The Portable Antenna

2012-02-10T13:27:00.000-08:00

After several attempts to thread the 1/4 inch aluminum rod, I finally gave up. For the most part the threads were crooked. However with Winter being here it was time to tackle this again. This time some better tools helped. Part of the problem was the threading die getting crooked on the rod and making threads at an angle. The picture here shows my solution. I took a 2 inch square board and drilled a 1/4 inch hole in it. Sliding it on the rod ahead of the treading die keeps the die correctly aligned and makes a nice thread.

Here is the assembled PAC 12 with a 20M coil attached. You will note there is no joint in the aluminum section. Jim Bennett originally designed this to fit in a 12 inch parcel. I really did not need that so I left rod at 24 inches instead of cutting them at 12 and adding a coupler. I have added a small tripod used for spotting scopes as a base. I have tried it on the commercial version and the work fairly well. I will test it out shortly.

2011-05-03T20:58:00.000-07:00

Last September, I had the opportunity to take a trip up to Mt Evans in Colorado while visiting family. The image is from a cell phone, yes I forgot to take a real camera. The young person is my grandson. Next to me is the Elecraft K1 attached to my PAC 12 antenna set for 20Meters. The view is looking south from the peak at 14,210 ft. Tried working K9JKLR in Hebron, IN but 5 watts even at 14,000 plus feet was not enough to make the trip. Could not raise anyone else either. The view is just below the peak looking south.
The trip was pretty spontaneous and I did not know about the Summits on the Air program (SOTA) or would have tried activate Mt Evans perhaps stay longer and make some contacts.
With warmer weather headed up North, it will be time to get out for portable operations. I will be looking at a new vertical and a couple of wire antennas.
73

KC8ZTJ

Pac 12 Production

2010-08-11T19:09:00.000-07:00

James Bennett anounced on the Pac 12 Yahoo Group that Pacific Antenna was suspending production for lack of machined parts. James will not outsource so he has refunded money on current orders. So It looks like back to the original design and home brewing. Here we are cutting threads on the !/4 inch aluminum rod. Will post more as I go along. You can access the original Pac 12 here. Directions are pretty complete and it uses very available hardware. The only issue is with the Collapsible section. I have tried to contact Pacific Antenna but have not had a response yet. There a couple leads to follow. Buddipole offers a 72inch telescopic antenna with a threaded base. One is on order.

2010-08-08T10:08:00.000-07:00

Several people have asked about the Pac 12 at club meetings and Lost Team outings. Glad to see that but have also found out that Pacific Antenna has stopped taking orders due to a parts shortage. I gather that one of there suppliers has closed shop? So the club build of the Pac 12 is on hold until we can find the necessary parts. There are a couple of promising leads but will wait until we have parts in hand before proceeding.

Portable at the Red Cross Chapter House

2010-07-15T19:39:00.000-07:00

Took the Pac 12 to the Red Cross Chapter House in support of my presentation on the Soft Rock Lite II SDR radio. Everything worked well. The Pac 12 is mounted on a spotting scope stand. The scope stand has worked very well. However, one has to watch for wind as it can be blown over easily.

2010-06-22T10:27:00.000-07:00

Operating today from the same public park in Portage, Michigan. While it is not very clear, I have added a 40m counterpoise made of TV twin lead. You can barely see in the picture above. Conditions today were not so good for QRP radio. Did manage to QSO with K3MZY Leo in South Carolina using the counterpoise. Still do not have coils wound for 15M or 20M which would help.

New coils are the next project and working from a different location.

Hypothesis

2010-06-13T12:13:00.000-07:00

I wrote about the twisted feed point wires and how untwisting them seem to correct a problem. I got to thinking that maybe my contact with Pete in Minnesota was dumb luck or just better band conditions. I knew that I would have replicate the original conditions and find a way to measure the result.

I occurred to me that I could use a field strength meter. I dug out an cheap Vanco SWR/Field Strength meter. I also decided to set up a local park to get away from the antennas at home and interference they might provide. Lakeview Park in Portage, Mi is about a mile from my house and nice place to visit. Plenty of picnic tables to use as a test bench. Not exactly the same conditions as the last time but very close.

