Lowering cockpit RF interference

Thank you Dan for your article link

John DeRosa wrote:
Your question is less about "I have a problem and want to fix it." versus, "I don't want any problems in the first place.

Exactly.

Do late model sailplanes actually have a "factory" grounding point?

Am I correct to assume the best grounding point would be the heaviest metal frame work closest to the instrument panel such as the control yoke or the adjustable rudder pedal track?

So in the perfect world all things metal (especially long lengths like push rods) and your negative instrument buss should be grounded to a common ground point?

On 12/20/2012 7:58 AM, wrote:
Thank you Dan for your article link

John DeRosa wrote:
Your question is less about "I have a problem and want to fix it."
versus, "I don't want any problems in the first place.

Exactly.

Do late model sailplanes actually have a "factory" grounding point?

Am I correct to assume the best grounding point would be the heaviest
metal frame work closest to the instrument panel such as the control
yoke or the adjustable rudder pedal track?

So in the perfect world all things metal (especially long lengths
like push rods) and your negative instrument buss should be grounded
to a common ground point?

I don't know how many adhere to the "single grounding point"; however,
note that the point is for the instruments, not necessarily everything.
The other metal bits, which are not carrying signals, can be grounded
elsewhere, such as the near the battery. A powered sailplane will likely
also have an "engine" ground, so the starter currents, ignition system,
generator, etc. are kept from the instrument ground.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

wrote:
Thank you Dan for your article link

John DeRosa wrote:
Your question is less about "I have a problem and want to fix it." versus, "I don't want any problems in the first place.

Exactly.

Do late model sailplanes actually have a "factory" grounding point?

Certainly not when they are in the air!

OK, that's a joke, but it does bring into sharp
relief that the "ground" concept is a fiction
(except under limited circumstances that are not
relevant here). It is also a fiction on the ground
as well, particularly where RF is concerned (see
any book on antenna design).


Am I correct to assume the best grounding point
would be the heaviest metal frame work closest
to the instrument panel such as the control yoke
or the adjustable rudder pedal track?

I doubt it, but read the service manual and contact
a competent engineer/technician. I would be
very reluctant to allow electricity to be conducted
through any part of the airframe.

On 12/20/2012 9:17 AM, Tom Gardner wrote:
wrote:
Thank you Dan for your article link

John DeRosa wrote:
Your question is less about "I have a problem and want to fix it."
versus, "I don't want any problems in the first place.

Exactly.

Do late model sailplanes actually have a "factory" grounding point?

Certainly not when they are in the air!

OK, that's a joke, but it does bring into sharp
relief that the "ground" concept is a fiction
(except under limited circumstances that are not
relevant here). It is also a fiction on the ground
as well, particularly where RF is concerned (see
any book on antenna design).

How do you think we should be discussing the issue?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Eric Greenwell wrote:
On 12/20/2012 9:17 AM, Tom Gardner wrote:
wrote:
Thank you Dan for your article link

John DeRosa wrote:
Your question is less about "I have a problem and want to fix it."
versus, "I don't want any problems in the first place.

Exactly.

Do late model sailplanes actually have a "factory" grounding point?

Certainly not when they are in the air!

OK, that's a joke, but it does bring into sharp
relief that the "ground" concept is a fiction
(except under limited circumstances that are not
relevant here). It is also a fiction on the ground
as well, particularly where RF is concerned (see
any book on antenna design).

How do you think we should be discussing the issue?

I don't really understand the question, but maybe
we shouldn't be discussing it here. Interference
arises due to many causes, is transmitted by many
means, and is received in different ways [1]. A specific
solution to one combination of source/route/destination
will not be effective for other combinations. I'm
sorry, but there aren't any generic solutions.

Probably the best general advice is to have good quality
equipment, cables and connectors, and to ensure the
connectors are properly tightened.

And even that won't prevent the "rusty bolt effect"


[1] as a single _simple_ example, given signals coupling
from one wire to another leading to interference, there
are two types of interference, near-end crosstalk and
far-end crosstalk. The causes are different and the
solutions are different.

RF introduces a whole slew of more subtle effects.
There are _many_ books on the topic, which is a good
indication that it isn't a simple problem with a simple
solution.

But of course one solution to one problem may well
be simple.