November 28, 2017
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I have been doing some EZNEC & Propagation studies on various vertical configurations. First off is the Ground Beam QEC antenna. The EZNEC model looks like this:
The model indicates (and the performance seems to confirm) that this antenna is directive but the small number of ground radials causes gain to suffer. The main benefit of this antenna over a vertical is that it has some F/B reduction. Running some optimization on this models indicates some improvement by significantly lengthening the reflector. The gain increases slightly but the F/B ratio improves. Unfortunately, the reflector would have to be 7m long for a 20M antenna making deployment difficult using the telescopic fishing poles.
I was thinking about the homebrew Buddistick I built a while back and remembered it exhibited modest forward gain in the direction of the single elevated radial. Here is the model:
This antenna is somewhat directional but also has considerable high angle radiation. It would still appear to be a better performer as a beam than either the 1/4 wave vertical or the ground beam QEC antenna. Drawbacks?…not as lightweight.
My final candidate is a 2 element vertical beam. Making a few compromises in mounting I can use the fishing poles to make a full size 1/4 wave vertical on 20m using a single elevated radial. The feed point is only 3 feet off the ground. Here is the model:
This can be built in a manner very similar to the ground beam QEC. I just need to figure out how to mount the ends a bit higher. Horizontal space needed is about 16 feet greater than the ground beam QEC. here are the radiation patterns from the model:
To summarize this chart, the GB-QEC is almost equal to the 1/4 wave vertical in forward direction but with some rear rejection. The 20m Buddistick has greater forward gain, some rear rejection but considerable high angle radiation. This antenna makes a great Field day antenna at my QTH as it can point north and cover most of the USA and Canada. Finally the two element vertical beam provides 3db greater gain then the 1/4 wave vertical with 8db F/B ratio and good low angle radiation.
This info leads me to want to try the 2 element beam next. These parasitic beams are of course fixed in direction. The phased 2 element vertical array has the advantage it will provide some steering.
June 17, 2017
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I took out the military poles and tripod today for the first time with the intent of getting the homebrew Buddipole up around 30 ft. The mast itself works pretty well with the tripod hub. I mounted the Buddipole on top as I have before with the painters pole except this time I replaced the thread adapter with a 3/4″ PVC pipe adapter and used a length of pipe to fit inside the mast section. I guyed it near the top. I sent it up and it promptly got swung around in the wind and tangled in a tree. After twisting and turning awhile I got it clear and up to 28 ft then tied off the guys. I left the last section off as I did not have enough coax to get it in the shack.
Started operating on SSB and made a strong 59 contact into Arizona then noticed that my SWR was swinging around. Looked outside and saw that one half of the dipole was swinging into more of a v-beam. Moments later it fell off completely. Doh!
The section landed cleanly and did no damage but I had to take the whole thing down. Guy lines get tangled, the aluminum mast sections are burning hot to the touch and my temper starts flaring. Did I mention it’s 97 degrees outside with 51% humidity?
So I carefully sort out the guy lines, move the tripod a few feet away from the tree and place a wedge in to keep it from swinging as much. Sent it up again and adjusted the guy lines. Went back inside the shack and hooked up the SWR meter. It started a sweep and was looking good when I heard a SNAP and the meter SWR reading went full scale. I looked out the window and sure enough the half of the dipole fell again. On inspection I was not so lucky as I broke the whip off at the base. Doh!
So thus ends my Field Day Preps today.I am goign to use something much simpler next week. Either the Homebrew Buddistick which I have used before, an end fed vertical up about 30 feet or a 1/4 wave vertical for 20m with four ground radials. The Buddipole is going to be limited to lower heights using the painters pole. If I had more time I’d try an inverted V for 20m using the Spiderbeam mast.
June 12, 2017
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Working on Field Day antenna selection this week. I am down to using the Homebrew Buddipole, Buddistick or end fed vertical antenna this year. I plan to operate as 1B battery operation so I am limited to 5W on SSB. This will be my main challenge this year given the worsening band conditions as the solar cycle continues the drop.
A previous post showed some data on the homebrew Buddipole mounted at 16 ft with a painters pole. I am working on a few tweaks now that will bring resonance into the band and simplify the azimuth adjustments.
The Homebrew Buddistick served me well in 2015 but band conditions are shifting. Here is some modeling data comparing the Buddipole at various heights vs the Buddistick on 20m:
The Buddipole at 16ft and 20 ft outperforms the Buddistick down to about 25 to 20 degrees. The Buddistick has more gain below these take off angles. At 30 ft the Buddipole is better or equal to the Buddistick from 60 degrees all the way way down to zero.
One thing I could do is use both antennas and switch back and forth as needed. This would not be overly complex to do. My challenge is getting the Buddipole up above 16 ft. If I can get setup using the military poles I can get the Buddipole up to 30 ft and only use the one antenna.
