K1DEU
160 ft Rohn 45g Tower
Premium
join:2007-10-30
Stamford, VT
edit:
October 9th, @01:14PM
| Converting less expensive 2.4 GHz Grids to 1.9 MHz Grids
This applies to the large 26T Parabolic Grids that measure 39 wide by 23 1/2 inches assembled and the smaller 18T models.
like »awapps.commscope.com/catalog/pro···id=6478#
I purchased the very expensive Andrew/CommScope 26T model 26T-1900F. Andrew uses the same grid reflector and driven element dipole inside black PVC in all three of their models the T-2400, T127 and T1900 with grid slot spacing of just over 3/4 inches in all models. The only difference is that in their lowest frequency T-1900 1.7 -2.1 GHz model they include a plastic spacer that spaces out the small aluminum 3 slot reflector at the focal point a additional 1/2 inch from the driven element for lower S.W.R. The spacer is notched at each end to keep the reflector parallel to the driven element. I would just use all temperature glue and a longer sheet metal screw with any insulated spacer.
The 2.4 GHz (Wi-Fi frequency) Parabolic Grid antennas are much cheaper being manufactured and sold in very large quantities. Many sellers carry these similar looking grid antennas
Regards John
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»www.spiritualpeaceproject.com |
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caribconsult
Premium
join:2003-03-19
Mayaguez, PR
 ·Millenicom
·Sprint Mobile Broa..
 ·HughesNet Satellit..
| Thanks for the tip about the spacer notching. I examined mine (a T1900) and sure enough, I had the spacer inserted backwards. Now it's in correctly, and I'm waiting for an adaptor to hook it up. I made the stupidest error in the world when I ordered the antenna; I thought the rest of my wiring had N connectors when in fact they were TNC, so the antenna arrived with an N-Female connector, which of course would not connect to the TNC at the end of my cable!
Mike at »criterioncellular.com (from whom I bought the grid) helped me straighten this out. They have a good photo display along with critical measurements of most of the common antenna connectors and that explained everything. I have no idea why I was so positive my wiring was N that I didn't even check this before ordering the antenna. Dumb award of the year to me!
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Franklin CDU680/Assent MBR400 combo, CAY1912 panel antenna, Millenicom, 4 XPPro stations, Mozilla everywhere. |
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K1DEU
160 ft Rohn 45g Tower
Premium
join:2007-10-30
Stamford, VT
edit:
October 9th, @12:55PM
| Here is the data sheet for the 18T and larger 26T Andrew/CommScope grids
Showing the little 1/2 inch spacer bar for 1900 MHz PCS, low S.W.R.
The Larger 26T Model has about 23DBi gain at 1,900 and 24 DBi gain at 2,400 MHz. The wind load is low when the wind blows for there is slightly over 3/4 inches open space between the reflector grids.
Type "N" female connectors are nearly 5/8 ths OD to fit on 1/2 inch transmission line (coaxial cable or hardline like LMR400) and are very waterproof if installed correctly, without air voids inside. They are large as the more Common type "UHF" connectors popular for CB and Ham Radios, which are not waterproof.
Regards John
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»www.spiritualpeaceproject.com |
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Beaverlake
@sbcglobal.net
| reply to K1DEU
Your instructions were timely as I was in the process of installing an HG2424, and was thinking about changing the lenght to the dipole-reflector to get closer to 1900MHZ, but had no idea of how much to increase. The Highgain doesn't come with a spacer and the plastic built in spacer from the dipole does not lend itself to adding another spacer to it. Anyway I drilled out the alum rivets on the brackets and extended the dipole with the reflector out another 1/2". I don't know if this got me closer to 1900MHZ but it did help the signal strenght by 4-5DB. I'm located in hills and trees with no LOS so any improvement was welcome. If I screwed up by moving the dipole, I can always change it back. I'm strickly a newbie at this as I am coming from a satellite connection so anyone with more knowledge, please add comments. |
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