Tag Archives: Antennas

Completed Linked EFHW

I completed the linked EFHW later yesterday afternoon and tuned the 15m, 17m & 20m bands. I removed about 6″ of wire to tune 15m, 2″ to tune 17m and about 3″ to tune 20m. The antenna is deployed vertically on a SOTAbeams Travel pole up 30 feet. I am using a TV mast tripod as a base. In the field I would lash the mast to a fence post or other similar support.

I tested the antenna on my base rig at 100W and made three easy SSB contacts. Two of these were EU DX contacts. I  left it tuned for 20m and ran WSPR for the last 12 hours. Here is the map:

2017-06-22_7-27-12

This works out to 112 unique heard spots with 66 unique heard by spots when running 1/2W. Looks like the antenna is a winner for Field Day! Only thing I will likely try today is adding a 1:1 choke as I am seeing the SWR swing a bit on SSB transmit.

Linked EFHW Coming Together

I purchased the following for $1 at Home Depot yesterday to form links for the EFHW I plan to use for Field Day:

Photo Jun 21, 10 47 20 AM

These are buckles to make paracord bracelets. Here is how the resulting link looks like using these, a couple of cable ties and a pair of Anderson Power Poles:

Photo Jun 21, 11 01 22 AMPhoto Jun 21, 11 01 32 AM

I have made initial wire cuts for 15m, 17m, 20m and 40m. I also cut 1/10 wavelength counterpoise wires for each band. I have also prepped the Travel Mast and the TV Tripod so I will hopefully setup later this afternoon (when it cools off a bit) and tune the wires. I’ll run 15m-20m as a vertical and 40m as an inverted V.

The only other prep I am working on today is I’ve taken the solar generator box I built last year and set it up outside with the two 15W panels to charge them up.

Update: Just did the calculations on the 40m inverted V and found that I probably don’t have enough space to lay that out in the backyard due to obstacles. Will configure the first half as a vertical and then the remaining half as a sloper which I’ll aim towards the north and terminate 4 feet off the ground. Only need a radius of about 16ft. A quick run on EZNEC show the following pattern:

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Plan B for Field Day Antennas

I was pondering what I would do for a Field Day antenna after yesterday’s debacle with the Homebrew Buddipole and military mast. It just hit me a few minutes ago. I’ll run the EFHW antenna as a vertical on 20m and 15m. It is a proven performer and it is resonant thus no tuner needed. I’ll use the TV Mast tripod Cliff gave me to support it during the contest on the SOTABeams Travel mast.  What I will do this week is set that up and cut some links for 15m, 20m and possibly even 40m. Will be much more manageable as a vertical. I have 5 days to work out the details. Tomorrow morning I’ll put put the battery packs and solar panels to top off the charge. This should work!

Buddipole 1:1 Current Balun

Here is the 1:1 Current Balun for the Homebrew Buddipole antenna. I sourced the parts kit from Ebay and just had to assemble it as before. This is ready to test as soon as tomorrow. I am planning to setup the 30 ft military pole with the Buddipole for the first time tomorrow if the wind cooperates. This should work very well at 30 ft!

Photo Jun 13, 2 49 18 PM

Photo Jun 14, 5 25 02 PM

Working 40m and 17m this Weekend

I reconfigured what has become my main antenna, the 40m 1/4 wave vertical. This is still a temporary installation but I am growing increasingly happy with the results I am getting. I frankly can’t remember the last time I used the horizontal end fed. I have had to roll up the radials on occasion to mow the yard and have not yet deployed my permanent radials. Currently I am using the 30 foot travel mast from SOTAbeams to support the vertical wire and have four 27 foot radials deployed. I am using my homebrew 1:1 current balun at the feedpoint and running to the shack with 50 ft of RG-8X.

If I get the chance I’ll start operating around 6:30 am local time on 40m JT-65. I can usually snag several contacts in Japan with the occasional contact into Australia, Indonesia or the Philippines. The action is over by about 7:30am local time as the band closes quickly after sunrise.

