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Radio Issues...


Guest OzChris
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Guest OzChris

HELP...

 

I fly a Thruster TST-E and use a Vertex transceiver...

 

My problem is, that when I transmit no one can hear me :[

 

I can hear others perfectly - but my transition is (reportedly) hardly even static!

 

Does anyone else suffer from this problem in their ultralights? Im guessing it is a problem with most 'rag & tube' types...it sure is frustrating though.

 

I have ordered a product called: Miracle Air whip - its supposed to be an antenna system for this type of aircraft...not sure if it will work or not and am a bit concerned about spending $200 on it if it doesnt.

 

Any thoughts??

 

 

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Guest OzChris

I got the new Antenna in the post today - looks unusual...

 

 

It apparently fits inside of the canopy...

 

I am going out flying tomorrow (thursday) and am going to install it and test it out.

 

Im hoping others will hear my radio calls...will report back

 

 

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Guest Michael Coates

The only problem with putting it inside the canopy is that its close to your head (which you cant do - even with a 1 watt radio) and it will create masses of RF which means you will probably get a squeel when you transmit and silly thinks like your tacho will jump when you transmit etc....

 

I did a big reply to you yesterday but the site wanted to do some sort of popup and when i accepted it completely deleted a page of information. I will send you more through again tomorrow.

 

 

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Guest OzChris

hhmmmm - thats what I was worried about Michael.

 

The people who sold me the 'miracle air whip' told me that this is the ants pants and will work - I have my doubts.

 

I think the radio I use is 5 watts and the Air Whip antenna is around 25 watts (max)?

 

I wonder whether putting a 'Power Mate' on will help with the RF???

 

The main issue with the 'Air Whip' antenna is that it cant touch or be within 5 inches of metal...its ground independent

 

 

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Guest Michael Coates

Okay, I will try and do my reply again. I got about a page of information done for you yesterday and a pop-up from the site went and deleted everything I had done ???

 

Basically, the radio you have is a hand-held radio. It is designed to be used in your hand, on the ground and is ideally suited to talking to aircraft that are taxiing in etc etc. They have never been designed to go in aircraft and used as the sole aircraft radio but this does not mean they cannot be adapted for this use. It just means that they are not ideal and I guess would be considered a compromise.

 

The Vertex standard radio that you have is sold as a 5 W radio but in reality it is a 1 W radio. What this means is that the carrier power of the radio when you depress the PTT and say nothing it will give a reading of around 1 W. If you talk and shout into the microphone that reading will go up to say three, four or maybe more Watts... this is called modulation and if the radio is modulated at 100% (which is basically impossible) it will put out 5 W... But in reality it is a 1 W radio (carrier) and is sold as a 5 W radio because it can be modulated to output 5 W PEP (peak emission power) (kind of deceptive advertising but it happens with every hand-held radio manufacturer).

 

A radio like the Microair for example is a 3.5 W radio, that is a 3.5 W carrier and it has a PEP (peak emission power) of between 12 and 14 W. The XCOM is a 6 W radio and has a peak emission power of around 20 W. The ICOM ICA 200 is an 8 W radio and has a peak emission power of around 27 to 28 W. It is important when talking about the power output from your radio that you actually know exactly what your radio is putting out and generally the industry uses the carrier power.

 

Now, back to your original question the aerial which you have purchased should be adequate for the job. It needs to be positioned correctly and it needs to be away from your body otherwise every time you transmit you will be putting RF Power from the aerial straight into your body which can damage things like your eyeballs, testes etc.... Obviously you are going to do a lot more damage using an 8 W radio like the ICOM than you will do using the 1 W radio but you still need to be careful.

 

Another concern of using an aerial on the canopy is that the RF transmission which is radiated out of the aerial needs to go somewhere. In an ideal world the radiation from your aerial gets transmitted out into the blueness to be heard by other aircraft without affecting your own aircraft. With the aerial placed very close to the aircraft panel it will do all sorts of things by getting itself back into your headset leads, the wiring harness for both the radio and the aircraft and anywhere else it shouldn't be going. I imagine there are a lot of people here reading this that would recognise when they press the PTT button that their tacho goes all the way up into the red! No, it is not nitrous oxide injection it is RF getting into your aircraft wiring harness.

