See Update 1 or Update 2 or Update 3 or Update 4

A group of us hams met in D8 and went to the roof to asses the situation of the 80 Meter Vertical antenna. Here is what we found.

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Update 1

After contacting Joe Barger, Google Image Search, and my photo archives, I have found out more information. The mount actually does do the isolation. It is likely this product from DX Engineering. I did find pictures from 2021 that show how the wires hook up.

What we should do:

• Clean Matching Box
• Replace screws
• Make antenna and ground cables
• Reinstall matching box
• Replace guy lines with fresh Dacron (I think this is in the D8 shack)
• Test for resonance
• Hook up to radio

Email from Joe

Hi Kirk,

It’s good to hear from you. You’re doing a great job leading the club. Lots of work, but I’m sure the club members appreciate it.

Let’s see … 20+ years ago when I put the 43 ft vert up I matched it for 80m with a coil and cap in a plastic box. Of course in a couple of years the UV wiped out the plastic box, so I looked around for something a little more permanent. It’s been awhile, so I don’t recall exactly all the details, but the best I recall is I built (or maybe bought) the toroid match described in the first part of the attached article. Photo A looks similar to the picture you took of the inside of the box on the D8 roof. There are band select jumpers on the input and output that should be accessible from the outside of the box. If I had to guess, the three posts near the coax input are the input band select jumpers, the two posts on the left side of the external picture are the 80M select output shorting posts and the post on the right side of the external picture is the output to the antenna. Note that the antenna itself is isolated from ground. The matching box should be grounded and I believe it was mounted to the D8 superstructure (which also served as radials for the antenna). All of the wiring should be verified and the resonant frequency checked with an antenna analyzer (which the club should have somewhere).

That’s about it. My memory about how the box was acquired/built is very foggy. Best to make sure nothing is burned out, shorted, etc. If I built it, there should be some documentation in the D8 desk somewhere. There’s also a chance I wired the match box for 80 only since a) at the time I was primarily interested in 80 and b) running to the D8 roof to change bands was somewhat inconvenient (and annoyed the guards).

And good luck trying to keep the vertical straight. Use UV resistant non conducting material, which will eventually have to be replaced anyway. And make sure as best you can to keep people from strangling on the guys (i.e., bright colored flags at eye level at least) or the maintenance people will want to have a talk …

Let me know if you have any more questions, but I think that’s about all I can recall.

73

Joe N6KK

PDF from Joe

Update 2

On Thursday 3/6 I went to the D8 Shack (D8/3302) and worked on the box. Dr Joe Touch joined me as an observer on the teams meeting.

I tightened all the bolts in the box. and figured out that it would be better if the bolts were reversed, with the head inside the box and the screw portion outside the box. That way we can use ring connectors for the connections to the antenna and ground and not have to remove the entire screw. So I reversed the screw for the Antenna and Ground connection. I also put labels on the box inside and out for these bolts. Joe suggested the inside labels. Thanks Joe!

I then cleaned up the lid a bit and found some screws in the shack to hold it on. They are not stainless steel, so I will replace them with stainless next week.

I need to get a wire stripper/crimper into the shack so I can attach the cables to the antenna and ground points. I will schedule another meeting for next week to do that.

I also think we should replace the dacron guy lines. I searched the shack and there is no dacron that could be used to replace them so I will order some. We may have to tilt the antenna down to replace the guy lines. Those should be replaced about every 5 years. So if we replace them now, they should last until we have to evacuate D8 in 2029.

Here are some pictures of the box. We may also want to replace the band selector with a fresh cable.

Update 3

We met in the D8 Shack on 3/12/25 at 11:30 AM. We were able to make cables and add some more labels to the box. We installed the new stainless screws in the lid. We went to the roof and cut and connected the ground and antenna lines to the ground point and antenna bolt. Then we tested the SWR with the club’s portable SWR meter. It is fine. <3 for most of the band, but the high end goes up to 6. The low point is 1.6 at 3.7 MHz. We tested at the box with a short piece of BNC going to the SWR Meter. Then we hooked up the coax to the box and went back to the D8 Shack. There we discovered a very high SWR and no signal. I suspect there is a break in the coax somewhere. Meeting time was over so we cleaned up and put away stuff and then ended the meeting.

Next time we need to check the coax for breaks. I will bring my nano-vna and we can also physically walk the cable and check it out.

Update 4

3/13/25 11:30 AM. I went to the shack with my nano VNA and laptop. Scott Simpson, Kevin Kirio and Doug McNulty were online. I was able to measure the length of the cable with the Nano VNA software and it measured 160ft. This seems right. So I concluded there is no break in the cable. I measured the SWR curve and it shows the dip being between 1 and 2 MHz, and not on the 80M band of 3-4MHz. I was able to use the ATU in the Elecraft amplifier and use the system on many bands. I had good communication with Doug in Leesburg VA on 12M. I suspect we may have the matching box in the 160M mode by accident, or the loss of 1/4 of the capacitive hat has changed things too. Next time we can take my Nano VNA to the roof and do a better scan, and open the box again and confirm electrically that we are on the 80 Meter setting.