Topband: ZS6BKW(G5RV) on 160m?

[kolson at rcn.com]

Mike, this is exactly the antenna I use here at the home QTH. Mine is set up as a 92 ft flattop and 42 ft feeder , one end at 50 ft the other at 25 ft (that's what I had to work with). I have a switching box at the bottom that has three modes: 

a)the ladderline is connected directly to the coax running back from the box to the shack (with a bit of trimming this gives you tunerless operation on 40,20,18,12 and 10 meters. 

b)the ladderline is "passed through" to an extention random piece of ladderline to a tuner at the shack for 80,30 and 15 meters 

c)the feeder is shorted and fed to a coax connector to a dedicated  external tuning unit for 160, then back into another connector where it goes back to the shack through the same piece of coax as the a) arrangement. I have out 30 radials, I know you can't do as many but one does what one can. 

This arrangement is one of the best modest all band antennas I have used, and it does fairly well on 160, I have worked over 100 countries with this, not awesome, but not to o bad for a small station with a so-so operator. I use a K9AY for RX here. Just for a dumb comparison, it greatly outperforms a butternut (not that hard to do, LOL). 

I modeled this with a simple antenna modeling program (that I barely knew how to use) and the matching network it came up with got me in the ballpark. I wish I remember what figures I got... 

Best, Kevin K3OX 
----- Original Message -----

From: "Mike Smith VE9AA" <ve9aa at nbnet.nb.ca> 
To: topband at contesting.com 
Sent: Wednesday, March 25, 2015 8:57:18 PM 
Subject: Topband: ZS6BKW(G5RV) on 160m? 

I might have a chance to operate from a portable location this summer for a 
contest or two but at the location they have no antennas, nor is there room 
for any huge vertical, inverted L, guys ropes etc. etc. and no permission to 
climb roofs, chimneys, or put a bolt in the building, nor touch the trees. 
All very restrictive. 

  

I might be able to erect a 35' freestanding fiberglass mast with a ZS6BKW. 
Maybe.  The ZS6BKW is basically a 94' dipole with a 40' downlead of 450ohm 
ladeer line..which will be sloped slightly, as I don't see a way to get the 
peak above 35' 

  

Suffice to say, the best I MIGHT be able to do is sneak in this low 
ZS6BKW(G5RV) as an inv. vee to run 10m-80m but I am looking for a way to 
ALSO be on 160m to make a few dozen contacts in a contest or two. 

I am thinking the peak of the ZS6BKW (G5RV like antenna) would be at max 
35'.   

  

For 160m, could I short the 2 leads of the 450ohm ladder line together where 
they meet the coax run and sneak out 2 x 65' (bent) ground radials and 
attach them to the braid side of the coax? 

(maybe I'll even make up a switchbox so I don't have to be running around in 
the dark a few times a night reconfiguring bare wires in an unfamiliar 
location.) 

  

I've read 3830 contest reports where folks have done this type of thing, but 
of all the antennas I have ever had (many!_) I have never EVER tried this 
shorting of the ladder line or coax and feeding what is a G5RV as a T-Top 
vertical. 

with a couple of radials. 

  

I am not sure how a 40' tall vertical with 94' of toploading, models in NEC, 
but it seems like it might be close-ish(?) to resonating on 160m. (will I be 
in the ballpark?) What kind of matching will I need if any?   

I could maybe even add more coax or ladder line to the "vertical" section 
when on 160m, however it will also have to be sloped/bent and on or very 
near the ground (probably not good, eh?) 

I'll be using a modern transceiver with internal ATU. 

  

I am not looking to run pileups on 160m.(where I am going is not rare, just 
a nice summer place)..I just want to pick up a few 160m mults in a contest 
or two.   

  

Ideas?  Remember, I am very restricted.  Gotta have the ZS6BKW for my 
antenna.and I may not be permitted to have more than 1 coax run out to the 
antenna.  I doubt adding a couple extra 65' legs is possible either. (no 
square footage for that. 

  

Thanks 

  

Mike VE9AA 

Mike, Coreen & Corey 

Keswick Ridge, NB 

  

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