 

The best location for an aerial is on top of the aircraft placed on a ground plane, a ground plane is a small sheet of aluminium or some other metalic material which can be used as a base for the aerial to radiate out from. The ground plane also protects the occupants somewhat from stray RF. This means that you can have the aerial on the roof of your Thruster very close to your head but because there is a ground plane between you and the aerial it limits the amount of RF coming back into your body and into the wiring harness of the aircraft.

 

To complicate things even further if you are trying to use your hand-held radio inside the cockpit with the standard rubber ducky aerial then all you are doing is transmitting the signal into all of the airframe so basically most of your transmission power is being absorbed in all the metal tubes and wiring harnesses within the aircraft. Very little of your signal will be transmitted into the blueness which means people will not hear you.

 

You can get a Vertex radio to work quite well in an aircraft but it must have an external aerial and good quality coax cable which is as short as possible. The longer your coax cable the more the signal drops of between your radio and the aerial. The aerial must be positioned vertical or as close to vertical as possible e.g. between vertical and 45°.

 

You will notice even on all of the jet aircraft like 747s etc they still have an aerial like the Comant 121 stuck on top of the roof for VHF transmissions. If Boeing can't work out how to do it without using a normal aerial then I'm sure we can't.

 

If you decide to use the new aerial you have got then please don't lay it around the bottom of your canopy between the Lexan and the panel because the aerial will then be horizontally polarised. That means it will transmit radio waves horizontally instead of vertically. In a perfect world the transmissions would be vertical because nearly every other aircraft has a vertical aerial and every control tower that i have ever seen has a vertical aerial, if you decide on having your aerial mounted horizontally you will need to pull the aircraft up vertically every time you want to make a long-distance transmission.

 

Finally, if you get everything to work with your new aerial then that it would be fantastic but as soon as you go and plug in a more powerful radio you will be introducing all sorts of additional problems because of the increased output power.

 

Please note, I am not an absolute expert in avionics. I only repeat what I am told by other people who have vastly more experience and engineering degrees than what I have. I do hope however that you find this information and my experience helpful. As for giving you the ideal place to position your aerial I am really unsure, if you put it down the front of your windscreen say from the roof to the top of the panel then it will be too close to everything inside your aircraft and when you transmit you will get squealing sounds or very poor transmission. Much of your transmission power will be absorbed into the metal poles and being a 1 W radio means that you don't have a lot of power in the first place. An ideal spot would be in the wing but the polarity is incorrect because the aerial will be horizontal. Most of the Thruster/X-Air type of aircraft usually have a conventional aerial mounted where the trailing edge of the wing attaches to the boom. This then makes the airframe itself the ground plain and the aerial uses the main fuselage boom tube and the wing structure as a ground plane.

 

Good luck and keep us posted with your progress, you never stop learning !.

 

 

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Guest OzChris

Thank you sooo much Michael - that is more information than I have been able to get to date :]

 

I am not very happy with the Air Whip - as it is sold/marketed as an ideal antenna for a Thruster & Drifter...but the instruction say (as you have mentioned above) that it HAS to be clear of ANY metal. Well the thruster and Drifter is all tube with a tiny bit of rag...WHAT???

 

On my Thruster there is a plate half way down the main boom between the tail and trailing edge (see picture below) - Im guessing this is where they have had an antenna fitted in the past.

 

 

Michael, do you think it would be better to install an antenna down there with coax cable instead? That way it will be vertical, away from the cockpit and as far as I understand from your post, have its ground plane?

 

Thanks again Michael...I need to test this Air whip out - if Im not happy, I will get a vertical antenna...

