Monthly Archives: November 2017

Junction Box for Vertical Antenna

Here is a simple junction box I built to simplify setting up a vertical antenna. The hardware is all stainless steel. There is a 1Meg resistor across the feed-point to bleed off any static. This box will replace a coax pigtail. Ground radials connect to one lug and the vertical element to the other. The coax from the ugly balun connects directly to the UHF connector.

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Antenna Cleanup

I took down the ground beam QEC antenna and the 20m quarter wave element that I had connected to my 40m vertical today. I am not really seeing much of a difference on 20m although I need to use the tuner now.

I have some construction projects I need to finish before I make some additional antenna tests. I am building some boxes to clean up vertical antenna setups. I am also working on the phase transformer box for the 20m phased vertical experiments. There are feed lines to prepare for this.

Once I have the vertical feed boxes complete I would like to convert the vertical to an end fed with ground radials. I recall this configuration worked pretty well.

More Test Results of The Ground Beam QEC Antenna

Tried 20m FT-8 early this morning as VOACAP indicated this was the best time for EU contacts on this band. My signals were heard toward the Northeast US but very few were heard in the EU. I made no QSO’s. WSPR results over 24 hours are here:

wspr mapo

This data appears to confirm that this antenna is directional (I have it pointed at a 45° bearing from my QTH)  but the F/B ratio is still relatively poor. The antenna is about the same as the 1/4 wave vertical overall. I must say that my single reports in the forward direction on SSB have been very good. Propagation on 20m is not helping. VOACAP shows the following based on 100W SSB with the receiving antenna based on a dipole at 10m:

prop1prop2

20m has been largely dead after dark. This chart indicates that 20m contacts with this combination of antennas and power will be challenging to the EU.

Overall, The ground beam – QEC antenna is an easy to carry and deploy vertical antenna with just enough directionality to help in some situation. It is well suited to my QTH on filed day as it has a wide enough bandwidth to cover the USA and Canada.

Musings on Vertical Beam Antennas

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:

gbqec

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:

buddistick

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:

2el vert

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:

pattern

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.

More Experiments with the 2 Element Vertical Beam Antenna

I previously reported on m y attempt top build a 2 element vertical parasitic beam antenna based on a design by JP1QEC. My first attempt had mixed results and I beileve the lengths I used were incorrect and tuning was negatively influenced by proximity to a metal hurricane fence.

I contacted Mot-San, JP1QEC and he provided my with additional information including a recent article that was published in QRP Quarterly. Here is the configuration based on Mot-San’s design:

20171127_172846054_iOS

I followed this design and supported the vertical elements with the fiberglass fishing poles. It is pointed to radiate at a bearing of 45° (NE) from my QTH. First tests showed the minimum SWR was around 13.2 Mhz. I shortened the counterpoise wires by about 4 feet and that brought the min SWR to the middle of the band:

20M BEAM Custom

So the first question is whether it is directional. It is. Here is a plot of FT-8 spots after a few minutes of calling CQ:

2017-11-27_8-36-27

Hard to tell if I have reasonable forward gain improvement. So far very little activity to Europe has resulted. Best conditions to the EU would be at 7am local time so I’ll try tomorrow. Meanwhile, I have received excellent reports on SSB domestically. A quick A vs B with the 1/4 wave vertical showed about 1S unit improvement with a conact I made in Colorado. This would imply some gain.

So far so good. I’ll play with this some more over the next few days. This does look like a potentially good antenna to use on Field day as it provides good reports and is easy to setup in the field.

Local Club Seminar on Digital Voice

Our Local club C.H.A.R.R.O. held a seminar on Saturday which I was unable to attend. Part of the presentation was the following presentation by Bruce Perens, K6BP:

 

It is a very well done video by a legend in the open source community.

ARRl Sweepstakes 2017 – Roundup

The 2017 ARRL Sweepstakes was this weekend. I had some personal issues to deal with on Saturday and did not actually start working the contest until Saturday evening, 5 hours after the start of the contest. At this time of day 20m and up were closed down at the QTH. I started by working on 40m and spent most of my time there. The 40m 1/4 wave vertical worked great.I made contacts easily and the exchange was copied 100% about 95% of the time. I tried 80m on both the vertical and the DXtreme end fed and while both tuned up initially, there were problems when it came time to actually make contacts. The auto-tuner would start trying to re-tune every time I went to transmit. I only made one contact on 80m to North Texas. I worked Saturday until about 11:30 pm.

I ran a few more contacts on 40m early on Sunday morning before I left for church service. I picked up again in the early afternoon and started working on 20m and 15m. 20m was very busy and there was considerable QRM. 15m was open but there were significantly fewer stations. I struggled to make contacts initially but after about an hours they started to come in easily. I suspect that this was due to propagation changes. I quit around 5:30pm after making a few final contacts on 40m.

