Microair transmit issue in new Jabiru

[Roscoe]

Jabiru 230

Ok thanks, no idea what causes this?....over to the panel!

 

 

[frank marriott]

Just a question for you radio experts, my Microair radio generally works fine except when I fly past Coffs Harbour and abeam the airport I get radio interference and sound like several commercial radio station broadcasting on Coff tower freq, has happened several times but not with other radios in other aircraft, any ideas ? Seems it picks up more than it should. Has not happened anywhere else.

Happens regularly when close to high power transmissions - I put it down to the front end not being as selective as the more expensive radios. Not your radio happens on all of them (that I have flown anyway)

 

 

[Camel]

Thanks Frank.

 

 

[jetjr]

I get this near Shepparton, yes theres a big transmitter there.

 

Could it be to do with headsets ANR?

 

Can turn the microair off and still get the transmission!

 

 

[techie49]

Close to an AM transmitter your headset ANR components may pickup the transmission and you will hear the voice content. With any other kind of modulation you may just hear noise or unintelligible sounds. Where you pass close to a number of co-sited transmitters, on top of a hill for example, you can get a spurious response from your receiver on a frequency unrelated to the actual transmission frequency of any of the transmitters. This is a mixing process that occurs in the front end of the aircraft receiver known as intermodulation or intermodulation distortion. Various frequencies mix and produce a spurious transmission that your receiver demodulates as noise or speech on the monitored aircraft frequency. I worked in telecoms some years ago and had a complaint from a business that at certain times of day their telephone system was unusable due to a 'Donald Duck' voice on it. I guessed immediately the cause of the problem. Close by the business premises was a radio amateur who used an HF transmitter on SSB ( single sideband ). His aerial passed close by the business and the transmitter broke into the telephone system which tried to demodulate his transmission. SSB sounds to the ear, when not correctly tuned, like a 'Donald Duck' sounding voice. Some filtering and a change to the aerial location solved the problem.

 

Paul

 

 

[sfGnome]

Years back I walked around the transmitting station at Shep, and you could hear the program they were transmitting because it made the metal around the aerial cables vibrate. Then again, as a teenager, I had a mate who lived next door to 2CH's transmitter, and their oven played the radio all day and all night. As 2CH was the 'old folks' station in those days, it was a bit hard for us 'cool' teens to cope with...

 

 

[Jabiru7252]

The man next door said his wife could hear voices coming from her Lowrey organ. Thinking she was going batty he was ready to call the men in the white coats. Then, he heard the voices. It was me! My Ham Radio transmissions were being picked up quite clearly. Wrapping the speaker wire in the organ around a ferrite rod cured the problem. (The speaker wire was acting as an antenna, feeding the RF back into the organs electronics)

 

 

[AVOCET]

I've been telling everybody that the voices I hear are caused by my fillings !! ???

 

 

[Roscoe]

ThannksThanks Frank. Will let everybody know next week when Radio reconnected following fixing of the crimping at the Radio end of the coax. Fingers crossed

Hi Frank, I see there are a couple of Antennas on the market for mounting within the aircraft structure. What type do you use and where do you run the coax?

 

 

[frank marriott]

Coax is run in the channel where the other aerial coax and fuel line runs.

 

I do not know the brand name as mine came fitted, but any ground independent aerial (obviously in the air band frequency) would do. Just check you achieve a good SWR reading mid range - Preferably around 1.5 to 1 at about 125mhz.

 

 

[Roscoe]

Coax is run in the channel where the other aerial coax and fuel line runs.I do not know the brand name as mine came fitted, but any ground independent aerial (obviously in the air band frequency) would do. Just check you achieve a good SWR reading mid range - Preferably around 1.5 to 1 at about 125mhz.

[Roscoe]

Thanks Frank, and you are running 2 Microairs?

 

 

[deglestal]

Roscoe. I had some similar intermittent tx issues with my J230 and Icom a200. Long time spent checking radio, coax, antenna, audio panel wiring. Eventually found the crimping on the Molex terminals were poor/loose. Soldered them and been OK since. (I hope its more than a coincidence.)

 

 

[frank marriott]

Yes. No problems so far, since 2008.

 

 

[frank marriott]

I forgot to mention, I did have transponder interference (on Rx not Tx) but eliminated that by replacing transponder aerial lead with RG58 coax - it has better shielding then the original coax.

 

 

[Roscoe]

Roscoe. I had some similar intermittent tx issues with my J230 and Icom a200. Long time spent checking radio, coax, antenna, audio panel wiring. Eventually found the crimping on the Molex terminals were poor/loose. Soldered them and been OK since. (I hope its more than a coincidence.)

Thanks, was the poor crimping on the Radio end of the Antenna coax?

