Re a portable oscilloscope to look at noise signatures (the number of "points" on the waveform is a basic but good way and u can usually discern multiple sources too) is to use a audio spectrum analyZer ap on an iPhone. I assume these may be available on a Droid too. I use several and some are free or close to free. You can actually use the microphone on the fone as the pickup if you can couple to the receiver with a piece of cloth. These aps are fairly decent too being able to change time base and amplitude. Of course a small laptop with a PC based application is better and you can plug into the line input and get a more reliable reading and record the noise as well.
73 Pete W2PM Sent from my iPhone On Jan 6, 2013, at 6:40 AM, Pete Smith N4ZR <n...@contesting.com> wrote: > Or, since you don't really need a calibrated result, build a simple variable > attenuator. Just about anything works so long as you can vary the > sensitivity as you approach the power line. > > 73, Pete N4ZR > Check out the Reverse Beacon Network at > http://reversebeacon.net, > blog at reversebeacon.blogspot.com. > For spots, please go to your favorite > ARC V6 or VE7CC DX cluster node. > > On 1/5/2013 1:17 PM, donov...@starpower.net wrote: >> Hi Paul, >> >> You would helpful a step attenuator, in 1 dB steps, to be a valuable >> addition to your tool bag. There are situations where it helps isolate to >> an individual pole. Its much more accurate than an S-meter. >> >> Something like this, or many other alternatives: >> >> http://www.ebay.com/itm/Coaxial-RF-Step-Attenuator-Set-1-dB-steps-to-70-dB-total-DC-to-1-GHz-/200866468929?pt=LH_DefaultDomain_0&hash=item2ec4931441 >> >> 73 >> Frank >> W3LPL >> >> ---- Original message ---- >>> Date: Sat, 05 Jan 2013 11:44:08 -0500 >>> From: N1BUG <p...@n1bug.com> >>> Subject: Topband: Another take on power line noise hunting >>> To: Topband <topband@contesting.com> >>> >>> I've been following this discussion with interest. I spent the >>> summer tracking down more than 20 sources of power line noise. As an >>> offshoot of that I've made it my mission to help clean up RFI in my >>> little corner of the world. I've been slowly drifting away from >>> DXing and this has turned out to be my new area of interest. >>> >>> Since this topic is perhaps of interest to topbanders, and since my >>> experiences seem to vary somewhat from the typical reported here so >>> far, I thought I would take a moment to share some observations. I >>> should probably note I was dealing with a mix of 13.2 kV >>> distribution lines and 46 kV transmission lines. My hunt was made >>> more challenging by the fact I had multiple sources in a relatively >>> small area and could often hear more than one at a time even with >>> directional antennas and attenuation. >>> >>> My tools this summer were 135 MHz AM receiver with 3 element yagi >>> and step attenuator; LF/MF/HF/VHF/UHF AM receiver with DF loops for >>> low bands and 7 element yagi for 445 MHz; ultrasonic receiver with dish. >>> >>> Low frequencies, eg. AM BC or 160 meters were *occasionally* useful >>> in locating a general source area. Sometimes the area identified >>> turned out to be an area of *radiation* but the noise was >>> *generated* elsewhere. Often the relatively close proximity of >>> multiple sources made low frequency tracking useless. >>> >>> VHF was always useful in finding a source area, 80% of the time >>> resolving it to a single pole. The sharp, deep null at exactly 90 >>> degrees off axis of the yagi proved very useful for confirming a >>> source structure. Poor resolution/accuracy of signal strength >>> metering was perceived as a problem. >>> >>> UHF was very helpful in a few areas where the noise was particularly >>> strong at VHF and/or signal strength so close over a span of several >>> poles that VHF could not pick the source pole with high confidence. >>> So far, experience indicates this is more likely to happen on the >>> transmission lines. They're a bear. Again, poor or no signal >>> strength metering (signal below AGC threshold) was perceived as a >>> problem. >>> >>> The first ultrasonic unit tried was a waste, finding something at >>> only 10% of RF noisy poles. The second unit was able to hear >>> something from about 60% of the same 21 poles. The figures are >>> averages over more than 10 runs with each unit. The two were also >>> tested on a spark signal range under somewhat controlled conditions. >>> These things are definitely not created equal! >>> >>> To date I have identified and had the power company fix almost >>> everything I have worked on. The remaining open case involves a >>> short section of a 46 kV transmission line which is extremely >>> perplexing due to the specific nature of the issue (details on >>> request). Just when I starting thinking I was getting good at this, >>> I came up against this one. >>> >>> If I were doing this strictly for myself these tools would be more >>> than adequate. Since I'm not and I only have so many hours in a day >>> I have several upgrades on my wish list: >>> >>> HF/VHF/UHF AM receiver with wider bandwidth better signal strength >>> metering >>> >>> Log periodic dipole array covering ~100 to ~900 MHz for frequency >>> agility while maintaining some directional properties >>> >>> Portable oscilloscope for observing noise signatures in the field >>> (I'm hoping it helps sort out overlapping source radiations) >>> >>> Yet another upgrade of the ultrasonic unit. >>> >>> Comments are welcome, even if it's to tell me I'm clueless! :) >>> >>> 73 >>> -- >>> Paul Kelley, N1BUG >>> RFI Committee chair, >>> Piscataquis Amateur Radio Club >>> http://www.k1pq.org >>> _______________________________________________ >>> Stew Perry Topband Distance Challenge coming on December 29th. >> _______________________________________________ >> Stew Perry Topband Distance Challenge coming on December 29th. >> > > _______________________________________________ > Stew Perry Topband Distance Challenge coming on December 29th. _______________________________________________ Stew Perry Topband Distance Challenge coming on December 29th.