[amsat-bb] Re: mode J filter / Comet CF416c

[Anthony Monteiro]

At 10:51 PM 12/27/2007, K & R Yoksh wrote:
>Hello everyone,
>
>I'm planning to install a diplexer ahead of my 70cm mast-mount preamp soon,
>and was interested to know any tips or tricks before I buy a diplexer and
>climb the tower.
>...
>
>I had planned to mount the unit inside of a section of PVC pipe with a pipe
>cap glued on the top, and open at the bottom. A single U-bolt should attach
>the unit to the tower.


Hi Kyle,

I have had a CF-416c installed outdoors at around 40' for several years with
no problems. This unit is not waterproof though so before installing it,
I took the bottom cover off and ran a bead of Marine GOOP around the bottom
flange. Then I screwed the cover back on it. I mounted the CF-416 on top of
my preamp (SP-7000) using black wire ties with the bottom cover of the CF-416
facing down. The body of the CF-416 is a cast aluminum box so this keeps
water out except for the bottom plate. Mounted on the preamp, the water just
runs off. I did not do any thing special to the cables or connectors.

I have also used an unmodified (i.e. un-GOOP'd) CF-416c for several years for
portable operation (with occasional rain) and for extended outdoor 
antenna testing
(with lots of rain) with the unit just hanging by its coax cables and no
protection at all and it seems to have survived those ordeals with no 
ill effects.
I just now unscrewed the bottom cover to look at the insides and it seems fine.
The biggest potential issue is the aluminum tape over the tuning holes in the
bottom cover. This hasen't caused any problems for me but if you happen
to puncture the tape, you would have a hole in the bottom cover where water
could get in.

Best of luck with your projects,
Tony AA2TX