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Author Topic: de KO7i  (Read 849 times)

Offline KO7I

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de KO7i
« on: July 20, 2014, 20:32:56 UTC »
Hello, I found this club via a link from e-ham. Seems like a good web site, so I went ahead and registered.
My favorite operating event is Field Day and I have led my clubs effort (W7PIG WWA) for the past 4 years. Normally we compete in the 3A category (last year 11th overall), this year we gave 6A a try, and I think we got our butts kicked.
I am a subscriber of full size wire antenna's for the low bands in the field. On 20 & up we use small 3 el tri-band yagi's and tri-plexers. The club members like the 100W QRO category.
This year I picked up a KX3 so I brought it along to Field day. My band assignments were 15 & 40 Meters CW. During the daytime 15M CW ops I used a TS-850 as my run rig, and I used the KX3 for search and pounce ops on 40M CW. We had a 2 el 40M delta loop array up and rarely did I have to call twice, I did run the KX3 @ 10W for a small 3dB increase in signal strength.
My desire to run field day 5W QRP is very strong. Looking forward to something new next year.
Lately I have been running only the KX3 at home and have been having a lot of fun. On 40M I use a full size 1/4 wave vertical, it has 36 radials and performs very well. I am looking forward to this winter to try out a 80M wire element I added to it. I use a 33ft doublet fed with ladder line for 20M and up, it is 50 ft high on one end and 35 ft high on the other, it seems to be doing a good job.
Vy 73, Don KO7i
Don KO7i
Arlington, WA

QRP Rig: Elecraft KX3

Home Station Ant's:
Verticals 80 & 40M, with 36 radials.
Center Fed Dipole 34 ft long, 40 ft high, fed with ladder line and remote antenna tuner.

Offline W5HEH

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Re: de KO7i
« Reply #1 on: July 28, 2014, 12:03:33 UTC »
Don, sounds like your Vertical is a keeper, is it a homebrew ? i run 5 watts from my Argo Tentec 556 from the 1990s, into a OCF, looking for a better one on 40meters - i check into the 4sQRP group on 7122 Weds nites and Thurs mornings. i find a lot of QRN and M there, looking for quieter Antenna, thinking long wire or Vertical or Both to see which is best -I am thinking Delta Loop Full size , up 25-35ft is that high enough ? Have Fun, AJ 73s, and 2s, W5HEH

Offline KO7I

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Re: de KO7i
« Reply #2 on: July 30, 2014, 04:17:12 UTC »
A old contesting buddy gave me a pile of aluminum tubing. In the pile were yagi elements from tower crashes and in the pile was a base section for a Hustler 4BTV. I scabbed together enough tubing to come up with a 33 ft mono pole. I purchased tilt over base and radial plate from DX Engineering. It works pretty good. Thinking about adding another 30 radials to the antenna. The feed point impedance is about 35 ohms right now.

Vy 73, Don KO7i

Don KO7i
Arlington, WA

QRP Rig: Elecraft KX3

Home Station Ant's:
Verticals 80 & 40M, with 36 radials.
Center Fed Dipole 34 ft long, 40 ft high, fed with ladder line and remote antenna tuner.

Offline KO7I

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Re: de KO7i
« Reply #3 on: July 30, 2014, 05:07:24 UTC »
Regarding the 40M Delta Loop. You will need the apex to be 45FT high. Feed it a 1/4 wave down from the apex - this is VERY important.
We fed the loop with a 1/4 wave section of RG-11 that has been trimmed to length based upon the velocity factor of the cable. This is VERY important too. The velocity factor of our RG-11 coax cable was .659.
I found that tuning the loop to 7.150 MHz worked best.
If you build one, you won't be disappointed.
I am good on qrz, e-mail me if you want measurement details. We used #14G copper.

Vy 73, Don KO7i


Don KO7i
Arlington, WA

QRP Rig: Elecraft KX3

Home Station Ant's:
Verticals 80 & 40M, with 36 radials.
Center Fed Dipole 34 ft long, 40 ft high, fed with ladder line and remote antenna tuner.

Offline KO7I

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Re: de KO7i
« Reply #4 on: July 30, 2014, 05:22:51 UTC »
One last comment, You will find that a vertical with 30 radials will out perform a low horizontal long wire. Horizontal wires need to be 1/2 wavelength high to play well. On 40M that is 66ft. That is why my doublet is 34 ft for 20M and up, and on 40 & 80 Meters I use verticals.
Don KO7i
Arlington, WA

QRP Rig: Elecraft KX3

Home Station Ant's:
Verticals 80 & 40M, with 36 radials.
Center Fed Dipole 34 ft long, 40 ft high, fed with ladder line and remote antenna tuner.