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.

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).

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.

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?

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

Thanks...

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

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.
_____________

I know of commercial AM broadcast stations using 6-8, ~1/4-wave radials
elevated less than 20 feet over (rocky) ground, with an antenna system
radiation efficiency meeting the FCC minimum for broadcast station use.

Also this quoted conclusion hasn't been supported by the NEC evaluations of
L.B. Cebik as given in the paper linked below. Figure 16 in that paper
shows that the gain of a vertical radiator is within tenths of a decibel of
its peak maximum value with four radials each 1/4-wave long, when the whole
system is elevated only 0.075 wavelengths above the earth (about 41 feet at
1.8 MHz).

http://www.cebik.com/fdim/fdim4.html

RF

On Feb 21, 11:56 am, "Richard Fry" wrote:
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.

_____________

I know of commercial AM broadcast stations using 6-8, ~1/4-wave radials
elevated less than 20 feet over (rocky) ground, with an antenna system
radiation efficiency meeting the FCC minimum for broadcast station use.

How does that minimum compare to the usual 120 or so radials on the
ground?


Also this quoted conclusion hasn't been supported by the NEC evaluations of
L.B. Cebik as given in the paper linked below. Figure 16 in that paper
shows that the gain of a vertical radiator is within tenths of a decibel of
its peak maximum value with four radials each 1/4-wave long, when the whole
system is elevated only 0.075 wavelengths above the earth (about 41 feet at
1.8 MHz).

Well, a model can say one thing, and the real world performance
another.
I'm not saying it wouldn't radiate. It would. But it's not going to be
any world
beater for dx. For sure, it won't be living up to it's full
potential.
Four elevated resonant radials at 40 ft are better than 4 ground mount
radials, but
at that height you really need quite a few more if you want to equal a
stout
ground mount setup. If you have 60 radials on the ground, you need
about
20-30 at 1/8 wave up to equal the same appx ground loss. And 1/8 wave
on
160 is about 60 ft or more.
When I had a 40 meter ground plane at 1/4 wave up, "four sloping
radials"
I tried using it lowered to about 1/8 wave after working on it, and I
had the mast
down. I tried it for a night. It didn't work near as well as when it
was fully up to 1/4
wave when working most anyone. VK was probably almost 2 S units down
from my
usual report, just using that crude estimate to compare. It was
noticable for sure.
If you can get up to a 1/4 wave, and have at least 4 radials, then it
is pretty good.
And even that is not quite optimum, 10 would be better. It's close
enough though...
I've read of quite a few low band ops trying verticals, with low
elevated radials, with
usually a low amount. Most of them end up scrapping it after a few
nights of #$%&,
and laying out 30-60 ground radials. Most claim it woke the antenna
up.
I'm a great fan of elevated verticals on the low bands. The one I had
on 40 was very
stout. But I don't recommend them low to the ground with only a few
radials, unless
you are ready to accept the quite noticable hit in performance.
That's what can give the verticals a bad name..
You would probably be better off setting up a good mobile antenna on a
large truck and running
coax to it. :/ No joke.
But it wouldn't hurt anything to try out what he proposes.. If it
doesn't pan out, he can
always go back and lay the wire down. It would be much better than not
operating at all.
On 160, a lot will depend on the noise level.. Some nights a weaker
signal will do ok,
other nights, it's teeth grinding torture... On the low bands, I don't
like to throw away power to the
ground, that could otherwise be radiated if I can avoid it. Sometimes
it's hard to avoid
with some locations, restrictions, etc..
It's not that I try to discourage running less than optimum verticals,
I just hate to see
people try them, and then end up thinking most all verticals perform
about the same. If they
scrimp in some way, either with height, or number, they will lose
some performance.
MK

Check out ON4UN's book on Low Band DXing. He does address elevated radials.
Certainly less than the 120 buried radials that commercial radio stations
have used.

Bill, W4WNT


"Eric" wrote in message
news

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.

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).

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.

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?

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

Thanks...

I know of commercial AM broadcast stations using 6-8, ~1/4-wave radials
elevated less than 20 feet over (rocky) ground, with an antenna system
radiation efficiency meeting the FCC minimum for broadcast station use.

wrote
How does that minimum compare to the usual 120 or so radials
on the ground?
____________

Here are the minimum h-plane, r.m.s. fields required by the FCC for
commercial AM broadcast stations of the various classes at 1 km, for 1 kW of
applied power.

1) Class A: 362 mV/m
2) Class B: 282 mV/m
3) Class C: 241 mV/m

That value for a typical 1/4-wave vertical monopole with 120 buried radials
each at least 1/4-wavelength is about 306 mV/m (regardless of frequency and
the ground characteristics at the antenna site).

The theoretical maximum h-plane r.m.s. field at 1 km from a perfect 1/4-wave
monopole over a perfect, flat ground plane is about 313 mV/m for 1 kW of
applied power.

RF