Thread: Choke enough?
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Old January 15th 04, 03:28 PM
Ken Bessler
 
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Default Choke enough?

Here's my setup: My FT-817 feeds an LDG Z100 autotuner. The
output from the tuner goes to a nearby window via 8' of RG-58
coax. There the coax is formed into a coil. The coil form was one
of those round CD-R cases (you know, the cake shaped 50 packs
you see at Wal-mart). I wound 12 turns of coax neatly around
this form, glued the turns together with superglue and baking
soda then removed the form.

The output from this choke attaches to 50' of 450 ohm ladder
line which connects to a 134' inverted V with an apex of 35'
and ends at 15'. Without the tuner, I get 2:1 SWR points at:

2.125-2.375 Mhz
3.995-4.305 Mhz
4.905-5.595 Mhz
9.335-10.605 Mhz
12.145-13.725 Mhz
16.545-18.685 Mhz
20.475-21.785 Mhz
23.765-26.725 Mhz
28.615-30.125 Mhz

Now - this morning I was talking on the phone with Barry, W4WB
of W4RT electronics and I described the antenna system to him.
His opinion was that while the choke was surely doing it's job, I
would get better performance (radiation efficiancy) if between the
ladder line and choke I would install a 4:1 balun.

What do you guys think? Kinda makes sense to me.

Ken KG0WX