It is a common solution to put a 160 meter band pass filter on the SWR meter and it will work.
I had to do this on both 160 meters and 80 meters at A73A. The high power AM station was miles away. Tree N6TR On Fri, Nov 2, 2012 at 3:22 PM, HAROLD SMITH JR <[email protected]>wrote: > MFJ makes a filter for their Antenna analysers. I am sure that if it does > not > work for you, you can get your monies back. > > 73......Price W0RI > > > > I have the same problem with a 50KW FM station a couple of miles away > affecting my Palstar ZM-30. It is useable on the rig side of an antenna > tuning unit, but most of my antennas are self resonate therefore the FM > broadcast RF rides right into the bridge making it mostly worthless when > directly attached to any antenna such as a dipole, vertical, yagi, etc. > > Sometimes I can get a useable reading if I turn the antenna 90 to the > broadcast tower, but that only works with the rotatable antennas. > > Experiments with filtering using small value caps, small pi networks, a > series FM trap, or ferrites have been unsuccessful. Any filter I put in > front of the analyzer influences the reading substantially. BTW... this > broadcast station also comes in on my frequency counter too, with no > antenna > attached. > > Please let the group know if any of you have come up with a "transparent at > ham frequencies" inline filter. > > 73 > > Lloyd - N9LB > > -----Original Message----- > From: Topband [mailto:[email protected]]On Behalf Of Tom > Boucher > Sent: Friday, November 02, 2012 4:21 PM > To: 160 reflector > Subject: Topband: Antenna analysers in close proximity to BC station. > > > > > A ham friend asked me to design a matching network for his 160 metre end > fed > quarter wave, so I asked him to provide an impedance reading using his > MFJ-259B. I would then use the Berkley site > ( > http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch. > html<http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html>) > to provide the necessary values for an 'L' network, as I have done > many times at my own station. > > The readings he provided were total nonsense and quite erratic, so we > concluded his MFJ-259B was dead. He assured me that he always does a static > discharge before connecting the MFJ. > > So I paid him a visit, taking along my Palstar Antenna analyser thing, > which > has always performed well at home, and what-do-you-know, the readings on > that were also erratic, total nonsense and it behaved in a way I have never > seen before. > > Than someone suggested the problem may be due to a 50Kw BC station on 909 > KHz, situated less than 5 miles away, causing both antenna analysers to > misbehave. > > > > We ended up with a good old-fashioned link coupled parallel tuned circuit > with the antenna tapped a few turns up from the ground end. This works fine > but he is power limited due to arcing across the tuning capacitor. So we > would ideally like to revert to the 'L' network plan, but how to use the > antenna analyser in the presence of a high BC station field. Anyone any > ideas? > > > > 73 > > Tom G3OLB > _______________________________________________ > Topband reflector - [email protected] > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.930 / Virus Database: 2441.1.1/5369 - Release Date: 11/02/12 > 02:34:00 > > _______________________________________________ > Topband reflector - [email protected] > _______________________________________________ > Topband reflector - [email protected] > _______________________________________________ Topband reflector - [email protected]
