HELP

[andreb]

I desperately need some help. Been struggling with my comms for ages.
I have had radio in to Composite Technologies and they cannot find problem with Vertex VXA-210.
Buzzcom has looked at my comms box and they find no issue.
Buzzcom gave me a loan radio (Icom) and this worked almost perfectly.
Have checked aerial and seemed ok to me. Hans re did earth wire to body last week.

Some symptoms:
1. When I plug into pilot and switch is to transmit pilot only, then passenger cannot hear me. If I switch to both, then passenger can hear me.
2. I can hear all transmissions perfectly.
3. My transmissions have got worse and worse and have now disintegrate into a noise
4. When I push PTT, my revs go up!!! (only noticed this recently)
5. Buzzcom did change my power cable and PTT cable and when I plugged in my radio Saturday, everything worked 100%. When I started the plane, the comms went haywaire again. I think I have now damaged my radio with some sort of spike (We did try and run Buzzcom straight from battery, but radio was still useless). I have a feeling this has something to do with the rev counter/PTT issue. Maybe rewiring of aerial earth has somethign to do with this.

I am not electrnically minded and dont know what to do. Seems the problem is on my plane, so i need someone to come and look at it and fix. All my flyign mates at Microland will tell you the endless hassles we have had.

I need help please....anyone.

[John Young]

When I push PTT, my revs go up!!! (only noticed this recently)

Turbocharger linked to PTT?

Don’t sweat – this is common – anything from 200 to 600 rpm. It’s just an RF field (electric wires) exciting the rev counter in the vicinity. Rerouting offensive wires will cure it.

Saturday, everything worked 100%. When I started the plane, the comms went haywaire again. I think I have now damaged my radio with some sort of spike (We did try and run Buzzcom straight from battery, but radio was still useless).

Are you taking power from the plane without a 12v regulator in the circuit and feeding this into the radio? If so the radio may need repairing as >13.5v can make these radios very “unhappy”.

I will look up the link to a cheap and very effective power supply and post it here.

Regards
John ZU-CIB

[John Young]

Hi andreb,

There have been a couple of posts about the RF Choke - here'e one -

viewtopic.php?t=1135&highlight=choke

The entire lot cost me R70 and it works like a dream.

The components are: -

1. Toroid coil (approx 40mm diameter) - cost R 45 (or ask a Ham Radio mate to find you one for free).
2. 2 X 12v voltage regulators - cost R 4 each. Ensure that the radio requires 12v and not 11v)
3. 1 X 16v 2,200 uF (micro fared) capacitor - cost R 2.
4. 2 X small electrical boxes (one to house the toroid and the other to house the voltage regulators) - cost R 4 each.
5. 1 metre of 6 amp twin power cable (red & black - approx 3mm in diameter) - cost R 3
6. Grommets for the wiring.

The circuit is simple. Connect to ignition switch (the fuse is normally located between the battery and the ignition switch, meaning that the circuit is already protected). Wind power cord around the toroid about 20 times and fit the capacitor in parrallel after the toroid winding. Split the power cord into two and route each through a voltage regulator. Connect each of the two cords to the power jacks normally provided on the instrument pod for the radio and intercom.

Regards
John ZU-CIB

[andreb]

Thanks John.
The power for radio is from Buzzcom box.

Paul has PM'd me and is helping as well.

I appreciate the quick reply.

[ZULU1]

Hiya Andre and others.

The VXA 210 (and 710 as well as the Microair760) are totally different in design to the Icom ranges and also the other VXA series the 220, 300 as they have no adjustable side tone facility. We have had some fun with Massimos and Ranger installations. I may aadd as well as some Hf SSB Motorola also !!

Firstly the side tone is adjustable by the volume knob and not separately as in the Icom Ica 5/23, 6/24, Vertex Standard 220,300 series. So when you press the PTT you can get a audio feed back loop and this is exaggerated with increased radio power.

Secondly the radio is susceptible to rf ingress in the power supply (talk to Massimo!) we fix this with a line choke (not a torroid as the frequencies are totally out) and a rf bead on the incomer. It works. The capacitor advised just helps line induced noise an not rf. The best bead to use is the Icom unit supplied with the charger.

Thirdly

You state that the revs rise, you are receiving a reflected power from your antenna as the SWR is haywire, probably caused by a poor connection, back to the rec counter ,this compounded with the fact that the Vertex does deliver a true 1,5 watts

The fixes

Contact the Intercom manufacturers and ask them to reduce the audio return to the intercom when the ptt is pressed. Also known as the side tone. We use a 4016 quad switch and bridge the "contacts" with a 56k resistor. I can post details if needed.

Purchase a rf bead and apply to the power line as close as possible to the radio.

Trash your antenna and buy a new one especially if its a device with the soldered connection on the bottom.

Major fault lies in the audio line; as you said a loan radio works perfectly.

We have done two now with stress as well as good results, the radio is a good piece of kit.

viewtopic.php?t=4807

eish Zulu1

[andreb]

Thanks
I will call you Monday Paul. I am not good with electrics or electronics and fear that I will damage more than fix.

[Mogas]

Morph/John
Thanks for this diagram.
I have a 9v battery powered intercom, is it possible to change one of the 12v regulators to a 9v one? though it lasts a while, I want to get rid of the pesky battery that goes flat at inconvenient times.