June 4, 2017
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I have two more weekends to prep for 2017 ARRL Field Day. Next weekend I plan to test the Homebrew buddistick on 20m WSPR and compare to the 20m Buddipole I tested last week. I need to complete a 1:1 current balun for both of these antennas. I am also reconfiguring my go-kits. I have a case for solar power generation, another to carry gear for digital ops, and yet another for the FT-817ND and other equipment. I have also sourced a “tarp tent” which I hope to test next weekend as well. Just missing a field portable chair and table at this point. Need the shade and will need plenty of water as well.
My plan now is to run solar powered battery operation from start of the event on Saturday, run 20m & 15m through the day then switch to 40m once the sunsets and operate till the late evening. I will not likely operate on Sunday at all. I plan to start with SSB and switch to digital PSK31 if band conditions limit QRP SSB operation.
May 28, 2017
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The Homebrew Buddistick and the Magnetic Loop antenna both require mounting on a camera tripod. Up to now I had been using a tripod without the pan head and inserting the 3/4″ PVC pipe with a pressure fit. This worked OK for awhile but eventually the tripod fitting pulled out and the tripod was ruined. I have been thinking for some time about how to make an adapter that would fit the standard tripod pan head and allow me to mount the antenna. A trip to Home Depot this afternoon yielded a solution. I built a mount with these four components:
- 2″ Pipe PVC cap – These have a flat cap surface
- 2″ to 3/4″ PVC pipe adapter
- 2″ PVC pipe coupling
- A 1/4″-20 threaded insert.
Building this was simple enough. First drill an 11/16″ hole in the middle of the pipe cap. Then using a 6mm hex key drive the 1/4-20 insert into the pipe cap until it is flush. Here is the cap mounted on the tripod:
To complete this adapter install the coupling along with the 3/4″ adapter and it will be ready to mount the antenna. Here is the finished adapter mounted on the tripod:
I finished this just in time as I need it to start testing the Homebrew Buddistick as I’d like to compare it’s WSPR performance to the Homebrew Buddipole.
UPDATE 6/13/2017: This turned into a fail. I tested this mount on the mag loop antenna and the weight and balance was too much for the tripod head. The clamp mechanism snapped and rendered the head useless. I removed the head and and am back to using it as before, i.e. with the pvc pipe jammed onto the tripod vertical post.
January 11, 2017
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Fixed the homemade Buddistick but the trusty Sunpack 5200D tripod finally failed fully. I have a spare but really need to make an adapter that will allow me to use the pan head 1/4″-20 screw and some how mount a 3/4″ piece of PVC pipe. Will think this one through a bit.
May 28, 2016
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I presented a seminar today at our local Ham Club entitled “A Solar Powered Portable Station for Field Day”. Here is a copy of the presentation and an associated spreadsheet for making power budget calculations.
Solar Powered Portable Field Day Station
Power Usage Calcs for Battery
The presentation went quite well and we are getting more local ham’s attending the C.H.A.R.R.O. club seminars. Next month no seminar as it will coincide with 2016 Field Day.
April 11, 2016
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The title says it all.
I had a great first Field Day last year running as a single op battery power station and made close to 50 contacts on 5W SSB from my dad’s house in Mercedes. I plan to work the same mode as well as add some digital PSK31 to the mix. The main thing is to make sure I can run a laptop on solar power during the contest. The stress tests I am running should all help me decide what I can do for Field Day this year.
December 26, 2015
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Managed to finish rewiring some of the shack for shorter cable runs and lower RFI. The shorter cables are especially handy on the FT-817ND. I can now neatly accommodate any combination of radio, amp, tuner and SWR meter. It is crazy windy out here today so I will likely wait until next week and setup the Buddistick and run the FT-817ND at 45 watts portable.
The APRS cable project has been de;ayed by the lack of a correct cable for the radio. The correct cable should arrive on Tuesday so I will wrap that project up then.
Been rethinking the 20m-10m portable beam project and am doing some EZNEC modeling. The issues I am looking at revolve around a portable 20m 2 element yagi that I can only raise up to about 20ft versus vertical buddisticks.
November 13, 2015
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The December 2015 edition of QST published the final Field Day scores. I entered my scores this year as a 1B1B station, i.e., one operator, 5 watts or less running on battery power. If you recall I ran my first ARRL Field Day from my dad’s front porch in Mercedes, TX. I only operated for about 4 hours right after the 1800UTC start. I made a total of 45 SSB contacts on 20m and 15m during that afternoon running my solar powered FT-817ND and the homemade Buddistick.Here is my call on the QST list:
Next year more points will require that I work more stations on Phone or I have to learn CW or operate digital. It is interesting that QRP phone earns less points than QRP CW which would seem to be harder to make contacts. Oh well, good incentive to finally learn CW!