DB408's hang upside-down quite nicely, and work just as well too. You do
have to drill new weep holes in the elements - put them in the same location
as they would be if the antenna were right side up. Whatever you do, DON'T
drill weep holes in the very bottom of the element as it will split once
water gets inside and freezes (been there, done that, even talked to Decibel
about it).
Not a real good idea to invert-mount a DB420 because of the way the two
halves are joined together. The joint relies somewhat on gravity to help it
stay together, and if you turn it upside-down, you may come to the tower
site one day and rather than seeing a DB420 on the tower you might see
something resembling a DB408 up on the tower and something resembling a
DB408 sticking up out of the ground :-)
I have a DB408 invert-mounted on a platform 550' up a tower and it's been
working nicely for over 10 years now. It's one of the real 440-450 MHz
antennas which, alas, you can't order any more...
--- Jeff
> -----Original Message-----
> From: [email protected]
> [mailto:[EMAIL PROTECTED] On Behalf Of Jamey Wright
> Sent: Tuesday, March 06, 2007 5:07 PM
> To: [email protected]
> Subject: [Repeater-Builder] Antenna Mounting Question
>
> I'm sure this has been covered here before but I'll ask again.
>
>
>
> I have the opportunity to place a repeater at a very good
> site. I can probably get an antenna at the 250 ft mark on
> the tower. The repeater would be in the 444.xxx range so I
> was looking at using either a DB408 or a DB420. The catch is
> that there is already a DB224 on that same mount so I was
> thinking I could invert my 2 choices for an antenna hang it
> from the bottom of the bracket. The mount is a 6 Ft sidearm
> on a Rohn 80 tower so it is beefy enough to handle the 2nd
> antenna. My question is this: Will inverting the antenna
> create any pattern problems or send all of my signal into the
> ground?
>
>
>
> Thanks for the input.
>
>
>
>
>
> Jamey Wright
>
> KD4SIY
>
>
>
>
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>
