Replacing com antennas

On Wed, 10 May 2006 13:13:56 -0700, "Mike Noel"
wrote:

I can now partially answer my own question since I've received the antennas
from Spruce. The only thing in the box is the antenna and a base gasket.
I'll need to purchase new nuts and screws and evidently no 'conductive
grease' is needed.

It's probably just my ignorance, but the only conductive grease I've
ever encountered in electronics is the stuff you used to use between
the bottom of a power transistor in a TO3 can and the mica washer.
(Or was it between the washer and the heat sink?) It was thermally,
rather than electrically, conductive.

Don

Don ...

Both the graphite grease and the copper grease we use on spark plugs to make
them easier to remove are electrically conductive as well as thermally
conductive. HOWEVER, no such grease is needed (or wanted) on the COM
antenna(s).

On the other hand, I generally put a VERY thin film (almost a whisper) of
Dow Corning silicone grease (NOT SILICONE SEAL) on both sides of the rubber
gasket to keep rainwater out of the aircraft.

Jim



It's probably just my ignorance, but the only conductive grease I've
ever encountered in electronics is the stuff you used to use between
the bottom of a power transistor in a TO3 can and the mica washer.
(Or was it between the washer and the heat sink?) It was thermally,
rather than electrically, conductive.

Don

Evidently the antennas have a special coating over the fiberglass to allow
them to conduct away static charges that can build up. I think the charge
is allowed to pass to the airframe via the antenna base and the mounting
screws and then out the static wicks. If the static is allowed to build up
it is said to cause noise in the radio. I would imagine the idea of
conductive grease was to allow a more robust path for static drain to the
airframe.

The countersink surfaces on the antenna base for the mounting screws are
bare metal. I suppose this is intentional to allow static discharge. When
corrosion occurs at these small conductive surfaces perhaps the performance
of the antenna will be compromised when conditions are right for static
buildup. I understant that when an antenna ages and the conductive coating
on the outside of the fiberglass degrades, this can also cause static
problems. Supposedly these are the rational for replacing antennas when
installing new radios.

--
Best Regards,
Mike
http://photoshow.comcast.net/mikenoel
"Don Tuite" wrote in message
...
On Wed, 10 May 2006 13:13:56 -0700, "Mike Noel"
wrote:

I can now partially answer my own question since I've received the
antennas
from Spruce. The only thing in the box is the antenna and a base gasket.
I'll need to purchase new nuts and screws and evidently no 'conductive
grease' is needed.

It's probably just my ignorance, but the only conductive grease I've
ever encountered in electronics is the stuff you used to use between
the bottom of a power transistor in a TO3 can and the mica washer.
(Or was it between the washer and the heat sink?) It was thermally,
rather than electrically, conductive.

Don

Where do you get the "evidently"?

Jim


"Mike Noel" wrote in message
. ..

Evidently

What I was proposing is based on discussions or articles I've run across on
usenet, and some dealer sites like Avionics West. I mean them as points
for further discussion, not well know facts.

--
Best Regards,
Mike
http://photoshow.comcast.net/mikenoel
"RST Engineering" wrote in message
.. .
Where do you get the "evidently"?

Jim


"Mike Noel" wrote in message
. ..

Evidently