 

 

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Guest Michael Coates

It looks like that is where the aerial was mounted and it should work ok there but i would prefer to have it near the wing trailing edge to get a better ground plane to the sides. You have 2 choices... Play with the aerial you have got (If you have the time to play) or simply get the correct aerial to start with and go flying. The aerial you have is ideal for wooden aircraft, perhaps some composites (But NOT Carbon Fibre) but it's not really perfect for a Thruster. I dont know what to say, i would be asking the supplier why they have recommended the aerial and the instructions say its not really suitable.

 

If you go looking for another aerial let me know and i will send you some info about aerials or you can download a "Dummies Guide to Aircraft Aerials" which has really good info from this link (Its generic info for ANY plane and ANY radio)

 

http://www.mcp.com.au/xcom760/education/XCOM-Aerial-Dummies-Guide.pdf

 

 

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Yes, a very helpful post indeed

 

Once again Michael it is good to have someone like yourself here who can give our members assistance like this.

 

 

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Guest OzChris

OK - so I fitted this fantastical 'Miracle Air Whip' antenna today...

 

The verdict was better than I expected - at most RPM settings it was fairly clear transmissions with slight background 'fuzzzz'

 

I asked 3 times for a radio check and each time it was returned a 4 or 5

 

So that's ok - certainly better than a 0 like it was :]

 

I ended up sticking it in the nose canopy of the Thruster, running it from the back of the panel to the front of the nose. I let the end of it 'droop' down to face away from the ignition source and to give a slight vertical angle to the antenna. Seems to work well...

 

Thanks again to Michael for the brilliant information (as usual).

 

 

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Guest OzChris

Michael - I think it would be a great line for you to keep...

 

I did circuits to check it out, and it seemed to be working very well right throughout the pattern. Even aircraft behind could hear me - which is good as there is a slight front bias on this antenna as this is the way it is facing and the rear tube absorbs a lot of the radiation (apparently).

 

This is what I like about the Miracle Air Whip Antenna:

 

1. It is small

 

2. EASY to install (even I could do it)

 

3. It can be installed in a number of places (not on metal though)

 

4. No holes in the fuse - it sticks inside of the front with sticky tape/silicon/etc

 

5. Comes with the connector for the Radio - just plug and play :]

 

6. It takes up to 25 watts of Radio (apparently)

 

It cost me $203.00 Delivered, which was a bit more expensive than some others - but with a name like 'Miracle Air whip' I had to have it :]

 

This is the info I got on it:

 

Sport aircraft are a unique challenge for air band antennas. Fabric fuselages offer no ready ground-planes, unfiltered electrical systems mean lots of spikey noise, and available mountings and vibration pose mechanical constraints. The AeroWhip offers a neat solution to these challenges.The AeroWhip can be attached in many locations, ie you can fit to the inside of a fiberglass nose - using silicone, tape or non-metallic cable clamps, just make sure it's not going to shake loose in flight.

 

The AeroWhip is a full half-wave dipole-this allows it to be pre-tuned for maximum radiation at manufacture, it operates completely independent of a ground plane. This ground plane independence can even help eliminate ground-loop induced noise in your coax feed. You get much more effective radiation, less shadowing from the airframe, and an extended frequency response.

 

Installs in the nose/tail/side of your Sport Aircraft (Drifter, Thruster etc), Gyro, Glider or Vintage aircraft in minutes.

 

  • A full half-wave dipole so it doesn't need a ground plane.
     
     
  • Pre-tuned for the highest effective radiated power from your transceiver.
     
     
  • Mainly omni-directional pattern with slight bias towards your heading.
     
     
  • Extended frequency response compared to most whips.
     
     
  • Highest quality mil-spec connectors, cable and other materials.
     
     

 

 

AEROWHIP ANTENNA $ 189.00

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  • 3 years later...

Chris,

 

Where did you get it from? the reason i ask is the where i was getting them is getting very hard to get along with, since we had a couple of words about 1 order.

 

I have been using them in my Xenon gyros with excellent results with the microair 760, the only aerial i could find that would just work first time everytime.

 

the full fibreglass cabin was the main problem trying to get a good ground plane, these solved the problem, as you can see by my avitar.

 

 

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