Funke ATR833 VHF incoming noise issue

[Janex]

Hi!

New at the forum. I know this is an issue that has a lot of posts. But I havent found any similaritys to mine.

I have a problem with my Funke Avionics ATR833 radio in my Sonex taildragger.
I purchased a built plane with basic instrumentation. Have done an upgrade of the entire airplane with engine mods and avionics installation.
The issue i'm having is that when there is an incoming transmission on the radio, there is about a second of a "brrp" sound when senders PTT is released.
Witch is really annoying. I transmit and recieve at high quality. Seems like the radio isn't able to cut the transmission fast enough. Have tried squelch up and down with no difference.
It is RF from the engine, as it is only when running. Have a Jabiru2200 with SDS Efi. MGL Xtreme EFIS, Microair transponder.
Have installed ferrite cores all over, installed shielded wires to magnetos, intercom and antenna. Moved cables around to get segregation from power wires.

Anyone had an issue like this, or any ideas on this?

[Corby202]

I also have a Funke radio and a Jab 2200. Works fine. Could the noise you describe be coming from the Intercom. If I have the intercom sensitivity set to high on mine it would do something similar to what you describe.

[Janex]

I think I have tried the intercom as well. With no success. But will try again. Have done a lot of things since last time I tried.
There was a microair installed first. Bought the ATR833 with converter from Micro to Funke. But after a while I thought maby that the noise was a product of the converter.
I have soldered a new connector to the Funke, but still the same noise.
What kind of setup do you have? Any filters?

[Corby202]

The radio I have is a Funke ATR 600. Definitely nothing special with the set up. The aerial is under the plane just in front of the spar box. The headset cables run from the radio to jacks midway behind the seat. I have a three wire noise suppressor on the power supply to the radio, 10amp I think it is, the type you can get cheaply at the auto store or ebay.
www.ebay.com.au/itm/10A-Noise-Suppresso ... Swx2dYG1NG
I doubt if it would help with the type of noise you describe.

[Wolle]

Hi Janex. Did you find a solution to your problem? I would really want to hear if you succeeded to fix the problem.
I have got what seems to be the exact same problem as you describe. Very bad noise for a second or so when a reception is ending. Otherwise the radio works well.
I have got a FUNKE ATR833 radio with complete original cable harness from FUNKE. My engine is a Jabiru A2200 build year 2008. I am using a Lightspeed Sierra headset, or the classic David Clark 13.4-10. I have tried all sorts of trouble shooting, replacing antenna and antenna cable. Power the radio from separate battery. Switching all other electric equipment off etc. etc. Nothing helps. It is quite obvious the noise on my plane is somehow from the ignition. If I with the engine on turn off the squelch I get this constant noise on the radio. Then I rev up the engine and switch off the ignition for just half a second before switching the ignition on again. Instantly when the ignition is switched off the noise disappears but comes back again instantly when the ignition is on again. With the squelch on lowest setting - which is 2 - the continuous noise is not there. So the squelch works, but for some reason the noise is not suppressed when a transmission from another aircraft or ground station is ending. No matter the squelch setting - even with maximum squelch.

[n502pd]

The following is my opinion, and is worth the exact ammount anyone pays for it!! therefore, after a few years (in my youth) working at an avionics shop, and being a ham operator since 13 yrs old,, I have run across very simular things, as what you describe. It can be called a 'long squelch tail', and to understand some of what may be happening,a brief description of the squelch philosophy of design in the radios I have worked on (not any Funke items),two signals are used to perform the closed-open-closed squelch operation. one is signal+noise, the other is filtered into just noise. If no audio signal is heard, both paths thru the radio are mostly equal, and squelch stays closed. When audio is present, one path (signal+noise) is greater that just noise path, and that difference trips the 'squelch gate circuit' to open the receiver to hear the audio received and presented to the operator. When audio ends, there most likely is a time delay for both channels to bedcome reballanced, and close the squelch.This delay may be a built in design point, oversite, or some component drift over time. The time delay is what you are hearing, hence the long squelch tail. Some radios may have internal adjustments to ballance the channels better, or even sque that ballance to greatly elliminate the long tail. This may not be something that is externally available, but may be on software setup, or by external axcessed potentioneter on the side of the case, as in side tone adjustments.

The real culperit may well be your ignition system, engine to battery to airfrane grounds, plug wire type...carbon core vs copper wire...and /or resister plugs. Antenna grounding must be more that good, must be great.

And , like I said, my humble opinion, and its worth every cent you pay for it!! Please let us know how things work out!

[Wolle]

Hi Joe
Thank you for your input. I recently found out that one of the guys at my home airfield is profesionally working with radio communication, and he is about to get some equipment that can test radio signal quality and strength etc. He believes I have a bad signal/noise ratio which fits quite well with what you describe. When the signal reception is only slightly stronger than the noise reception, the squelsh needs more time to realise that the gate shall be closed.

[n502pd]

I am glad that you can find someone with proper equipment to do these measurments, and check all the allignment points, maybe, as some of the rf and if amps need specific tune settings to be able to properly operate on all selectable frequencies. i didnt mention, but please check the swr, at the radio going to the antenna, because if it isnt minimized properly, it might have a detrimental effect on how the radio actually performs on reception, as well as on transmit. your friend should be aware on how to do this if you need assistance. Please let us all know the resolution!!

fly safe!!

[Janex]

Hi again. Seems like Wolle and I have the same issue. But what can be done with the signal/noise ratio? At our airfield we have 3 Sonex aircraft, and I am the only one with this problem. The only thing different with my fuselage is that it has been coated on the inside of the aluminium. Thinking the contunuity in the metal is disrupted. Reading thru countless forums, I stumbeled upon static buildup. Could it be possible that I need bonding on fuselage and wings? I read that there should be a minimal amount of resistance thru all metal components. Will try to do some measurements from main ground to wings and tail.

[n502pd]

One thing to be aware of when looking for very small ammounts of resistance, or may be two things..!
1) make sure that the leads you are using, no matter how long,(wire that is very flexable, and in the #10 to #12 dia should work fine) are connected to the meter such that they will display a near zero, or actually a zero, indication, repeatadly while and after the leads are moved around. this way, your data for the varrious master ground to suspect areas on the surface, will actually show that areas resistance, and not include lead varriability resistances. You do not want to have faulty data leading you to a place on the surface of the plane and do 'work' to fix a phantom problem.

2) do what ever sequence of surface data collections several times, to make sure you can reproduce the readings. otherwise, if you can not reporduce the readings accurately enough, the data most likely would not point to the actual defect in resistance. this way you wont be tearing something up or apart needlessly.

Just another thought, do any of the other aircraft have the same radio? would they let you put yours into their planes to see if the noise is the radio, or your installation? the old devide and conquor thing!

what is the coating used on the inside of your plane?

I have recently...sever months ago...found what I think is a bad/leaky/broken HV insulator on some HV power transmission lines about 3/4 mile west of my home base to seemingly cause my squelch to open as I fly overhead, at many different altitudes. I used a direction finding antenna hooked to my com handheald and was able to verrify its location below my flight path. I tightened my squelch a bit, and still get some of the noise, experimented with communication ability while over the powerline and have found a value of squelch that is accdeptable so as to not miss important com info. Could this be simular to your problem?

please keep up reports on what you find as I know others may well be needing it!

fly safe!!