[Antennas] question about a 6BTV (long)

Mon Nov 15 15:27:17 EST 2010

Hello Ken,

	As a long time (over 40 years) user of the Hustler BTV verticals I
can give you a perfect answer to your question.

	As many as you are physically and have the $$$ to do and make them
any length you have space to put them. That's as good as it gets on the
ground.
	If you would like to read the best tutorial I have ever seen for the
effects of radials on amateur verticals, check out Rudy Stevens articles. If
they seem a bit technical then read them anyway because the highlights are
better than most of the fable data out in the Amateur world. ;>)

	Here are the links:'
His antennas home page.
http://www.antennasbyn6lf.com/

The ground systems page.
http://www.antennasbyn6lf.com/2009/12/series-of-qex-articles-on-ground-syste
m-experiments.html

Do yourself a favor and just download the files and save them to a folder
called "Ground Systems Testing by N6LF". That way you will have the data
available when you want to read it.

Basically he says put in 32 and the system will be very close to its maximum
efficiency.

Interestingly his test results for the length of wire produces a very
interesting result.
Using 40 meters as the test band, he installed a fixed number of radials and
started cutting them back from a quarter wave length and measuring the
results (figuring out the loss and efficiency of the system as a whole). He
determined that a length of 23' seemed to be the optimum for that band under
those test conditions. Interesting. This length is approx 69.69% of full
quarter length. 
So what does that mean for you and me?
If you have enough space around the location of the vertical, install
radials that are 69.69% of the quarter wave length of the lowest band you
intend to operate, OR some covenant length that fits in the space you have
that IS 69.69% of any ham band.

3.5Mhz	56 feet
7.1Mhz	23 feet
10.1 Mhz	16.1 feet
14.1 Mhz	11.5 feet
18.1 Mhz	9 feet
21.2 Mhz	7.7 feet
24.94 Mhz	6.5 feet
28.3 Mhz	5.7 feet

Now if you have a 6BTV then you don't have the 18.1Mhz and 24.9Mhz band so
you can ignore those lengths if you choose or include them in case you
decide to add those bands later with a DX Engineering kit.

So perhaps a good compromise for all bands would be say 4 to 6 radials per
band IF you have room. 32 to 48 radials if you figure 6 per band for all
bands or, 24 to 36 radials if you figure just the 6 bands. Again, only if
you have the room.

If it all seems too involved, PUNT. Just put down what WILL fit in the space
available and make them straight. If you only have 7' in one direction, 12
feet in another, 80 feet in another and 20 feet in the last direction then
follow the first rule. Whatever fits that you can afford and have the
strength to do..

Don't kill yourself. It doesn't have to be done all in the same day.
Take time laying out the radial field and put a colored top nail in the
location of the end of the radial that is the farthest away. When you have
done that now you have a defined radial field. 
Figure out the lengths and how much wire you need.  18 to 14 gage wire can
be had reasonably from places like Home Depot and Loews. I purchased a 500'
spool of 14G wire for about $26 as I recall a few months ago.

If you have a radial mounting plate, cool. If not use the mast at the bottom
of the antenna to secure each radial while you run them out.
Put them all down, OR whatever you have time and energy to do. Only 4 today,
4 tomorrow, 8 the next day, etc.

Don't forget the Noalox anti fouling and corrosion compound on the screw
hardware and the contact between all the metal parts. Wires to connections.
It keeps the corrosion off and maintains a good conductive joint.

In my own case, I basically just described my lot size to fit my radials
into. Most likely I will put them in at no more than 23 feet in length and
live with the results. More is better than length. If you 10' all around,
put in as many as you can that fit. Shoot for 32+. 

As you can see from Rudy's results, going past 60 radials doesn't gain you
much. The biggest gain is had up to about the first 32 or so.

Have fun with you antenna. The DO work. I moved into this house 11 years ago
and put mine up with 4 elevated radials per band and worked over 200
countries the first year with about 100watts output mostly on 40M in the
mornings. During the DX contests, I would be within 1 Zone of matching the
leaders so they do work.

Best 72, 73.

Michael Baker  K7DD
k7dd at cox.net

-----Original Message-----
From: antennas-bounces at mailman.qth.net
[mailto:antennas-bounces at mailman.qth.net] On Behalf Of Ken Snipes
Sent: Sunday, November 14, 2010 8:17 PM
To: Antennas at mailman.qth.net
Subject: [Antennas] question about a 6BTV

I was given a used , but it real good shape, a 6BTV, and I'm thinking 
of ground mounting it, but was a bit curious as to the radial system 
to use... should I run as many separate wires , or perhaps a full 
circle of  wire mesh , or a big metal circle under the vertical?

What would YOU do in this situation?

KD4IEN
10-10# 74734

You can also find me on the WEB at...
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