Originally appearing on his forum, Unchained Preppers, this post is a pretty good summary of improvements needed to make a very common antenna, the G5RV, an actual multi-band solution. While I don’t use the G5RV, I recognize a lot of folks do, so this might be pretty important if you’re looking to boost its capability.
I have been shopping for a new G5RV type antenna since Radio Works in VA. was sold. I currently have one running east-west (North south lopes) and I wanted one that goes north-south (west-east lopes). The new owner is focusing his production in a different direction than the G5RV right now. What it comes down to, is for me to make my own G5RV antenna.
Knowing that some of you are working on new antenna’s over the winter I thought I would share this with the folks here.
Now many folks carry manufactured G5RV antenna’s and market them as multi-band antenna’s when in fact they are not. They are weak on 75/80 and 10-meters and will not pick up 60, 30, and 15 meters. Eventually my search lead me to reading an article entitled, The Truth about the G5RV Antenna.
The article spoke to two different versions of the G5RV antenna – The ZS6BKW and W0BTU Antenna’s. As it is tough in life to get an all encompassing piece of equipment ala “getting your cake and eating it too”, both the ZS6BKW and W0BTU antenna’s are an improvement over the G5RV antenna however, neither one is all encompassing.
Because I hate wasting my time, and prefer doing something once rather than twice, I contacted Cecil Moore, W5DXP who has reportedly made some considerable improvements to the ZS6BKW and W0BTU antenna’s.
Moore and I have been trading emails over the past few months and he just published an article entitled How to Transform Your ZS6BKW Into an All-HF-Band Antenna.
In essence the antenna is a dipole flattop 92′ long with 39′ of 450 ohm ladder line into a 1:1 choke-balun to 50 ohm coax. If you just did this your SWR’s (Standing Wave Ratio) would be the following in the following band’s:
If you don’t want to have to use a tuner you really want to keep SWR below 1.5. If you use a tuner to control SWR lets say taming a high SWR, there is no tuner I am aware of that will bring an antenna’s SWR down south of 2.0 if the SWR is north of 10.0.
* You will need a tuner
** You can not tune
These results bring us to Option 1.
To bring 80-meters down to 1.2 SWR add a 500pf Doorknob capacitor*** post the 1:1 balun on the center coax center conductor. When you do this the SWR on 80-meters drops to around 1.2. The capacitor does not adversely affect SWR when left in line to 40, 20, 17, 12, & 10-meters.
*** Leaving the capacitor in line does not adversely affect the higher frequencies when you add ladder line as described in Option 2.
What can you do to optimize 40, 20, 17, 12, & 10-meters after adding the capacitor for 80-meters is to add/delete 450 ohm ladder line in 1 or 2-foot lengths. An easy way to do this without manually adding/deleting ladder line using banana clips, is to use a DPDT knife switch. By adding one or two feet to the existing 39-feet of ladder line helps SWR in the 40, 20, 17, 12, & 10-meter bands with the capacitor still in line.
Here are the SWR’s for the following frequency’s with an inline capacitor and by adding 1-2-feet of ladder line to the original 39-feet of ladder line via the DPDT knife switch.
Meters SWR Configuration
80 1.2 500pf capacitor & original 39′ Ladder line
40 1.5 500pf capacitor using knife switch add 1′ ladder line
20 1.0 500pf capacitor using knife switch add 1′ ladder line
17 1.4 500pf capacitor original 39′ ladder line no additions
12 1.2 500pf capacitor using knife switch add 1′ ladder line
10 1.8 500pf capacitor using knife switch add 2′ ladder line
By using options 1 & 2 combined, SWR is great except for 60, 30, and 15-meters. Now we get into a bit more complicated procedure as it involves a couple more knife switches, a relay switch, and some additional capacitors (60-meters a 128pf, 30-meters 104pf, 15-meters 44.5pf). If you execute on this last procedure you will in fact have a true multi-band antenna from 80-10-meters.
This is what the SWR looks like for 60, 30, & 15-meters.
Meters SWR Configuration
80 1.2 Capacitor & original 39′ Ladder line
60 1.5 Using knife switch add 2′ ladder line PLUS using relay switch add 128pf capacitor
40 1.5 Using knife switch add 1′ ladder line
30 1.1 Using knife switch add 2′ ladder line PLUS using relay switch add 104pf capacitor
20 1.0 Using knife switch add 1′ ladder line
17 1.4 Original 39′ ladder line no additions
15 1.0 Original 39′ ladder line PLUS using relay switch add 44.5pf capacitor
12 1.2 Using knife switch add 1′ ladder line
10 1.8 Using knife switch add 2′ ladder line
Please take the time to read both articles as they do much more justice than my short explanation does complete with PICTURES and GRAPHS.
With deer season ending for now, and my outside projects coming to a close do to weather, I will build this antenna and document all of my moves. Once done I will hoist and let you know how it works.