On Feb 21, 9:28 am, Eric wrote:
Any of you have any experience with the Butternut HF-9V with TBR-160S
160-meter add-on, when mounted as a ground plane with the base elevated
to, say, 20 or 30 feet?

I'm wondering how that will work with four ground plane radials as
contrasted with ground-mounting and an extensive buried radial system.

Most likely the buried radial system would be quite a bit better.

I have the ideal place to mount one, about 25 feet in elevation at the
base, and can string two radials for 160, three radials for 80, and four
radials for 40, tilted down a little (but not the 35 degrees of downward
tilt that I read somewhere is the ideal downward tilt for a ground plane
to raise the feedpoint impedance to 50 ohms).

The problem for 160 is the antenna is still real low in height as far
as
wavelength. To have *good* performance with an elevated GP and 4
radials,
you really want the base at least 1/4 wave up. Less will work, but the
number
of radials required to maintain the same performance skyrockets...

I'm hoping that those radials will also be enough for operation on 20
meters... it would be difficult (but not impossible) to also string four
more radials for 20 meters.

It might work, but it would do quite a bit better with extra 20m
radials.
If the radials are not resonant for the band in use, they won't work
very
well, and decoupling will usually be poor. You can use 3/4 wave
radials,
so if any of those low band radials come out to 3/4 wave on a higher
band,
they will work ok. But 80 or 40 meter radials won't quite work out for
that.

Ground mounting this antenna with an extensive buried radial system would
be very difficult (but not quite impossible if it would REALLY make the
difference).

What are my chances for good success working DX with this setup and about
70 watts of power?

Fairly lackluster unless the band is super quiet.

Would it be worth the extra effort to try to get the base of the antenna
up to 40 feet rather than 25 feet?

Yes and no... Will help 40 a lot. 80 some.. 160, not a whole heck of a
lot..
40 ft is still low in terms of wavelength on 160.
Say you had a ground mount with 60 radials.. To equal that ground loss
with
four radials will require the antenna to be at about 1/4 wave height.
At 1/8 wave up, you would probably need at least 30-40 to equal the
same performance. And 1/8 wave up on 160m is about 60-70 ft...
At 25 ft up, it might as well be on the ground as far as the number
of
radials needed for 160m. 20 meters would be just fine at that height
though using just 4 radials.
MK