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Originally Posted by Gerry
Hi all, based on its length the I-Max is close enough to be regarded as a .64wl NOT a 6/8wl as I previously stated, the I-Max 2000 will have a small dbd gain advantage over a true 5/8wl antenna, but not so much that the human eye or ear could discern the difference.
Grounding ANY vertical is desireable, mainly to reduce static which can be a real pain at times. It is good practise to use large diameter ground wire, and keep it as short as possible, running it to a COMMON connection in the shack, to which all RF equipment should be connected. You should be careful that the length of ground wire is NOT RESONANT at the frequency of operation, otherwise it will be ineffective, and may contribute to RF entering the shack. Also, keeping the antenna as far away from the shack as possible is a good idea, otherwise RF may enter in even with good grounding. Sometimes it may prove necessary to use ferrite rings or clip-ons to cool a hot mic. It's wise to use a LOW PASS FILTER such as the Kenwood LF-30A, and in addition, the use of a LINE ISOLATER (or two) such as Radio Works model T4 Plus, both exiting the rig and at the base of the antenna. This helps eliminate RF returning into the shack via the coax shield. It is wise to watch the VSWR when using Line Isolators as high levels can cause them to run kinda hot, but, at CB output levels it might not be a problem!
OK all, I hope all this is of some help to you, I'll be offline for some time, so don't expect a come back to respond to any aspect of this anyway soon.
Good luck and 73.
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Hi again, just a quick comment on ground rods.
I use six eight foot copper ground rods, spaced about one metre apart, and what I neglected to say previously, linked together with earth wire. In formation they describe a square. A simple test to establish if you have a good earth - get a PP3 9 volt battery and a suitable bulb, check it's working first, then connect the +v wire to the positive battery terminal the touch the negative lead to your earth rod(s), if the bulb glows brightly, the earth is good, if not, seek experienced assistance.
Too old to DX BB? Heck I was talking to a gentleman recently aged ninenty nine, still hale and hearty! Build yourself a three element circular polarised beam antenna, you can purchase plans for that as CB City International, I think it's still owned by a guy called Lou Franklin in Phoenix Arizona. Great little beam, I built one way back about 1981, it holds the skip like nothing you've ever used before. Build the beam and cut the phasing harness, this makes one polarisation operate ninenty degrees out of phase and generates the circular transmission. It virtually eliminates multi-path fading as DX polarisation being random shifts between vertical and horizontal to something in between, this beam catches it all. Highly recommended for DX!
Good DX es 73.
October 24th 05, 09:57 PM
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