Martin - Upon moving my K9AY loop from one QTH to another, I lost all
directivity, despite a grd rod and multiple radials. Per N4ZR's suggestion on
this site in 2009, I installed the Center-tapped bead choke described in
ON4UN's book for feeeding a Beverage. I put a second grd rod 16 ft from the
loop base along the coax direction, installed two 3 ft pieces of coax w/ 100
ferrite beads (available from DX Engineering) each joined by a double female
connector which I clamped to the rod. Once connected to the loop and feedline -
directivity restored . . . the feedline is decoupled from the system and does
not act like a radial - common mode current problem solved. I also buried the
coax and control line.
Best regards,
Alan K9MBQ
-----Original Message-----
>From: DM4iM <hamradio@vr-web.de>
>Sent: Dec 14, 2010 5:28 PM
>To: topband@contesting.com
>Subject: Topband: K9AY-loop?
>
>Topbanders,
>i set up a K9AY-Loop over the weekend and currently am testing it.
>I had nice Q's with W9ZR and VE3JM saturday night ,
>both Q's were a joy with the signal wandering from one ear to the other.
>I use a K3 with SUB-RX for the loop and a 1/2 wave dipole for the Main
>RX/TX.
>Sunday afternoon i added 3 Radials for each leg of the loop and a short
>ground rod, abt. 1m only.
>There was no improvement , it made things worse instead . Well at least
>i feel so.
>Without the radials and ground rod, i feel that the directivity is a lot
>better. OTOH, on AM-BC, the directivity is impressive with the ground
>rod and radials.
>
>What is going wrong?
>
>Is the size of the loop critical? Mine is a bit bigger (abt 2 or 3m)
>than the original design by K9AY cuz i goofed with the math...
>
>The coax is not grounded at the switch-box (it shouldn't be, right?).
>The radials are just as long as the leg of the loop,
>one is under the wire , 2 more split about 30-40 degrees each side.
>
>If i optimize the Resistor for best Null, will it work for topband only?
>
>All input welcome.
>
>
>--
>
>73,
>Martin DM4iM
>_______________________________________________
>UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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