I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good and
the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna. Wonder
if the grease is the problem or maybe this antenna just picks up a lot of
background hiss.

Andy


"John Ferrell" wrote in message
...
On Sun, 20 Jul 2008 11:23:02 +0100, "Andy"
wrote:

I have finally got my Cushcraft MA5B up in the air. But I am very
disappointed with it.

Is it normal for this antenna to have a lot of background noise behind
strong signals 9+?

The reason I ask is that I also own a cobwebb antenna and the side by side
comparison between them, there is no background hiss on the same strong
signals on the cobwebb S4 - 9+ but there is on the same signal on the MA5B
and it is enough to make listening on the MA5B very unpleasant even at
S9+.

Is this normal?

73 Andy

I will place my bet on a bad connector. How hard is it to swap
feedlines?
John Ferrell W8CCW

On Jul 23, 3:34*am, "Andy" wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good and
the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna. Wonder
if the grease is the problem or maybe this antenna just picks up a lot of
background hiss.

Noise is RF the same as any other signal. The only exception would
be bad connections, etc that cause "locally generated" noise.
You need to find out if the source is received, or from a local
problem.
The SWR means little as far as receive. Any difference in level
due to SWR changes should be very small, and it would not effect
the s/n ratio if it did.
Does rotating the antenna vary the level of the noise? If so, the
noise is most likely received. You should be able to semi null
it out using the right direction if this was the case.
I doubt the element connections are the problem, or you would
see sudden spikes in the SWR when the connections flaked out.
What band is this on?
At this point just not enough info to tell what the deal is.
I could tell a lot more if I heard it. Can you record a sample
and post it somewhere?
Like I say, there should be little if any real difference in s/n
ratio if both antennas are pointed in the same direction.
Even if one had more gain in that direction, or was more
efficient overall, this would not effect the s/n ratio.
Noise and desired signals should increase in a linear
fashion.
IE: If antenna A receives the base noise level at S5, and the
desired signal is S8, and then you switch to antenna B
and the base noise is S7, and the desired signals are S9+,
they should still "sound" the same through the speaker.
The noise shouldn't seem any louder on antenna B, as
the desired signals and noise increase at an equal level.
This is why I say overall, it doesn't make much sense.
The reason I asked about the noise blanker is they
really degrade the dynamic range when strong signals
are present, and many overlook this while trying everything
else in the book. But.. A NB usually causes more of a
distorted audio sound, not static.
Do you get this same static when the band is "dead"?
That would tend to point to a pretty close noise source.
Either locally generated by bad connections, etc, or a
noise source nearby that is received normally.
But like I say, if you receive the noise, you should be
able to effect the level by turning the antenna.

Andy wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good and
the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna. Wonder
if the grease is the problem or maybe this antenna just picks up a lot of
background hiss.

Andy

The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have
a low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their
HF6V, but puts an air core choke (from memory, 15-20 turns, 14 awg,
approx 1" dia x 2.5" long) across the feedpoint. That may just be for
noise because the antenna seems to have the same performance with, or
without it. Perhaps you could try the same with the MA5V.

I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get
quieter when you thread the barrel on. If it doesn't do that, then
there may be a connectivity problem somewhere.

ac6xg

The noise stays the same when I turn the beam.

I will try to get a recording done this weekend if I can.

I just pulled out the PL259, so just the canter pin on the PL259 on the
canter fed dipole was connected
and the noise increased with the signal and then dropped when the PL259 was
screwed back in. I had the same on the Cobwebb.

When I did this on the MA5B the 10, 12, 15 and 17 meter bands did the same ,
on 20 meters it was different. When I pulled out the PL259 so just the
canter pin of the PL259 was connected the noise dropped and with the PL259
screwed in
fully the noise went up. The opposite to what I thought would happen after
trying this out on my other antennas.

Andy


"Jim Kelley" wrote in message
...
Andy wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good
and the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna.
Wonder if the grease is the problem or maybe this antenna just picks up a
lot of background hiss.

Andy

The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have a
low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their HF6V,
but puts an air core choke (from memory, 15-20 turns, 14 awg, approx 1"
dia x 2.5" long) across the feedpoint. That may just be for noise because
the antenna seems to have the same performance with, or without it.
Perhaps you could try the same with the MA5V.

