More on my 20 meter Endfed Zepp

I've always been a little worried about feed line loss in my portable antenna /  20 meter Endfed Zepp.

TV twin lead does have more loss then lots of other feed lines that may be used but it is light and we're talking about less than 15 feet of the stuff here. Estimates I've found on the web show .5 - 1 dB loss per 100' for dry, clean, matched TV twin lead. The loss for 15' then comes out around .1 dB. Since my intended use of this antenna is temporary QRP-in-th-Park sort of operating, keeping the twin lead clean and dry should not be a problem. If it's raining, I just QRT, packup and go home.

Loss due to mismatch at the antenna is the other issue. See K5DVW's Nov 2006 QST article posted at http://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf Assuming that the EFHW wire presents a 3000 ohm load to the 300 ohm feedline then the SWR is about 10:1. Extrapolating off the left edge of K5DVW's figure 1 chart leads me to conclude that this 10:1 feedline mismatch adds another .5 dB loss for about.6 dB total. Feedline loss for 30' of RG-58 (about the most I'd want to carry any distance) feeding a matched dipole at 14MHz is .4-.5 dB.

It appears that the feedline loss difference between 15' of twin lead feeding an EFHW wire and 30' of coax feeding a dipole is negligible.

My classic 20 meter endfed zepp antenna with quarter wavelength feed does require a tuner. While in theory the feedline could be trimmed and stubbed to present a 50 ohm load to the transmitter (see http://www.mfjenterprises.com/antennatalk8.php ) it is sensitive to antenna configuration and adjacent objects. A tuner of some sort is required to take care of the variable mismatch, but, since it is close to 50 ohms, the tuner does not need to be "wide range".

So based on my observations for this antenna -
- Some sort of tuner is required (built into many QRP rigs these days)
- Feedline loss is essentially same as coax
- Allows flexible deployment (Vee, L, vertical, sloper)
- No ground (or radial or conterpoise) requirement
- Light weight
- Entire antenna system is off the ground
- Usually requires only one support
- Optimized for one band but usually can be tuned as a random length end wire for other bands

One last visit to the Park

Yesterday it was sunny and the temperature reached 70 degrees, almost 20 degrees above normal for this time of year. Looking at the forecast it looked like this might be one last warm day until next spring. I felt a picnic table calling my name.

Beth picked up lunch at our local KFC while I set up my KX3 and 20 meter zepp at Silver Lake Park here in Rochester. The Reverse Beacon Network showed that conditions were not that good. Only one skimmer gave me a two digit signal report. After going through the effort of setting up I went ahead and called CQ.

The couple of hours on the air/eating lunch/enjoying the weather and company netted me three contacts, about average for me on one of these local QRPxpeditions: WB3AAI/4 / Florida, KF4CLO / Texas and KC2ICA / New York. QSB up and down was the norm for the day. It was neat, though, that KC2ICA was running only 1 watt to a random length wire. That was just 28 miles short of 1000 miles per watt.

Time now to crank up the heat a little and switch over to winter operating ... Boat Anchors in the Basement.

Travels with a KX3

Big Bay State Park,
Madeline Island, WI

Beth and I have just returned from a short excursion to Wisconsin. We spent a couple of nights on Madeline Island, the largest of the Apostle Islands on Lake Superior and a long weekend near

Bukolt Park
Stevens Point, WI

Stevens Point in central Wisconsin. Of course my KX3 bag was one of the first things in the car.

My operating style is never highly competitive ... I find a picnic spot with a handy tree  (and, maybe, a good view), setup and then call CQ while checking the reverse beacon network to see if anyone might hear me. During this trip I was on both 20 and 30 meter CW working both coasts and as far south as MO. Along the way I also got to talk about ham radio to curious passers-by that happened to notice the wire in the tree and the techie looking gizmo on the table.

Spring 2015 in the Park

It is warming up nicely here in SE Minnesota and the city parks are finally open. Yesterday I took my KX3 along with my 20 meter end fed zepp to Essex park here in Rochester. I didn't have a lot of action but both QSOs were neat. I finally had to QRT when the high school kids started showing up for prom photos and it looked like I might be in the background.

