Sunday, January 29, 2023

Sky Loop is Back

Glad to Have the Sky Loop "Pentabus" Up

After some tramping through the forest with a flashlight, field soldering, and assorted comical behavior, I managed to get the Super Sky Loop back in the trees.


This time, a five-sided rhombus sort-of-shaped thing.  A Pentabus?   Total wire this time about 470 feet, just shy of the 500' spool.   If I added more wire it would droop a bit.  The wire here is taunt between trees.    Plain 14 AWG insulated wire.  Green to hide among the trees.

Anchored in each corner with a guy-line and PVC insulator.  I can bring each corner down as needed for servicing the antenna.

Fed at the N-W Corner with 450 window line to a (legacy 2010) Palstar AT-AUTO (the version pre-Palstar split. So this would be the Kessler design).

Cost of antenna

$40 worth of guy line.
$60 worth of wire
$2 worth of zip-tie.
Surplus Window Line (I've had it for 10+ years, probably 120 feet involved here)
$8 worth of SCH-40 PVC


It tunes the following bands quite easily:

10 m
12 m
15 m
30 m
40 m
80 m


I cannot get a 1:1 VSWR on 17 or 20 m.    As close as I can get is about 1.2 VSWR on 20m and 1.8 on 17 meters.

I'm not sure why yet.  I did make some coax changes in the shack between radio and amplifier and antenna switches and so on, so the add-up of coax between Rig/Tuner/Amp has changed some since the last time I had the Loop running.   I will be experimenting with a quick fix with different lengths of coax in the shack before I look further. 


No balun/unun at all.  The AT-AUTO (for lack of a better case) is the tuner and the pi-network in the tuner does what it needs to do.

It's brilliant on 40m and 30m.  I can drive 35W on the Elecraft K3 and deliver 700W via the homebrew linear amplifier (4kV Plate voltage, Class AB-2, Grounded Grid, Pair 3-500ZG -- new valves just got 'em!)

Anyway, this is a vast improvement over the 43 foot vertical I was running.  Although the vertical was fine for 80, 40, 30, and 10, it also could not load for 20/17 either via AT-AUTO.

But the Loop is back in action.

I will making use of it to reach 40m contacts as before, DX and W's.    When I get the 20 meter load figured out better, I will reach out on 20 meters also.

Just glad it's back.

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