I just recently received a pair of AS line isolator's. I had Jay + Bob modify
of the W1JR baluns.. and put 7-16 Dins on both sides of the large
NON-conductive nema box.
Inside, it consist of 4 x 'pass throughs' of RG-393 coax. IE: 3 x
external loops of
RG-393. The coax is arranged in a neat row, solenoid fashion, and not
Unlike the K9YC versions, with the external loops spread far apart, the loops
on mine are
packed in tight, 4 x 2 .4" OD , type 31 cores are used. The axis of the
cores is horizontal.
Everything is ty-rapped 16 ways to Sunday. Nothing moves, even with box
inverted and shaken.
The 4 x cores + coax are dead center in the middle of the nema box... with
loads of space below the
4 x cores. If mounted on a boom, etc, there is no stray C added.
I put my B+K 875-B LCR meter between the hot sides of both connectors and
measured 128 uh.
And 128.4 uh between the 2 x outer shields of the same connectors. Anybody
hazard a guess
what the choking Z of this arrangement would be..between 160-10m?
One of these line isolator box's will be installed on the INPUT side of my 1
in, 6 out remote switch box.
The remote box grnds the braids of all 7 x coax cables to the mast it's
mounted to. Since the line isolator
is on the INPUT side of the remote switch box, the shield on the output side
line isolator is also grnded..through
a very short piece of coax. Will the line isolator even work in this config ?
[ with the ant side of it grnded]
The 2nd line isolator is to be mounted on my SPG,in the basement, which conists
of a large sheet of
1/4" thick AL plate. The plate has a 1-0 cable running to outside 8' grnd
rod [cadwelded] . Bare 2 ga CU
wire is run just below the dirt.. all the way back to the tower.. and C
clamped, and tied into the 3 x 8' rods
at the base of the tower [ 3 x more cadwelds, below grnd level]. 2 ga [
RW-90] is used to cable from each
of the 3 x grnd rods to the 3 x tower legs.
I was planning on putting the lightning arrestor on the SPG plate, followed by
the line isolator, then the LP filter.
After drawing this out, I think the 2nd line isolator would be rendered
ineffective...since both sides of it are
bonded to the AL plate via short coax on each side. The lightning arrestor of
course is bonded to the al plate..
as is the large LP filter. If the idea is to have a High Z on the outer braid
of the coax, then grnding both sides
of the line isolator [ through short coax] I would think would render it 90%
ineffective ? Any residual RF current
on the outer braid would simply 'flow around' the line isolator... via the
SPG AL plate.
Plan B was to swap the line isolator and LP filter. Done this way.. only one
side of the line isolator is bonded to
AL plate [ant side] ... via the real short coax between line isolator + LP
filter. Will this work ? Trbl is...if I
run a 10' long, 6 ga wire / safety grnd, from RF amp chassis to SPG...
I'm back to having grnded both sides of the line
Plan C is to install the 2nd line isolator BEFORE the lightning arrestor.
Done that way, the XCVR/amp side of the
line isolator is grnded to the SPG plate... [ and not the ant side] . I
don't like the idea of the lightning arrestor
being downstream from the isolator, it may then render the lightning arrestor
ineffective, due to the high Z of the
isolator ? BTW, I have a 2nd lightning arrestor at the base of the tower,
tied into the grnd system at base
The pair of line isolator's was to just supplement the existing, individual
bead baluns used at the DE of the
4 x ants on the mast. [ 3 x yagi's = 1 x rotary dipole] .
Tnx...... Jim VE7RF
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