I have a couple of GP-9s and can tell you the gain figures are a bit
inflated and not referenced to anything. A dipole array with optimum
spacing between dipoles is about the most gain for size that I have
encountered in VHF/UHF antennas. For VHF, a four bay dipole array at
20ft in length has 6dBD gain omni and the GP-9 claims 8.5dB(?) from
three 5/8 elements. On UHF, a 16 element dipole array has about 9.8dBD
gain and the GP-9 claims 11.9dB(?) for eight 5/8 elements. Something
looks fishy to me.
Mike


Ken Bessler wrote:
OK, after the thread on PL-259 losses, I figured
my system (ant gain - connector losses - coax loss)

150 mhz total net gain 1.006 DBi
450 mhz total net gain 2.797 DBi
Antenna tip is 32'6" above ground

My proposed system would replace the RG 58 coax pieces
with a single section of Flexi 4XL and the antenna would
be a Comet GP-9. The new figures a

150 mhz total net gain 7.919 DBi
450 mhz total net gain 10.553 DBi
Antenna tip is 47'6" above ground

150 mhz = 6.913 db improvement
450 mhz = 7.756 db improvement
Antenna tip 15 feet higher

Cost - about $250 for the improvement.

Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.


Ken KG0WX