MA5B background noise
Andy wrote:
"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 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 |
MA5B background noise
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. |
MA5B background noise
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 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 |
MA5B background noise
I have taken down the beam and did a continuity test and re-checked that the
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" 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 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 |
MA5B background noise
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. -- 73, Cecil http://www.w5dxp.com |
MA5B background noise
Cecil Moore wrote:
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 |
MA5B background noise
In article ,
John Smith wrote: Cecil Moore wrote: 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 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 |
MA5B background noise
John Smith wrote:
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. -- 73, Cecil http://www.w5dxp.com |
MA5B background noise
Aw, come on Cecil. You just didn't have the vertical oriented right.
Sort of tilt it in the right direction... you know? - 'Doc (Yeah, I know I'm gonna regret that, but I couldn't resist.) |
MA5B background noise
Cecil Moore wrote:
John Smith wrote: 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. 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 |
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