[ZULU1]

Yes you can use LM 7809 in a TO 220 package or a LM317 as its adjustable or if you require 5 amps use a LM338 also available with a TO220 package. I pay about R9.00 each for them.

I manufacture them built up with a line choke and adjustable regulator.

Alternatively Google "LM 317" and you can download the pdf drawing from the web.

Zulu 1

[John Young]

Morph/John
Thanks for this diagram.
I have a 9v battery powered intercom, is it possible to change one of the 12v regulators to a 9v one? though it lasts a while, I want to get rid of the pesky battery that goes flat at inconvenient times.

Hi Mogas,

Yip - the 9v regulators readily available - about R2 each.

However, if you are using Buzzcom, there's no need to step down the voltage - 12v is fine.

I do agree with your thinking - batteries are a load of CR@P

Regards
John ZU-CIB

[John Young]

Secondly the radio is susceptible to rf ingress in the power supply (talk to Massimo!) we fix this with a line choke (not a torroid as the frequencies are totally out) and a rf bead on the incomer. It works. The capacitor advised just helps line induced noise an not rf. The best bead to use is the Icom unit supplied with the charger.

You state that the revs rise, you are receiving a reflected power from your antenna as the SWR is haywire, probably caused by a poor connection, back to the rec counter ,this compounded with the fact that the Vertex does deliver a true 1,5 watts

Howdy ZULU1,

The toroid coil when wound is indeed a very effective RF Choke.

The capacitor is parallel to absorb any ripple that might get through.

Doubt that the SWR at 1.5 watts is responsible for the "turbocharged rev counter".

Regards
John ZU-CIB

[ZULU1]

Hiya John and others

Yes the torroids work very well and I meant above in 95% of the cases, however with Massimos we failed and had to place the rf bead next to the radio itself. The rf got into the last 50mm and yes I was shocked.

Johns circuit works well; the regulator is a good piece of kit, try to source "ST" products as they are the leaders in these devices. We use them in our bomb disposal applications and also in the Rattel comms systems that we make for the Middle East. LM 7805 at 5 volts though.

Anyway in the case of Massimos and this is a quirk of the VXA 210 and the Microair 760, they have a feedback loop which comes back to the intercom as well. So you get a double whammy to confuse the installation. We also found that the reflected power also adds salt to the wound.

Johns circuit works very well and if using with a cap suggest some fuse before it and also some current limiting device for the ICA 3/22 series and don't remove the battery even if it is poked. Always use that circuit with a ICA5/23 series if running from the plane but you may have to use a LM317 or LM350 as they draw more than 1 amp. They are adjustable devices. We use the LM338 which is 5 amps and the only device that works well with the ICA 6/24 series. If you have space use a TO3 package instead of TO220 with a small ally heat sink to use as a bracket..yes they get warm.

I may add the we have been playing with Steve Mc Currochs Cheetah with the ICA 200, a torroid also didn't work, we used a wire wound device and a 22,000uf cap, still not fixed but 50% better. It is a power line problem.

So as I always said Rf is a black art, two planes will give you two different results.

Torroids are available from:

Bluebird Manufacturing, Wetton, Cape Town. Contact: Sherene Doveton or ourselves.

We also make all devices advised above. I am posting a list of all major suppliers on Morphs link for his BB for Electronics, cables and other goodies as he needs for his project.


Good Luck

Zulu1

[Massimo]

Hi All,

I can confirm with Zulu that initially we had some major teething problems but after some adjustments here and there, the sytem works very well.

I havent done too many hours with the new system (maybe 10) so ill update as i go along but no complaints at this stage. Im getting positive feedback from other airies confirming crystal clear audio all round.

[Tjoek]

I have a Microair 760 with Softcomm intercom. Although my audio performance is "fair" (i.e. not great), I note that when I transmit the rev counter is heavily affected (i.e. increased rev indication while the PTT is held).

[ZULU1]

Hiya Tjoek, I have done my fair share of "porridge" with the Microair. The best thing to help out transmissions as well as noise feedback etc.

If you have a pod and a small antenna you will have some feedback issues, best is to reduce your transmissions power out by turning down the rf to a comfortable 1,5 watts which is more than adequate.

Some are set at 6 watts..!! Under no circumstances press the PTT without an antenna connected, its not a Icom !!

To do this you will require some form of power meter and remove the shiny little sticker on the left hand side marked Q/C and a number, insert a small screwdriver and then reduce it on the meter.

You are probably having a torrid time with the intercom, that is difficult to overcome with standard headsets in a trike. You can adjust the side tone on the right hand side. We have had fair performance from them, the torroid John advises above is a good idea without the regulator installed, it does help with radio noise via the intercom on signal reception.

Good Luck

Zulu1

[andreb]

What can I say. A problem I have been having for weeks and weeks, and nobody could sort out IS NOW SORTED.
Simple actually, uninstall Buzzcom, send Vertex radio to Paul, he sends back with mods, new V antenna (on Kingpost), new comms box and headset.
Result is top quality tramsmission and communicatio, with no interference and background noise. I have to keep checking that I am transmitting and people can hear me....that is how quiet it is.

ALL SORTED OUT PAUL. THANK YOU.

Another Happy Customer

PS - The rev counter doesnt move a mm when I transmit!!