Cross band thoughts...
Since you're dealing with Amateur Bands, the best
way to go might the use of the DCI dual band
146/440 filter, which also functions as a diplexer.
The advantages are true "window filtering" vs
high-pass low-pass operation (of a more generic
diplexer) and a more rugged construction/capacity
against high energy discharges.
The cost is actually quite a bit higher, but you'd
probably need to lay out the bucks one time.
DCI will also custome build filters, I now have
them make commercial repeater window filters for
me and they work just killer.
You'd also get a true DC ground/return on the feedline.
Get a true dc grounded metal antenna at the top of the
tower. Decibel, Sinclar, Cushcraft and Antennex make
loop repeater antennas that have quite a bit of gain.
The US West Coast in Northern California trades away
Tornados, Huricanes and lightning storms for Earthquakes,
Smog, packed freeways, high home prices and bad drivers.
Its just cheaper for us out to run a repeater without
the bad lightning storms. I've had a Comet Tri and Di-
plexer in operation for years without fail. I consider
myself luck although I do monitor the feedline swr
(reflected power and mis-match) for trouble.
The dual band DCI unit will probably fit your needs,
but you'd have to buy two if you don't run duplexers.
cheers
skipp
www.radiowrench.com/sonic
> "derek_mcintyre" <[EMAIL PROTECTED]> wrote:
>
> Thanks for all replies. I have several of the Comet diplexers with
> PL-259's, one "Pro-Am" model, one Larsen, and one made by Daiwa.
One
> person commented on the duplex noise and I tend to get alot of this
> from all of these except the Larsen, which burnt up several years
> back with 60 watts of UHF running through it. A 3.3 pico capacitor
> smoked, and I replaced it with two 5.6's in series and all worked
OK,
> but I had to run the power down a little in order to keep things
from
> smoking again. If you look closely the paperwork on the comets and
> diamonds say "200 watts" but in the fine print, it says 200 watts
SSB.
>
> I am planning to run one line of 7/8 up a 350 foot tower, but want
2M
> and 440 repeaters, with two separate antennas. I don't want to use
a
> dual band antenna because the fiberglass comet and diamonds seem to
> disappear when hit by lightning.. I'd rather use 2 separate
antennas
> and one feedline, and split it once up top and once on bottom. I
> plan to put the diplexer in a box atop the tower.
>
> One person mentioned replacing the pigtails on the unit to make the
> duplex noise disappear. I replaced the ones on my Daiwa unit with
> some small hardline used on microwave equipment that is RG-58
sized.
> The duplex noise went away. Thanks for the suggestions.
>
> 73, KC4FWC
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