PRO-67-B V.2.S
SUGGESTIONS
Before hauling your antenna all the way up a tower, check it at least 10 to 12 feet off the ground. In checking the an-
tenna, DO NOT put the reflector on the ground and point the antenna up in the air. Place the antenna on a ladder,
temporary pole, or to the side of your tower in the horizontal plane. This will enable you to get an over view of the
antenna. That is, if you’re showing 2:1 everywhere, you have a problem. However, if you are seeing the antenna trying
to dip, but not going completely flat and/or the frequency is 50 to 80 kHz. lower in the band; the antenna is correctly
assembled. Remember at this low height you are coupling with ground. That can be both real ground and artificial
ground.
Due to the high “Q” of the antenna it will couple with ground. Artificial or real. This type of check will allow you to see
that the antenna is trying to dip and does possess a SWR curve. However, due to its nearness to ground or other
resonant objects this curve will be shifted lower in frequency and not totally bottom out to 1:1.
A problem with the assembly of the antenna would be indicated if all bands are showing in excess of 2:1 with no dip of
any kind. A coupling problem would be indicated when only one or two bands are unusual and the remainder are within
specifications.
WATCH OUT FOR ARTIFICIAL GROUND
Artificial ground is presented to an antenna through various means. Guy wires up under the antenna, roof top, other
resonant antennas near by are the most common.
This would cause a disruption of a few bands and also degrade the front to back ratio.
The PRO-67-B is doing so much for one antenna, it needs to have a clear area in which to perform.
The antenna should be at least a 1/4 wave length from any artificial ground at the lowest operating frequency of the
antenna. In the case of the PRO-67-B the lowest operating frequency is 40 meters or 7 MHz. With this in mind the
antenna should be at least 34 feet away from any artificial ground. Remember this is a minimum, in a commercial
installation this minimum would be 1/2 wave length.
To break up guy wires use an insulator ever 4' for the first 32', (8 insulators per leg), or use non metallic guys. This will
give a non resonant length under the antenna and will allow the PRO to perform as shown in our specifications. If these
procedures are ignored the antenna will still work very well, however, there will be some trade off in bandwidth, reso-
nance and front to back.
Due to the Q feed being above ground, avoid attaching the coax line coming in from the PRO to a common switch which
has other antennas with the same frequencies as the PRO or a harmonic to the PROs frequencies.
A high "Q" antenna needs to have a proper installation to get the most out of the system.
Doing these simple checks and following these basic rules concerning installation can save you and your crew a lot of
frustration. If you think you have a problem, would like to discuss your installation or something is going on you don’t
understand, please call us, 1-636-583-8595 we will be glad to help. We want you to be as happy as we are that you
chose MOSLEY!
PRO-67-B 1/93 Version 1.5 GAW
Copyright Mosley Electronics, Inc., 1993/2002
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