I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get quieter
when you thread the barrel on. If it doesn't do that, then there may be a
connectivity problem somewhere.

ac6xg

I also forgot to mention that the noise is on all bands from 10 - 20m, only
on the MA5B.


"Andy" wrote in message
...
The noise stays the same when I turn the beam.

I will try to get a recording done this weekend if I can.

I just pulled out the PL259, so just the canter pin on the PL259 on the
canter fed dipole was connected
and the noise increased with the signal and then dropped when the PL259
was
screwed back in. I had the same on the Cobwebb.

When I did this on the MA5B the 10, 12, 15 and 17 meter bands did the same
,
on 20 meters it was different. When I pulled out the PL259 so just the
canter pin of the PL259 was connected the noise dropped and with the PL259
screwed in
fully the noise went up. The opposite to what I thought would happen after
trying this out on my other antennas.

Andy


"Jim Kelley" wrote in message
...
Andy wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good
and the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna.
Wonder if the grease is the problem or maybe this antenna just picks up
a
lot of background hiss.

Andy

The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have a
low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their HF6V,
but puts an air core choke (from memory, 15-20 turns, 14 awg, approx 1"
dia x 2.5" long) across the feedpoint. That may just be for noise
because
the antenna seems to have the same performance with, or without it.
Perhaps you could try the same with the MA5V.

I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get
quieter
when you thread the barrel on. If it doesn't do that, then there may be
a
connectivity problem somewhere.

ac6xg

I have managed to make an mp3 up. The first 10 seconds is on the Cobwebb
followed by another 10 seconds on the MA5B beam pointed in there direction
and then back and forth every 10 seconds. The click is the antenna switch
clicking over.

It can be found here. http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b4.mp3

If anyone needs to here a clearer one let me know, but it will be best after
the contest has finished.

Andy


"Andy" wrote in message
...
I also forgot to mention that the noise is on all bands from 10 - 20m, only
on the MA5B.


"Andy" wrote in message
...
The noise stays the same when I turn the beam.

I will try to get a recording done this weekend if I can.

I just pulled out the PL259, so just the canter pin on the PL259 on the
canter fed dipole was connected
and the noise increased with the signal and then dropped when the PL259
was
screwed back in. I had the same on the Cobwebb.

When I did this on the MA5B the 10, 12, 15 and 17 meter bands did the
same ,
on 20 meters it was different. When I pulled out the PL259 so just the
canter pin of the PL259 was connected the noise dropped and with the
PL259 screwed in
fully the noise went up. The opposite to what I thought would happen
after
trying this out on my other antennas.

Andy


"Jim Kelley" wrote in message
...
Andy wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good
and the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna.
Wonder if the grease is the problem or maybe this antenna just picks up
a
lot of background hiss.

Andy

The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have
a
low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their
HF6V,
but puts an air core choke (from memory, 15-20 turns, 14 awg, approx 1"
dia x 2.5" long) across the feedpoint. That may just be for noise
because
the antenna seems to have the same performance with, or without it.
Perhaps you could try the same with the MA5V.

I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get
quieter
when you thread the barrel on. If it doesn't do that, then there may be
a
connectivity problem somewhere.

ac6xg

Andy wrote:
I have managed to make an mp3 up. The first 10 seconds is on the Cobwebb
followed by another 10 seconds on the MA5B beam pointed in there direction
and then back and forth every 10 seconds. The click is the antenna switch
clicking over.

It can be found here. http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b4.mp3

If anyone needs to here a clearer one let me know, but it will be best after
the contest has finished.

Andy

This sounds to me as if the MA5B has a very high angle lobe which the
Cobwebb may not. More galactic noise in proportion to the wanted signal?

John

"John Livingston" wrote in message
...
Andy wrote:
I have managed to make an mp3 up. The first 10 seconds is on the Cobwebb
followed by another 10 seconds on the MA5B beam pointed in there
direction and then back and forth every 10 seconds. The click is the
antenna switch clicking over.

It can be found here.
http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b4.mp3

If anyone needs to here a clearer one let me know, but it will be best
after the contest has finished.

Andy

This sounds to me as if the MA5B has a very high angle lobe which the
Cobwebb may not. More galactic noise in proportion to the wanted signal?

John



Do you think the 2m/70cm collinear above the beam could cause this?

