EARCHI antenna test

With the matchbox completed the next step was to attach the antenna wire and perform some further testing in addition to some operating.

The recommended antenna wire length is 30 feet. I chose to use Wireman 532. I also chose to use a counterpoise of 16 feet of Wireman 532. The coax feedline can also serve as a counterpoise but I read varying reports of improved results with a wire counterpoise so I choose to experiment with and without one.

The antenna was supported by a Spiderbeam 12m fiberglass pole. I taped the end of the antenna to the tip of the Spiderbeam pole and stood it up, bungee corded to a picnic table.

For the first day of testing I had assistance from a friend of the  family, Ross, who is interested in Amateur Radio. It was nice to be able to show him that antennas can be as simple as a piece of wire in the air. The first day of testing I simply used my TS-480SAT, a Welz SP-220 SWR meter, and a Dentron JR Monitor antenna tuner. Power was provided by a trolling motor battery.

Portable radio setup

Portable radio setup

I hooked up the antenna, went to 20m, and checked the tune of the antenna. After a few tweeks to the Dentron I was able to work W3US, an NPOTA station at NP52, Theodore Roosevelt National Park in North Dakota. A wee bit later I attempted to break a giant pile-up with IZ5HZO and IU5DBS to no avail. Ross was suitably impressed that I could sit in my backyard in Jackson, WI and communicate with people with a piece of wire.

The first day of testing it was nice and calm. The second day that I tested it was quite a bit more windy and warm. The Spiderbeam pole collapsed on itself three times so I added some masking tape to the joints and there were no further problems.

On the second day of testing I had help from a friend and fellow operator, Josh KD9DZP who’s a newly minted General class ticket holder. Josh recently bought a used Kenwood TS-590S that we were going to A\B test with my TS-480 but we ran out of time. We’ll get to it another day.

EARCHI antenna on a Spiderbeam pole

EARCHI antenna on a Spiderbeam pole

The matchbox was dangling in mid-air about 9-10 feet from the ground. The feedline was 20 feet of RG-8X.

Matchbox

Matchbox

The cat took a well earned nap after chasing the antenna wire and walking on the feedline while putting the antenna up. He’s a big help.

Cat nap in action

Cat nap in action

Testing with the MFJ-259B directly (no tuner) both with and without a counterpoise gave the following results:

20m SWR readings
(Direct – no tuner)
Feedline – 20 ft, RG-8X
Counterpoise (cp) – 16 ft. Wireman 532

Frequency w/ cp w/o cp
14.150 7.9 6.3
14.200 7.7 6.5
14.250 7.7 6.5
14.300 7.7 6.5
14.350 7.6 6.6

40m SWR readings
(Direct – no tuner)
Feedline – 20 ft, RG-8X
Counterpoise (cp) – 16 ft. Wireman 532

Frequency w/ cp w/o cp
7.125 3.5 5.7
7.225 4.4 5.7
7.300 3.5 5.7

10m SWR readings
(Direct – no tuner)
Feedline – 20 ft, RG-8X
Counterpoise (cp) – 16 ft. Wireman 532 (I didn’t test 10m w/o counterpoise)

Frequency w/ cp w/o cp
28.300 1.5 x
28.500 1.6 x
28.700 1.7 x
28.900 1.7 x
29.100 1.8 x
29.300 2.0 x
29.500 1.8 x
29.700 2.0 x

6m SWR readings
(Direct – no tuner)
Feedline – 20 ft, RG-8X
Counterpoise (cp) – 16 ft. Wireman 532

Frequency w/ cp w/o cp
50 4.8 4.6
52 4.3 3.7
53 3.6 3.1
54 4.3 3.7

So far the antenna appears to be working well enough to add it to my portable operation. I have some more experimenting to do with the counterpoise and varying it’s length in addition to varying the length of the antenna itself.

There are a lot of resources for EARCHI antennas specifically and end fed antennas in general and I found these two blog posts helpful:

Portable Antennas: The EARCHI End Fed

Fine Tuning the End Fed Antenna

 

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