MA5B background noise
Andy
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
lt...@yahoo.com
This is pure speculation so take it that way. I've noticed that
any antenna with 'sharp points' associated with it has typically been
noisier than antennas without those sharp points (capacity hats in
this case). That's certainly not 'definitive' in any way, so...
speculation. Also, considering where those cap-hats are mounted,
using a very smooth huge ball instead of those 'sharp-points' is sort
of dumb. So they did the best they could, right?
- 'Doc
(Completely beside the point. Once used a very large metal ball as a
capacitive hat on a mobile antenna. Worked fine sitting still. Not
very broad banded, but certainly shorter than the usual whip.
Absolute catastrophe when trying to drive! Didn't last long at all.)
Cecil Moore
> This is pure speculation so take it that way. I've noticed that
> any antenna with 'sharp points' associated with it has typically been
Not speculative at all. Corona loves sharp points.
--
73, Cecil http://www.w5dxp.com
nm...@wt.net
Dunno. Doesn't really make sense.. As far as receive, there should be
little difference between the two as far as s/n ratio.
I'm not sure if I'm buying that it's corona buildup. That would
depend on your climate, wx, etc..
Being as you seem to notice it most on the strongest signals,
I'd have to ask one thing first.
Is your noise blanker on?
Andy
Andy
<nm...@wt.net> wrote in message
news:9385e9e6-75b5-423e...@z16g2000prn.googlegroups.com...
John Ferrell
wrote:
I will place my bet on a bad connector. How hard is it to swap
feedlines?
John Ferrell W8CCW
Andy
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" <johnf...@sprintmail.com> wrote in message
news:71q984le446f80c9d...@4ax.com...
nm...@wt.net
> 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.
Jim Kelley
> 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
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" <jwke...@uci.edu> wrote in message
news:g68jag$npp$1...@news.service.uci.edu...
Andy
on the MA5B.
"Andy" <dx...@blueyounder.co.uk> wrote in message
news:7Dlik.177$zA7...@newsfe28.ams2...
Jim Kelley
> 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
> center 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
Sorry, but my previous comments pertained to the MA5V (vertical).
Having just assembled a TH-3, I can only suggest that perhaps you have
an open trap or two. Did you check the electrical continuity along each
of the elements after assembling them? What is the SWR on 20?
ac6xg
Andy
No I didn't do a continuity test. I did put an analyser on the beam and the
SWR on all bands at the moment are,
14.225 at 1.06:
18.130 at 1.45:1
21.300 at 1.34:1
24.960 at 1.5:1
28.850 at 1.5:1
How do I check for an open trap?
Andy
lt...@yahoo.com
Andy,
Just from those readings, I'd have to say the antenna seems to be
operating normally/correctly. Shaking things while doing that
continuity test is usually a fairly good idea, intermittents, although
shaking the antenna isn't going to be very easy, sort of.
Not making both connections at the antenna terminal, only the
center pin, and changing the antenna's characteristics is normal.
Sort of going from a "tuned"/resonant antenna to a random length wire
kind of thing. (Receivers just aren't as 'picky' as transmitters,
have different requirements. Not a very good way of putting it, but
you get the idea?)
Don't give up, I'm interested in what happens.
- 'Doc
Andy
<lt...@yahoo.com> wrote in message
news:955601df-b7aa-491f...@r66g2000hsg.googlegroups.com...
I have used some conductive grease for the first time on the beam. I've
never used grease before, do you think this might be the problem?
The other thing is, that the beam is at apex roof height and mounted on the
back of the house. I have no where else to try it out to see if this is a
problem.
The centre fed dipole has the element that connects to the centre pin of the
PL259 at house end and I don't suffer any noise hiss on that like I do on
the beam and the Cobwebb is at the bottom of the garden away from the house
and that has a very quite receive on it.
Andy
Richard Clark
wrote:
>I have used some conductive grease for the first time on the beam. I've
>never used grease before, do you think this might be the problem?
Hi Andy,
It is not the problem.
>The other thing is, that the beam is at apex roof height and mounted on the
>back of the house. I have no where else to try it out to see if this is a
>problem.
You are closer to noise in the home.