All in all, I worked the contest for only 6 hours and 33 minutes, made 124 QSO’s across 63 of the 83 available sections. I worked enough “rare” states that I completed my ARRL WAS for the phone endorsement using only LoTW confirmations.

What worked:

  1. Very pleased with the 1/4 wave vertical, with the IC-7300 and received several complements on my audio quality.
  2.  The Timewave ANC-4 has become easier and easier to setup and use. It is very valuable when noise conditions changes during the day. I am finding it to be effective at reducing shack noise.
  3. N1MM logger+ is very very handy for contest especially with the spectrum display on the PC with the IC-7300

What I need to improve:

  1. I don’t have a capability to work 80m and below effectively. This is a problem that I need to address as there were rich contact opportunities on 80m during the evening hours. I thought I could use the DXtreme for this purpose as I did in 2015 but I suspect there is something with that antenna that has changed. It may be time to bring it down.
  2. My foot gets tired using the foot switch. I switched back to the hand switch occasionally but I need a better switch for this purpose.
  3. Need to work on adjusting the receiver when there are many stations close in causing QRM.

I don’t really compete in contests for the prizes or fame. I work contests to test my setup over various bands and look for areas that I can improve. I think I was successful in that this year. That being said I was only 20 sections from a clean sweep mug so who knows? maybe next year?

 

 

 

2017 Field Day Results

New QST came in with the results of this years Field Day. Here is my score. My score is #3 on the following list:

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I was only one of two stations claiming a 1B1 class in the STX section and I had the higher score. Out of all STX stations reportiong across all classes I came in 54 out of 72 stations. In the 1B1 class, I came in at 60 out of 102 stations. Top score had 1371 Q’s! Overall happy with these results considering I only worked FD for about 8 hours and was running 45W on solar charged battery power. Looking forward to improving the score in 2018!

A 20m 2 element Vertical Array

I previously reported on my tests of the Garden-beam antenna. While I haven’t given up on this design I did come across some “gotchas” in my implementation. Working on this antenna lead me to think about my soil conditions which I have now measured and confirmed to be quite good due to our proximity to the Gulf coast. I also starting thinking about implementing a 2 element vertical array. So here are a few options that I am looking at trying. The first step is of course to build two 20m 1/4 verticals and match them as closely as possible. I’ll get into the spacing between the elements shortly.

After considerable research I came across the first design that looked interesting in “Practical Antenna Handbook” by Joseph Carr. The idea is to space the two elements at 1/2 wavelength and use a phase transform to switch between o° and 180° phase. The phase transformer is made using a 1:1 balun kit wired as follows:

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The switch changes the phase 180°. The arrangement give the following two patterns:

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The only “gotcha” here is the 1/2 wave spacing is about 33 feet. My backyard may not be able to accommodate this due to a slope down to the resaca as well as some patio areas having pavers. A 1/4 would work much nicer but gives the following patterns:

quarter onequarter two

Not as cool but still workable.

The last option is two use 1/4 wavelength spacing and Christman Phasing. This technique uses lengths of feedline to provide the appropriate delays into each leg to provide for 0° and 90° phasing. The feed arrangement is as follows:

twin_vertical_relay_layout_spst_

For a 20m array using RG-8X cable having a velocity factor of 0.82 and at 14.20 Mhz, the 84° line should be 13.253 ft long and the 71° line should be 11.202 ft long. When both feed-lines are equal there will be a 0° case  and the pattern will be as follows:

quarter one

The 71° feed-line can be added to either leg and creates the following pattern (direction dependent on which leg it is added to):

90 degree

So these are my options, I’ll be measuring out the backyard and see what I can accommodate. Based on my QTH, I’d like to arrange the array to point to 45° with the directions as follows:

world

I’d like to start with the first arrangement but need to confirm I have the space.

 

Working Asia on 40m FT-8 & JT-65

Band conditions on 40m to Asia have been quite good the past few days. Generally good conditions in Japan especially after 7:00 am until about 8:30 am local time. Here is my PSKreporter spots page after a few minutes of sending CQ DX this morning:

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Nice ring of stations hearing my FT-8 signals starting in Hawaii then on to Figi, New Caledonia, Australia, Indonesia, South Korea and Japan. Also notice the density of signals on the waterfall. So many stations working FT-8 that there are increasingly few open areas to park in.

In contrast JT-65 is increasingly quiet. This is actually an advantage in tha the stations that are there can pick up my signal easily with little effect from nearby strong stations. here is my JT-65 map:

2017-11-15 (2)

I am starting to get used to the pacer of FT-8 and today found the longer time on JT-65 a bit tedious. I guess it is hard to change gears and accommodate a different rhythm of QSO’s.JT-65 is definitely more relaxed now that there are fewer competing signals.

I continue to be very pleased with the performance of the 40m 1/4 wave vertical.