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btrayfors · 10-04-2010, 07:06

Quote:

Originally Posted by fairbank56

......

Antenna gain does not increase signal power. .....

Eric

Antenna gain does, indeed, increase ERP (effective radiated power). That's why it's called "gain". Gain is usually measured in db against either an isotropic antenna (DBi) or a dipole antenna (DBd).

Agree with Eric's other points. There are some relatively minor technical inaccuracies in the article, but overall it's as Gord said, "not too bad".

Bill
WA6CCA

surfmachine · 10-04-2010, 07:22

Get the end up on the mast put on by a professional, with one of those epoxy sealed plugs and soldered properly and it will give you years of trouble free service. Dont tighten the antenna too much! Pull the cable down the mast witha messenger, and leave it in there, ie, pull it back up again.

The other end, at the base of the mast must be soldered insitu, this is where most problems occur, make it 150mm longer than needed so you can redo it when the wires corrode! Tape up the join with that self amalging tape to seal it each season.

Use a through deck connection that can unscrewed for when you lower the mast. really easy to do yourself, but get the top connection done professionally!
Cheers from Keith.

fairbank56 · 10-04-2010, 07:37

Quote:

Originally Posted by btrayfors

Antenna gain does, indeed, increase ERP (effective radiated power).

He didn't say that. He stated "A 9db antenna increases the signal power eightfold, a 6db antenna fourfold and a 3db antenna,...,doubles signal power."

That is very mis-leading. Antenna gain is a relative term. There is no increase in power is being produced by the antenna. Assuming no losses, power in equals power out. An antenna with gain merey focuses the power more in some directions than others giving you the effective radiated power. Claims of gain can be grossly overstated by antenna manufacturer's especially when the gain figure isn't referenced to anything as is often done. The Metz company doesn't even give a gain figure for their Manta 6 but claim that it will outperform conventional 54" 3db gain fiberglass antenna's hands down! They also claim "all connections soldered" which is not true. The internal coil is attached to the nickel plated support with a screw. They also show the coax receptacle as an SO-239 which it is not, it is a PL-258.

Eric