My first QSO was with NM5S in the Magdalena Mountains of New Mexico. He was operating SOTA (Summits on the Air). I've activited a couple of summits but no 10 pointers like Alan was yesterday. Later this summer I'll probably find a summit or two to activate myself.

My second QSO was with N1SZO. Rod was running 170mW using a

Rockmite transceiver and a 1/2 wave vertical. He was almost 100% copy here in MN, that's 5600 miles per watt!

I'm looking forward to more QRP outings to the park but next time I'll pack along a Coke and the BBQ grill so that I can make a day of it.

Back Home

Beth and I just returned from a 5100 mile road trip. My KX3 went along. Even with hot weather and family obligations I managed a few picnic table QRP QSOs.

One of our first stops was Pratt, KS. With 4 hours of free time I asked around for the local park. Lemon Park has lots of trees, shade and tables...prefect for my afternoon. I had nice QSOs with K5KW on 40 and W7LXN on 30

Another stop was Pullman, WA. Here I had an afternoon in Sunnyside Park. I set up next to a walking trail and the frizbee golf course so I had a couple of eyeball QSOs in addition to the ham radio ones. From here I worked KC4ZPB, W9CC and VE3XY, all on 20 CW.

My KX3 running 5 watts CW feeding a 20 mtr endfed zepp continues to be a fun traveling companion.

Update on Another Portable Antenna

I'm pretty happy with my new end fed antenna. Using it Friday evening through yesterday afternoon I've worked NM, PA and OH on 20 and OH and TX on 30. All on CW from my back deck and 5 watt KX3. While not foreign DX, the contacts have been easy to make. Most answered my CQs. Keep in mind also that most of this time band conditions were poor because of a solar flare/storm.

This one is replacing the 58' wire in my KX3 travel bag.

Another Portable Antenna

Tonight I got on the air with my latest endfed wire and had good success working both New Mexico and Pennsylvania.

I've been concerned about running a non-resonant endfed 58' wire with a single counterpoise laying on the ground. It sort of felt like an off center fed windom with half of the antenna on the ground.

I put together a 20 mtr end fed zepp (14'3" of TV twin lead with the hot side feeding 33'3' of wire) and arranged it as a sloper with the KX3/feedpoint on my deck about 8' off the ground, the twin lead/wire connection about 20' off the ground,  and the far end of the antenna about 1' off the ground. Now the ground side of the antenna system is up in the air rather then laying on the ground. It seems to work pretty good on 20 and as a bonus the KXAT3 antenna tuner can also load it up on 40, 30, 17 and 10. (Not the most efficient radiator on these "bonus" bands but if I can make contacts it is good enough). The reverse beacon system at http://www.reversebeacon.net says I'm getting out.

Besides set up as a sloper (more or less) this antenna can be deployed as an inverted V, an inverted L or a vertical...mostly how ever is convenient to get some part of it up in the air. The 33' 3"portion of mine is Radio Shack insulated 18 gauge stranded copper wire. It runs over tree limbs just fine. Unfortunately Radio Shack no longer sells the light weight twin lead that I used...but any twin lead or ladder line will work but the 14'3"length will need to be adjusted depending on the twin lead velocity factor.

(Just an additional note....where did 33'3" and 14'3" come from?
What I have is a 20mtr EFHW with a quarter wave matching section. At 14.060 MHz a EFHW is 468/14.060 or 33.3'. Even the KX3 ATU can't match this 33'3" wire directly, it is too high of an impedance. The quarter wave matching section transforms the high impedance feedpoint of the EFHW to a lower impedance that the KX3 can handle. At 14.060MHz a quarter wave is 246/14.060 or 17'6". Assuming a velocity factor of 80% gets the length to 14'3". )

(Something else, the  KXAT3/tuner is still needed, even on 20. Nothing's perfect and the twin lead quarter wave matching section can only be said to transform high impedance to low impedance. How high and how low changes with how/where this antenna is deployed. The KXAT3/tuner covers the variable.)