Makes sense Rob.
Probably a good approach is to find the capacitance needed and use
fixed vacuum caps in lieu of a vacuum variable. Then we have a bullet
proof feed sys. Fixed vac caps are plentiful on ebay. I have collected
a bunch of them.
What height would be adequate for a 160 elevated radial to have decent
decoupling ?
I think you are right, for most hams, including me, it is hard to get
very much height
so we must compromise, but we do the best that we can do.
Bob
K6UJ
On 11/8/16 2:55 PM, Rob Atkinson wrote:
A vacuum variable for L impedance matching is unnecessary. Vacuum
variable capacitors leak eventually. It take a long time for them to
go through their ranges and you have to have the mechanics outside if
you perform remote tuning, to sense or count turns to track when the
v.v. is nearing its maximum or minimum. It is far far easier and
faster to use an air variable that rotates freely. You only need to
keep it sheltered.
Elevated radials are fine provided they are high enough to be
decoupled from earth, which for most hams is difficult to accomplish
on 160 m.
73
Rob
K5UJ
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