOT work  

with a cell phone into the aux input.  I believe it is due to the RF from  the 

cell phone's transmitter causing interference to the circuitry of the  headsets. 

 Mine changed with location of the cell phone with respect to the  headsets.  

If I could have gotten the phone 20 feet away from the headsets  it would 

have probably been OK.  I worked with Lightspeed (over the phone)  when first 

having them "upgraded" about 2 years ago for several weeks before  giving up.  

Personally, I liked the Lightspeeds better before having them  overhauled.  

Having said that, Lightspeed was more than willing to try to  help, and offered to 

convert them back.  I decided to let it ride for a  while and see if they 

came up with a solution and ended up just forgetting  about it.

 

Dan Hopper K9WEK

Walton, IN

 

 

In a message dated 6/19/2006 7:24:50 A.M. Eastern Daylight Time,  

noelloveys(at)yahoo.ca writes:



In a  message dated 6/18/2006 10:59:33 PM Eastern Daylight  Time,

joplin1(at)charter.net writes:



I want to thank all of you for  your help.



I think a VSWR check might be a good place to start.  I  am not sure how to

locate a 'ham' radio operator in my  area.

joplin1(at)charter.net
Guest

Posted: Mon Jun 19, 2006 7:31 am Post subject: Dual Comm Transmitter Problem

I have tried two of my SoftComm headsets as well as the LightSPEED.  The headset doesn't seem to be the problem.  My KLX135A and KY97A still send out weak, scratchy transmissions with a max range of about 15 miles.  Both receivers are excellent under all conditions.



Actually, my LightSPEED-cell phone hookup works OK on the ground with the engine at idle RPM.   I assume that all of the aluminum between me and the relay towers degrades my cell phone antenna output when I reach altitude.  But, it is strong enough to dial out and hold a connection with a phone on the ground.  The cell phone reception is excellent, but my transmissions are mostly static and unreadable.  Also, my super loud Lycoming IO-540 engine noise needs to be filtered out of my mike transmissions.  I do get the static you talk about when I move my cell phone close to the headset battery box, but it isn't bad when I put the phone a couple of feet away on the opposite side of the cockpit .  



The reason I mentioned my cell phone experiment was because I was concerned that I might have damaged something in the aircraft VHF comm circuit.  I'm sure one of you would have mentioned that possibility if it is something that should be looked at.  Both radios have bench checked good.  



 -----------------------------

Dan wrote: my Lightspeed 20XLs will NOT work  

with a cell phone into the aux input.  I believe it is due to the RF from  the 

cell phone's transmitter causing interference to the circuitry of the  headsets. 

 Mine changed with location of the cell phone with respect to the  headsets.  

If I could have gotten the phone 20 feet away from the headsets  it would 

have probably been OK.  



--------------------------

Noel wrote:You are right in suspecting the Lightspeed Aux input.  I did a bit of work

on a Bell 206 L that was having intermittent problems with it's HF

transmitter.  The problem was traced to a loose ground in a unit called a

Cellset.  This was basically a unit that allowed the cell phone to be wired

into the audio panel.  The surprising thing is that a few hours before the

Cellset had been returned form the repair depot where it had been repaired

of another problem.  The problem with the Cellset was internal.  Your problem may also be.

KD4ZHA(at)aol.com
Guest

Posted: Tue Jun 20, 2006 4:57 pm Post subject: Dual Comm Transmitter Problem

Maybe I should keep quiet on this, as I don't want to create 

controversy (this subject always does), but the subject has already been broached.  The 

subject is cell phone use in aircraft (including your private aircraft).  

I'll just say this, and then you can do the research to confirm or dispell my 

statement.  Cell phone use in your private aircraft is legal .... until the 

wheels leave the ground!  Once airborne, cell phone use can disrupt and interfere 

with cell phone communications across a very wide area (line of sight just like 

VHF), including emergency services.  Your encrypted cell phone number is 

automatically recorded as a matter of record, and you can be held accountable for 

disrupting service.  Don't look for it in the FAR's!  It's covered by the FCC!

joplin1(at)charter.net
Guest

Posted: Wed Jun 21, 2006 6:37 am Post subject: Dual Comm Transmitter Problem

Thanks for your input.  I had planned to use my cell phone only as a back-up in an emergency situation.  I discovered that the transmitter does not work well while airborne, although it does provide a way to receive up to the minute ASOS weather recordings.  This could provide valuable information in choosing an alternate airport if my aircraft experienced complete electrical failure.



