Category Archives: HF Portable

A 20m Vertical Dipole…(I am a glutton for punishment)…

Here in South Texas you hear a lot about the Canicula. July 14 through August 24th is considered to be the hottest part of the year. It’s 94° F here today but when you add the 54% humidity we get a heat index of 106° F. So naturally I choose today to play with a new antenna!

I built a vertical dipole for 20m today using two Workman Hamsticks. I thought this would be fairly easy as I didn’t have to get it too far off the ground. More on that later…

I read that one ham had pretty good luck with the stinger set at 38″ so I set that as a starting point. I set it up vertically on a painters pole with the bottom stinger about a foot off the ground and found the SWR minimum was in the 13.5 Mhz range. I shortend the stingers and the SWR went down to the 13 Mhz range. I played with this for some time until the whole mess collapsed in the breeze. Arrrgh!

I came inside and after re-hydrating played around with the antenna again. Nothing I did seemsed to work in getting it to tune in the 14m band. I got it back to the original configuration and ventured outside again. I set it up as before and the SWR was in the 13.5Mhz range again. This time I guyed the painters pole and sent it up a few feet. The SWR started going down with the minimum frequency going up into the 20m band…Aha! I raised it up so the feed point was about 15 to 16 ft off the ground. This put the end of the stinger at about 8 feet.  Now the SWR response looked good with 2:1 or less across most of the 20m band.

Inside again now I started to tune around and found the SWR swinging again. Suspected Common Mode Currents again so went outside and lowered the antenna to 8 feet, redressed the coax so that it comes out away from the feed point at 90° for about three feet. Now everything is working out fine. I made an SSB contact to Chile and to Guatemala right off.

So here is what I learned today:

  1. It is too hot in South Texas in August to play with antennas…wait till early morning or very late in the afternoon next time.
  2. A vertical dipole needs to be a few feet off the ground to tune properly
  3. It is vitally important that the coax feed line in a vertical dipole come out at at 90° angle for several feet to avoid common mode currents.

Here is a view of the antenna:

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Here is the SWR plot:

20m dipole vert

Will run 1W WSPR for 24 hours and compare data with the 1/4 Wave vertical.

 

 

First QSO’s from South Padre Island

Setup the end fed antenna on the 3rd floor condo balcony this afternoon. This time I had about 10 feet of wire hanging off the end with the remaining 20ft aligned with the telescoping fishing pole at a 45° angle. Radio, tuner and amp were configured as before. Band conditions were generally bad. SFI of 68 with a sunspot number of zero. That being said I did manage four QSO’s over about an hour and a half. Two were on 20m and two were on 10m. Most copied me at between 55 and 57. So it works! Here is the rig on the coffee table:

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Here is the antenna deployed on the balcony:

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First Beachside Setup

Got started a bit late last night but managed to set up the beachside balcony station. I wrapped 30 feet of wire around the fishing pole and attached the end fed matchbox. I strung the coax around the balancing floor. The “mast” is self supporting in a nearly vertical orientation. I set up the FT-817ND with the tuner and amplifier set for 45w out.

The 20m band tuned right up but the band was quite dead by the late night evening. I moved to 40m and found a bit more activity but no contacts were made. The noise floor was surprisingly low on 40m considering there was lightning visible offshore. No contacts were made although I did pick up Roberto I2VRN with a solid 59. Could not bust the pileup.

All this being said will try this setup again this afternoon and try and scare up a QSO.

To the Beach!

Taking the FT-817 to South Padre Island today. I don’t have the artificial ground yet but will try without it. I can try two antennas. The first is the end fed antenna with a 9:1 matchbox. Will try and wind 30 ft of wire on the 26 foot pole. I’ll have to run with a tuner and spread out the coax on the floor of the balcony. May also run a wire down about 20 feet as a counterpoise. Next choice is a vertical 20m dipole. For that I’ll run a 16 ft wire vertical and another hanging from the balcony and use a 1:1 current balun. I am on the third floor of a wood and brick structure and an about 150 yards from the Gulf of Mexico.

