"David" wrote in
:


The noise level does not change when I turn the beam 360 deg.

You did give S meter readings, but with respect, they are meaningless in
the context you have given. Radios are not iniversally well calibrated,
and most hams could not tell us what radio setting (eg PREAMP ON/OFF) put
the radio in the calibrated mode.

Remember that a directive antenna does not reduce noise that is non-
directional, for all that it reduces noise picked up off the main lobe,
it increases noise picked up on the main lobe.

Ok, we hear that the noise is not strongly directional. You didn't care
to share how you worked that out. If you had an extremely high noise
level, it would quite likely be local, that is the way of things. It it
appears to not be directional, it is probably very close (ie under the
antenna). It could be in your own home, it could be some kind of fault
with the installation.

If it is within your own home, resolution is somewhat simplified. To
clear away your own home as a source, turn EVERYTHING off and run a
receiver on battery. No prizes for missing something, turn things off at
the main switchboard.

Does the noise vary by hour, day? Is it the same level when all the TVs
and Inverter Air Conditioners should be off.

If the noise is excessive, and it is real local, you have the choice of
dealing with the source, and/or reducing your pickup (eg minimising the
effects of feedline common mode current... good coax, effective
connectors, an effecive balun, system grounding).

Owen

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


The noise level does not change when I turn the beam 360 deg.

You did give S meter readings, but with respect, they are meaningless in
the context you have given. Radios are not iniversally well calibrated,
and most hams could not tell us what radio setting (eg PREAMP ON/OFF) put
the radio in the calibrated mode.

Remember that a directive antenna does not reduce noise that is non-
directional, for all that it reduces noise picked up off the main lobe,
it increases noise picked up on the main lobe.

Ok, we hear that the noise is not strongly directional. You didn't care
to share how you worked that out. If you had an extremely high noise
level, it would quite likely be local, that is the way of things. It it
appears to not be directional, it is probably very close (ie under the
antenna). It could be in your own home, it could be some kind of fault
with the installation.

If it is within your own home, resolution is somewhat simplified. To
clear away your own home as a source, turn EVERYTHING off and run a
receiver on battery. No prizes for missing something, turn things off at
the main switchboard.

Does the noise vary by hour, day? Is it the same level when all the TVs
and Inverter Air Conditioners should be off.

If the noise is excessive, and it is real local, you have the choice of
dealing with the source, and/or reducing your pickup (eg minimising the
effects of feedline common mode current... good coax, effective
connectors, an effecive balun, system grounding).

Owen


If I can here a weak station on any of my other antennas that is fully
readable but weak and I then switch over to the beam the station gets lost
in the noise.
On stations that are a bit stronger but under a S9 after switching to the
beam then there is a noticeable amount of noise in with there audio. Of
course the beam brings the whole signal in a lot stronger as it should do
with but with this large increase of hiss/background noise that is some how
mixed in with there audio that wasn't there before.

I do not get the same noise on any of my other antennas even when they are
positioned in the same spot as the beam and connected to the same coax line.
I have tried the Cushcraft R4 and the R5 the Cobwebb and several mobile
whips and I do not pick the same noise up..

I have had the MA5B down and I cannot see any thing wrong with the
installation.

I have ordered some Ferrite and I will make a coke balun up and see if it
improves.

I will let you know what happens.

"David" wrote in
:

David,

If your tests are not exposed to temporal effects (eg comparing the R4 last
year with the MA5B now), then the reduction in S/N with the MA5B on
boresight is telling. Something is wrong somewhere. (A prophetic statement
I know!)

Some of the earlier suggestions remain relevant. Does the noise in a
battery powered receiver reduce significantly when you turn the power off
to everything in your own premises?

Owen

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

David,

If your tests are not exposed to temporal effects (eg comparing the R4
last
year with the MA5B now), then the reduction in S/N with the MA5B on
boresight is telling. Something is wrong somewhere. (A prophetic statement
I know!)

Some of the earlier suggestions remain relevant. Does the noise in a
battery powered receiver reduce significantly when you turn the power off
to everything in your own premises?

Owen


Sorry Owen. I forgot to put this in.
I have turned all power off to the house and ran it from a battery. There
wasn't a lot of difference.

Maybe its coming from a neighbours house close by or the overhead power
lines on poles that feed all the homes along this road. I noticed today
there are also some that feed power to the homes over the back as well. But
that doesn't explain the fact that I do not get the same noise from any
other antenna. All antenna tests were all done in the last couple of days.

If the choke doesn't work then I will bring the antenna back down and take
it apart and start a fresh rebuild.
The only thing I can think of that is different is that I used some special
grease from Vine Antennas on all the joints that was advertised for antenna
joints.

