Plasticos Omega wrote:
Hi,
I am shunt feeding my tower on 160 mts and abt 12 feet I have a Tintanex V-80, I suspect that there is some kind of coupling between them.
How may I verify my suspicious?
KV4FZ wrote: Open up the feed line at the bottom of the V-80 and insert an RF amp meter to ground to measure the current flow. If one is not available you can get some idea of the coupling by simply putting a incandescent lightbuld to ground across the antenna terminal. (The wattage level determined by the power you run into the master antenna. Another thing you can do is use a field strength meter and make some measurements with the V-80 feed open (floating), connected to the feedline, or shorted to ground. Look for radical changes. If none occur and the directivity or the feed point match is not compromised, then you can more assured that the interaction is not a problem. Additionally, it will help to wind a choke balun at the base of the V-80 to isolate it even further. The effect of the feed line may also depend on its length. If it is a multiple of an electrical half wave, and your coax selector switch is like the one that I use and grounds every unused connection, then that ground is replicated at the the end of the transmission line right at the feed point of the V-80. This may be not what you wish to happen or maybe it is. Only testing will various combinations will let you know.
73
Herb Schoenbohm, KV4FZ
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