Building a Dipole
I built a 40-meter dipole yesterday, out of 14 gauge solid wire and some PVC pipe fittings. Here is a picture of the center insulator and of the ends of the feedline - and my good friend the butane soldering iron:
After soldering it all together and after liberally applying paint-on electrical tape, it was done:
I drilled holes in each of the end insulators big enough to put paracord through.
Hanging the dipole
I really wasn't sure how to do this. The only two trees that would reasonably accommodate a dipole are about 105 feet apart, on an east-west line. I bought two 50-foot pieces of paracord thinking that 65 feet of dipole plus 40 feet of cord would leave me about 30 feet of cord on each end - plenty to tie off with.
I decided that I would want to hang pulleys from each of the trees so that I could get the antenna down if I wanted to. That meant that I couldn't use the bow-and-arrow or slingshot method to get a rope up into the tree - I actually had to get up there myself. Thankfully, I have a fiberglass extension ladder that let me stand about 15 feet off the ground.
After lunch, I started outside to get busy on this. This was the point at which it decided to start snowing. I headed back inside to get a hat.
I started with the tree in the back yard. It's a maple tree with a couple limbs that could at act as ladder supports. I cut enough paracord off of one section so that it would wrap around the portion of the trunk that I wanted to tie the pulley to. I tied the rest of the paracord to the end insulator and took it up the ladder with me while my mother-in-law held the ladder steady. I tied the short cord for the pulley around the trunk, leaving about 3 inches of slack in the loop for future tree growth. Then I threaded the antenna rope through the pulley and tied it off on a lower branch.
The other end of the antenna would attach to a poplar tree in the front yard. My friend Chris offered to come by with his tree climber that he uses for deer hunting. He showed up with it, took one look at the tree, and said "Nope, tree's too big." So, I brought the ladder around to the front yard. I looked up the trunk, made a size estimate on the circumference at about 20 feet off the ground, and cut a piece of paracord off of the other 50-foot section to use as a loop to attach the pulley. I attached the rest of the cord to other end insulator and headed up the ladder.
When I got up as far as I was willing to climb, I realized that the tree trunk was somewhat larger than I had estimated. My piece of paracord for the pulley loop ended up being about a foot short of useful (not to mention about 2 inches short of making it around the trunk). I pulled up more of the antenna cord and wrapped it around the trunk, making a pulley loop before cutting the cord. (I should have done it this way the first time!)
I threaded the antenna support through the pulley and started taking up some slack, and then I tied it off to the ladder. I planned on making the antenna "closer" to the maple tree, so the tie-off point would be higher on the poplar tree. This initial tie-off was temporary, so that we could get the antenna into place. This was when I noticed something that I hadn't considered to this point.
I had obstacles.
The Obstacle Course
The first thing that the antenna ran into was my homebrew 2-meter yagi at the northwest corner of the back porch. I managed to "toss" the antenna over the yagi (it's only up about 12 feet), and then the antenna was catching on the shingles at the edge of the roof. Once it got unhooked from the shingles, it was actually mostly lined up between the two trees.
The second thing that the antenna ran into was the ornamental cherry tree about halfway between the maple tree and the poplar tree. At this point, Chris suggested that I get up on the roof. I could use the feedline to pull the antenna sideways, while Chris adjusted the tension. This worked great, and soon the antenna was out of the cherry tree. Chris suggested running the antenna across the corner of the peak of the roof right next to the cherry tree to keep it out of the tree until we tightened it - a great idea. I decided it was time to really tie off the antenna on the poplar tree, so we found a couple branch stubs to anchor the paracord and I tied it off good and tight.
Chris started adding tension to the antenna, and that's when we found the third obstacle: branches in the maple tree. Thankfully, I had a pole trimmer in the garage. Chris and I worked together to remove half a dozen small branches that were in the way, and then we started adding more and more tension.
The fourth obstacle: The paracord came off of the pulley in the maple tree. I had to bring the extension ladder back from the poplar tree and fix the pulley. Once I did that, we discovered another couple branches that needed to be trimmed. Then we were able to pull the antenna reasonably tight and tie it off to the maple tree.
My intention is to replace the "tie-off" on the maple tree with a weight instead; that way as the two trees sway in the wind, it won't change the tension on the antenna - the weight will keep that constant.
I know there are bits missing from this story; I went up and down the ladders more, and I was actually on the roof three times. Both of us ended up with muddy feet and dirty hands.
I opened the screen to the window behind my radio, shoved the end of the coax in there, and headed inside. I invited Chris in to listen to his handiwork.
