Tag Archives: EARCHI antenna

NPOTA activations

It’s September which means there are only four months left for the NPOTA event. As I write this there have been over 612,000 QSOs with over 11,000 activations of the 489 units. If you look at the stats you’ll see that there are only 40 units that haven’t been activated. This means that over 90% of the 489 units have been activated at least once, with many of those activated a number of times. I wonder if anyone at the ARRL and the NPS thought that this event would generate this level of interest.

Some significant portion of those 11,000 activations involved Amateur Radio in the view of the public at the units. What a great promotion for the hobby. My activations have drawn interest from people at the units that I’ve activated with the first question usually something like “what are you doing?” followed by the typical responses of either “people still do that?” or “my <fill in the blank family member> used to be an Amateur Radio operator.” All the interest I’ve seen has been very positive. I’ve enjoyed doing activations as it’s fun to be on the other end of the pile-up. It’s not like being some ultra rare DX such as Outer Swobovia but I’m not likely to travel there anytime soon so a pile-up in Wisconsin will serve. I’ve also enjoyed the chase as well. As of this moment I’ve done nine activations and have 107 units confirmed.

Wisconsin doesn’t have any National Parks but we do have five units on the list:

  • Apostle Islands National Lakeshore – LK01
  • Ice Age National Scenic Trail – TR05
  • Ice Age National Scientific Reserve – AA11
  • Saint Croix National Scenic Riverway – WR09
  • North Country National Scenic Trail – TR04

Of which two, Ice Age National Scenic Trail – TR05 and Ice Age National Scientific Reserve – AA11 have multiple locations throughout the state, many of which are very near my home or where my XYL and I camp.

Ice Age Trail - Point Beach Segment

Ice Age Trail – Point Beach Segment

NPOTA TR05 portable station

NPOTA TR05 portable station

At one activation I had some assistance from a dragonfly:

Dragonfly counterpoise

and an odd little bee that spent about 20 minutes flying around and walking about my portable station:

QRB???

QRB???

For all of the activations I’ve used my Kenwood TS-480SAT @100 Watts powered by a trolling motor battery and either my Alpha Antenna DX Sr, EARCHI end fed, or LNR EF-Quad end fed, all with good results.

NPOTA portable station

NPOTA portable station

On occasion I’ve used my folding wagon to transport the station equipment:

Portable station transport

And other times I’ve worked largely out of the back of my truck:

Ice Age Trail - Northern Kettle Moraine

Ice Age Trail – Northern Kettle Moraine

NPOTA station @ TR05 and AA11

NPOTA station @ TR05 and AA11

The current run rate is about 76,000 QSOs per month so with four months to go the final tally will probably be just over 900,000 QSOs. Maybe there will be a push through the fall and we’ll break one million QSOs for the year. Who knows.

I’ve visited a number of the units over the years and it’s been fun to work them in this event, recalling the times that I’ve visited the unit in the past. With the popularity of this event, and the interest that it has generated I wonder what the ARRL is going to come up with next. I know that I’ve enjoyed it immensely.

 

 

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

 

EARCHI antenna

The antenna I used for portable operation  last year was the BuddiPole of friend and fellow radio operator Mike, AB9ON. BuddiPoles clearly work but I wanted to build some wire antennas in order to have some additional options. The first antenna on the list is the EARCHI End Fed 6–40 meter multiband HF antenna. The EARC club used to sell kits but they don’t anymore however the instructions are on their site here and it’s certainly not a difficult antenna to build.

The first thing that you need to do is to build the 9:1 matching transformer. It is built on a T130-2 toroid.

T130-2 Toroid

T130-2 Toroid

The instructions are plenty clear as to how to wind the transformer.

Winding complete

Winding complete

Transformer complete

Transformer complete

For the enclosure I choose a Hammond 1591B. It’s nice and small and I like the transparent blue but the side walls are a bit short so you will need to use a bulkhead chassis mount SO-239 instead of a flange chassis mount as there isn’t enough room to mount the latter.

Installed in project box with connectors

Installed in project box with connectors

Once the matchbox was completed I tested it with my MFJ-259B. I soldered some resistors in series to get 450Ω (in this case 491Ω) with the expectation of seeing around 50Ω through the frequency range.

Testing with MFJ-259B

Testing with MFJ-259B

Results were as follows:

Test results

Test results

 

Frequency R Ω SWR
7.000 30 2.8
7.300 31 2.7
14.000 60 1.7
14.350 60 1.7
21.000 62 1.5
21.450 62 1.5
28.000 55 1.5
29.700 58 1.5
50.000 116 3.0
54.000 148 3.7

It stays around 50Ω through the intended frequency range with the exception of 6m but that’s OK. I have other antenna choices for 6m.

The next thing to do is to attach the antenna wire and try it out.