Tag Archives: radio

The Go Forward Backoff

Went to Belton, TX for the Ham Radio Expo held there twice a year. Big swapmeet and convention. Picked up a trunk-lip antenna mount for the car and a multiband antenna for HF — 80m through 2m. Cool thing about the antenna is that instead of using lossy traps to keep the antenna resonant for each band, it features jacks along the length so you can use the included jumper cable to manually select each band.

I took the new kit out yesterday for a test run, and unfortunately I’m not impressed. When connected to my antenna analyzer, the SWR on the antenna looks like it could go down to 1.25:1 after tweaking the length of the whip, but the moment I connect it to my radio and push 100W, the SWR gets so bad that my radio automatically backs off its power output to save itself. 40W is the limit, apparently.

My biggest suspicion is that the antenna mount isn’t fully grounded to the car frame. The frame is an essential part of the antenna system (it functions as the ground plane for the vertical antenna), and if it’s not properly connected, that RF energy goes back down the feedline and into the radio.

The mount has a rubber pad to protect the paint on the topside, and the clamp on the underside has four set-screws, an unpainted metal plate for protection, and that’s directly against the painted underside of the lip. What I need to do is take my roll of steel grounding strap and run that under the lip clamp, over to a bolt hole under the trunk decking, down to the trunk mount, and then underneath to the frame with some sort of lock washers and bolts to dig into the paint a little. Electrical conductivity is not the same as RF conductivity, and it’s for that reason that the ground strap is necessary.

If I still don’t get any better results, I’ll have to get an ATU (Automatic Tuner Unit) and put it electrically close to the antenna mount and run a line from that to the radio. Maybe even rewire the mount with a thicker cable. As long as the ATU can get a good tune, the radio won’t care and I might be able to run full power.

All antennas are compromise antennas. Too bad I can’t run a dipole on my car, eh? More news to follow.

Surplus

Was just thinking about a guy I went to high school with. Boyd. He was a cool cat; we had mechanical drawing class together. Anyway, he was into model aircraft as a hobby. I was into model railroad. We bonded for a short few years, satellites to each other’s planet.

Funny that I remember him by full name almost 30 years later. But whatever; hope he’s doing well.

Got me thinking about my chosen hobbies. Strange, but it seems I’ve gravitated to the exact same sorts of hobbies that didn’t exist until the post-war period after 1945. Model railroads. Model planes. Ham radio. Home electronics. Hi-fi stereos. Electronic music.

Really, these are all a product of the post-war suburban ethic, that part of American culture, that part of the American landscape, that’s only made possible by a life of planned stability, of suburbs and highways and open space. That dream of owning a piece of God’s green earth, of being part of a community, of having enough free resources to dispose of that we’re allowed the luxury of committing ourselves and our talents to things that aren’t immediately necessary for survival.

I can eat just fine without a radio. I can get around OK without building my own engine.

This is all part of the American Dream, strange as it sounds. I like radio for the engineering aspect, for the technical problems, for the creative solutions, for the edification that comes from learning so much about physical laws. But I understand my privilege: I have enough disposable income to throw at these pursuits. I have enough free time to dedicate to it. I have enough time to craft it, build it, use it, enjoy it, share it, talk about it, and go to meetings about it.

Really, it’s the modern equivalent of pruning bonsai trees; it’s the human hope that we have enough, make enough, own enough, and aren’t too hungry and infirm that we can spend a few hours a week to trimming a few leaves and keeping a fruit-bearing tree so small that it doesn’t bear fruit, and we don’t starve because of it.

That, that right there, is the post-war American dream. The stuff that so many of the books that I checked out of my junior-high library showed to me. That I can have a life where I can do things that aren’t necessary for survival, that aren’t crucial to the continued existence of myself and those around me, that are fun. Fun! That’s the Dream.

I think it’s in that vast, breathless hope, that I enjoy my hobbies. And now, in repose, I understand why I do this.

Know your causes.

Mobile Power Project: Ham Radio on the go! By KG5RHR

Mobile Power Project: Ham Radio On the Go!

Intent:

It seems minor, but installing the power cables for a ham radio in a car is a major project if you want it done right. After months of thoughts and tactics, I made good on my plan to install a 25 Amp circuit into my car to power my portable amateur radio equipment. I’ve been needing this capability for a while. It gives me another option for operating away from home, allowing me to drive to any convenient spot and make HF contacts, as well as allowing me to make VHF contacts while on the road. I’ll have radio power for as long as I have gas in the tank.

It took me a while to get around to doing it, but once I started, it was two evenings well-spent. Here’s the details. Continue reading

Backstop

I’ve heard of it being done, but I kinda secretly want to wire my radio and my antenna tuner to a softball backstop fence to see what kind of signal I can get out.

I have no idea if I can match the impedance of a backstop, or if I will be able to deal with the RF coming back down the feedline to my radio. I don’t even know if the fact that the backstop is anchored in the ground with concrete and touching the ground for its entire length will cause it to be its own ground plane. Does it act as a random wire antenna? Is it a longwire antenna? Is it good only for reception? What kind of harmful harmonics does it put out? How does the pair of 45º bends with the 90º straight legs affect the radiation pattern? What’s the optimum frequency band for it?

So what the hell…I gotta try it.

Hey, if someone can make long-distance contacts by wiring their radio, amplifier, and antenna tuner to a cast-iron skillet hanging from a swing set, I can make contacts with a backstop.

Stay tuned.

First QSO, First DX

So today was a crap day, but what happened when I left work and raised my antenna was a soothing balm that made everything alright. The good news is that today I made my very first HF contact (called a QSO) on the 20-meter band with my good radio. That’s a first. Also, on the very same contact, I made my first international contact (called a DX). On the same call!

Here’s a shout out to Gil VE2MAM from Quebec, Canada, who was calling CQ/DX to collect American counties. His signal was coming in strong and clear with a little bit of fading, so I decided to give it a try. I turned up my amp power, keyed up my mic, and responded with my callsign. He eventually heard me in the noise and we had an exchange of signal reports and a few other things like my location and county. I gave him a “59” signal report, meaning he was readable and had a strong signal. He gave me a “555”, meaning I was readable, my signal was fairly good, but there was some modulation on my signal (these can be dealt with).

I’m just happy that I’m finally learning how to make it happen. As it turns out, the modular vertical antenna I’ve been using (which is ultra-portable) isn’t so good for making anything other than regional contacts. It’s easy to set up and tune, but it’s just not that efficient at putting out a radio signal. What i did tonight was string my 20-meter dipole between two trees in Mueller park. It took me a little bit of trial and error to throw the ropes high enough and get enough distance between trees so the antenna wasn’t in the branches, but I figured it out.

Gil, I certainly hope your log of our QSO doesn’t need me to submit a log from my end for you to get credit, but it was nice talking with you. 73, good sir. Merci!

First QSO, 14.289MHz 20170609 0:00 UTC

20-meter dipole strung between two trees