Antenna install

My Terra radio installation instruction says "Porper attachment of any
antenna to the aircraft surface is of primary importance. Carefull
clean all paint and corrosion off the mounting surface and apply an
anti-corrosion treatment."

Question 1, does "clean all paint" mean strip all paint to bare
aluminum?

Question 2, what type of "anti-corrosion treatment" should I use?

Thanks in advance,

Robin Hou

In article
,
" wrote:

My Terra radio installation instruction says "Porper attachment of any
antenna to the aircraft surface is of primary importance. Carefull
clean all paint and corrosion off the mounting surface and apply an
anti-corrosion treatment."

Question 1, does "clean all paint" mean strip all paint to bare
aluminum?

Question 2, what type of "anti-corrosion treatment" should I use?

Thanks in advance,

Robin Hou

The antenna MUST have a good electrical contact with the aluminum, in
order to have a ground plane. You might get by if you strip the aluminum
at the bolt holes on the inside of the aircraft, as the ground gets
contact through those bolts.

Alodine is a good anticorrosion treatment. Be sure to make provision to
keep any water away from the antenna/airframe contact.

--
Remove _'s from email address to talk to me.

Remove paint which includes primer to the bare metal...
Wipe the metal with an aluminum prep..
Then install the antenna...

Now, some details where the devil lives of how "I" do it...
You can put a tape dam outlining the area of the base of the
antenna... Make the area of the dam just slightly smaller than the
base of the antenna so there is a thin rim of paint projecting under
the base - 1/4" will work... Thin line striping tape from the auto
body store works like gangbusters... Then tape a plastic bib around
that to protect the sorrounding paint... Then remove paint and primer
inside the dam with a paint stripper... Do not sand or abrade the
exposed metal because you will scratch through the cladding (the thin
outer surface of pure aluminum that protects the aluminum alloy from
oxygen and water)... Then put a thin smear of NOALOX on the exposed
metal and install your antenna... It also will not hurt to put a thin
layer of non hardening gasket on the paint rim to seal against water
intrusion - Permatex FORM-A-GASKET #2 has always worked for me... Work
carefully and be neat... Once the antenna is installed than use a rag
with a bit of mineral spirits to clean up the Permatex that squeezes
out...

Now on the inside of the skin where the clamp plate squeezes the
metal, also take that area back to bare metal... No need to leave a
rim of primer here (dry interior)... Just a dab of NOALOX and you are
good to go...

denny

Except for the fact that the antenna ships with a thin rubber gasket to keep
water out of the airframe (and insulates the antenna from the airframe
mechaincally).

The antenna "grounds" to the airframe mechanically through the three bolts
holding it to the airframe. Make sure that they are cutting through to the
metal of the antenna base/airframe. Electrically, the antenna is connecting
to the airframe through the capacitor formed by the base of the antenna to
the airframe with the rubber gasket as the dielectric.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle


"Denny" wrote in message
...
Remove paint which includes primer to the bare metal...
Wipe the metal with an aluminum prep..
Then install the antenna...

Now, some details where the devil lives of how "I" do it...
You can put a tape dam outlining the area of the base of the
antenna... Make the area of the dam just slightly smaller than the
base of the antenna so there is a thin rim of paint projecting under
the base - 1/4" will work... Thin line striping tape from the auto
body store works like gangbusters... Then tape a plastic bib around
that to protect the sorrounding paint... Then remove paint and primer
inside the dam with a paint stripper... Do not sand or abrade the
exposed metal because you will scratch through the cladding (the thin
outer surface of pure aluminum that protects the aluminum alloy from
oxygen and water)... Then put a thin smear of NOALOX on the exposed
metal and install your antenna... It also will not hurt to put a thin
layer of non hardening gasket on the paint rim to seal against water
intrusion - Permatex FORM-A-GASKET #2 has always worked for me... Work
carefully and be neat... Once the antenna is installed than use a rag
with a bit of mineral spirits to clean up the Permatex that squeezes
out...

Now on the inside of the skin where the clamp plate squeezes the
metal, also take that area back to bare metal... No need to leave a
rim of primer here (dry interior)... Just a dab of NOALOX and you are
good to go...

denny

RST Engineering wrote:
Except for the fact that the antenna ships with a thin rubber gasket to keep
water out of the airframe (and insulates the antenna from the airframe
mechaincally).

The antenna "grounds" to the airframe mechanically through the three bolts
holding it to the airframe. Make sure that they are cutting through to the
metal of the antenna base/airframe. Electrically, the antenna is connecting
to the airframe through the capacitor formed by the base of the antenna to
the airframe with the rubber gasket as the dielectric.

Jim

Effectively, the capacitor Jim mentions is shorted by the three/four
mounting bolts, so the mounting bolts must make a good electrical
contact with the aluminum skin on the inside of the aircraft. I like the
NoAlOx, too.

Dont forget a doubler plate. Mounting the antenna directly only to the
aircraft skin is a no-no.

On the off chance you are using just a stainless whip mounted on the
porcelin feed-thru bushing, then the coax cable shield needs to be
grounded to the aircraft skin within an inch or two from the antenna
base, and the coax center conductor connects to the whip.

Would that it were true, Mike. That nice tough epoxy paint on the antenna
and the nice smooth side of the head of a flathead screw rarely cuts through
to the metal of the antenna base. If you don't know the trick of grinding
down the paint inside the screw well to bare antenna base metal, those
screws aren't going to short anything out.

Jim



Effectively, the capacitor Jim mentions is shorted by the three/four
mounting bolts, so the mounting bolts must make a good electrical contact
with the aluminum skin on the inside of the aircraft. I like the NoAlOx,
too.