This is the second installment of JohnnyMac’s Inverted L antenna project for 160m. Catch the first here. Check out the original on his forum. The ability to build your own gear and get it working is not only a rewarding skill, but both economical and can never be taken away. True preparedness comes from knowledge.
Article Two – The Execution
The items ordered and purchased locally for the proposed 160-meter, 3/8 wave, inverted ‘L’ was stockpiled in my work shed. I received the afore mentioned pneumatic potato gun i at my local ham clubs Christmas party on December 9th, so I had run out of excuses to not get “cracken” and hoist that bad boy.
I started shooting the mortar shell the next day over the selected trees. It wasn’t as easy as it might sound as temperatures were in the teens and the wind was a steady 10 mph with some 20 mph gusts to consider. Not unlike a sniper working up a dope sheet it took me awhile to get the right angel and windage to make it over the correct spot on the tree. Then also consider the temperature which as mentioned earlier, was in the teens. Apparently, the PVC ball valve leaked when outside too long due to the temperature. So, I would get one to two launches before I had to take the gun back into the cabin to warm up.
Started with 60 psi which got me up to around 70 feet, which was too low for my needs. Finally ended up having to use 120 psi to get the mortar shell and monofilament line over the 120-foot-high pine trees located in the desired locations.
Once I was successful launching the mortar at the right angle, taking windage into account, and warming the launcher to the appropriate temperature it was time to send up the first messenger line. The messenger line was Paracord, which I like to use as it is light and smooth so easier to send up first over a limb of a tree. The Paracord would eventually be pulled back with the heavier and rougher ¼”, 3-strand polyester line with a sailboat block spliced to the end. By the time I had accomplished setting the line for both trees I tied off the bitter ends of the anchor line, went inside to warm up, and start our Sunday roast.
Being close to Christmas with lots of errands to run and some poor snowy weather I didn’t get back to hoisting the wire until the beginning of the following week. I solicited my 14-year-old neighbor Gannon, who holds a General Ticket for help. We first started building the end for the antenna. Below is the finished product.
As you can see in this picture we had a piece of 1 ½” x 1-foot length of PVC pipe which we drilled two 5/16” holes about 1 ½” in on both ends which we passed a 5/16”, 3” carriage bolt through. We used lock nuts to secure the bolts against the PVC walls.
As illustrated below, we slipped a piece of heat shrink on the wire end to be used later. Bent about 1 foot of wire around a 1/16” galvanized eye and wound the bitter end three times to secure the bitter end wire to the thimble. Once done about three inches from the thimble-throat down the wire we took 2” of the cover off the main wire and 3” of coating off the bitter end and wrapped the two bare wires together then soldered. Once this was done we scooted up the shrink wrap over the soldered point and 3-wire wrap to the thimble throat and applied heat to shrink it down. Last, we warped the thimble with amalgamated tape and then over the shrink wrap. I am sure this step was not necessary but being a recovering boater and having crossed several oceans in small sailboats, I tend to go a bit overboard on connections.
Once that was accomplished we moved to the ¼” 3-strand line which would pass through the block that will be hoisted as the anchoring point for the end of the antenna. Again, we used a ¼” galvanized thimble and spliced the bitter end into the line. Now we could have just used a bowline knot instead of splicing the block and anchor point for the antenna however, a knot only gives you 50% of breaking strength of the line while a splice iii gives you 90%.
Last, we ran the bolts for both ends through their respective eyes on the PVC end piece using lock nuts to secure the bolts to the PVC. Care must be taken NOT TO OVER TORK the buts or the PVC pipe will crack.
Now let me digress just a bit to review the securing system for the antenna. As written in Part One we were using an anchoring line with a sailboat block attached to one end. The anchoring line would provide the desired height of the antenna. The adjusting line would pass through the block while the other end was attached to the antenna. This line would be used to adjust the horizontal/vertical/length and position of the antenna.
As we also discussed in Part One, the antenna wire was set up as 3/8 length of a 160-meter wave which equated out to 200 feet. We measured/determined the middle of the wire and affixed red surveyors tape at that point. Once accomplished we took a ¾” 90-degree PVC pipe and did a clinch knot around the middle of the PVC pipe and spliced the bitter end into the line. Passed the bitter end of the wire through the PVC pipe to the red surveyors tape in preparation for hoisting.
Once that was done it was time to hoist the anchor line at the north tree (Antenna horizontal end) and at the south tree (90 degree PVC elbow). Once both locations looked horizontal we hoisted the PVC Pipe end and 90-degree end using the adjusting lines in unison.
At about this time my helpers father and the clubs President whose antenna I was copying showed up. What a blessing indeed as we needed the extra hands and eyes to get the wire positioning correct and get past some tree branches in the middle of the antenna.
Using the two adjusting lines at both anchoring points, we let out or took in the wire to position it just right. One person stood away from the antenna and instructed folks to raise/lower the support or anchor line to position it just right. Once done there was hot chocolate and coffee served for all.
The next part was simple enough. I took a 2 x 6 x 48” piece of scrap board, screwed it to a log on the ground under the vertical drop of the antenna. Fastened the aforementioned 4:1 Unun Balun v to the board and ran the antenna wire to the antenna side of the balun.
Once I accomplished that task I pounded into the ground a 4’ copper ground rod under the balun/antenna wire. Ran a 4’ piece of 12 gauge wire from the grounding rod to the ground part of the balun. Measured out three pieces of wire to use as radials for the ground at: 70’, 45’,30’ and were attached to the grounding rod and ran out in a ‘Y’ pattern from the rod set at about 120 degrees apart.
Gratefully went inside to warm up and solder on the PL-259 connectors to both ends of the 100’ hank of RG-213U marine grade coax. Hooked up the coax to the balun and the other end to my Yaesu 817nd QRP radio. Waited till dark to try it out after that night’s dinner.
After dinner and with the sun set the moment of truth came. I tuned the coax using my LDG Z-817 tuner and unfortunately the tuner would not tune the antenna. However, I listened to a lot of chatter while I spun the dial.
To my surprise I heard an amazing amount of traffic on 160-meters. Finally, I threw caution to the wind, said my call during a pause of a rage chew, and was promptly invited to join the friendly QSO. The stations were hearing me and of course I could hear them. It was reported that I was coming in just above the noise but 100% readable. One of the stations asked what I was running. When I told him, I was promptly lectured on my use of a 5-watt QRP radio on the 160-meter band. I let him lambaste me and may have egged him on a bit for fun and to check out my antennas TX and RX-ing qualities. After we said our 73, I moved on up the dial to call CQ on an open frequency. I was immediately picked up by a ham about 300 miles away who gave me a signal report. Although he was hearing me like the earlier contact reported, I was just above the noise level. Regardless he was amazed that I was hitting him with the 5-watt radio on my new antenna. He strongly suggested I take an analyzer to tweak my antenna length to obtain a better resonance. I moved over to 75/80 meters and again I got several contacts tuning with the Z-817 tuner which tuned up nicely. The next day, I was able to make contacts on 20 and 40 meters too, using the Z-817 tuner.
In my next and final installment of my Home Brew, 160-meter, 3/8th wave inverted ‘L’ I will discuss the process of tuning the antenna to 160-meters.