Hi there! I'm new to Reddit, so please excuse me if I'm stepping on any toes. I joined only because of this very active and insightful community.
TL;DR: My club's station has had some 10m success by day, but has also seen punishing broadband S7-S9 noise floors. We can't move our QTH, and our QTH is the office of a tech company in San Francisco, which means we need to find ways to modify our equipment to help with the noise floor.
Due to a series of fortunate events, I am now a newly-minted Extra, and I'm also the president of a small club founded in my workplace...and my employer was kind enough to gift our club a Kenwood TS-590 transceiver to get started. I am still working out all the red tape with building management to install our first HF antenna on the roof of our office; until then, I bought a Buddipole which we can set up and take down as need be. Our office has a large concrete deck on the 4th story of the building which connects to one of our commons areas. When we want to operate HF, we set up the Buddipole on the deck (east-west, perpendicular to the line of the building so as to not radiate back into it), run the coax back into the building through a door, and set up the transceiver and its power supply on a table in the commons.
This worked great the first time we did an operating event. 10m sounded quite nice, we got some great QSOs and had our turns in pile-ups on special events stations. As the sun set, 10m closed out and we tried 40m, where we heard many, many stations but could not seem to be heard for some reason. We considered this a very successful day for our scrappy rig.
The second event was a complete disaster. Same arrangement as before, with the Buddipole outside the building on our deck, perpendicular to the building, and the transceiver inside. It was after sunset, and we tried every band 40m-15m, and we couldn't hear anything over the S7-S9 noise floor that followed us everywhere. The noise floor was so smooth and uniform that I didn't even notice I'd tuned so far off one of the bands that I started picking up a commercial shortwave broadcast!
My club's really looking to me for guidance on getting consistent results, and I don't know enough to really even start being effective. The setup I've described above is completely as-is. I haven't started adding chokes to the feedline or the DC power lines, for example. Because everything has to be done as a temporary setup, we don't know how to connect up a station ground (and, in fact, I read controversy about whether or not it helps). Power, Kenwood, Buddipole...that's it on the equipment.
To throw in some extra x-factors, it's worth noting that we're operating out of downtown San Francisco and that our office is a tech company. We really can't change those things; everyone at the club has their life centered around their workplace and most live near work, and we can't really change the fact that there are hundreds of computers, wireless networking equipment, fluorescent lights, motors for refrigerators, etc, etc, etc. I've read some articles on RFI control that often encourage using common mode chokes on the sources of interference, but this isn't a home environment. Supposedly, the outer layer of the building is an RF shield, and I had hoped that just getting the antenna outside would help, but it clearly wasn't enough.
So, given the limitations that I have, what can I do to try and drive down the noise floor more reliably? Like I said, we've had a successful day of 10m operating before, so I know it's possible for us to use the setup, but I don't really understand how or why this massive noise floor has hit us or what to do about it.
Submitted December 01, 2014 at 01:14AM by roadriverrail http://www.reddit.com/r/amateurradio/comments/2nv8m3/help_with_high_noise_floor/ amateurradio
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