Back in mid-November, I told the story about one of my antennas being messed up and discovering it almost accidentally when I got the tower repaired and back up.
The bottom line about that was that there was a Delrin (plastic) insulator that had gotten damaged by my overtightening a screw holding a few connections to one side of the antenna. In there, I say I'm not sure exactly how to fix it and that's pretty much where we left the topic.
In the next day or two, I contacted the manufacturer of the antenna kit, Directive Systems & Engineering (all commercial antennas are kits to some degree) and explained what happened. The owner, Terry (W8ZN). Terry told me in the year since I bought my antenna they had been starting to transition to using pressed-in, threaded inserts in the plastic specifically for this sort of problem because it had come up a few times. He offered to send me some of the new standoffs, no charge, so that I could get the work done before Thanksgiving. Those arrived on Saturday, November 19th, which was the day of my bike accident. A minor problem was that Terry told me by email that day that he thought he had a brain fart and sent me the wrong size standoffs (from a different model antenna). He told me to check the length of the replacements versus the originals and sure enough they were wrong. He then said to hang on for another few days for the correct ones. He shipped USPS Priority Mail both times and ate the cost.
Unfortunately, that Tuesday was the day the effects of my concussion from the bike accident became evident and I spent it in the ER. The standoffs ended up taking longer to get here, until this past Monday (12/5), but I wouldn't have been able to work on the antenna tower the previous week due to the dizziness from the concussion.
That's a long story, but it sets up my being able to say it took until Thursday for me to be stable enough to stand up, use a ladder and do all the other steps to getting the antenna working. I'm happy to say that I was able to replace the standoffs, taking the feedpoint of the antenna apart and rebuilding it Thursday morning, and then after waiting until the heat of the day was past, getting the tower back up and in place later on Thursday. This is the Before picture from the first post I linked to. I don't have an after picture of this area. It's hard to tell a difference looking at it, though. The main visible difference is that I coated the area with the recommended Krylon clear coat after cleaning off some of the aluminum corrosion.
Instead of an after photograph, I have before and after network analyzer plots of the antenna's performance.
I've yet to figure out how to combine before and after scans in the NanoVNA software I mentioned before, so I used my older AIM 4170. Plots from that single port antenna analyzer have appeared here before.
Because there's three traces per sweep and a half dozen sweeps, it's a bit cluttered. The VSWR plot is in red, Z (impedance) magnitude is in green and Z phase angle in purple. Green and purple can be ignored. All but the last one of these plots were taken with tower leaning over, supported by a wooden ladder and the back of the yagi (director) about 4' off the ground. The antenna was pointing about 25 degrees south of vertical. At the very left edge of the plot, 50.0 to 50.250, you can see a bunch of traces with a slight orange-red looking line a little above the redder bunch. That's after I put the tower back up and the antenna was about 25' above ground, parallel to the ground, and pointing south.
The VSWR from 50 to over 52.0 is < 2:1, and around 1.15:1 where I spend the most time. I don't even use the radio's builtin antenna tuner on this band. Because the scale is a different, it's easier to read in this plot from the NanoVNA-App. Bottom right hand plot shows VSWR.
The last couple of days have been the first time since hurricane Ian back on September 29th that the station has been fully usable, so being back to normal is a refreshing change. I've been playing on various bands since Thursday afternoon.
Oh, and you may have gathered that the dizziness from the (probably) BPPV after the concussion is around 90% gone. Certain motions mess me up, but I haven't taken one of the pills in several days, and can go hours without noticing it.
Ah, post-concussion weirdness. Just make sure you don't turn your head too quickly. And I highly recommend you get a hardhat for working around the yard or on your antennae so that bonking damage will be mitigated. You can even get a hardhat version of a cowboy or safari hat and rock it in style while also protecting you from the Glowing Orb of Pain.
ReplyDeleteGlad the fix worked.
Instead of green wire try braid and recheck.
ReplyDeleteI swear we're birds of a feather - I was trying to get the hydraulic lifters replaced in my Jeep's engine (one went bad but I am replacing the whole set) when I got cellulitis in my lower left leg. Leg's almost healed. Two days ago I found that 9 of the 16 lifters were wrong and I had to send 'em back to Rock Auto, the new ones will be here next Thursday or Friday!
ReplyDeleteWell done, SiG! Glad to hear you're on the mend.
ReplyDeleteThe vertigo usually fades away completely over time.
ReplyDeleteI have lost count of the problem sights I rewired the IFLs to correct problem transmission or receive patterns. About half of them was dumb luck as I was not sure what the problem was, usually connections as I got lucky. The other half I found kinks, fod, and bad connections that caused the problem. For my last 10 years I was the companies golden field engineer fixing the f'ups the install engineers seemed to put in place. A lot of it was luck or narrowing down the problem but not knowing how to fix it. Like a system that would cause a zero read every time the AC kicked on with the test equipment.
ReplyDeletetsquared - if you come back, I'd appreciate a little more detail, like what "IFLs" means. These are antennas, right? What frequency or wavelength? (Approximately is fine) Does a system that would cause a zero read every time the AC kicked on with the test equipment. mean that when that when the air conditioner turned on a power glitch or something reset the test equipment?
DeleteAs I usually say, "pretend I don't know anything about your expertise."