engine messing up radio

[paramotorbart]

hi can any one help my engine is messing with my radio when i transmitt and recieve how can i fix this problem thanx

[pete_b]

hi can any one help my engine is messing with my radio when i transmitt and recieve how can i fix this problem thanx

Use a resistor cap or plug.

[woody]

as Pete B says, but not both!

I have also seen wrapping the HT lead in a wire screen to shield it, this will help eliminate the RF emissions from the ignition system interfering with the Radio.

I'm guessing your using an airband? PMR doesnt suffer from this as its on a different frequency.

Hope that helps,

Woody.

[alan_k]

Can you be more specific about the problem, particularly what the problem is with transmit and receive separately

On receive is it ignition interference Loud clicks that speed up and slow down with the engine revs.

On transmit is the audio at the receiving end very distorted and difficult to understand, see my posting in the Radio Comms section.

Cheers,

Alan

[aquatix]

Just tried searching in the Radio Comms section but couldn't find anything specific.

I have a similar problem with a VX-7R which I have to turn up almost full volume in my headset to hear over the engine noise. It works fine on the ground, but in flight it just gives a deafening squallk of clicks and high pitched whining noises when receiving. It is impossible to hear what anyone is saying so I just have to switch it off, which isn't much use.

I'm flying a Walkerjet with NGK BR9HS spark plug, which is a standard resistor type so should be OK. Would adding a resistor cap to the HT lead improve things at all or would it degrade the spark ?

Any ideas welcome .......

[alan_k]

I have a particular abhorrence of unreliable comms.

The posting I was reffering to is viewtopic.php?f=45&t=4691

I have a similar problem with a VX-7R which I have to turn up almost full volume in my headset to hear over the engine noise.

Does your headset provide a reasonable quietening of the engine noise?

The audio output power of the VX-7R is quite high. When close to the other radio station so you have a strong received signal, run the motor on your back and try to tell if the received audio is distorting in your headset because you need to have it loud. You could need a quieter headset.

Secondly when close to the other station do you get ignition interference? A strong received signal should prevent this (to do with the limiting characteristic of FM by the radio), but you probably will get interference when far away from the other station.

and high pitched whining noises when receiving.

Does the pitch of the whining noise follow the engine revs?

Are you powering the radio from the paramotor? Sometimes the noise can get in via the power lead. With a small handheld radio there isn't much space inside for good power line filtering.

Is the interference less when the radio is on battery?

Another point about radio reception is the orientation of the antenna relative to the transmitting station. Vertical is the accepted norm, if your antenna is in a different plane to the transmitter you lose a lot of signal. Should only be a problem at far distances.

Try to have the antenna a reasonable distance away from yourself as the body also absorbs/shields the signal.

Here to help,

Alan

[aquatix]

Hi Alan - thanks for your detailed reply.

I gave it a quck test last night on the ground, with my machine revving at a fast idle - both received and transmitted speech was heavily distorted, over a short distance across the field to other people. It worked fine with the paramotor off, at a reasonably loud level without distortion, which should be more than enough for communication even if I have to ease off the throttle to send and receive clearly.

The VX-7R is only running on its internal battery, vertical, but close to my body as that is the only location I have for it. I have tried an aftermarket aerial as well as the standard one, with no difference. The one test I should have done (will do next time) is to have someone else rev my motor and see if their system is similarly affected.

My headset is a budget model, built into the paramotor helmet with ear cups and helmet PTT buttons. It provides similar isolation from motor noise as a decent pair of ear defenders from a DIY store, so should be adequate. The connecting lead has a secondary lapel clip with another PTT and volume control.

The motor is a standard Walkerjet RR200 apart from a modification to upgrade the battery pack to NiMh cells, which was done by 'pete b' on this forum prior to my purchase. I'm assuming the ignition / HT circuit is to blame rather than the charging circuit ?

Any further advice would be greatly appreciated as it is limiting my ability to do longer XC's until I have some form of communication ....

Regards,

Alan

Edited April 18, 2010 by Guest

[alan_k]

Hi Alan,

This is a puzzler. I'll run through some less likely scenarios.

Does the Walkerjet have an electronic ignition or just a standard magneto/coil?

Another way for handhelds to be affected is by the transmitted RF getting 'back into' the radio via the external microphone/headset socket. This seems unlikely in this case as it works OK without the motor running.

For the sake of eliminating this can you try the following:

See if you can try another headset, I know this may be a problem because of the specific connector.

With the motor running so you have the problem, transmit to the other station and put your hand loosely around the antenna to absorb the RF (this isn't hazardous) and see if the transmitted audio becomes less distorted.

With the antenna you have does it connect directly to the radio on the antenna socket? This type of connector is called an SMA.

If you need to use an adapter between SMA and BNC (the more usual larger connector) this could possibly be problematic as some of the cheaper adapters are rubbish. They may fit OK but can be very lossy and cause a mismatch to the radio. This is another way the RF can screw up the radio.

General question: Does anyone else have this problem with the VX-7R, particularly with a Walkerjet?

