Z6SBKW requires 70' of coax?

[zero_frequency]

Just looking for a little guidance here to make sure I've got this right. I am wanting to try the optimized version of the G5RV called the Z6SBKW from NI4L. What I don't understand about it is this statement ...

"As with all models of the G5RV antenna, the Optimized version also requires a minimum of 70 feet of 50-52 ohm coax to complete the matching network. Without this 70 foot of coax, the antenna will NOT function correctly."

I have maybe 20' of coax from my station to the single-point ground panel on the exterior of my wall.

My question is, is that statement saying I need 70' (I already have 20), so another 50' of LMR400 even if I have to coil it up as the antenna is not that far away. I have yet to setup the antenna, but understanding this will help me understand where to place the antenna.

Any help much appreciated.

 

[prcguy]

By design a ZS6BKW does not need any specific length of coax to work on advertised bands. I've run many ZS6BKW antennas with many different lengths of coax and never noticed any significant difference.

What some companies do with a G5RV is advertise it with 75ft of RG-8X knowing the coax loss will smooth out VSWR and allow that antenna to work with most internal antenna tuners. The ZS6BKW is different offering an ok match on most HF bands except 80m and one other. If you don't have an antenna tuner you may have trouble on some bands with a ZS6BKW but with any kind of tuner you should be good.

BTW all my ZS6BKW antennas were home brew using 14ga 450 ohm ladderline and its a great all band antenna. Highly recommended over a G5RV which was only designed as a 20m antenna and everywhere else its just a random length dipole.

 

[K6GBW]

Take that stuff with a grain of salt. I have never run any of the G5RV type antennas with a long coax and they still work fine. I’m currently using a G5RV Jr. with about six feet of coax to the ground rod and then maybe another 12 feet to the tuner and it works fine.

 

[Golay]

I myself have never run a Z6SBKW. But I've run a few G5RV Juniors thru the years. Strung up in an attic. Strung up in a park. Strung between my house and a basketball net. Never with more than 30 or so feet of coax. Worked fine for me.

 

[prcguy]

I myself have never run a Z6SBKW. But I've run a few G5RV Juniors thru the years. Strung up in an attic. Strung up in a park. Strung between my house and a basketball net. Never with more than 30 or so feet of coax. Worked fine for me.

The original G5RV was designed almost 80yrs ago as a 20M antenna with a little gain and it just happens to be big enough to use with a tuner on all bands 80-10m but the VSWR is really bad on some bands. This causes your coax to be operating under extreme VSWR conditions and the coax loss goes way up loosing a lot of power. The G5RV Jr is a 10m antenna and sort of works 40-10m and maybe 6m. It has the same problem of all bands besides 10m having a terrible match and high coax loss.

The ZS6BKW on the other hand is a modern computer designed antenna that has a good match on most bands 40-10m and its similar to a G5RV on 80m having a roughly 5:1 to 7:1 match there and lots of extra coax loss. 30yrs ago I ran an original G5RV at home, at work and sometimes portable until I discovered the ZS6BKW and I never used a G5RV again, replacing them with the ZS6BKW everywhere for awhile.

Then came resonant EFHWs and OCFDs using the unusual dimensions from Danny at MyAntennas and I retired all my ZS6BKWs. I didn't mention lots of other antennas I have or tried over the last 50yrs with each one having some good and some bad merits. I would say mostly bad otherwise they would be on my roof(s) right now.

 

[Dessiccant101]

I have the video of G5RV Luis himself giving a lecture at the Norfolk radio club of the G5s operation and everyone gets this wrong re it was designed as a 20 metre antenna, it was not,here he clearly goes through the different bands of operation as it was designed, so can we clear that up once and for all, in addition to this the best ZS6BKW is with Zero coax at all and the feeder terminates into a balanced ATU for best efficiency..
Please look at the papers from DL1JWD for the facts here and not guesswork..
Thank you
73

 

[merlin]

designed as a 20 metre antenna, it was not

Actually, it was. Like any dipole, it was designed for multiband. At 90 foot end to end, it is not a great performer on 80 meters.
At the feed point, R is like 20 ohms and about a 7:1 match. Most ATUs can tune this.
40 meters, this antenna is as good as any. R is about 40 ohms and a 1:1 match. 20 meters, about the same.
30 and 15 meters, this needs an ATU. 12 meters is on the edge, about 2:1, 100 ohm.
10 and 6 meter, not perfect, but close, maybe 1.3:1 and about 60 ohms.
Coax: with a 1:1 balun at the feed point, you can run any length, 50 ohm coax to the shack.

 

[Dessiccant101]

The 102ft G5RV ( not Zs6BKW) was not designed as a 20 metre antenna…
It was indeed designed as a multibander..
It was designed as a multibander that was good on 20 40 and 80 , terrible on 10
I have the film with him giving the lecture…
Years before there was a Collins multibander of 102 ft also..
73

 

[prcguy]

The 102ft G5RV ( not Zs6BKW) was not designed as a 20 metre antenna…
It was indeed designed as a multibander..
It was designed as a multibander that was good on 20 40 and 80 , terrible on 10
I have the film with him giving the lecture…
Years before there was a Collins multibander of 102 ft also..
73

Louis Varney who designed the G5RV in the 1940s claims its a 20m gain type antenna and not originally intended to cover other bands. You can make just about anything work with a tuner.

 

[Dessiccant101]

Louis Varney who designed the G5RV in the 1940s claims its a 20m gain type antenna and not originally intended to cover other bands. You can make just about anything work with a tuner.

It did indeed have a nice pattern on 20m
But as I said, I have the old colour lecture on film that he gave to the Norfolk (England) radio club in which he goes into great detail of its success as a multibander..
He stresses that in order to achieve this full success on ALL bands it needs no coax in the system, if you are going to use coax there are losses on 30,17 and 10 and those losses are unacceptable.
If you can, take the tuned feeder all the way to the ATU/AMU…
Even if you insist on using coax keep it very very short…or use a ZS6BKW, but then again even that antenna benefits from being able to take the 12.2 metres of 450 ohm tuned feeder directly to the Tuner if at all possible ..