Topband: 9 circle array
Has anyone built the DX Engineering version of the YCCC 9 circle array ?I am considering one and would like anyone's feedback. I have read the NCJ article and was on the list for the original kit version until it got squashed. Also is anyone using the W7IUV preamp with an array of verticals? If so did you build it on a pc board or on perfboard? Glenn, w...@ww4b.net _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: 160 puzzle
Post is pressure treated and has been outdoors a couple of years .Antenna is insulated with a PVC pipe sleeve .My hand does not effect it till I touch, if only 1/16 inch away .The effect is greater if I touch the one of the u bolts clamping the PVC to the wooden post .The u bolt is insulated from the antenna by the pcv. No effect if I touch the PVC. If I disconnect the base loading and put the analyzer direct to the antenna , resonance is about 8 MHz and touching the u bolt or post has no effect. Glenn, w...@ww4b.net _ Topband Reflector
Topband: 160 receive antenna puzzle update
Thanks to everyone who responded .The posts by K7TJR and W8JI were most helpful in understanding what is going on .I should add that the phasing box in the shack is continuously variable, (NCC-1) so changes in the phasing caused by changes in the antenna surroundings came be compensated . It works quite well but I think there maybe some benefit to change the elements to top loaded style. 73 Glenn WW4B _ Topband Reflector
Topband: A 160 Meter antenne puzzle
Hi everybody and happy new year . I have what I think is an interesting antenna riddle . I have some receive antenna verticals (4) that are selected by relays in pair and the pair is fed back to the shack to a phasing boxing .Each antenna is AL tubing about 30 feet tall, base loaded with an inductor and a resistor very much like ON4UN has for his 4 square receive array .There is a 1 to 1 balun between the antenna and the feed line . The tubing is insulated with an eight inch length of pvc pipe from the 4x4 that supports it .The overlap between the tubing and the 4x4 is about eight inches as well . I was doing some testing today and discovered that touching the 4x4 at the top caused the swr to increase from about 1.2 to 1 to 1.7 to 1 . The lower on the 4x4 I touch the less the effect . I am only moving my finger a fraction of an inch and my hand not at all when this happens .The feed lines are disconnected when this is going on .There is no dc continuity between the antenna and any mounting hardware or th e post .I disconnected the base loading and put the analyzer on it and it is resonant at about 8 mhz and touching the post causes no change with this setup . There are eight 30 foot radials laying on the ground and a 2 inch wide copper strap about 3 foot long in the hole that the 4x4 is in . What is going on here and should I make an effort to limit the coupling between the 4x4 and the antenna? 73 , Glenn WW4B _ Topband Reflector
Topband: Receive Antenna interaction with Transmit Antenna
Hi everyone. I am in the process of building some new receive antennas and have been modeling a number of choices .My Transmit antenna is a full wave vertical loop 70 foot high and about 210 feet long .Currently I have a pair of short (28 ' ) base loaded verticals toward EU phased with a DX Engineering NCC-1 and one 550 foot beverage toward EU .They both work fairly well toward EU ,I would rate them about the same . I have been considering some type of circle array but it would be fairly close to the loop ~ 175 ft. When I start modeling vertical receive arrays the interaction is quite bad .I have been unable to come up with a scheme to detune the loop from the shack ,the only way I have come up with so far requires a relay at 2 points on the loop. Beverages in the same area don't seem to be affected very much . I understand about the need to limit the rf the receiver sees, I am just concerned about how to limit the degradation of the receive array . Question 1 Are receive arrays with active antennas less affected than arrays with passive elements . I don't know how to model the active antennas . Do you just put a high resistance load at the bottom of the vertical to simulate the amplifier ? Question 2 Is there a better way to detune the loop ? Lastly am I too concerned about the interaction on receive antenna performance ? Thanks for you time . Glenn WW4B ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
