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Paul – good problem and the solution you used is good information to share with our members. The approach you used to isolate the source of the noise is a good one – especially when you consider that we will all experience this type of problem at sometime in our life.
Broadband noise sources can be caused by a wide range of sources both inside and outside a home. Poorly designed switching power supplies (i.e. low voltage DC wallwart supplies), arcing AC wiring switches and contacts, HV AC power line leakage or low level plasma discharge, and/or poor NETWORK wiring can all be a potential source for this type of problem.
Most of the noise sources we’ll encounter will usually be broadband due to the rich harmonic content associated with transient and/or non-sinusoidal signal (digital) sources. The use of an old AM portable radio tuned to an unused AM channel near the low end of the AM dial can often be helpful in locating the signal source. Note: As an aside, monitoring around 500 KHZ at the low end of the AM broadcast band is a good warning of approaching electrical storms.
Your addition of an old DSL filter to your cable network phone line was an effective solution and I would like to add that clamp on ferrite RFI filters might offer a good working solution as well. (It is usually helpful to have a couple of clamp on ferrites your shack and many major electronic part suppliers stock them).
I searched the web to learn more details about the internals of a typical DSL filter and stumbled across a couple of interesting articles. W8JI documents a slightly different problem where his 160M operation would crash his DSL network. The details of his problem and a low pass filter that he reportedly added (to prevent his RF leaking into his DSL network) offers another interesting RFI prospective. You might enjoy reading W8JI’s “My ADSL Modem Filter” for future reference.
Again, good information and thanks for sharing your experience with the forum readers.
contact me at [email protected] for analyzer.
Howdy~
First, Fred’s talk last night was quite good on HF portable and mobile rigs. There’s a lot of similarities to what I’m trying to do, and I found it very valuable. Thanks!
Tom, I’d love to take you up on the offer to borrow the meter.
I did run across one more article that I’ve re-read a few times now, and I think I’m convinced that 3 distinct sets of elevated radials might be in store for me. Elevation at a few feet off the ground can be accomplished with 4 wooden sticks and a tie-off of the radial. At 160M and 80M, they’ve found in the article (link provided at the bottom) that a length of LESS than 60 degrees of the WL or more than 120 degrees capped at 135 degrees is optimal, and four of them actually performed better than more ground based ones. My hypothesis is that this can be accomplished as well on the 10M, 20M and 40M bands using less wire, and within 14% efficiency of the many radials/counterpoise approach.
With this approach, on 10M and even 20M I should be able to get pretty close to the ’45 degree angles’ as the 1/8th radial lengths should be about 4 and 8 feet. With an antenna about 7 feet off the ground on a tripod, that would be pretty easy.
Add that to a Yeasu 100W transmitter, and I think I’m in business.
Thanks!
Jay
KU1DUhttps://www.nonstopsystems.com/radio/pdf-ant/article-ant-5IU-97.pdf
Jay,
I have an MFJ-259 you are welcome to borrow. I can vouch for the advice of the other replies. I have an MFJ screwdriver antenna that I have used portable with 8 radials off a DX Engineering radial plate. I cut mine for a little over 22″ and was hitting central Europe with my Kenwood TS-140s and 100 watts when I used it on the Cape. Sea water was a great help, I’m sure. I also have 20 radials installed in my yard for an LDG s9 31 foot collapsible antenna. 4 of the radials are the suggested 28’10” the others are around 22’8″. Used another DX engineering radial plate. I used the calculations for the shorter ones from one of the articles attached to an earlier reply. Had good results with the set up. As has been stated, it’s a matter of try this, then that until you get either frustrated or good results. For me this is the “fun” (i.e, satisfaction) in amateur radio.73
Tom
AB1NSFred – I actually came across that article in my research! The ‘relative’ question is how elevated is elevated? Meaning, if I hang three 1/4 wave counterpoises angled down from the antenna who’s as high up (6 or 7 feet for the bottom antenna connection) as I can get it on the stand I have and terminate them about a foot from the ground, which makes the downward angle around 30 degrees of slope gives me between 40 and 50 ohms of impedance which ‘should’ give me a decent swr.
But, and there’s always a but, if the impedance numbers are only true if the antenna is at least 1/4 wave above the earth, I still might be better off with the 4-8 ground radials at 33.5′.
The other school of thought though is do I extend the ‘whip’ on top of this 1/4 wave antenna by about 33.5 feet and call it a day… A 1/2 wave antenna technically shouldn’t need radials, and with the automated screwdriver adjustment of the atas120a, that should be easy to tune at 40M, 20M and potentially 10M as well. I do happen to have a pretty tall oak tree on that side of the house… Hmmmm. 2M and 70cm work perfectly already, so no big deal there.
Does the club ‘rent’ SWR meters for those, who like me, are still in the ‘tinkering’ process?
Thanks!
J
KU1DU
Well then, I should see you tonite! This is exactly what I’m trying to do! I’m hoping some good ol’ antenna theory might be part of the discussions!
Best to K1EL!
Thanks Fred! I’ll be replying to your email soon.
From the research I’ve been doing, length DOES matter here until I hit around 32-40 counterpoise wires, when longer than 1/4 wavelength seems to work better. Originally I had tried 8 counterpoises at 18 feet, and while I was able to hear even Barcelona Spain, when I dropped to 10M for the club Net, I had tuning issues again. I’m wondering if 2 tuned wires per band might be the right answer here – which I hope to figure out later.
Is there anyone else using this antenna out there – NOT mounted on a vehicle?
Thanks!
Jay
KU1DU
Hi Jamey,
I went out to hunt with my son Joe today KC1FZF.
We found a Ham Radio Club President.
Little fox stopped working… (Sadly, as we got close it)
Joe & I went on to find the Big Fox.
Joe enjoyed the Candy!
Merry Christmas Everyone!
Thank you Jamey.
Ari WB1ABC