John

  ---

KD4ZHA(at)aol.com
Guest

Posted: Wed Jun 21, 2006 9:16 am Post subject: Dual Comm Transmitter Problem

I agree, John!  In an emergency, I'll use any and all communications I deem 

necessary, including semaphore!

noelloveys(at)yahoo.ca
Guest

Posted: Wed Jun 21, 2006 5:46 pm Post subject: Dual Comm Transmitter Problem

No smoke signals pleeeze!!!



Noel



[quote] --

joplin1(at)charter.net
Guest

Posted: Wed Jun 21, 2006 8:44 pm Post subject: Dual Comm Transmitter Problem

Several of you have advised me that an a VSWR check should be my next step.  (my radios bench checked good, receivers are excellent, but my transmissions are weak and scratchy)



I contacted a gentleman who has a 'ham' business in town.  He deals pretty much with the shortwave spectrum, not the VHF.  He told me that he doesn't have the MFJ-259B  meter.  But, he feels sure that I can find someone in a local club who does.  He mentioned that the meter needs to be inserted into the feed line between the radio and the antenna and he suspects adapters might be required to do that.  Before I start trying to find someone with a MFJ-295B, what should I know about inserting the meter into the feed line? Remember, I am Radio Illiterate. I just want to be sure that I can provide the 'ham' with the required adapters and any other information that he might need.  It is possible that will have no experience with aircraft radios.



Thanks,



John Linman

  To locate a local ham, look for a house with an "antenna farm"!  Many  hams 

  these days have the MFJ-259B which is a very good tool for checking VSWR  

  across the VHF band.  This is a very easy test to do.  One only needs  to plug the 

  coax from the antenna into the unit and turn a knob.

   

   

  Dan Hopper K9WEK

  Walton, IN

j.rippengal(at)cytanet.co
Guest

Posted: Thu Jun 22, 2006 1:59 am Post subject: Dual Comm Transmitter Problem

Connecting a VSWRmeter in the feed line involves:



unplugging the antenna from the radio;



plugging the input to the meter into the output of the radio which will 

require a short lead with the appropriate plug (probably a BNC plug) on it 

to suit the radio output;



plugging the antenna coax into the output of the VSWR meter (you will 

probably need a UHF to BNC adapter for that assuming the antenna lead has a 

BNC plug on it.)



Radio hams will be familiar with this nomenclature.

It is a simple operation and you would be well advised to get a VSWR meter 

yourself for future reference once you have seen how it is done.



If the tests show the transmitters and antennas are ok as far as power and 

VSWR is concerned then you will have to look at the audio input circuits. I 

can't quite remember, but didn't you say you had been trying to incorporate 

a mobile phone into the system?? Or was that somone else??



John



 	  Quote: 	
		   



 Several of you have advised me that an a VSWR check should be my next 

 step.  (my radios bench checked good, receivers are excellent, but my 

 transmissions are weak and scratchy)



 I contacted a gentleman who has a 'ham' business in town.  He deals pretty 

 much with the shortwave spectrum, not the VHF.  He told me that he doesn't 

 have the MFJ-259B  meter.  But, he feels sure that I can find someone in a 

 local club who does.  He mentioned that the meter needs to be inserted 

 into the feed line between the radio and the antenna and he suspects 

 adapters might be required to do that.  Before I start trying to find 

 someone with a MFJ-295B, what should I know about inserting the meter into 

 the feed line? Remember, I am Radio Illiterate. I just want to be sure 

 that I can provide the 'ham' with the required adapters and any other 

 information that he might need.  It is possible that will have no 

 experience with aircraft radios.



