MGL Avionics User Forum

I have dual v16 and Razors.

Recently ventured further afield and found two frequencies that I am getting carpet wave/static no matter what I do.

Comm 1 gives this static at 126.00 and 122.00 (82 db), Comm 2 gives static at 126.00 (74db) only.

Has anyone else had this or any ideas what it could be, removing the antenna changes nothing and I have checked all shields are grounded to audio ground.

Turning everything else off makes no difference and engine running or not doesn't affect it.

I'm wondering if over cooked some internal components somehow.

Mike

That's a bit odd.
Neither of those two frequencies are related to any clock frequency used in the V16 or Razor so can't be a harmonic.
-74dbm is a pretty strong signal. What happens if you unplug the Razors so they are not running ? Don't think it can be those - the only harmonic that would be of concern would be 128Mhz (8th harmonic of the 16Mhz clock source in the Razor) and to a lessor extent 120 and 136Mhz (subharmonics).
The clock in the V16 is carefully chosen so no harmonics come anywhere near the entire VHF band (i.e. a very high frequency TCXO is used).

Do you have any USB sockets with power supplies anywhere on your aircraft ? I have found these to be serious radiators of EMI.

I haven't tried the razors, but will do.

I do have USB chargers, but they are all individually switched, and on or off makes no difference.

Turning off the iefis makes no difference either.

The only other thing powered is the PM3000 intercom.

Mike

Turn off your hangar lights and see. Some LED and fluorescent lights will cause a static like this.

A quick update.

Rainier,

I have disconnected the razors with no change to the static.

Adam,

I'm pretty sure it's not a localised problem at I first noticed it in the air when I had to change to 126.00 for any area frequency.

I have a poor man's intercom, with a mute for Comm 2 and a mic switch between com 1 and 2. There are short lengths of unshielded wire around these switche so I'm thinking there may be some RF getting in around this area. Although I still can't work out the source as I have isolated all other possible producers of RF (That I can think of anyway).

It might be time to use this issue as justification to buy the A16.

Mike

Hi

I also have an issue with an interference signal appearing to be generated within the V16 itself, in my case exactly 128.000MHz

I have 2 MGLV16s installed in an LSA, one to a top antenna and the other to a bottom antenna.I noticed that both radios appear to have an interference signal at 128.000 Mhz.The interference is not noticed above 128.010Mhz or below 127.990Mhz and has a slight whistling characteristic.

Normally inflight I have both squelch settings at -98db. In the hanger these can be set to -100db.
Both radios continuously receive the interference signal at about
-87db which of course disappears when the squelch is set high enough.

I first noticed it in flight when tuned to a nearby CTAF of 128.000Mhz but also notice it when parked in the hanger.

Both Radios are connected to Razor Heads using twisted Raychem 400 for the Can bus (1meter and 200mm), 120ohm terminations at both ends and a separate twisted pair for power. Both radios interface to a Dynon intercom.

The signal is still present when the only items powered in the aircraft are the dynon intercom and a single V16 radio powered from a separate 12volt gel cell and with a dummy antenna load as the antenna.

Could this be interference from a harmonic of a clock generator?

Doug

Doug19

The second post of this topic by Rainier talks about the possible cause of 128 interference.

I have bitten the bullet and purchased an A16, so hoping that will fix my problem.

Mike

Hi
All
When I disconnect the the razor head unit by unplugging at the razor end the interference remains, so it is not a harmonic of the razors clock.
The noise floor for 128.025 is -101db
The noise floor for 127.975 is -101db
The interference signal for 128.000 is -77db
My previous experiment of only powering the V16 via a separate battery seems to indicate the interference is coming from the V16 itself?
Cannot think what else it could be.
Doug