David

"David" wrote in
:


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

David,

If your tests are not exposed to temporal effects (eg comparing the
R4 last
year with the MA5B now), then the reduction in S/N with the MA5B on
boresight is telling. Something is wrong somewhere. (A prophetic
statement I know!)

Some of the earlier suggestions remain relevant. Does the noise in a
battery powered receiver reduce significantly when you turn the power
off to everything in your own premises?

Owen


....
The only thing I can think of that is different is that I used some
special grease from Vine Antennas on all the joints that was
advertised for antenna joints.

These compounds are often a waterproof grease of some kind with granular
metal particles, often zinc. The concept is that the grease excludes
oxygen and water from the joint and so reduces corrosion, and the
irregular zinc particles improve conductivity by 'punching through' the
oxide layer on the aluminium.

It is conceivable that the stuff you have used may create some kind of
galvanic action which could produce some noise. The goop that I have used
has always worked without apparent problems, but it will depend on the
recipe, and different recipes exist for compatibility with different
metals.

BTW, it is my experience that marine grease does just as good a job on
clean aluminium without being nearly as messy. I use a small stainless
wire brush in a dremel tool to clean the inside of mating tubes, a
regular stainless scratch brush to do the outside, and a little marine
grease on the mating surfaces. Don't be overzealous with the wire
brushing as you embed steel in the aluminium. People often propose non-
metallic scourers, but they also embend non conductive material in the
aluminium surface.

Have you looked for other current loops that could generate noise, AC and
DC. DC loops can be 'powered' by galvanic action from things such as
mixed earth electrodes (eg copper or copper clad electrodes bonded to
galvanised iron water pipes or masts).

Owen

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


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

David,

If your tests are not exposed to temporal effects (eg comparing the
R4 last
year with the MA5B now), then the reduction in S/N with the MA5B on
boresight is telling. Something is wrong somewhere. (A prophetic
statement I know!)

Some of the earlier suggestions remain relevant. Does the noise in a
battery powered receiver reduce significantly when you turn the power
off to everything in your own premises?

Owen


...
The only thing I can think of that is different is that I used some
special grease from Vine Antennas on all the joints that was
advertised for antenna joints.

These compounds are often a waterproof grease of some kind with granular
metal particles, often zinc. The concept is that the grease excludes
oxygen and water from the joint and so reduces corrosion, and the
irregular zinc particles improve conductivity by 'punching through' the
oxide layer on the aluminium.

It is conceivable that the stuff you have used may create some kind of
galvanic action which could produce some noise. The goop that I have used
has always worked without apparent problems, but it will depend on the
recipe, and different recipes exist for compatibility with different
metals.

BTW, it is my experience that marine grease does just as good a job on
clean aluminium without being nearly as messy. I use a small stainless
wire brush in a dremel tool to clean the inside of mating tubes, a
regular stainless scratch brush to do the outside, and a little marine
grease on the mating surfaces. Don't be overzealous with the wire
brushing as you embed steel in the aluminium. People often propose non-
metallic scourers, but they also embend non conductive material in the
aluminium surface.

Have you looked for other current loops that could generate noise, AC and
DC. DC loops can be 'powered' by galvanic action from things such as
mixed earth electrodes (eg copper or copper clad electrodes bonded to
galvanised iron water pipes or masts).

Owen

I still haven't found enough time to be able to bring the MA5B back down to
ground for a good look and put a good choke balun in line to see if the
noise improves.

I do know that when I purchased the grease it did say its a conductive
grease for aluminium. It didn't come with any instructions so I applied the
grease as thick as I could to prevent any corrosion. It looks like using to
much grease might be all or some of my problem. 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.

As soon as I can find enough time I will post back with my findings.

Thanks

On Tue, 30 Mar 2010 09:10:59 +0100, "David"
wrote:

I applied the
grease as thick as I could to prevent any corrosion.

Hi David,

Protection is not often a product of liberal application.

It looks like using to
much grease might be all or some of my problem.

Hard to imagine. If you are clamping things together, the notion of
"too much" takes care of itself. i.e. You cannot have "too much"
toothpaste in the tube if you squeeze hard.

If, as you say, this is "conductive" grease, then clamping down hard
also brings electrical continuity and there is no issue of having "too
much" grease.

So, what this basically devolves to is: "did you apply enough
clamping?"

The only place I didn't put
any grease was on the elements were the matching network connects to.

Why?

I used
clear silicon sealant for those.

This has an acid base (depending upon the formulation being one of the
common, garden variety sealers) that sometimes brings problems of
corrosion. Again, this depends on the formulation.

However, the noise you describe is not one ascribed to grease in any
form, nor to sealants whatever their propensity is for corrosion.

73's
Richard Clark, KB7QHC

"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