"Owen Duffy" wrote in message
...
"David" wrote in
:


"Owen Duffy" wrote in message
...
"David" wrote in
:

...
The only place I didn't put any grease was on the elements were the
matching network connects to. I used clear silicon sealant for
those.

Was it a water based silcone sealant? I have observed high VSWR and
noise on an antenna feed that used such, until the stuff had
thoroughly dried / cured. It does not seem to be affected by rain
since the initial cure.

If it was not a neutral cure silicone, perhaps there is something
galvanic going on?

Owen

It was normal sealant silicone from a diy store.

What is "normal".

There are two kinds commonly available, neutral cure and acetic acid
cure. Some of the neutral cure ones are water based (ie water washup of
un-cured material).

If you use acetic acid cured silicone on metals, it corrodes them.
Silicone sealants intended for roofing will have a neutral cure.

Do you know what you used?

Owen

Thanks for the explanation. I didn't know that the did a neutral (water
based silicone).

The one that I have used is the acetic acid cured silicone.

"David" wrote in news:Wpitn.580013$DL1.346763
@newsfe25.ams2:

The one that I have used is the acetic acid cured silicone.

Then it is corrosive on aluminium. The galvanic currents created may be
causing or contributing to your noise problem.

I would be removing the stuff, difficult as it is to do, but if it is in
contact with metal, it is not suited to your application.

Owen

"Owen Duffy" wrote in message
...
"David" wrote in news:Wpitn.580013$DL1.346763
@newsfe25.ams2:

The one that I have used is the acetic acid cured silicone.

Then it is corrosive on aluminium. The galvanic currents created may be
causing or contributing to your noise problem.

I would be removing the stuff, difficult as it is to do, but if it is in
contact with metal, it is not suited to your application.

Owen

Ok Owen. I will remove it as soon as I get the time to bring it back down to
ground level.

Thanks

Hi all

I took down the antenna and I could not find any fault with it. I decided to
move the antenna down the bottom of my garden @ 20ft off the ground and hay
presto. Every thing is working 100%. All my hiss is gone. I can only think
that it must have been caused by some thing very near to my house.

Thanks all

I'm now a happy chappy.

73
"David" wrote in message
...

"Owen Duffy" wrote in message
...
"David" wrote in news:Wpitn.580013$DL1.346763
@newsfe25.ams2:

The one that I have used is the acetic acid cured silicone.

Then it is corrosive on aluminium. The galvanic currents created may be
causing or contributing to your noise problem.

I would be removing the stuff, difficult as it is to do, but if it is in
contact with metal, it is not suited to your application.

Owen

Ok Owen. I will remove it as soon as I get the time to bring it back down
to ground level.

Thanks

David Inscribed thus:

Hi all

I took down the antenna and I could not find any fault with it. I
decided to move the antenna down the bottom of my garden @ 20ft off
the ground and hay presto. Every thing is working 100%. All my hiss is
gone. I can only think that it must have been caused by some thing
very near to my house.

Thanks all

I'm now a happy chappy.

73
"David" wrote in message
...

"Owen Duffy" wrote in message
...
"David" wrote in
news:Wpitn.580013$DL1.346763 @newsfe25.ams2:

The one that I have used is the acetic acid cured silicone.

Then it is corrosive on aluminium. The galvanic currents created may
be causing or contributing to your noise problem.

I would be removing the stuff, difficult as it is to do, but if it
is in contact with metal, it is not suited to your application.

Owen

Ok Owen. I will remove it as soon as I get the time to bring it back
down to ground level.

Thanks

Its surprising how much noise and interference is generated by or in our
own home.

--
Best Regards:
Baron.