LAA11160
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Hello all....
Wonder if anyone out there is using the K9AY terminated loop. I built
one and just got it in service last week. I also built a 50 foot vertical
with a 10 foot diameter capacity hat on the top. The vertical is tuned
with a base loading coil and has a bandwidth of approx 60-70 KHz. I am
using about 120 feet of 4 foot chicken wire for a ground screen. Off both
ends of this I have an additional 60 feet of wire just barely buried in the
ground. The antenna transmits & receives quite well.
As far as my K9AY loop is concerned..... I get good nulls when I
switch the relays but the signal strength & readability is never as good as
the vertical. I also get a lot of BCI from the AM broadcast band. I'm not
sure if this is normal.... I realize that the vertical is a resonant
antenna & the loop is not. I'm also wondering if I wound the impedance
matching transformer correctly and if I used the proper toroid form. To
take this variable out of the picture, I ordered a ICE-180 matching
transformer from Inducomm Inc. I also have a ARR preamplifier in the
outdoor control box (1 - 30 MHz). I thought at first that perhaps my BCI
was coming from intermod in the preamp. When I bypassed it however, I
still had just as much BCI, only weaker... and the desired 160M signals
were a lot weaker also. I found that without the preamp, all signals on
the loop were very weak (more ammo to convince me that the matching
transformer wasn't right).
On the loop itself, I do not have the ends of the loop elevated 5 feet
above the ground as per Gary's diagram. The loop bottom is only about 18
inches off the ground... it looks like a big triangle. If this is a
factor, I can easily elevate the loop ends up to 5 feet. I am feeding the
vertical into the main antenna port of a MFJ-1026 phasing unit... the loop
goes to the aux antenna port. It is very easy to compare the signal
strengths from both antennas this way... just turn down the gain on one,
and up on the other. It also makes it easy to use the MFJ phaser to null
out the RFI caused by my daughters Halogen floor lamp (the scourge of
amateur radio!).
I noticed that Inducomm carries some interesting bandpass filters. One
that is advertised to pass 2-4 MHz looks interesting.... If my BCI problem
isn't cured by the ICE-180 transformer I may try one of these. Any
thoughts.... similiar experiences?
73
Dick, WA3USG
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