 

Roscoe. I had some similar intermittent tx issues with my J230 and Icom a200. Long time spent checking radio, coax, antenna, audio panel wiring. Eventually found the crimping on the Molex terminals were poor/loose. Soldered them and been OK since. (I hope its more than a coincidence.)

ks

 

 

[deglestal]

The BNC wasn't the problem, it was the 30 pin molex connector into the back of the radio. Factory built 06 model and had other electrical crimping faults as well (not radio related). When I first read your post it sounded just like my issues

 

 

[Roscoe]

The BNC wasn't the problem, it was the 30 pin molex connector into the back of the radio. Factory built 06 model and had other electrical crimping faults as well (not radio related). When I first read your post it sounded just like my issues

I've had the coax Antenna re crimped at the Radio end and my Battery was low as well. Did a Radio check in the Hangar with good result so just waiting for winds to drop and check it in the air.

 

 

[Roscoe]

RoscoeIgnoring any voice aspects what is the signal strength, or to put it another way a 5W airborne radio close to a receiver when you key the transmitter and do nothing/say nothing should immediately trigger the receiver squelch circuit and you should hear virtually no hiss. That shows that the transmitter circuit carrier is working fine. Try it high and low frequency.

 

When it comes to the voice aspect what does unreadable actually mean, is it:-

 

1) The receiver can barely hear any modulation (voice) against a strong carrier

 

2) The receiver can hear plenty of voice but its distorted (describe distortion()

 

3) The receiver can hear something but it doesn't sound like voice (describe or record what it does sound like)

 

Now, ignoring the receiver what can you hear in your headset (sidetone) when you transmit and does it sound Ok?

 

Lastly, has anything new from an avionics perspective been added to the aircraft? doesn't matter what it is and whether its related to the radio, if anything added let us know what and when

 

also try all the above when wiggling the mic/headset leads, could be a dodgy connector (we are only looking for problems, not trying to create them so be gentle)

 

Andy

Andy do you run 2 MicroAirs in your Jab, and where did you put the second Antenna?

 

 

[Guest Andys@coffs]

Roscoe

 

I don't go into CTA so there is no need for me to run dual radio's in my 230.

 

Andy

 

 

[Jabiru Phil]

RoscoeI don't go into CTA so there is no need for me to run dual radio's in my 230.

 

Andy

I had dual micro airs fitted after two failures whilst a very long way from home and had to rely on a hand held.

 

Well worth the extra expense if travelling interstate, long xc etc.

 

They were factory fitted as an option when built so don't know all the installation details.

 

I do know that you mustn't have both radios on the same frequency when transmitting, seems to stuff up the spare.

 

Phil.

 

 

[Roscoe]

Thanks Phil, I have one fitted and wondering whether to have another as a backup. Maybe should have had 2 from the outset (factory build). Did the Handheld have enough power to transmit properly?and could you hear transmissions above the engine noise?

 

 

[Jabiru Phil]

Thanks Phil, I have one fitted and wondering whether to have another as a backup. Maybe should have had 2 from the outset (factory build). Did the Handheld have enough power to transmit properly?and could you hear transmissions above the engine noise?

Rosco,

 

Fortunately I had an headset adaptor in the flight bag. Changing frequencies caused a bit of concern. I had to dig out the hand held instructions booklet as the memory freq were not the ones I needed.

 

Couldn't have happened at a worse time, just as Tyndall opened. I had to change to three different frequencies to get away, which took some time.

 

Definite much lower power and distance performance and sitting on lap is not the best place to carry, I remember that I inadvertently moved the freq knob a couple of times.

 

Reception with adaptor and headsets in range was great.

 

Phil.

 

 

[Roscoe]

Rosco,Fortunately I had an headset adaptor in the flight bag. Changing frequencies caused a bit of concern. I had to dig out the hand held instructions booklet as the memory freq were not the I needed.

Couldn't have happened at a worse time, just as Tyndall opened. I had to change to three different frequencies to get away, which took some time.

 

Definite much lower power and distance performance and sitting on lap is not the best place to carry, I remember that I inadvertently moved the freq knob a couple of times.

 

Reception with adaptor and headsets in range was great.

 

Phil.[/

 

Rosco,Fortunately I had an headset adaptor in the flight bag. Changing frequencies caused a bit of concern. I had to dig out the hand held instructions booklet as the memory freq were not the ones I needed.

Couldn't have happened at a worse time, just as Tyndall opened. I had to change to three different frequencies to get away, which took some time.

 

Definite much lower power and distance performance and sitting on lap is not the best place to carry, I remember that I inadvertently moved the freq knob a couple of times.

 

Reception with adaptor and headsets in range was great.

 

Phil.

Rosco,Fortunately I had an headset adaptor in the flight bag. Changing frequencies caused a bit of concern. I had to dig out the hand held instructions booklet as the memory freq were not the ones I needed.

Couldn't have happened at a worse time, just as Tyndall opened. I had to change to three different frequencies to get away, which took some time.

 

Definite much lower power and distance performance and sitting on lap is not the best place to carry, I remember that I inadvertently moved the freq knob a couple of times.

 

Reception with adaptor and headsets in range was great.

 

Phil.

[Roscoe]

OK thanks Phil