Tag Archives: EFHW

Antenna Experiments Continue

First up is a broadband EFHW using an auto-transformer wound on an FT240-43 Ferrite toroid. I used 18 gauge doorbell wire (had to remove the outer jacket of the wire pair first. The basic wiring looks like this (thanks to PA3HHO):

2017-08-31_10-40-14

What is not shown here is a 150pF capacitor across points A & B. Here is the completed toroid:

20170831_153149704_iOS

Here I test the matching by connecting a 3.9KOhm resistor across point B & C along with the 150pF capacitor across A & B. Here is the SWR plot:

20170831_153018134_iOS

SWR is below 2:1 across nearly the entire band 80m to 12m 10m is 5:1 well within range of a tuner. I will mount this in a box with a UHF connector and two banana jacks, One for the antenna wire and the other as a ground connection. Once complete I’ll try first with 40m 1/2 wave wire. That should give me a good match on 40m, 20m, and 15m. The wire will be around 66 ft long.  I should be able to add 80m by adding a loading coil and an additional 2.5m piece of wire. Planning to un the first 10m of wire up the travel mast then bring the rest down as a sloper.

Advertisements

New Antenna Projects

I am going to build a matching transformer for a multiband EFHW antenna. The idea is to use a 1/2 wave wire and not have to use a tuner across several bands. More details to come. Also will build an inverted V for 20m to use as a reference antenna.

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.

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:

2017-06-21_13-10-142017-06-21_13-10-32

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!

20m EFHW is Back On The Air!

Lawn maintenance time again and I still haven’t permanently deployed my radials. Took the 40m 1/4 wave down today and picked up the radials.This is a tedious process but not too time consuming. I had the most difficulty in getting the travel mast to retract as it sticks sometimes. Went ahead and setup  and re-tuned the EFHW for 20m as it doesn’t need radials to get hung up in the lawn mower. I am running WSPR as NO5V/1 now to compare against earlier data. I made several USB contacts this afternoon with it. Band conditions were terrible as geomagnetic storms are still raging. The QSB was awful but I did manage to secure a solid 59 into Vancouver.

Fixes to the EFHW Matchbox

I have decided to use the EFHW antenna as my primary portable antenna. My previous reports on this antenna have centered around testing on 20m which performed quite well. I want to set this up now for multi-band operation using connection links to add or remove wire as needed to tune it on a specific band. The capacitor I used tested between 9.5pF and 310pF which would let me operate between 40m and 10m. I was disappointed to find the matchbox would barely tune up 10m and would not come even close to 40m. I originally suspected stray capacitance and yes some did exist but what I found today solved the mystery. Turns out that I had connected to the wrong lug of the capacitor which limited the upper capacitance to around 100pF. I changed the connection point and am now able to tune down to 40m but have lost 12m and 10m as there is added capacitance on the low end as well. So my plan now is to run this match box on 40m, 20m, 17m and 15m which should be a pretty good range for this point in the solar cycle. The 40m half wave will be ~ 66 feet long so I’ll likely figure a way to configure that as either an inverted L or as an inverted V.  All other configurations will be as verticals. Next step is to cut a wire length for 15m then add wire to get to each of the successive bands. Band changes will require taking it up and down but it will be resonant. The backup antenna will be the end fed 9:1 matchbox and a tuner. Both will fit nicely into the soon to be reconfigured go-box.

Busy Week on 20m WSPR

I have been running experiments on various antennas this week on 20m WSPR. NO5V is my current base antenna, the Ultimax DXtreme 53 footer up about 20 feet and horizontal. NO5V/1 is the EFHW tuned for 20m and NO5V/2 is the same wire as the EFHW but run as a non-resonant end fed with a 9:1 matchbox and about 30 feet of coax as counterpoise. I am also able to compare this data with that from N5CEY who is running a 1/4 wave vertical at his QTH about 20 miles from here. I will be looking at formally crunching the data but what is apparent is that the current base antenna is not as sensitive on receive as the vertical antennas. This is based on the WSPR Challenge results and A vs. B listening tests. The verticals are nearly equal in receive capability with the EFHW marginally the best. Both of my verticals compare well with N5CEY’s 1/4 wave vertical but he still seems to have a slightly more sensitive system as he gets better signal reports on WSPR from more DX stations.I plan to setup my own 1/4 wave vertical this week to evaluate before I turn my attention to the S9V31.

I did a quick test on 40m in the NO5V/2 configuration and was getting good 40m results as well.

Two Days of EFHW 20m WSPR Data

I got the travel mast back up and this time added some electrical tape to help keep it from collapsing. It has been fairly breezy here this week with gusts up to 15 to 20 mph which plays hob with keeping the mast deployed. I am running the 20m EFHW with on WSPR as NO5V/1 with 500mW. I have run this configuration for two full days and made the WSPR challenge list on both days. I am comparing this data with N5CEY which is a nearby station running WSPR recieve only with a 1/4 wave vertical. Here are the results:

2/27/17 – #46 with 116 unique stations recieved vs. N5CEY at #42 with 121 unique stations

2/28/17 – #46 with 122 unique stations recieved vs. N5CEY at #40 with 130 unique stations

I should note that the mast partially collapsed about 4-6 hours before 00:00 UTC on the last day and I lost about 6 feet of mast height. There did not seem to be much of a difference in performance with WSPR. When mapped N5CEY is clearing getting more DX spots. This is interesting because a 1/2 antenna should do better at lower angles than a 1/4 antenna. I suspect that I have some losses with the EFHW matchbox in terms of lossy wiring which I am going to address today and then retry

20m EFHW Vertical Revisited

Back in December, I setup the 20m EFHW antenna up as a 20m vertical and was able to make enough unique receive contacts to make the WSPR Challenge board.I have not since reproduced this performance. Today I started from scratch in a way. I first checked the matchbox I had built previously and confirmed the capacitor setting for 20m. This was dead on as before with a 3.9k Ohm resistor. Next up I replaced the 20 gauge wire with 16 gauge. This required about 30.5 feet to start out with . I setup the travel mast and the wire and then pruned it to resonance on the 20m capacitor position. I wired it up and immediately started seeing good performance on SSB compared to the end fed wire horizontal. There was a marked improvement in received signal strength. Running about an hour on WSPR showed 50 unique receive spots. Running JT65 is showing my signal making good rounds to Europe, South America and Japan.

I am going to play with this setup awhile and then turn it over to WSPR overnight and see how it does.

UPDATE: Should note that I made an SSB contact in South Carolina today and received a S9+10dB for the first time using this antenna. Right around dusk the travel mast collapsed and it was to dark to fix…sigh