Tag Archives: HF Portable

40-20-15m EFHW Round 2 – Update

WSPR results o 40m and 20m WSPR look good with the EFHW. here is 40m during nightime hours:


And 20m for just a few hours yesterday and so far this morning:


On 40m there have been 103 unique heard vs 106 heard by (@1/2 W). On 20m, this is 124 unique heard vs. 74 heard by (also @1/2 W). These numbers indicate good overall performance.

I found a great write up on how to build one of these antennas titled “A Shortened Multi-band End-Fed half Wave (EFHW) Antenna for 80-10m” by Steve Nichols, G0KYA.

I am going to do some work on how to best deploy this in the field given my typical situation (i.e. lack of tall trees). this could be a great Field Day antenna.


20m Hamstick for Balcony Operating

I discussed a 20m vertical using a hamstick for balcony operation. I put this together this afternoon and ran some tests. Here is a view of the antenna attached to a lawn chair about four feet off the ground.

The antenna performed well on receive against the 1/4 wave vertical but WSPR results were not to good. No stations heard my signal even up to 5W. Not sure if the band conditions were a factor. The only contact I made was to Costa Rica on SSB so it’s does work! The stinger was adjusted to 36″ and the SWR was below 2:1 across the band.

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 45Ā° 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:


Here is the antenna deployed on the balcony:

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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!

Field Day Antenna Selection

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 challengeĀ  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.



Field Day Preps Continue

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.

Checking Solar Panels for Portable Use

Decided to check the batteries and solar panels for portable use. Good thing I did as there is a fault of some kind on the 60W folding panel I bought off of Ebay. It started reading ~15V in bright sun but when I folded it up and then later took it out again is showing no voltage. I am going to have to open it up and debug the issue. Meanwhile I have two 4S, 10Ahr LiFePo batteries on the way. I plan to replace the Lead Acid SLA batteries in my go-boxes with these.

Update 4/20/17: The panel is hosed. I am going to try and salvage some of the cells and try to eventually rebuild it. This was a great idea but a poorly executed panel. I’ll likely buy a 50W foldup panel soon as a replacement although the other panels I have will work fine. The LiFePo batteries arrive today so I will be reconfiguring my go kits this weekend (hopefully).

Snagged a Netbook

I was going through a local pawn shop earlier this week and came across a Gateway LT4004u netbook that had just hit the floor a couple of days earlier. It turns out to be in great shape with 2GB ram (maxed out), 150GB drive and a decent set of USB and other ports. I have been wanting a netbook for its size and low power requirements to work HF portable digital modes. This little unit fit the bill perfectly and for $60 I could not go wrong. I have ordered a 12V to 19V converter so that I can use this with my solar generator. I re-installed Windows 7 on it and after hunting a bit was able to load all the orginall drivers. Only thing I plan to add to it at this time is a Bluetooth dongle so that I can control my FT-817ND with a bluetooth CAT gizmo I acquired some time ago. Battery life on this looks quite good so I’d say I lucked out.


Connectors Soldered!

I did manage to solder the connectors to the ends of the copper tubes for the variable capacitor. Don’t even bother trying this with a soldering iron as there is just not enough heat.I clamped the connectors in my vise then stacked the pipe on top. A propane torch did the heating. Warm it up for about 30 seconds then start applying solder. Once it is nice and hot the solder will wick up nicely. Keep applying solder and work your way around the connector till done. Let them cool completely before handling as they are hot! The resultant joints looks mechanically solid. On to the PE film wrapping!


Homebrew Hi-voltage Variable Capacitor is Taking Shape

I mentioned in a post a while back that I successfully built a variable capacitor out of copper pipe and polyethylene sheet as a dielectric. The PE sheet has a dielectric strength of 22 kV/mm and the capacitor I have tested has a gap of almost 2.5mm! The problem that I have been working on is how to adjust this on a 40m magnetic loop antenna that I am testing for EMCOMM NVIS use. My initial tries at this either would not work mechanically or require quite a bit of structure to build. So I sat on this project awhile hoping to find a solution. I was sitting down at church last Sunday and just before the service started…BAM! the answer just popped into my head!

The secret is soldering the SO-239 connectors to the end of the pipe that form the capacitor. In this way, I not only minimize the losses but I can make the capacitor part of the mounting structure. A quick visit to Home Depot during the week yielded various PVC fittings and hardware. Here is how the prototype is looking thus far:


The PVC cylinder in the center forms part of the structure. The screw eye will be used to hoist this up onto a suitable tree branch or other support. The bottom part of this fitting will take a 1/2″ PVC pipe as a spreader which will join two together in the center. The copper pipe is the capacitor. In this test of the mechanism, I have not soldered the SO-239’s in place or have the PE sheet on the smaller tube. The block on the end of the smaller copper pipe has a couple of lock nuts sandwiching a delrin block forming a crude bearing. The other end of the threaded rod attached to a nut force fit into the PVC support. As the threaded rod is turned the smaller pipe will move in and out of the larger pipe giving me variable adjustment. The mechanism works so now I have to figure out how to solder the connectors in place, wrap the small pipe with the 45″ long piece of 4 mil PE sheet and epoxy down the parts that need to stay fixed. I have figured that for a magnetic loop that only works on the 40m band I need an adjustment range of 5pF which is about an inch of slide. The target capacitance range is 37 to 42pF. Each turn of the screw will work out to about 1/4pF so plenty sensitive to adjustment.

Stay tuned as I get out the oven mitt and the butane torch and try and do some heavy duty soldering.