Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?






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On Wed, 26 Jan 2005 08:29:08 -0800, Frank Gilliland
wrote:

Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?


Isn't that already done by the relay box? There is 29' of coax hooked
to the undriven elements.

On Wed, 26 Jan 2005 19:52:11 GMT, Lancer wrote in
:

On Wed, 26 Jan 2005 08:29:08 -0800, Frank Gilliland
wrote:

Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?


Isn't that already done by the relay box? There is 29' of coax hooked
to the undriven elements.


I think that's 29 inches, not feet. But you made me realize that the
feedpoint impedance of the dipoles is going to be lower because of
their proximity to each other, and that coax is probably cut to make a
conjugate match. At least it's possible. Maybe I'll just go with a
phased array.....

On Wed, 26 Jan 2005 12:31:40 -0800, Frank Gilliland
wrote:

On Wed, 26 Jan 2005 19:52:11 GMT, Lancer wrote in
:

On Wed, 26 Jan 2005 08:29:08 -0800, Frank Gilliland
wrote:

Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?


Isn't that already done by the relay box? There is 29' of coax hooked
to the undriven elements.


I think that's 29 inches, not feet. But you made me realize that the
feedpoint impedance of the dipoles is going to be lower because of
their proximity to each other, and that coax is probably cut to make a
conjugate match. At least it's possible. Maybe I'll just go with a
phased array.....



If its 29", then those elements at the most are 29" from the center
hub. I think you would probably be happier with a phased array. A
lot easier to control your patterns and matching.

If qsl.net ever comes back up, this link

http://www.qsl.net/ve3sqb/

had a program to design a super scanner.

On Wed, 26 Jan 2005 20:40:36 GMT, Lancer wrote in
:

snip
If qsl.net ever comes back up, this link

http://www.qsl.net/ve3sqb/

had a program to design a super scanner.


I found the file and ran it. For 27MHz it gives a radius of just over
38" which, I'm pretty sure, is a bit longer than the 29" coax that
feeds each dipole. Apparently there are two versions of this antenna:

The first is the original and has a cardioid radiation pattern. The
second is VE3SQB's version that has better forward gain and deep nulls
to the rear corners, but has a larger radius and the dipoles are fed
with a 1/4-wave section of coax. It seems that the second version
behaves more like a phased array instead of a parasitic beam.

I might email the guy and see if he has the specs for the version with
the cardioid pattern.

If I make a pyramid out of empty beer cans, is that a 'Beverage' antenna?
lol...sorry!


"Frank Gilliland" wrote in message
...
On Wed, 26 Jan 2005 20:40:36 GMT, Lancer wrote in
:

snip
If qsl.net ever comes back up, this link

http://www.qsl.net/ve3sqb/

had a program to design a super scanner.


I found the file and ran it. For 27MHz it gives a radius of just over
38" which, I'm pretty sure, is a bit longer than the 29" coax that
feeds each dipole. Apparently there are two versions of this antenna:

The first is the original and has a cardioid radiation pattern. The
second is VE3SQB's version that has better forward gain and deep nulls
to the rear corners, but has a larger radius and the dipoles are fed
with a 1/4-wave section of coax. It seems that the second version
behaves more like a phased array instead of a parasitic beam.

I might email the guy and see if he has the specs for the version with
the cardioid pattern.

"Frank Gilliland" wrote in message
...
Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?



If you look around in some technical manuals, you'll need to understand the
wavelength formula to build it correctly.
There is a specific formula for determining how the elements are cut and
spaced.

If you've got a good ham shack around, go talk to them about it.
Or basically follow a 10 meter design. It's close, but it should work.

What you have is a basic yagi antenna.
http://www.signalengineering.com/ult...ment_yagi.html

Scroll to the bottom of the page for details on lengths required.

Have fun.

Frank Gilliland wrote:
Okay, I've been looking for a Super-Scanner for a while and can't find
one for sale. So I decided to make my own. The manual has enough info
to build a pretty close copy except for one detail: the boom length.
What should the spacing be when one dipole is the radiator and the
other two are reflectors?

And would there be any advantage to adding a little reactance
(electrical length) to a dipole when it's switched in as a reflector?






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Watch out for blown caps!

-SSB