Homebrew Artificial Ground

I will be operating on a third floor condo by the beach at South Padre Island, Texas soon and am thinking through the antenna. I have clear space above the balcony so a temporary vertical is certainly feasible using the new 7.2m crappie poles I just got in from Ebay. The problem is that I can’t really set up a decent ground system. An end fed vertical comes to mind but would need at least 30 ft of coax snaking around the balcony. Ground radials are out as are elevated radials. A vertical dipole would be feasible either with wire or perhaps a pair of ham sticks. Issue may be keeping the lower half coming in contact with folks in the lower balconies.

I’ll likely work out a vertical dipole but I am thinking of using an artificial ground with an end fed vertical. I have some plans for such a unit and may convert a unused manual MFG tuner to that purpose. Will scope out the site today and see what is feasible.

Update: 7/24/2017 Found a used MFJ artificial ground unit on eBay and won a low ball bid. Will try that with the end fed antenna and some counterpoise wire. 

Post Field Day Report

I got a late start to field day this year due to a late breaking family commitment. Our club tried to setup at the local weather station but cancelled operations due to a large noise source crashing the bands at that location.

I started operating about 19:30 UTC. I started at 5W on SSB but over the first hour only made one contact. The band conditions were not good on 20m with lots of QRM and QSB. I added the amplifier and started to work on 45W. My power draw was significantly higher but my Q rate increased. The solar panel kept up with the power consumption even though there was quite a bit of cloudiness. I continued to operate on 20m until dusk when I switched to 40m. Overall I made 60 Phone contacts over the course of about 8 hours. My score this year will be lower even with more Q’s due to the higher power I ran. I did not get a chance to run digital.

What worked:

  1. Digital logging – netbook needed one charge cycle during this period. The 12V to 18V DC-DC converter was running at abou 2.2A during the charging cycle. I used a 7Ahr for this through a spare Solar Charge controller. I am going to look at a tablet for next year.
  2. The EFHW antenna worked great on 20m.
  3. SOTAbeams travel mast + TV tripod worked great to support antenna with no guy lines.
  4. Solar generator box had enough juice to supply the day’s activity even at the higher power consumption and had some power to spare.
  5. Tube Tarp came in real handy as shade. Luckily no rain on Saturday. I’ll do better with the depolyment next time as I figured out how to guy it better.

What did not work so good:

  1. Can’t run digital mode while using an amp. The amp uses the ACC port on the radio but provides no pass through. I am looking at how I can accomplish this for next time.
  2. I don’t have the battery budget to run 45W phone for 24 hours. I figure I would have run out of power after about 12 hours. Partly cloudy day didn’t help.
  3. Didn’t take advantage of more 6 stations to raise Q count.
  4. Calling CQ consumes a lot of power. Need to refactor the power budget.

So I figure my score this year for 60 SSB QSO’s + bonus points for emergency power will work out to 310 for my 1B station. I am convinced now that I have to finish learning CW so that next year I can run 5W on CW and up my point count. A more directional antenna would be nice but a portable beam antenna remains elusive. For some reason I seemed to be doing better with stations in California than on the more densely populated east coast.

In summary, A great afternoon of outdoor radio fun and already looking forward to next year.

Field Day Preps Complete!

My Field Day preps are done. Tested the EFHW and its ready to roll on 20m and 15m. There is 12Ahr of solar charged battery ready as well. I won’t be able to join the club at the NWS office as I have a commitment in the morning I have to deal with. I may start late but I am ready for operations in the backyard. Will get some water bottles and snacks for daytime ops. There is a 30% of rain tomorrow afternoon so I’ll keep an eye on that as well to see if I need to deploy the tarp tent. Rain means clouds so that may help moderate the heat. Today the NWS is advising people to stay indoors between 1pm and 5pm!

Tested the EFHW a bit and am finding Common Mode Current issues if I run higher than 90W. The SWR increases with power and foldback starts kicking in if I try and run at 100W. This should not be a problem on FD as I’ll be running at 5W where everything behaves itself. I’ll be trying computer logging this year as well. If things get real tough on Phone I plan to try PSK31 and have setup some DM78- macros for that.

Looking forward to a great Field Day in the outdoors!

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:

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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!