Towertalk
[Top] [All Lists]

Re: [TowerTalk] 4 square for 80

To: <towertalk@contesting.com>
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 80

I 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 80

Personally I have never choked the 4 feedlines to the verticals. I fail to
see why the shield of the feedlines is different from the radials it is
connect 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 vertical
they 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 to
reduce 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 electrical
length 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 whether
signal 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

<Prev in Thread] Current Thread [Next in Thread>