From Junk to the Super Scanner Antenna on 10 Meters!
Modify an 11 Meter Super Scanner Antenna for 10 Meter Use
By Ken, KD0AGV
With special credit to Bill O'Connor, who lives near Harrisburg Pa.
Without his help, this project would never have gotten this far!
View of completed antenna
Many years ago, the Super Scanner Antenna M-119 by Antenna Specialists was a very popular antenna for 11 meter use. It was designed as a "compromise" antenna with the properties that made it into an antenna that was somewhere between a beam and a ground plane type antenna. The "beam" property of the Super Scanner was the result of electronically rotating the pattern rather than using a rotor.
The omni directional property and "beam" effect was designed into the controls and phasing, enabling the antenna to be used as a "beam" (sort of), or it could be "switched" into the omni directional pattern.
This fit the needs of many thousands of CB'ers who did not have the room for both types of antennas! The resulting pattern of it was in 3 major lobes spaced 120 degrees apart giving an almost circular pattern. The switching of the lobes was accomplished by a control box near the radio which sent signals to a relay box at the antenna which cut in or out various relays and phasing lines to accomplish the pattern change.
According to various sources, the antenna had an "impressive" 5.75 dbi gain in the omni mode and an 8.75 dbi gain in the directional mode. These "gain" numbers really impressed a number of people who used them compared to regular ground planes and the numbers especially impressed those that could not have a beam for one reason or another. Of course, those of you who know a bit about gain figures see that the numbers are based on "I" isotrophic rather than "d" for dipole which is the standard reference antenna! So to many CB'ers, they saw some BIG numbers in those "gain" figures.
This project should be only considered by experienced antenna builders who are familiar with reading schematics, soldering, using electronic components, work well with hand tools and have lots of mechanical ability in order to fabricate the various brackets, mounting arms, coax assemblies, etc. It is in no way meant to be a step by step instruction guide but to give you the basics behind the construction of the antenna. You will have to leave much to your "ham ingenuity".
Here we will show you how to duplicate the construction of the Super Scanner antenna modified for 10 meter Amateur Radio use by using a Super Scanner antenna calculator and a formula that we discovered by experimentation!
A bit of background first. The original CB band (23 channels), covered from 26.965mhz to 27.255mhz (290khz wide), back when this antenna was very popular, so the Super Scanner was designed for this band of frequencies and not 10 meters.
This project has attempted the design for use over the entire 10 meter ham band which is 1.7mhz wide! It "favors" the low end of the 10 meter band with lowest swr around 28.000mhz to 28.300mhz with a 1.3 - 1.4 to 1 swr over that range. On the high end at 29.100mhz to 29.700mhz swr was 1.8 - 1.9 to 1. Your end results may be different depending on your design!
In the Omni mode I got a flat 1.2:1. The single vertical sections give a little higher SWR. Ive found it tunes up quite easy.
The Scanner design program from VE3SQB was used for the lengths and spacing of the various elements, support arms, etc. Download and save it here! You will need it!
A workable formula below was derived by experimentation for the phasing coax lengths from the relay box to the individual elements due to the fact that there were no calculations in the VE3SQB program for the phasing line lengths!
This formula appears to work well:
220/freqmhz = length in feet for each phasing line using RG-58 coax
Example: 220 / 28.500mhz = 7.71 feet = 92.63 inches. (round off to 92 1/2 inches)
Editors note: We tried this formula for finding the original phasing line lengths on an old Scanner antenna used in this project using the low end (channel 1), frequency of the CB band and came up with the exact length that was used on the CB band version. We have no idea why Antenna Specialists used this length! But using the formula above gives us the same length as the mfg used on the original antenna....so it does work.
You will also need to refer to the original instruction manual. You can download it at the link below. They are in pdf file format.
http://www.scribd.com/doc/3359466/superscanner
Unless specified, all drawings below were taken from an original instruction manual for this antenna designed for 11 meter CB and are for reference only to give you some ideas as to your construction.
Drawing taken from original Antenna Specialists manual
The overall layout. Not to scale!
In the drawing above, there are three vertical dipoles each oriented 120 degrees around the center section and insulated from and mounted on individual boom supports. The supports are mounted to a triangular bracket that is attached to the mast with "U" bolts seen in the drawing below.
Triangular mounting bracket and rectangular booms
The relay box shown above containing relays, the phasing line connections and switching connections, is mounted at the bottom of the triangular mounting bracket.
Refer to the pdf file instruction manual in the links above for the schematics of the relay box and the control box.
Original Control Box 19-2425
(If you are in luck, you may find an original relay box and the control box
complete on ebay or other classified ad type sources)
View of saddle bracket and feed points with center conductor
of phasing line connected to top half and shield to bottom half.
Note the insulator on the top half keeping it away from the bracket!
Side view of saddle bracket, insulator and support arm
Additional notes and information:
The tips of the antenna were about 4' off the ground for the swr measurements.
The relay box on the antenna is the mfg part number,19-1921. It only uses 2 relays, the measurements I took for the coax was from the plate where the coax enters the relay box to the end (at the 92.75 mark, I left about 1.25 inches to strip back and connect). The coax is RG-58/U solid center. It is easier to work with. The vertical sections are made up of three pieces. I slid the bottom and the top piece into the center section, drilled one hole and used new self tapping screws in place of the old screws. Everything else is stock from the original antenna.
The arms are 1 square aluminum (it's carried at Lowes). The original length of the arms is 38.5. I removed 2 inches from the arms. Also you need to be careful with the plastic isolators (top sections). The end of the arms are re-enforced with steel inserts (about 2 inches long, 1/16 steel). The aluminum arms need to be strong enough to prevent twisting of the vertical elements. I would either get the thickest walled aluminum you can find or re-enforce the aluminum with some other metal. When attaching the coax to the vertical sections, (SOLDER SPADE LUGS) to the coax.
If the antenna is subject to windy conditions, guy it below the cross arms using non-conductive material strong enough to do the job.
Get help putting it in the air and stay well clear of power lines!
Keep metal guy wires below the lowest end of the antenna or break them up about every 7 feet with insulators.
The phasing lines, connections on the relay box, control box and the cross arms must be color coded in such a way in order to know that the element directions match up with the control box directional control! See the instruction manual.
Further Experimentation!
Initial experimentation with the Super Scanner 10 meter modification was using vertical polarization.
Ken is in the process of further experimentation using the antenna in the horizontal position with a rotor. The unique mounting method simply "flips" it from vertical to horizontal polarization. See pictures below:
Supper Scanner mod in horizontal position using unique 90 degree mounting.
(Shown with rotor attached for "aiming")
Mounting method for horizontal polarization using 90 degree bent into mast.
(Rotor is out of picture below the 90 degree bend)
Initial on the air results in the "low" part of the Solar cycle and poor band conditions are very good and the antenna is much less noise prone. 73, Ken KD0AGV
Questions:
For more information about this project,
Email to Ken - KD0AGV - fullofblarney at comcast dot net
Editors note:
Our hat is off to Ken, KD0AGV, for all his hard work (fun) in putting this project together for all to enjoy. It's hams like himself that make this "hobby" great.
Thanks Ken! 73, Don N4UJW
Notice!
This article and project is intended for educational an informational purposes ONLY for those wishing to build or modify the antenna for non-commercial use. The Antenna Specialists company is still in business and may hold a copyright on this design! The name "Super Scanner" may be trademarked by Antenna Specialists. No trademark or copyright infringement is intended in this article and it is intended for Amateur Radio Operator's personal use only. |
