We Need More Whimsy
There once was a young lady named Sue
Whose Morse was slower than glue.
Said she, I’m glad to relate
That if you’re running FT8,
I may be slow but I’m faster than you.
Portable Operation–An Antenna Idea
Nice weather, tolerable temperatures, and a ham’s fancy lightly turns to…. portable operation. Perhaps it’s a vacation, or Field Day, or a Parks On The Air operation, or any other excuse to get out and enjoy the outdoors. Whatever. Any excuse is ample.
Here with a simple, cheap, effective portable antenna:
Like I said, I’m an OT. I’m going to operate from some point accessible by car. So why not use the car body as ground with a vertical on top? This has the advantage of getting the feed point up away from Earth, and that is important for efficiency.
My shopping was done at Aliexpress.com and at the NPS store on Main St. in Layton. NPS supplied the antenna base, and the other hardware came from Aliexpress.
A square yard of Faraday cloth provides AC coupling to the top of a vehicle. Mine came with pieces of conductive tape, and I pinched one of those into a T and stuck it to the Faraday cloth for an alligator clip ground point. I roll out the cloth, and stick it down with ceramic magnets.
On top of the Faraday cloth sits the antenna base, cut from a $6 high density polyethylene cutting board, with one corner whacked out to allow easy connection to the Faraday cloth. The 5 feet are 63mm rubber covered magnetic feet (get the female thread) with spacers beneath the board. The vertical antenna mount is a 10mm extension nut with a hole drilled for easy connection via an alligator clip or banana plug.
The antenna itself is a light weight 18.4 foot telescoping antenna (~$17) with a 10mm threaded base.
You can match the antenna two different ways:
- Put a tuner at the base of the fully extended antenna, as I did. Tuners at the transceiver work for trimming slightly mismatched antennas. Tuners at the feed point are better, and keep losses down with large mismatches.
- Adjust the height of the antenna to ¼ wave for the band you are using. This approach is cheap and effective. It won’t let you do 30 or 40 meters, but it will add 6 meters to the menu.
The little black box with banana sockets houses a loading coil for 40 meters. That’s 24 turns of #18 enameled wire evenly spaced on a T-106-2 core (8.8 μHenry).
The fully extended antenna, with the tuner, works all bands, 40-10, and the effectiveness rivals that of my base station antenna. On 12 meters, retract the antenna by one section. On 40 meters, put the loading coil in series with the base.
This antenna goes up in just a few minutes, it’s cheap to build, and it’s efficient and effective, plus it does not require a tree limb for support (think Antelope Island, Farmington Bay).
My transceiver is a compact, old, but sincere IC-706MkIIG. On SSB, I run full power but on FT-8, I dial it back to about 40-50 watts. At first, I obsessed with counting and minimizing every milliamp of battery draw, but then I stopped worrying and learned to love a 50 AH LiFePO4 battery.
73 for now,
Denton
W7DB