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Author Topic: Radio Vacation  (Read 752 times)

dylan

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Radio Vacation
« on: July 29, 2018, 05:56:38 PM »
Hi folks. Thanks for sharing so many great stories, reviews, and ideas.

I am planning to be on 20 and 40 meters CW this week, operating with an MTR5b and EFHW antenna from the north coast of California. I'll likely be hanging out near the middle of the CW portion of the bands, between 1-3pm pacific standard time. I think that is a -7 GMT offset. I'll send a photo and review of my temporary station once I get it setup.

Dylan

gil

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Re: Radio Vacation
« Reply #1 on: July 30, 2018, 08:24:37 AM »
So that would be 22:00 for me here in France. Maybe I'll listen on my MTR3b :)
Keep us all updated!
Gil.

dylan

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Re: Radio Vacation
« Reply #2 on: July 30, 2018, 11:26:15 AM »
I suspect that you have "heard" this radio before, I bought it from Ray. I'm still trying to figure out the best way to attach the EFHW to the QRPGuys EFHW tuner so that the antenna wire isn't pulled out from under the wing nut.

dylan

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Re: Radio Vacation
« Reply #3 on: July 31, 2018, 07:49:27 PM »
Well shucks. Called CQ for about an hour around 14.060, +/- a little and no replies. Otherwise perfect day in the woods. The EFHW tunes up with an SWR around 1.3:1. The antenna is pointing due south and elevated 10-15' above the ground.

dylan

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Re: Radio Vacation
« Reply #4 on: August 06, 2018, 09:51:53 PM »
Some updates, still trying to figure out the radiation pattern to expect from an EFHW antenna. Over the last 20 years most of my antennas have been half-wave doublets.

The 20m EFHW was setup as a "sloper" with the feed point at about 5' from the ground and terminating at about 15' from the ground. Connecting this kind of antenna to the EFHW QRPGuys tuner has always been a challenge as there aren't many options for strain relief. This time I tried something new, as I had an overhead shade that I could use as an anchor. I put a single loop in the antenna wire around a bowline tied into some paracord that was anchored from above. This transferred tension from the "long part" of the antenna wire and left me with about 3' of slack which could be connected to the tuner (attached image). I suppose you could do something similar with an anchor from below, perhaps tied to a tent peg.

I used 26 AWG "silky" wire in this latest experiment which was far lighter and easier to work with than my previous attempts with 14 AWG stranded copper wire.

The counterpoise wire was tossed out on the ground below the driven element. Tinkering with the antenna analyzer seemed to suggest that this gave the best SWR and broadest local minimum in the SWR curve.


Some questions come to mind:

1. Does this kind of strain relief (e.g. a single loop of wire) affect tuning characteristics? It didn't seem to, as my antenna analyzer reported reasonable SWR curves over the 20m band.

2. I found this neat page (http://www.qsl.net/kk4obi/EFHW%20Sloping.html) on the theoretical radiation patterns for sloping EFHW antennas, but it still isn't clear to me what the resulting radiation pattern for my recent setup should be (in theory). Based on the linked table (http://www.qsl.net/kk4obi/EFHW%20Elev%20Effects%20Sloping.html) It would appear that this antenna, hoisted to about 15' (~ 0.25 wavelength) radiates most of the energy straight up! That doesn't seem right, or does it?






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Re: Radio Vacation
« Reply #4 on: August 06, 2018, 09:51:53 PM »