 Thanks,



 John Linman

noelloveys(at)yahoo.ca
Guest

Posted: Thu Jun 22, 2006 6:20 am Post subject: Dual Comm Transmitter Problem

I expect the patch cables will only have to be BNC The ham should have more

patch cables than Lipton got tea bags.  You can also check with the local

telco if they offered a VHF radio phone service.  Be sure their technicians

have everything and more to do the job!



Noel



[quote] --

joplin1(at)charter.net
Guest

Posted: Thu Jun 22, 2006 7:13 am Post subject: Dual Comm Transmitter Problem

In answer to your question "If the tests show the transmitters and antennas are ok as far as power and VSWR is concerned then you will have to look at the audio input circuits. I can't quite remember, but didn't you say you had been trying to incorporate a mobile phone into the system?? Or was that somone else??"



My LightSPEED headset does have the capability to connect to a cell phone.  I experimented with it and found that my calls out were too weak and broken for others to understand.  My cell phone receiver was excellent though.  I have acknowledge that cell phone use in the air is illegal so please no more responses to that.



I no longer have a cell phone connected to the system.  My question:  Is it possible that my experiment with the cell phone damaged the system?  The radios bench check good.



I do have a Sigtronics Intercom system with stereo music capability.  It can take music from a portable disk player and pipes it through the intercom.  I seldom use it, but perhaps that circuit is faulty.  



Thanks,



John



  ---

Hopperdhh(at)aol.com
Guest

Posted: Thu Jun 22, 2006 7:54 am Post subject: Dual Comm Transmitter Problem

John,

 

The MFJ-259B needs an SO-239 to BNC adapter and then perhaps male-to-male  or 

female-to-female BNC connectors to allow it to connect to your antenna  

somehow.  I have found that you can sometimes take a BNC and butcher it up  to 

connect directly into the radio tray (after removing the radio) to test the  whole 

feedline plus antenna.

 

The 259B does not use the radio for the signal source to measure VSWR, it  

has its own signal generator and counter, so it does not go inline like a  

standard SWR meter.  (VSWR and SWR are used interchangeably here.   Also the SWR 

meter is sometimes called an SWR bridge -- same thing.)  The  259B only tests 

the antenna and coax beyond where you connect it in.  I  think you have already 

tested the radio, so this way you can isolate the  problem.

 

Dan Hopper K9WEK

RV-7A

 

 

In a message dated 6/22/2006 12:47:29 A.M. Eastern Daylight Time,  

joplin1(at)charter.net writes:



I  contacted a gentleman who has a 'ham' business in town.  He deals pretty  

much with the shortwave spectrum, not the VHF.  He told me that he  doesn't 

have the MFJ-259B  meter.  But, he feels sure that I can  find someone in a 

local club who does.  He mentioned that the meter needs  to be inserted into the 

feed line between the radio and the antenna and he  suspects adapters might be 

required to do that.  Before I start trying to  find someone with a MFJ-295B, 

what should I know about inserting the meter  into the feed line? Remember, I 

am Radio Illiterate. I just want to be sure  that I can provide the 'ham' with 

the required adapters and any other  information that he might need.  It is 

possible that will have no  experience with aircraft radios.



Thanks,



John  Linman

j.rippengal(at)cytanet.co
Guest

Posted: Thu Jun 22, 2006 11:38 am Post subject: Dual Comm Transmitter Problem

No intention of giving any lectures on legality John. It's just that I am 

puzzled by both receiver paths being ok which tends to suggest the 

antenna/feeders may also be ok. If both transmitters are giving poor results 

then the common thing is the audio source and if you have been 'playing' 

with it there may have been some damage done inadvertently.

J



 	  Quote: 	
		   



 In answer to your question "If the tests show the transmitters and 

 antennas are ok as far as power and VSWR is concerned then you will have 

 to look at the audio input circuits. I can't quite remember, but didn't 

 you say you had been trying to incorporate a mobile phone into the 

 system?? Or was that somone else??"



 My LightSPEED headset does have the capability to connect to a cell phone. 

 I experimented with it and found that my calls out were too weak and 

 broken for others to understand.  My cell phone receiver was excellent 

 though.  I have acknowledge that cell phone use in the air is illegal so 

 please no more responses to that.