I chose the 40 meter coil and low and behold I found that I had forgotten my radials at home. However I did have a TV twin lead counterpoise so that was attached in place of the Pac 12 radials. Barely visible in the picture is an orange spot back by the tree which is my winder for the lead.

I also brought some test leads try and replicate the miss wired feed point. One can sort of see the test leads on the antenna to the right in the picture. After finding a spot on 40Meters that was clear I called CQ and took the follow reading on the Vanco FSM.

Of course the next step was to remove the test leads and retake the reading.

Viola! it worked. Test is I believe reasonably accurate. I stood in the same place both times and used the same power setting on the radio. I am confident I can replicate the test in the future. While at the park with all this equipment was able to make another CW contact with Ray KC0URL in Minnesota again.
Lesson learned.

2010-06-13T11:44:00.000-07:00

I built ( or assembled if you must) the PAC 12 portable antenna to take on a trip to Texas this past May. Pacific Antenna who make the kit, produce a fine product at a reasonable price. The kit consists of several pieces of aluminum rod threaded for 1/4-20 SAE along with several feet of 18AWG magnet wire for two coils and the forms. A more complete description can be found at Pacific Antenna Site . My kit went together well or so it seemed. I did not have time to thoroughly test the antenna once it was made before I left on my trip. The result was poor performance in the hill country of Texas.
Once back home I experienced the same lack of performance. Turns on the 40Meter coil were recounted and the whole thing reviewed. The antenna on an analyzer would tune to about a 1.1 to 1 SWR at the bottom of the 40 meter band. It behaved exactly as the designer explained howerer I could not get out on the darn thing.
I know that as a shortened radiator, performance would not be as robust as my Center Fed Zepp or even my quarter wave vertical. I was also working with 5 or 6 watts at most. so told myself to keep expectations real. One of the local elmers lent me a TV twin lead counterpoise to try out. That did not help. At this point I posted on the Pacific antenna yahoo group. The response while not helpful, at least got me to thinking about the problem. How can all of these antennas work and not mine?

Back to the elmer's house for more discussion. While listening to him talk with another local ham about his mobile antenna mount he said something that got me thinking. He said, "remember you are not just dealing with a DC circuit with the antenna but an RF circuit." This got me to thinking. Suppose my problem was at the feed point. In my haste to get the antenna ready for travel, I soldered the wires in the kit to the BNC connector and then to the screw tabs. I left the wires the length I was given and let the wires cross. Again DC thinking, they are insulated so no issue! The picture shows just about how I had the wires from the BNC connector going to the points on the antenna. Well wrong.
I resoldered the wires to make them not only shorter, but also so they are separated as much as possible.
The reward was my first contact with the K1 and the Pac12 with N0FKC Pete in Minnesota. Pete gave me a 579 signal report just before it clouded up for rain. Thank you Pete for hanging in there with my experiments. The lesson here is that one has to think like RF in working with Antennas not just DC!

2010-05-16T08:29:00.000-07:00

I am starting this to present my experiences in using portable HF antennas. Portable antennas became an issue after I had started working on learning Morse code or CW. While I had passed the 5 WPM test to upgrade my FCC license, I never used CW and eventually wound up doing mostly digital and sound card HF radio work. I finally got proficient enough to get on the air and started making CW contacts and was amazed at how much fun I was having.

This lead to my acquiring an Elecraft K1 from a local Silent Key's estate. This radio probably deserves it's own blog it has so many features in such a small space. The portability of this radio led me to look into portable HF operating. My home station has a center fed zepp and an S9 vertical. I can cover 80Meters thru 6 Meters with these. Being able to set a station in a park or take my HF station on vacation was just too much of an opportunity to resist.

Introduction

2010-05-14T08:46:00.000-07:00

Hello:
This is my first venture into blogging and have resisted until now. I have found some blogs well written and thoughtful. Others, not so much. Blogging seems to add cacophony to human discourse without the clarity provided by in depth research or fact checking. Because it is in print whether on the printed page or printed screen does not make it a fact. So violating my own tenant, I will start this blog and limit it to my experiences building portable antennas. My credentials can be found at QRZ.COM at my call sign KC8ZTJ.

I do not purport to be an expert just experienced. My blog will document my adventures in portable operating on the HF amateur radio bands. Thanks for reading.

73