>The centre fed dipole has the element that connects to the centre pin of the
>PL259 at house end and I don't suffer any noise hiss on that like I do on
>the beam
However close one arm of the dipole is to the house, I will bet the
feedline is far, far away from the noise source.
>and the Cobwebb is at the bottom of the garden away from the house
>and that has a very quite receive on it.
Even further away from the noise source.
So far, no one has asked, and you haven't offered a comprehensive
meaning to this noise.... hiss is not remarkably unique at HF. For
comprehensive you do not state what frequencies it inhabits. OK, its
on the five bands, but is it everywhere else? Is it equally
strengthed?
A portable radio is a must for noise troubleshooting. If the S-9
noise covers 5 bands, this freestanding radio should hear it all. The
noise seems to be uniquely near the house, but can you wander the
neighborhood with a transistor radio and hear it other places? Can
you bring a transistor radio near the point the antenna is mounted and
hear the noise? If you hear it there, do you hear it in the garden?
On the other hand, if you cannot hear noise on a portable; then it is
not over-the-air, it is conducted noise. Severely corroded joints
could do that, but you already state this is a new(?), greased (that
is what the grease is for) joint antenna. Is the feedpoint choked?
(This is common advice.) Does the feedline pass near noise sources?
(Use your portable along the length of the line.)
How do you ground your shack? Some folks think that ground wires
everywhere does the job - often that is the problem. Could that hiss
be a hum? Poor antenna connections would be more like a sizzle.
Descriptive terms are not often reliable symptom indicators.
You have a ground loop with your new installation.
73's
Richard Clark, KB7QHC
Andy
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" <dx...@blueyounder.co.uk> wrote in message
news:Oynik.16244$9I1....@newsfe16.ams2...
John Livingston
> 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
Andy
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
Andy
"John Livingston" <nu...@nospam.com> wrote in message
news:Gt6dnQV_6umP6RHV...@bt.com...
Do you think the 2m/70cm collinear above the beam could cause this?
Andy
John Livingston
Quite possible. The influence of all large metallic objects in the near
field of the antenna will have a marked effect on the polar diagram. Try
removing the collinear to see what happens.
John
nm...@wt.net
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.
Jim Kelley
> 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
Judging by the signal to noise ratio, it sounds like the beam is a
better antenna than the cobweb when it's pointed at the transmitting
station. You might be able to tell that more readily if you turned off
the AGC. You can even watch the AGC changing on the Windows Media
Player spectrum scope when you switch antennas.
Quieter antennas are usually quieter both ways.
ac6xg
Andy
beam is put together correct and all seems to be ok.
Interesting about is could be power line noise. There are some over heads
street power cables close by that supplies power to the houses. Strange how
its just the beam that is effected by this. I have had HF verticals up here
before with no problem.
I have just laid my hands on a Timewave ANC-4. Using its own small antenna
it can cut out 80% of the noise but also cuts down the received signal to
less than being received on the Cobwebb. But at least its a good start in
the right direction. There was no manual with it. Any ideas on how to get it
working better would be appreciated.
I will let you all know how I get on.
73 Andy
"Jim Kelley" <jwke...@uci.edu> wrote in message
news:g6lagp$l89$1...@news.service.uci.edu...
Cecil Moore
> Interesting about is could be power line noise.
At my last QTH, the culprit on 40m was a ~33 foot
ground wire running down my front yard power pole
from a transformer and capacitor. It caused my
vertical to have 2 S-units more noise than my
horizontal dipole.
John Smith
> Andy wrote:
>> Interesting about is could be power line noise.
>
> At my last QTH, the culprit on 40m was a ~33 foot
> ground wire running down my front yard power pole
> from a transformer and capacitor. It caused my
> vertical to have 2 S-units more noise than my
> horizontal dipole.
Cecil;
Don't quit there!
Did you ever manage to have it "fixed?"
How did you manage it? Who did you report it to?
Thanks in advance,
regards,
JS
Bruce in alaska
John Smith <assembl...@gmail.com> wrote:
Usually the your Electrical Utility, will have a supervisor in the
Distribution Department, that is responsible for dealing with
interference issues. Some utilities are more responsive than others.
When I lived down in the Flatlands, (Seattle, WA) Seattle City Light
had a guy that regularly meet with the local Interference Committee
which also included an FCC Engineer, the local ARRL Section Mgr, and
just about all the Marine and LMR Service Shops. He was also a Ham,
and used the information, developed by the committee, to track down
broken and failing insulators thru out their Distribution System.
