[Boatanchors] Sealing Cobraheads and other Inv Vee Dipole questions

[Philip Atchley]

Hi all,  this was also posted to the Antenna reflector,

I'm in the process of cleaning up a couple B&W Dipole Cobraheads for 
reuse in some Inverted Vee Fan Dipoles.  These appeared to have been 
sealed with some sort of black gasket compound, which I'm cleaning off.  
The coax braid, which was probably VERY old was as shiny as the day it 
was new.

Questions.
1.  I'm planning on sealing with standard RTV.  Will the fumes build up 
too much in the Cobrahead and be "trapped", causing future problems?

2.  I realize that when making "fan" multiband dipoles, even harmonicly 
related bands are best (7/14MC etc) due to the unused dipole being of 
higher impedance.  How about Non-harmonically related.  As they are 
going to be used as guy wires on a pushup pole and their relative 
lengths, I'm proposing the following "band pairs".

1.  7.2 & 10.1MC for the  topmost Inverted Vee pair, perhaps using the 
7MC one for 21MC also.  Are the 7 & 10MC freqs too close?
2.  14.2 & 28.6MC for the next lower pair on the mast.  Mounted lower to 
keep the Apex angle a little wider).


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73 de Phil,  KO6BB
If it's over 1dB above the Noise Floor, "IT AIN'T DX"!

THE BEACONEER'S LAIR:  http://www.geocities.com/ko6bb/
QSL GALLERY: http://photobucket.com/albums/y123/KO6BB/
Merced, Central California,    37.3N  120.48W  CM97sh

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