Topband: ZS6BKW(G5RV) on 160m?

Thu Mar 26 21:41:07 EDT 2015

Here is what  I would  do. First, build the proposed antenna, set it up at home with the coax connected directly to the ladder line at the bottom, the hot and ground each to one leg. Trim the ladder for lowest SWR on the low end of 40 meters (this should get 20,18,12 and 10 more or less right). Then see if your internal tuner will tune the antenna as it sits through the coax on 80, 30 and  15 meters. At this point, you will know if you have a viable all band antenna (unfortunately, most internal tuners are not wide rang e things).  If you are good to here, put down your radials and reconfigure the feedpoint by shorting the ladder line at the bottom and connect that to the hot side of the coax and the radials to ground side. Now t ry to tune this arrangement with the internal tuner. If this doesn't work and you have a 4 to one balun around, you can put it between the output of the rig and the coax to the antenna and try to bring the load into the range of the internal tuner with that. It's worth a try... 

If you find a workable arrangement in test, b uild a remote switch box and "ghost" the 12 volts to key the remo te relay box  through the Coax. You will need a small switch  box at the shack end and a relay box at the antenna end, basically you need a simplified version of the Ameritron RCS-4 (schematic on Ameritron website) system. This will switch between 4 antennas through the coax without a control wire , but y ou only need 0 and +12 volts and one relay at the antenna, so all you need is a two position on-off toggle , the capacitor/choke/input- output connectors and 12 volt connection at the shack end  and a DPDT relay, choke/capacitor arrangement, one coax connector and a pair of banana jacks for the ladder line  and a DPDT relay at the relay box end.  The relay is set up with one side of the ladder line to each relay section and the deenergized side hooked up to the coax connector back to the shack directly and the energized contacts sending both sides of the ladder line to the center conductor of the connector. Mak e a ground connection on the relay box to hook your radials to. If you really wanted to get slick, you could add another relay and a small matching network (a coil and a capacitor) for 160 in the relay box (I assume you will only run 100 watts) if the internal tuner won't match on 160. 

Good luck. What you want to do won't be easy, but could be worth it if you can make it happen ! 

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

From: "Mike Smith VE9AA" <ve9aa at nbnet.nb.ca> 
To: topband at contesting.com 
Sent: Thursday, March 26, 2015 5:12:11 PM 
Subject: Re: Topband: ZS6BKW(G5RV) on 160m? 

Marsh, Kevin, Jim, everyone 

This is great info.  Hey, thanks guys,.////As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of  450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? 

It’s a long story, but I am thinking I am going to be limited to one antenna, and there may not be any more than one coax, and no going in and out the building in the wee hours of the morning.  A restrictive scenario, but you’ll just have to trust me. 

So, if I could have, let’s say…..10’ of coax in the “shack”, then let’s just say for example, 40’ feet of coax and then the 40’ of ladder line, could I short the coax 10’ from the rig in the shack (and even add a coil ?), then if I wanted to get back on the other bands, simply unshort the 10’ run and put everything as normal?  My goal would be to work some W1’s/W2’s/VE3’s and perhaps a G/EA, Carib? on 160m just for mults.  I’d rather not carry too much gear with me, so if I could get it in the ballpark and let the Icom’s internal tuner handle a small mismatch, I’d be OK with that.  I might even rethink the 2 gnd radials and tie into the cottage gnd, but whatever works.  I’m not clear yet what the trip hazard ratio will be where I am at. 

Hope I was clear.   Yes, it’s a strange scenario.hi hi, I even laugh, but I can’t really tell the whole story.  One coax, one antenna-ZS6BKW, no going outside at night, no external remote tuners …all bands 10-160.  Hmmmmm. 

If I had more flexibility, I’d string up an inverted L off my proposed 35’ fiberglass mast and run a 2nd coax, but for this particular place, I am constricted. 

I can build and test this before I leave, but I still have to find bare ground first.  We still have many FEET of snow everywhere.  Spring has not really sprung yet. 

Mike VE9AA 

Mike, Coreen & Corey 

Keswick Ridge, NB 

From: kolson at rcn.com [mailto:kolson at rcn.com] 
Sent: March 26, 2015 2:33 AM 
To: Mike Smith VE9AA 
Cc: topband at contesting.com 
Subject: Re: Topband: ZS6BKW(G5RV) on 160m? 

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 too 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 

  _____   

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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