I'll think some more, there has to be a good reason for this,

Cheers,

Alan

[aquatix]

The Walkerjet manual (such as it is) says the ignition is "Electronic / Processor CDI" with just a simple regulator to convert the AC charge current for in flight battery charging. I will try and test the output from this, and change the spark plug before the next flight.

If someone else tries my motor I will know if it is the machine or my radio / headset causing the problem.

The antenna simply screws onto the VX-7R without an adapter. The helmet and connector lead are basically the same as this one, but without the additional finger PTT connection:

http://www.paramotor-store.com/paramotor-ulm-helmets/speedcom-ppg-ulm-helmet/speedcom-ulm-ppg-helmet-2.html

Here's hoping we can get to the botom of this mystery !

[weesplat]

Hi,

I have the same helmet and had the same problem. Its nothing to do with the radio its the helmet.

If you pull out the foam insert from the helmet and look at the leads they have no shielding and all connect at the back of the helmet close to the engine. I never did get it sorted ended up just keeping the helmet stripped of its wires and bits and using a throat mike for coms.

Hope you have better luck .

Cheers Col....

[aquatix]

I have the same helmet and had the same problem.

Thats not good news ! Bit of a cheek selling a paramotor helmet that doesn't work in a paramotor !! I wonder if a bit of tinfoil lining would help (or just keep the government from reading my thoughts) ... ?

Looking at other headsets for the VX-7R (below) it appears they all share the same type of conecting lead which doesn't have any additional shielding.

http://cgi.ebay.co.uk/Noise-reduction-Headset-for-VX-7R-VX-6R-VX-170-E80bY7_W0QQitemZ330417570766QQcmdZViewItemQQptZUK_ConsumerElectronics_SpecialistRadioEquipment_SM?hash=item4cee6c03ce

http://cgi.ebay.co.uk/E83yY7-Noise-reduction-Headse-VX-6R-VX-7R-VX-170-VX-177_W0QQitemZ150426491096QQcmdZViewItemQQptZUK_ConsumerElectronics_SpecialistRadioEquipment_SM?hash=item23061e18d8

[alan_k]

Hi,

I have the same helmet and had the same problem.

I never did get it sorted ended up just keeping the helmet stripped of its wires and bits ...

Cheers Col....

Hi Col, have you still got the wires and bits. This shouldn't be an unsurmountable problem with improved wiring and/or adding decoupling components.

Would you consider sending them over to me so I can re-engineer them?

I don't like to give up easily on problems.

Cheers,

Alan

[weesplat]

Hi Alan

Sorry afraid all the bits were ripped out rather than taken out and were just scrap after that so binned.

On footflier .com there is a design for a universal headset/mike set up which might be an option. Now I've got the throat mike stuff I cant belive how much beter it is no wind or engine noise when you transmit and decent loudnes without distortion on recieve.

Cheers Col........

[alan_k]

Oh well

From my earlier post: Another way for handhelds to be affected is by the transmitted RF getting 'back into' the radio via the external microphone/headset socket.

I think this is what's happening in this case. It sounds like ignition interference is also getting into the mix.

From Cols post I'm assuming the headset is 'fitted in' to the helmet so an in line RF filter is all I can suggest. This will have to be made up.

4 pole 3.5mm jack plugs are available from Maplin, part no QT65V but sockets are more difficult to find.

If you can get the connectors I'll knock one up.

cheers,

Alan

[aquatix]

It sounds like ignition interference is also getting into the mix.

From Cols post I'm assuming the headset is 'fitted in' to the helmet so an in line RF filter is all I can suggest. This will have to be made up.

Just a quick update. As Col suggested I removed the padding from the helmet, and there were lots of thin, unscreened wires running from the mini-DIN plug at the back to the twin PTT's, Mic & Earphones.

As a 'quick fix' I placed a sheet of (cheapo thin) tin foil between the wires and outer shell of the helmet. Very crude but it actually worked to a certain extent ! I can now hear reception in flight with the motor running mid throttle. Not perfect as there is still a lot of interference, but just about intelligible & better than squalks & buzzing !! My transmission is still quite distorted, but I'll try doing a better job of it now by wrapping each wire in foil back to the internal DIN socket, plus a few extra layers inside the shell.

No idea how to fit an RF filter but hopefully this will do for now, and I've also ordered a cheap throat mic to try out. Might splash out on a proper NAC helmet & Peltor headset once funds allow ....

[alan_k]

Good some progress at last.

The RF filter idea is to plug into the radio socket then the headset plugs into the filter. This is to eliminate the RF and possibly some of the interference getting into the radio circuitry.

I have parts to make the filter part of it, you would need a 4 pole 3.5mm jack plug, available from Maplin part no QT65V, plus a matching jack socket - this needs some searching on t'internet for a source.

If you can get the plug and socket to me I will make up an 'in line' filter for you to try.

My transmission is still quite distorted....

I think this is down to too much gain on the mic circuit as mentioned before. With the VX-7R circuitry the gain can be reduced by having a resistor in line with the microphone externally to the radio, so no mods are need to the radio.

I'll be interested to hear if there is more improvement with more screening.

Cheers,

Alan