Ham Radio – it’s a dirty business

I could have given this post a title such as “How I Became Dependent on Alcohol” but enough of the linguistic deception. Some of my recent experiences with operating in the field have convinced me to spend more time maintaining my equipment. Oh, and yes, alcohol does enter into it.

It started back in the spring. My wife and I were out on a multi-day trailer camping trip. The trip was scheduled to involve multiple park activations and a routine check-in to a weekly 80m CW net.

It was late May in southern Ontario and the tiny winged blood-sucking pestilences were out in force. I was sitting at a picnic table, all set up ready for the net. I knew my keying would be erratic (or more so than usual) if I had to continually swing my bug blatter at all the determined aerial attackers zeroing in around me.

In a pre-emptive move I sprayed myself liberally with insect repellent. I heard the net control station call QNI to announce he was ready for check-ins. While still swinging my surface-to-air defense weapon I hit the memory button to send my callsign. Net control acknowledged me and invited me to transmit.

Reaching for my new CWMorse CNC machined paddles I started to send – and abruptly stopped when only the “dit” paddle seemed to be working. The “dah” paddle was silent, dead, bereft of function. My first reaction was to curse the manufacturer. I had only just taken delivery of these new paddles – could they have failed so early?

The net proceeded without me – presuming perhaps that since I was operating outdoors in an area of Ontario which is home to a community of 3000 black bears, that maybe I was involuntarily QRT.

Well, yes I was involuntarily QRT (no longer transmitting) but for a less traumatic technical reason. After flipping the cover off the paddles, I examined the contacts – everything was clean and sparkling and mechanically sound. Instinct led me to try cleaning the contacts. I tore off a small strip of paper and pulled it through the contacts on the “dah” side, then repeated the procedure on the “dit” side – just to be thorough.

“That should fix it” I thought. The net was still in progress so I tried for a re-check. Problem! Now both sides of the paddles failed to do their job. It is hard to describe the feelings I experienced at that moment while dealing with an inexplicable technical problem that was getting worse – not better. Meanwhile, the squadron of merciless mosquitoes were doing their worst; the late afternoon sun was beating down on my brow and I was running out of expletives to utter.

Maybe the old trick of using a thin strip of paper to clean delicate paddle contacts wasn’t working; I needed alcohol. The only source of alcohol available was hand sanitizer, so I tried it. That probably made the problem ten times worse. Well, to bring a long sorry story to an end, my paddles did finally respond to cleaning – but too late for the net.

Analyzing the situation later I concluded it was the bug spray that had gotten onto the paddle contacts and the hand sanitizer wasn’t at all the right product for cleaning them. By the way, my CWMorse paddles have given me excellent service since that day. My only criticism of them is the magnets on the base, for which I paid extra, are barely strong enough to deflect a compass needle!

More Problems!

Throughout the summer, and through quite a few more POTA activations I started experiencing intermittent problems with my feedline and my Common Mode Current Choke. My coax feedline was home made from a reel of good quality RG-58 I had bought for peanuts at an auction, and a pair of excellent, silver-plated PL-259 connectors. My CMC choke was wound around a FT240-43 core with a commercial RG-58 cable from which I had removed the far-end PL-259 connector and replaced it with another silver-plated connector.

I have some experience in soldering PL-259 connectors onto coax; the secret is a really hot soldering iron. Both the choke and feedline coax tested good in my shack. My nanoVNA showed better than 30dB common mode current attentuation across the 80-10m bands. The feedline coax showed 1:1 SWR into the dummy load in my MFJ-949E Versa Tuner.

But still – out in the field – intermittent problems arose randomly and unexpectedly. Most recently, I joined a group of fellow members of the Georgian Bay Amateur Radio Club in an outdoor event at an acreage belonging to one of the members. Hams and equipment were carried in an ATV deep into the bush to a site selected by the owner. It was an exciting ride but the ATV could be delicately described as being well overdue for detailing.

Swinging Through the Trees

I set up a Jungle Knot ridgeline with an A-frame tarp for shelter (mainly from the copious falling leaves) then launched a line into a tree using the technique I described in a recent post. The antenna of choice was a Rybakov (also described in a previous post) but instead of using the usual fishing pole for support, the line hanging from the tree kept the radiating element vertical. Inches from the ground the vertical and single radial plugged into a 4:1 current unun. My DIY field coax ran from the unun across the ground to my station under the tarp.

Happy Hunting Ground

QSOs came easily as I hunted SOTA and POTA stations on 17m, 20m, 30m and 40m. After a lunch break I returned to the radio and decided to go back to 20m where a lot of POTA activators were spotted. Strangely, my LDG-100 Pro auto tuner struggled to find a sweet spot. It should have recalled the settings from memory, but something was wrong.

Back in the shack I checked the feedline for continuity and shorts – all good. Then I fired some RF through the coax into the dummy load again and – high SWR! Another continuity test followed, with some brutal tugs and wiggles of the coax near the connectors, but no problem found. I ran the RF test into a dummy load once more and – 1:1 SWR?

Problem Solved

Clearly the solution was more complex than a bad solder joint, or a whisker of braid intermittently shorting to the center pin inside the PL-259. Or maybe not! Recalling my experiences from the spring camping trip I decided to try a simple cleaning of the coax connectors. Using a cotton bud soaked in alcohol I wiped inside the shells of each PL-259. The cotton bud emerged bearing a thin coating of greasy grime.

This particular feedline is used only for field portable operations, and as I have written previously, my field ops usually involve getting well away from my truck, often hiking into the bush. Feedlines get dragged through the grass, dirt, weeds and anything else mother nature uses to carpet her planet.

Parks often spray their grass with chemicals to slow weed growth and grass cutting equipment maybe leaves an oily deposit behind. Who knows what other pollutants lurk out there in the Big Blue Sky Shack! This I know, I will be doubling down on cleaning and protecting my equipment from now on.

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