Topband: 160M INV-L with 2 Elevated Radials

[Mark K3MSB]

 Greetings Fellow Night-Owls!

My 160 meter antennas are typically put up in mid November and taken down
at the end of March as my wife likes the grass mowed on a regular basis.
The transmit antenna is a quarter wave INV-L with 15 to 20 ground radials
as long as I can make them. RX Antennas are a BOG towards EU and last year
I sported an RBOG NW/SE for JA (and Bouvet....).

I wanted to work KH1 this summer so I experimented with a pair of
“gull-winged” radials on the INV-L. The antenna feed point was still at
ground level, and the length was still 128 feet. Running the one radial
west wasn't an issue as it was all on my property. East was another story.
The good news is the the farmer that lives next door is a wonderful
neighbor and she had no objections if I ran the radial up along the side of
the planted field. In fact, she said if I needed to run it among the corn
she would call the farmer that rents that field and ask. I ran the east
radial along the plowed field (be thankful for what you get!).

The radials went from the feed point to about 5 feet in height about 5 to
10 feet away, then up to 10 feet height for the rest of the length.
Direction was pretty much east/west.

I purchased 10 foot lengths of rebar at my local hardware store and cut
them to 5 foot lengths. At the appropriate places I sunk then into the
ground for 24 inches.

I also purchased 10 foot sections of electrical conduit to place over the
rebar. At the ends of each section of conduit I cut a U-channel for the
radial wire to rest in. My intention was that I could “scoop” the wire into
the U-channel then raise it up to the desired height. This worked well; I
put the wire in the channel, attached an end-cap, then just raised the
pole. I then placed the “mast” over one of the pieces or rebar. It worked
well (and if my grandmother was still alive she'd probably ask why I was
putting up a clothes line.....)

With the two radials (I didn't do any tuning) my analyzer showed 2.4:1 SWR
and a resistance of 20 ohms. My notation says “SWR w/G-Rod” – I assume that
meant with the two radials also attached. I then used my multi-tap UNUN to
match the RG-213 cable. I selected the 22 to 50 ohm taps and got an SWR of
1.1 and 40 ohms resistance at 1825. The other closes choice was the 28 to
50 ohm taps which yielded an SWR of 1.2 and 30 ohms resistance at 1825. I
have an old MJF-251 so I can't read R+jX, but I can guess it said I needed
a capacitor to do some matching...

The results were very encouraging, even though I was unsuccessful in
working KH1 on TB. I heard them weakly on two occasions but not well enough
to really work, just a few calls here and there to try to catch them on QSB
peaks. On their last day they were rising up nicely near my SR, then
suddenly sent QRX 10 at my SR-10. Well, they didn't get back on until my
SR+20, and they were down in the proverbial mud by that time. Nuts. I will
let George AA7JV regale the group with what happened during those 30
minutes if he so desires, but after hearing about it, an “Act of God” would
be a most appropriate title for those 30 minutes! Great job by the KH1 team
overall!

Now for the encouraging news. I was able to work Manuel LU5OM on two
occasions with the INV-L and elevated radials (in July). After the first
QSO he emailed me and said I was a nice 559 with QSB. During this time Phil
VK6GX made numerous attempts to work me at my SR and his SS (which are
quite near each other). On my morning of the July 6th at about 0930Z he
heard me enough to answer me. Unfortunately, I did not copy him at all on
either the INV-L or BOG (or any other of my antennas that I was frantically
switching through.....) That was exciting and frustrating at the same time.
Phil is typing on the chat room “I'm answering you” and I hear nothing. A
minute or so later Pete N0FW types “He's answering you Mark” and still
nothing! At least I knew the INV-L with the 2 raised radials was making the
trip to VK6 land ! And Phil, if you're reading this, many thanks and God
Bless you for putting up with my numerous sked requests to give me Zone 29
on TB!

Next Steps for the 2018/2019 Season: I plan to replace the 128 foot INV-L
with a longer one (probably 150 feet) and match it with an air variable
capacitor. I also plan to use a different mounting scheme that does not use
a tree branch for the vertical part, but rather a tilt base with
telescoping aluminum tubing, 50 feet min. Also I'm thinking of raising the
feed point to about 5 feet. We'll see how everything works out. Again, I
plan on using 2 raised radials. I don't think the farmer will have any
problems with me running it along her field during the winter. Phil VK6GX
said I needed to read the articles by N6LF on raised radial installations.
I briefly went over them at lunch yesterday. I may be able to use 4 raised
radials, but more than likely due to property considerations, I will only
be able to use 2.

Finally, I purchased a HI-Z 3 system from a local amateur that is retiring
from 160M. This will replace my BOG and RBOG this winter.

My intent is to have everything up and working by mid-November. Lord
willing......

73 Mark K3MSB