Saturday afternoon, I was checking the bands and came across a strong VK station on 17m SSB. We exchanged signals reports in the 54 to 55 range. I moved over to JT-65 and found that there was DX activity including another VK contact. Today Sunday I am finding about the same conditions, great 40m propagation to the far east in the early morning and some light DX into Europe & South America on 17m in the late afternoon.

 

Some Thoughts On WSPR Data for Antenna Comparisons

I have been keen on using WSPR data to compare the performance of antenna systems. I haven’t worked out a detailed metric but I thought I’d share some thoughts on how the data can be broken down. When looking at 24 hours of WSPR data on a specific band I am seeing the the number of unique stations received is a clear indicator of the antenna’s overall performance and pattern. If this is enough to make the WSPR Challenge board for that period then another clear indicator. As an example, the homebrew Buddipole on 20m (even with resonance being outside the band high) came in at #22 on the WSPR Challenge site with 143 unique stations. I have been hard pressed to make the WSPR Challenge board with the end fed horizontal or the magnetic loop antenna (indoors). So the higher then number the better.

The number of stations hearing me on WSPR is a different story. The ratio of stations heard to stations hearing me is rarely equal. This really depends on the efficiency of the antenna, something that is not evaluated on receive. If I transmit at 1/2W I can expect fewer stations received than if I transmit at say 1W. This will not be a linear increase. What I am seeing is that some antennas have a high count of “heard by” stations for a given power than others. This gives a relative indication of the antenna efficiency. There may be a way to correlate this with a given antenna by testing at different power levels.

 

Vertical Weathers a Thunderstorm

We had some much needed rain at the QTH last night. I had taken down to work on the Homebrew Buddipole early last evening but left the 40m vertical in place. The storm blew through at about 4am and dropped over an inch and a half of rain with gusty winds up to 25 Mph. My wife went outside early this morning and came in to tell me we had debris in the back yard and oh by the way your antenna is bent. Doh!

Went outside expecting the worst. I have heard stories of fiberglass tubes breaking off in high winds. I was relieved to find that the antenna was indeed bent near the top, but only because the vertical wire had blow into and tangled into a tree branch holding it over. I shook it loose and it popped back vertical instantly. Three sections had telescoped back in near the base so after pulling them back out I am back in business. This SOTABeams travel mast has taken some real abuse!

Camera Tripod Adapter

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:

  1. 2″ Pipe PVC cap – These have a flat cap surface
  2. 2″ to 3/4″ PVC pipe adapter
  3. 2″ PVC pipe coupling
  4. 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:

Photo May 28, 4 35 19 PM

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:

Photo May 28, 4 35 37 PM

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.

Homebrew Buddipole Shakedown Testing

Sometime ago I built a homebrew version of a Buddipole horizontal dipole antenna. I only deployed it once to test and have not really used it much since. I am considering using this antenna for Field Day this year on the 20m band and wanted to test it out. Happy I did for several reasons. Here is the antenna deployed at 16ft with a painters pole:

Photo May 27, 1 47 33 PM

The antenna is guyed at two levels. The painters pole is inserted into a speaker stand tripod. Here is the SWR plot:

BUDDIPOLE Custom

Most of SWR is below 2 however the resonance point is outside the band on the high side.  So I have to lengthen the antenna slightly. The whips are already at their max so I will have to adjust the loading coils. One more turn on each should give me room to adjust with the whip lengths if necessary.

Something else that needs to be addressed is that the antenna swings around in the wind. I need to add an attachment point for a separate line to secure it from swinging. The old “Armstrong” method of swinging the antenna around. Finally, I need to put a true 1:1 current balun at the feed-point. I have the kit to build one and will do so this week.

The antenna has performed well. I called CQ this afternoon and made 5 contacts from South Dakota to Florida and North Carolina. Band Conditions have been fairly bad with considerable QSB. Europe will open up in a couple of hours and will try it again then.

 

 

Wire Vertical Tuning Tip

Rather than cutting off excess wire when tuning the vertical antenna, I would just gather up  and twist together a section of wire until I achieved the resonance point I was looking for. A couple of cable ties holds it in place.

Photo May 14, 1 54 34 PM