Surprisingly, it tuned up fine without one. I should have got a Smith chart when I had the VNA hooked up. A 20m ham stick in the same location needed a 150pF capacitor in order to match it.
I think you'll need the little adapter that has the threads for the spike on the bottom and the SO-239 on the side if it isn't included in the kit, but you should be able to use it as a vertical.
I wonder if the counterpoise would have made the SWL lower. I get a very low SWR, but only use the counterpoise ground mounted to the spike. On 20 meters the SWR meter on my G90 barely moved off 1:1.
Agreed, here is what comes with the JPC-7. And what comes with the JPC-12, you can see the 3 missing pieces which you can buy separately. The spike, SO-239 adapter and counterpoise, but you could easily make the counterpoise yourself.
Odd that both options come with 4 threaded extensions in spite of the dipole version having two elements. Looks like you could rig the dipole version in an L shape based on the center insulator. There is a 90 degree socket and a spot for the balun banana jack. Just guessing from the picture. It might make a passable directional vertical with a single counterpoise element. Aim the counterpoise element in the direction you want the signal to be strongest?
I just did a search on AliExpress and see that there is a JPC-12 to JPC-7 upgrade kit offered at £104 - that may be the way to achieve it - it would actually work out cheaper than buying the JPC-7 plus the missing bits... Martin (G8FXC)
Switching to JPC -12 by buying additional parts . . . The wire included with the JPC-12 (or PAC-12, same thing) is a four conductor wire that is used inside gear to connect circuit boards and so on. You are supposed to strip it down to make four separate wires to use as counterpoise, which is fine but they are extraordinary fine gauge. You don't need to buy this -- you could make a far better counterpoise yourself. Also, the "spike" that is included is almost totally worthless in compacted soil -- it may be somewhat useful in soft dirt or grass, but it's short and really the slightest breeze and the antenna falls over. When ours fell over, it broke the antenna, which means I'd also suggest you buy an extra whip. I wouldn't think the spike is anything special, at all. So, this leaves the one truly important item -- the SO-239 adaptor, with matching METRIC fastener to antenna. That's worth something -- buy that only, in my opinion, for this transition.
Dave, could there be different versions of the JPC-12? My spike worked great in 4 POTA activations at 3 different parks. I know some people bring a rubber mallet to insert the spike, but so far I have been able to insert and remove it without any extra tools. Also my ribbon cable has 10 conductors and I separated that into three ribbons. I did buy a counterpoise plate with 8 thumbscrews for the PAC-12, but have not found the need to try it. I get a good match on the bands I tried, 20 and 40 meters. For the size of the antenna I feel it has worked well with only 20 watts from mg G90. My last POTA activation I had 30+ contacts in 17 minutes.
I think you read my experience in the column. We give it a better rating for “getting out there” than durability. You’re right about the ribbon cable … I just looked at it again. Hope you’d agree that no ham needs to buy that! I’m in AZ. Spike worthless here.
Utah here. After driving an 8 foot copper clad steel ground rod into my soil, I have no illusions about how an aluminum spike would fare. I made an adapter plate for use with a camera tripod. 1/4" thick aluminum threaded 1/4"-20 for the tripod screw and a hole in it for a 10mm 1.5 bolt to attach the feedpoint assembly.
Whew . . . at last someone else with hard dirt shows up! Thank you. I think that folks back East or in Europe can't really appreciate these issues. I used to live in Ohio, and we had the most wonderful soft soil there. The topsoil, or grass, would be perfect for a stake like this (as long as it's not windy). For those with rough, concrete-like dirt, however, it's a no-go. I like your idea of the self-made tripod base! Dave
Haha! I grew up in Louisiana, just a few blocks from the Mississippi River. I installed a ground rod there by pushing it into the ground unaided. All 8 feet just pushed right in down to the last 6 inches. Granted, it had rained the day before, but still...
That is unbelievable, wow. My last 6 ft ground rod took a half day and totally wore me out. Used a fence post pounder over and over and over …
I put in 6 x 8 foot ground rods in our ground in a few hours, the ground must be a lot softer here. I used a sledge hammer and water softening of the ground to make it easier. I did another before that without the water and that took a few hours, so the water helped me a lot with the placing the ground rod.
Just curious if you drilled a hole before driving the ground rod. In hard/dry soil drilling often does help.
