KL7DTH and myself share a station. We have a DX engineering NCC-1 box specifically purchased to remove interference from the neighbor's plasma TV. Once we figured out how to use the unit, it completely removes the trash from the plasma RFI generator. And we mean completely - zip, nada, nothing left. It does not seem to detract from the intended signal at all.
We use the NCC-1 primarily on 75 meters, but it also works on 160 and 40. We are blessed with what is otherwise a very quiet receiving location. Our noise level on 75 and 40 meters is S-zero, on 160 is is about S-1. We use a full-sized cubical quad on 75 meters, arranged in a NVIS (vertical firing) configuration. We have similar antennas for 160 and 40, all made of wire and strung among the trees on our 2.5 acre, or just a bit more than a hectare for our metric friends. Some points: The :sense" or "noise" antenna needs to be located as close as possible to the noise source. The sense antenna need not be very high. In fact you want it to perform poorly on the frequency you are trying to hear. The sense antenna need not be resonant. As long as it gets enough noise signal to do the job, stop there. Resist the temptation to make the sense antenna perform like an ordinary ham antenna. We first tried a noise antenna about 200 feet away from the source, but performance was not impressive. We then erected a non-resonant dipole about 15 feet high but right on the property line between us and the neighbor. The results were immediate and impressive. Adjusting the controls of the NCC-1 resulted in complete cancellation of the plasma TV hash, and signals that were completely covered by the hash popped out of the noise and came in loud and clear. Some further points: First, the usual disclaimers apply - no connection, etc. Next. there are other units that may work equally well on this type of noise. We have only tried the one unit, and it worked, so we stopped looking. It should be quite possible to homebrew one of these units. There is no "rocket science" here. Parts should be easily available. I seem to remember that a design for something like this appeared in one of the RSGB or ARRL handbooks a while back. The NCC-1 is intended, according to DX engineering's literature, primarily for steering phased arrays, with a secondary use for interference reduction. On Topic note - considering the potential for assisting QRP operations, it seems to me that this type of unit would be a good candidate for an Elecraft kit. I know I would like one in a footprint small enough to carry around with my K2. - Jim, KL7CC David Cutter wrote: > > Secondly, the concern about ruining the performance of the rx with noise > phase cancelling boxes did not draw attention to the DX Engineering version > which, they say, is specifically designed to provide very high TOI. > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
