Radio Squelch - Electrical Noise Problems

I'm trying to sort out electrical noise upsetting many of my clubs radios.

I’ve had moderate but inconsistent results with separating radio wiring
and
use of ferrite beads.

Does anyone know of any on-line info / guides to reduce squelch problems?
(Especially with regard to squelch being upset by electrical noise from
chargers, voltage converters, digital instruments and data wiring).

The problem with cockpit devices causing the need for more aggressive
radio squelch setting seems to be getting worse. Winding up the squelch is

easier than minimising the ‘interference’ but I feel it’s like using
earplugs
instead of fixing a noisy wheel bearing.

I’ve seen and used lots of useful suggestions scattered through numerous

topics on RAS and a sprinkling of possible electrical noise fixes on
Google. I
would really appreciate a pointer to good info and any ‘golden rules’.


Max

If there is a specific voltage converter that seems to be spitting out a lot of noise you might try wrapping it in tin foil. That has worked for me in the past.

On Mon, 11 Jun 2018 23:28:23 -0700, Wyll Surf Air wrote:

If there is a specific voltage converter that seems to be spitting out a
lot of noise you might try wrapping it in tin foil. That has worked for
me in the past.

A cheap source of efficient 12v - 5v converters is to buy 'USB cigar
lighter chargers' from Ebay, throw away the plastic case and solder power
leads onto the 12v side of the PCB. However, these often produce RF noise
because they use a high frequency chopper circuit. I use them, of course,
since they are cheap and easy to find but I mount them inside a small
metal, rather than plastic, box and fit ferrite cores to both 12v and 5v
leads close to the box. I have no noise problems if they're used this way.

The only serious interference noise problem I've had was from a
mechanical T&B. Ferrite cores made no difference to it. The cure was to
fit a "12v interference suppression capacitor" across its its power
leads. These are special purpose polyester film capacitors. Mouser, among
others, sell them or a search using the term shown above will find many
sources, including fleabay.


--
Martin | martin at
Gregorie | gregorie dot org

With the help of a good avionics friend, we recently found that some of the little GPS pucker did interfere with my radio when powered (and connected to a Kobo), while other models (we switched to a dongle) didn’t.

It took a long systematic one by one elimination test, turning on and off one device at a time. One source of static can be your phone(s) obviously, so your testing must include those. Once you find the culprit the solution is probably simple or already explained by some of the pros above who know electronic better.

Good luck,
686

On Tuesday, June 12, 2018 at 12:28:25 AM UTC-6, Wyll Surf Air wrote:
you might try wrapping it in tin foil. That has worked for me in the past.

https://tinyurl.com/y7o8rnpy

I have to agree with PAGA.
It took almost a whole day but taking all units off line and adding them back one at a time identified what system was the source. Then it was a couple hours using ferrite devices to kill the noise. It was amazing to me how specific the positioning of the ferrite device on a wire/cable needed to be. Just moving the ferrite an inch back and forth on a wire/cable made a difference. Eventually, all became good in the world again.

On Tuesday, June 12, 2018 at 5:30:06 AM UTC+1, Maxx Ruff wrote:
I'm trying to sort out electrical noise upsetting many of my clubs radios..

I’ve had moderate but inconsistent results with separating radio wiring
and
use of ferrite beads.

Does anyone know of any on-line info / guides to reduce squelch problems?
(Especially with regard to squelch being upset by electrical noise from
chargers, voltage converters, digital instruments and data wiring).

The problem with cockpit devices causing the need for more aggressive
radio squelch setting seems to be getting worse. Winding up the squelch is

easier than minimising the ‘interference’ but I feel it’s like using
earplugs
instead of fixing a noisy wheel bearing.

I’ve seen and used lots of useful suggestions scattered through numerous

topics on RAS and a sprinkling of possible electrical noise fixes on
Google. I
would really appreciate a pointer to good info and any ‘golden rules’.


Max

It would be helpful to detail what you've done, what equipment is there, etc..

It would be helpful to detail what you've done, what equipment is there, etc..

Generally I try to modify the wiring to be as close as possible to John DeRosa's excellent presentations. I haven't found much on the topic of radio interference on his or any other website but would be happy to be corrected.

I've checked for voltage drops to the instruments, cleaned and tightened terminal blocks, grounding, fuses and connectors, separated Radio wiring as best I can (both physically and electrically), placed split ferrites on power, spr and mic/ptt leads to radio. Looped (twice) power wiring to the flarm through ferrite rings, clipped split ferrites on data leads to FLARM display and card readers if present.
I find that the first minute after the Master switch has been turned on is the noisiest, I assume things are initializing during this period. The Flarms seem to be the "primary culprits". A handheld radio confirms this.
The noise is stronger on some frequencies than others, 122.7 Mhz is moderately quieter than frequencies above 130 Mhz.
Should I try a ferrite on the Flarm GPS antenna or will this mess up the GPS?
Also, is a ferrite on the radio antenna cable a really, really bad idea?

I have assumed it is better to run both positive and ground wires to an instrument through the same ferrite OR would it be better to have a ferrite for each wire? Would it be better to have no ferrite on the radio ground so that its chassis is 'closer to RF ground'. Sigh.
I haven't tried a "12v interference suppression capacitor" yet, will order some. Will also order some copper foil to wrap around the flarms (or possibly to make a hat

On Tue, 12 Jun 2018 07:20:50 -0700, lbraithwaite wrote:

I haven't tried a "12v interference suppression capacitor" yet, will
order some. Will also order some copper foil to wrap around the flarms
(or possibly to make a hat

I could be wrong, but I think these capacitors are only useful for
dealing with interference generated by a sparking commutator and brushes
in an electric motor. In a glider you'll only find these in mechanical
T&Bs and artificial horizons.


--
Martin | martin at
Gregorie | gregorie dot org

On Tuesday, June 12, 2018 at 1:31:40 PM UTC-4, Martin Gregorie wrote:
On Tue, 12 Jun 2018 07:20:50 -0700, lbraithwaite wrote:

I haven't tried a "12v interference suppression capacitor" yet, will
order some. Will also order some copper foil to wrap around the flarms
(or possibly to make a hat

I could be wrong, but I think these capacitors are only useful for
dealing with interference generated by a sparking commutator and brushes
in an electric motor. In a glider you'll only find these in mechanical
T&Bs and artificial horizons.


--
Martin | martin at
Gregorie | gregorie dot org

Any energy at radio frequencies can be filtered that way. Probably best to combine both a capacitor (across the wires, only on power supply wires, not signal wires) and a ferrite ring in close proximity. Try the ring at either side of the capacitor, but I would expect the best noise reduction with the ring on the side towards the noise-generating device.