 I no longer have a cell phone connected to the system.  My question:  Is 

 it possible that my experiment with the cell phone damaged the system? 

 The radios bench check good.



 I do have a Sigtronics Intercom system with stereo music capability.  It 

 can take music from a portable disk player and pipes it through the 

 intercom.  I seldom use it, but perhaps that circuit is faulty.



 Thanks,



 John

douglist(at)macnauchtan.c
Guest

Posted: Thu Jun 22, 2006 2:26 pm Post subject: Dual Comm Transmitter Problem

At 22:34 +0300 6/22/06, John Rippengal wrote:

 	  Quote: 	
		  No intention of giving any lectures on legality John. It's just that I am puzzled by both receiver paths being ok which tends to suggest the antenna/feeders may also be ok. If both transmitters are giving poor results then the common thing is the audio source and if you have been 'playing' with it there may have been some damage done inadvertently.

J


	


Agreed. A good thing to look for is always some single thing that can affect both devices giving trouble.



In this case it's the incoming audio or possibly the aircraft power. It is unlikely that both antenna systems have failed simultaneously. Well they are on the belly. Were the wheels down?



The radio shop that did the bench testing. Did they use the microphone out of the aircraft? Did they say anything about modulation level? For many radios it's supposed to be adjusted for the microphone to be used though it's not terribly important with newer radios.



Are there different microphone jacks in the aircraft? Have they all been tried? Is there another microphone?



Can you be sure you're not transmitting on both radios at the same time? Did you turn one completely off. If both radios are tuned to the same frequency you can expect noise from the receiver associated with the transmitter not in use. Its input at the antenna will surely drive it into saturation. You should be sure that's not being switched into your audio system.



Get rid of all audio stuff by using a "standard" carbon microphone. If you have jacks that bypass the audio selector panel use them. If not consider installing some. Two radios with only one way to get to them doesn't support the extra reliability of having two.. Some microphones have been known to be sensitive to radiation from a transmitter. An unshielded wire on a headset can easily do that especially if the mic is not real carbon but one of the newer electrets or dynamic devices that require a transistor for operation.



With the antennas on the belly that VSWR test being discussed may be compromised especially if the ground below is electrically conductive - grass or wet. It won't be there while flying.



Are you sure you don't have aircraft power problems? The radios draw more current while transmitting and might be causing a drop in line voltage. Measure it. Check for changes in transmitted quality with the engine revved up. Check with the landing light and pitot heat on to make for more drain on the bus.

-- 

-->  The best programming tool is a soldering iron <--

noelloveys(at)yahoo.ca
Guest

Posted: Thu Jun 22, 2006 4:35 pm Post subject: Dual Comm Transmitter Problem

Find some one with a beastie called a Bird Wattmeter.  Read the forward

power and then reverse the slug to read the reflected power.  This will

check the power amp of your transmitter at the same time as checking your

antenna system.



While you are at it ask if any one has a Cushman station analyzer.  This

will do much much more.  Any one who has this equipment will know how to use

it.  If your radios are certified they may not want to go near them.  Not

because of lack of knowledge but because of legal implications.



Noel



[quote] --

joplin1(at)charter.net
Guest

Posted: Thu Jun 22, 2006 6:14 pm Post subject: Dual Comm Transmitter Problem

I am starting to get bogged down with technical stuff that I don't understand. I think my best solution now is to spend the $$ and take my aircraft to an Avionics Shop.  I have printed out all of your comments and suggestions.  They should be very helpful when I discuss my transmitter problems with avionics technicians.  I will stay after them until they have considered all of the possibilities that you have mentioned.



Actually, my radios are still useable ... just not as good as I'd like.  I will refrain from asking for radio checks in the future because I know the answer will be "weak and scratchy". Instead, I will just press on as if I don't have a problem.  I have found that all of the controlling agencies I deal with read me well enough so that they don't complain.  



Thanks again to all of you.



John



---

noelloveys(at)yahoo.ca
Guest

Posted: Fri Jun 23, 2006 4:45 am Post subject: Dual Comm Transmitter Problem

One last question ....  What does the audio of the side tone sound like??



Noel



[quote] --

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