To: | <towertalk@contesting.com> |
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Subject: | Re: [TowerTalk] 4 square for 80 |
From: | "StellarCAT" <rxdesign@ssvecnet.com> |
Date: | Sat, 24 Sep 2016 17:30:28 -0400 |
List-post: | <towertalk@contesting.com">mailto:towertalk@contesting.com> |
Wayne,Can you add more detail as to how it changed please - in the last scenario you have listed? I have no idea what this means: "DX reports = antenna #1 (NE) being the only one detectable ???? " ? Gary K9RX-----Original Message----- From: Wayne Kline Sent: Saturday, September 24, 2016 1:46 PM To: K1TTT ; towertalk@contesting.com Subject: Re: [TowerTalk] 4 square for 80I have been playing with 75/80 meter 4 sq. since I acquired a Colatcho ( SP) unit back in the late 80's ... First were wire 14 ga suspended from trees. This was on sloping ground and the radial were 1/4 wave laying on the ground 8 per antenna . I choked the feed line at the antennas bases with slide over 43 mix, 8 pieces per feed line. The performance was questionable IMO because of the 18 ft. difference in antenna orientation NE/SE . I moved to my now QTH in 99 and erected a 4 sq. out of modified Hi Gain high towers. I first used elevated radials 4 per base tuned and at first 1 ft off the ground . talk about erratic performance from a RAIN to DRY day .. RAIN = GOOD Dry =POORboth in FB and forward gain ... I then did the gull wing @ antenna base and 6 ft height. the dump power bandwidth narrowedand the pattern was not effected AS much from dry to wet I then bit the bulled and striped the area installed 14 ground rods , a X grid of 8 ga copper wire and 106 1/4 wave radials 20 ga insulated silver soldered at the intersecting 8 ga X grid . WOW Stability was achieved . The feed lines at first were NOT choked off at the base of the verticals I then installed new feedline in the PVC emt and choked off the base with 8 43 mix beads .. the dump power lowered and the bandwidth tightened up . with most DX reports = antenna #1 (NE) being the only one detectable ???? No NEC, just real world performance evaluation . Could the choke keep re reradiated RF out of the Comtec BOX ???But there was a noticeable difference with and with out the Beads. Wayne W3EA From: k1ttt@arrl.net To: towertalk@contesting.com Date: Sat, 24 Sep 2016 17:07:17 +0000 Subject: Re: [TowerTalk] 4 square for 80Personally I have never choked the 4 feedlines to the verticals. I fail tosee why the shield of the feedlines is different from the radials it isconnect to at the base of the vertical. On my raised 80m 4-square I have 7 radials from each base, starting with the one going to the adjacent verticalthey go outwards every 45 degrees using heavy aluminum wire, then the 8th one to complete the pattern is the shield of the coax going to the comtek box. David Robbins K1TTT e-mail: mailto:k1ttt@arrl.net web: http://wiki.k1ttt.net AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373 -----Original Message----- From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Brown Sent: Saturday, September 24, 2016 16:30 To: towertalk@contesting.com Subject: Re: [TowerTalk] 4 square for 80 On Sat,9/24/2016 7:15 AM, Steve London wrote: > How much better would the performance be with a multiturn choke ? Over > real ground, in the presence of real, possibly interacting structures > within N wavelengths, isn't there a finite limit to the performance, > regardless of your choice of "excellent" vs. "superb" common-mode > chokes ? Hi Steve,The primary reason for using common mode chokes in our antenna systems is toreduce RX noise. A string of beads choke is NOT a good choke at HF for the reason cited -- it's effectiveness is strongly dependent on the electricallength of the feedline considering it as an antenna (that is, considering it as a wire, not a transmission line). This is not a matter of "excellent" vs "superb," it is whether it is effective at suppressing RX noise, and whethersignal pickup on the coax fills in the nulls a bit. 73, Jim K9YC _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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