Re: Topband: K9AY minimum spacing from TX
On 12/7/2023 10:40 AM, K9AY wrote: Had no problem, but I think the Inv-L was at least partly detuned during receive by the T/R switch open circuit and length of coax. This is an important factor that we don't often think about. I've used this to create 2-el arrays from multiple 160M verticals, changing termination of the one I'm not feeding in the shack. Spent a LOT of time modeling to get there. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: K9AY minimum spacing from TX
I believe that it greatly depends on if the tower is closely resonant to 160 meters. In my case, the K9AY array is about 150 ft. from the tower. I tried detuning my tower and even though the tower is shunt fed with an Omega network, it made no difference. Yet at K9UWA and KD9SV and others, it made a significant difference. So, don't assume anything until you do what you can to detune anything that might interfere. At KD9SV, pine trees to the NE about 100 ft away corrupted the pattern quite a bit with the Hi-Z 4 square receive system. >>> How far should a K9AY be spaced from resonant antenna? I presume there is no impact from nearby trees. Jim - KR9U _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: K9AY minimum spacing from TX
Ash, The answer is "as far as necessary"! There seems to be a lot of variation in the degree of interaction with towers and other antennas. Every QTH is different. I suppose 100 feet is a good starting distance. The minimum I've installed the loops at my own QTH is 75 ft from an Inv-L. Had no problem, but I think the Inv-L was at least partly detuned during receive by the T/R switch open circuit and length of coax. Just try it, then be prepared to do some investigation if it doesn't work out. And yes, trees are not a problem. 73, Gary K9AY To: topband Subject: Topband: Message-ID: Content-Type: text/plain; charset="UTF-8" Hi All, How far should a K9AY be spaced from resonant antenna? I presume there is no impact from nearby trees. Please advise. -- Ash ~ 3V8SS/KF5EYY --- This email has been checked for viruses by AVG. https://www.avg.com _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: K9AY minimum spacing from TX
I don't want to say "No Impact" but my K9AY is in a line of trees and has very strong directivity with deep null. It is about 50 feet from the vertical element of my transmit T, and definitely in the shadow (80 feet below) of the top element of the transmit T. I can ground, unhook, etc. the transmit T and see no change in K9AY directivity or null. Tim N3QE On Thu, Dec 7, 2023 at 4:52 AM Ashraf Chaabane wrote: > Hi All, > > How far should a K9AY be spaced from resonant antenna? I presume there is > no impact from nearby trees. > > Please advise. > -- > Ash ~ 3V8SS/KF5EYY > http://www.kf5eyy.info/ > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: K9AY minimum spacing from TX
Well, on a small suburban lot with TALL pine trees (four and a large sweet gum tree in a square of 50 x60 feet), I had an inverted L with one L shaped elevated radial on the perimeter of the lot. One leg of the K9AY loop was about 6' away from the elevated radial. On receive I switched in an inductor to de-tune the transmit antenna to keep noise from being re-radiated to the loop. Now on transmit, a resistor burned up in the relay box. I added the same resistance except about 20 watts worth of dissipation and that took care of that problem. I used no more than 600 watts output in the Houston area. I did notice some directivity problems with the loop with the proximity of the wire and trees but still the signal to noise ratio was improved enough to work what I could not hear the the vertical. When living in TN I had a larger lot and used a top loaded vertical and the K9AY loop is about 50 feet from the transmit antenna and the loop seems to show better directivity.I do not worry much about signal directivity but noticed that I have better results when I orient the loop to null the noise. I hope this helps. 73, Mike WA5POK On Thursday, December 7, 2023 at 04:52:29 AM EST, Ashraf Chaabane wrote: Hi All, How far should a K9AY be spaced from resonant antenna? I presume there is no impact from nearby trees. Please advise. -- Ash ~ 3V8SS/KF5EYY http://www.kf5eyy.info/ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: K9AY minimum spacing from TX
Hi All, How far should a K9AY be spaced from resonant antenna? I presume there is no impact from nearby trees. Please advise. -- Ash ~ 3V8SS/KF5EYY http://www.kf5eyy.info/ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