The one outfit we could NEVER get to join the committee, was the
Cable TV Franshisee, and they generated MOST of the complaints.
Now I live out in the bush, and generate ALL my own power, so I am
the Utility, and I have to find and fix all the LF/MF/HF Noise if I want
to hear better. I usually have an MF/HF noise floor of less that 1.5
S-Units on my Kenwood TS690. I can hear, way farther than I can Talk,
due to the local Noise at the Receiving Station, masking out my
transmissions. It is frustrating to hear folks on 75 Meters with
S-7 Signals, but they can't hear me, due to S-9 noise at their end.
--
Bruce in alaska
add <path> after <fast> to reply
Cecil Moore
> Did you ever manage to have it "fixed?"
> How did you manage it? Who did you report it to?
The power pole ground wire didn't appear to be
broken, just radiating like crazy. I managed
it by transmitting on the vertical and receiving
on the dipole. In the process of A/B comparisons,
I discovered that the vertical was never better
than the dipole and usually worse. The EZNEC
comparisons are on my web page at:
http://www.w5dxp.com/dipvsver.htm
To be fair, since receiving was limited to East/
West QSOs, the Extended Zepp beat the socks off
the vertical.
lt...@yahoo.com
Sort of tilt it in the right direction... you know?
- 'Doc
(Yeah, I know I'm gonna regret that, but I couldn't resist.)
John Smith
On 40m, most run horiz. Horiz-to-horiz is always going to beat
horiz-to-vert.
Knowing you and your strong personality (at least from the news group) I
thought you might had been able to secure a fix from the power
companies' noise emissions. Was just wondering, and probably wouldn't
have helped with my problem anyway ...
Right now, I have an issue with a noise source I cannot even pinpoint
and is very broadband (and no, it is not BPL -- already ruled that out,
lol.) Noise is for blocks and remains fairly constant in strength.
This would lead me to think it was powerlines; however, the powerlines
are all underground! Which leads me to believe some noise IS on the
powerlines and the radiation is coming from the wiring in each
individual home/business. However, a scope, properly isolated and
hooked to my wiring doesn't give me a picture I can correlate to ... :-(
If it ain't one thing, it is another ... keeps life interesting, I guess.
Regards,
JS
Cecil Moore
> On 40m, most run horiz. Horiz-to-horiz is always going to beat
> horiz-to-vert.
That would certainly be true for ground-wave. But the
effect is minimized by polarization getting scrambled
through ionospheric reflection.
Cecil Moore
> Aw, come on Cecil. You just didn't have the vertical oriented right.
> Sort of tilt it in the right direction... you know?
You're right, I should have tilted it horizontal. :-)
John Smith
> John Smith wrote:
>> On 40m, most run horiz. Horiz-to-horiz is always going to beat
>> horiz-to-vert.
>
> That would certainly be true for ground-wave. But the
> effect is minimized by polarization getting scrambled
> through ionospheric reflection.
True, but isn't the horiz better suited for placing more signal in a
skywave which is, generally, more useful? i.e., a high vertical can put
a whopping skywave signal into Australia--but is better suited for
ground wave in USA--while a horiz does an acceptable ground wave and
skywave here in the USA, and the world, of course ... ? (and of course,
there are exceptions) Etc. It seems that way for me, anyway ...
verticals are my main choice from necessity ... however, thank God I
dumped that "big property" at the top of the market for this smaller
place! <grinning-ear-to-ear> I'd imagine, by the end of the year, or
middle of next, I can buy back the old place for 1/3 to 1/4 of what I
sold it for, IMHO we are just at the beginning of the "downhill run!"
<having-a-heart-attack-from-sheer-joy!>
Life is good ...
Regards,
JS
n2...@arrl.net
on the same ac line as some radio equipment, i switched the outlet and
the noise 90% disapeared, hope this helps,73 john
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
Andy
I will see if the next-door neighbours will unplug there's and see if that's
the problem.
I have had everything disconnected in here and the noise was still there.
73
Andy
<n2...@arrl.net> wrote in message
news:3c5661b0-9e0a-40da...@b2g2000prf.googlegroups.com...