Monday, August 23, 2010

50Mhz LFA loop construction.

My 7 ele 50Mhz  G0KSC  beam  was a bit low band edge tuned.
The SWR went up to 1:1.3  at 50.300 and 1:1 at 50.000
the edge to edge dimension of the loop should be 245cm  according to G0KSC
I measured  246cm.
I calculated 1cm # 200kHz

Then i cutted  1cm of both ends (4x sawing) of DE1 and DE2.
That was not yet enough. so another time 1cm cutting. Then the matching was  optimal  between 50.000  and  50.500   rising slight to 1:1.2 at both ends.

The edge to edge size now is 142cm
I used 12mm Alu tubing  for DE1 DE2  and the other elements.
The end pieces are 10mm  2 x 1m each  leaving enough length left after bending.
DE1 & DE2   134cm  allowing 4cm both ends for the radius  of the end pieces. 
With the end pieces maximal inserted  the size is 142cm.

I tested it  F/B was real good  it all looks fine.
But the  50MHz  season is over and I replaced the beam with my HF multi-band again.
The beam waits on the attic for next season.

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