"Luis Mansutti IV3PRK" Wrote:
Now this is my question:
- in the original '97 QST article K9AY uses a trifilar transformer, but
later
it was suggested by many to go to separated windings and to not ground the
coax cable at the antenna (well detailed in the last ON4UN book)
- but if I use a preamplifier in the switching box I must ground it, and
also the feedline and than connect on the same ground the low impedance
side of the transformer, is it right?
Luis,
You can use your cores with 6 turns of 34 swg ec wire for the low z feeder
and 18 turns 34 swg ec wire for the K9AY wound on top of the 6 turns. You
can also use a Siemens B64290K38X38 ring core with the above winding
technique, the loss is approx. 0.5dB
The amplifier ground connects the feeder outer only. The K9AY loop ground
goes to a separate ground stake.
The feeder outer should not be connected to ground; otherwise you may get
noise induced due to the "ground loop"
Concerning your noise problem; it is possible that you may have an ingress
of mains borne noise; is you receiver and other shack equipment isolated "RF
wise" from the power line?.
Here, I use a high inductance mains filter with the power line earth
isolated from the receiver. The receiving equipment use a separate clean
earth.
73s
Andy G8LUG
Andy Ikin e-mail: sales@wellbrook.uk.com
andy@wellbrook.uk.com
URL: http://www.wellbrook.uk.com
Wellbrook Communications
The Farthings
Beulah
Llanwrtyd Wells
Powys
Wales LD5 4YD UK
Tel. 01591 620316 Int.+44 1591 620316
Manufacturers of Broadband Loop Antennas
----- Original Message -----
From: "Luis Mansutti IV3PRK" <luisprk@tin.it>
To: "Topband Reflector" <topband@contesting.com>
Sent: Tuesday, September 06, 2005 10:51 PM
Subject: Topband: Pennants/Flag report and K9AY xfmr question
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