Andy

"Andy" wrote in message
...
I have managed to make an mp3 up. The first 10 seconds is on the Cobwebb
followed by another 10 seconds on the MA5B beam pointed in there direction
and then back and forth every 10 seconds. The click is the antenna switch
clicking over.

It can be found here. http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b4.mp3

If anyone needs to here a clearer one let me know, but it will be best
after the contest has finished.

Andy


"Andy" wrote in message
...
I also forgot to mention that the noise is on all bands from 10 - 20m,
only on the MA5B.


"Andy" wrote in message
...
The noise stays the same when I turn the beam.

I will try to get a recording done this weekend if I can.

I just pulled out the PL259, so just the canter pin on the PL259 on the
canter fed dipole was connected
and the noise increased with the signal and then dropped when the PL259
was
screwed back in. I had the same on the Cobwebb.

When I did this on the MA5B the 10, 12, 15 and 17 meter bands did the
same ,
on 20 meters it was different. When I pulled out the PL259 so just the
canter pin of the PL259 was connected the noise dropped and with the
PL259 screwed in
fully the noise went up. The opposite to what I thought would happen
after
trying this out on my other antennas.

Andy


"Jim Kelley" wrote in message
...
Andy wrote:
I've swapped the feed line over and its still the same.

When I put the antenna together I made sure all connections where good
and the analyser gave a good match on the frequencies I want to use.

I did use some conductive grease for the first time on the antenna.
Wonder if the grease is the problem or maybe this antenna just picks
up a
lot of background hiss.

Andy

The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have
a
low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their
HF6V,
but puts an air core choke (from memory, 15-20 turns, 14 awg, approx 1"
dia x 2.5" long) across the feedpoint. That may just be for noise
because
the antenna seems to have the same performance with, or without it.
Perhaps you could try the same with the MA5V.

I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get
quieter
when you thread the barrel on. If it doesn't do that, then there may
be a
connectivity problem somewhere.

ac6xg














I forgot to mention before that the Cobwebb is 3 meters lower than the MA5B
beam.
Here are some more recordings, as before 10 seconds from the Cobwebb
followed by 10 seconds from the beam followed by the Cobwebb and then by the
beam again and so on till the end of the recording. All recordings will be
like this to save me explaining over each time. The beam is pointed in there
direction. The noise and signal increases every time when switching to the
beam.

http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b5.mp3

http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b6.mp3

On Jul 27, 8:40*am, "Andy" wrote:
The beam is pointed in there
direction. The noise and signal increases every time when switching to the
beam.

http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b5.mp3

http://www.hobby.pwp.blueyonder.co.uk/ma5b/ma5b6.mp3

I think your antenna system itself is probably normal for the
most part. I do hear some "whine" though on a couple of
them. Not sure what that is, could be puter/monitor related..
How is yours mounted? Flat horizontal? I had to look up a picture
to see what they are, and the one in the picture seemed to be
tilted. ? Maybe that was just to show up better in the picture..
As far as the static in the last one , it sounded like power line
noise for the most part. Either the antenna has a strong lobe
towards that noise source, or you have some noise around you
that is being piped up the shield. But almost sounded more
like it was received by the antenna to me. You should be
able to vary the level of the static, and maybe even find a
null of sorts if you turn the antenna. If not, I would look at a
possible ingress problem, and the noise coming from your
shack or house.
I checked the feed, and they seem to use a matching device,
feeding two elements. I assume they are probably feeding 10m
with a separate DE, or something along those lines.
I doubt this matching device deals with decoupling the feedline.
So the first thing I would do is make a choke out of coax.
You can use the feedline you have now, and just roll a
choke at the antenna end. 8 turns using a 6 inch diameter
coil. You can use tie wraps, tape, etc to secure the windings.
That should take care of most any ingress/common mode
problems, if you have any. At the least, should put a pretty
good dent anyway. If the noise is still strong with the choke,
it's probably normally received line noise, fence, etc in the
area. And other than turning the antenna, not much you
can do about that.
That you seem to have a normal match on all bands seems
to indicate to me that your elements, matching device, and
coax are all probably ok.
I strongly recommend adding the choke though, just to nip
the possibilities of noise ingress in the bud. Just one less
thing to worry about, and just that much less RF you will
have on your coax when transmitting.