Terminating the Coax
I bought a couple crimp-on solderless PL-259 connectors from Radio Shack yesterday. Yes, I know they're not perfect or ideal - but I hoped they'd work. I pulled the coax in through the window and started stripping the end of it. Note to future self: buy a coax stripper. I was in a hurry and I got careless and I gave myself a nice cut on the finger from my pocket knife. One bloody paper towel later (while my wife looked for a Band-Aid), and the coax was stripped and ready. I attached the connector, squeezed it together with a pair of needle-nose pliers, hooked it into the back of my antenna tuner, and turned on the radio.
IT WORKS!
I started by tuning where I knew I'd probably find a good signal: the semi-permanent ragchew on 7.200. I heard Ken and Keith (as mentioned earlier on the blog) in there, along with a few others (mainly from Ohio). I thanked Chris profusely for his help and he headed out to go home in the snow.
I texted Ken to let him know that I heard him on 7.200; I heard him call for me on the radio. I texted him again to let him know that I didn't yet have a microphone hooked up, and to give me a few minutes. I listened while I worked.
So I rewired it!
The microphone I bought has three issues. One, as noted earlier, is that one of the PTT wires is broken in the cable. Another, also as noted earlier, is that the plug pinout doesn't match my radio. The third issue, which I found out later, is that while the D-104 itself is a high-impedance microphone, the amplified D-104 (with the TUG-8 stand) presents a low impedance from the preamp. My radio wants high-impedance, so it looks like I'll be bypassing the preamp for now.
I started by cutting the original plug off of the cable and going back another couple inches into the cable to see if the break was right at the plug end. A quick test with the multimeter showed this wasn't the case. So, in my haste to get on the air, I improvised.
I cut off a length of Radio-Shack 4-conductor signal wire (basically green-red-black-white ribbon cable) and peeled the white and green wires off of it. I stripped one end of the red and black wires and soldered them into the bottom of the microphone; I stripped the other end of the wires and soldered them into the appropriate pins of the new mic plug that I bought. That took care of the PTT issue, as verified by my multimeter.
For the audio impedance issue, I consulted the schematic for the mic. I unsoldered the white audio wire and moved it to the terminal where the crystal mic element is fed. Now the preamp was bypassed. I soldered the cable-end of the shielded audio wire to the other two pins of the connector.
At this point, I realized that I had not run the new PTT wires through the new connector, so I couldn't actually reassemble it. I just had to plug the unsealed connector into the radio.
Here are a couple pictures of the end result:
I tuned the radio to the dummy load on the tuner and keyed up the mic (with the meter set to ALC). I could hear the click of the antenna relay, and I could adjust the mic level with the Mic control. The mic worked!
Getting on the air
I went through the transmitter tuning procedure into the dummy load in the neighborhood of 7.205, and then I switched to the antenna - on bypass. After all, I just put up a 40 meter dipole and I was on 40 meters, so I decided to skip the tuner. I was clearly putting out over 100 watts, but this time it was into my own antenna. The cross-needle meter told me that my SWR was around 1.5:1 - pretty reasonable at this point.
I texted Ken again to tell him that I had the mic working, and to ask him if he'd find a frequency to call me on. He suggested 7.205. I tuned there and heard him ask if the frequency was in use. I never heard the response, but he did - and it was in fact in use. So, I tuned around a bit. 40 meters was pretty busy tonight due to a contest, but I found an open spot around 7.275 and texted him about it. He suggested 7.276 (there was another signal a little too close to 7.275). So, he called me on that frequency and I responded.
And he heard me!
We talked back and forth for a few minutes, discussing my wiring and my antenna hanging adventures, and hearing nearby signals and the occasional carrier of someone tuning up. We talked about band conditions and about the earlier conversations on 7.200. And then I realized that I had never retuned the transmitter after moving up the band. I asked Ken to hold on for a minute while I retuned.
I peaked the Drive control, and it JUMPED. I was quite a bit out of tune! And then I dipped the Plate current - which dipped considerably. Then I peaked the Load. I switched back to LSB mode and heard Ken say he was just waiting around for me - it was nice of him to keep the frequency occupied. I replied back to him.
His response back to me was "Mike, what did you do? You just jumped at least 10 dB!" I said, "Well, Ken, I peaked the Drive and dipped the Plate!" He laughed.
We talked some more; he asked me how long the rig had been powered up. I said probably about 90 minutes. He said that there was a little bit of drift in my signal; I tuned to where he was clearer and replied to him about that. He said that I also now sounded clearer and more natural, so it looks like my transmit and receive frequencies are very well aligned.
I told him that I needed to find some supper and get ready for church. He ended by saying that I have excellent audio quality from my old D-104. That made me quite happy.
All in all, an exceptionally productive weekend for getting my old Kenwood back on the air! And now, after a little over an hour writing this down, it's about time for bed.
I'll post some pictures of the antenna when daylight returns.
73 until later - K9MJA
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