Good Luck!
Do you have any equipment to tune it with after you build it?
Any how, Have you done a search for "2 meter duplexer construction"
from your favorite search engine? If not try it. You will find a few
good write ups including one on repeater-builder dot com site there
is even one out there on building a set of BpBr from I think 8 inch
copper pipe with color photos that really works.
73
--- In [email protected], DCFluX <[EMAIL PROTECTED]> wrote:
> Ok, I have some theroies, but I need confirmation from someone
that
> is like good with math and formulas and stuff as you know I
flunked my
> high school pre-algebra class.
>
> Anyway I want to make a 2 meter duplexer economy style as the
person
> who is building the repeater cannot afford a trip to the Zoo let
alone
> a set of big cans. So I wan't to build either a 6-pack or a 8
block
> of cavitiys, like the UHF mobile duplexers only longer. 2 - 3dB of
> insertion loss would be acceptable
>
> Doing some coaxial theory and using air as a di-elelctric. Will an
> inner conductor with a outter diameter of 3/8" and the outer
> conductor with an inner diameter 1" yield 70 ohms impedence? If
not
> what would the impedence be? And what would the dimensions of the
> outter conductor need to be if the inner is 3/8"?
>
> The present idea of mechanical construction is to use 3/8" copper
> solid ground rods cut to length for the inner conductor and
encasing
> in either 1" or 1 1/4" pipe. Then there would have to be a bushing
> fabricated that has allen set screws to adjust the length of the
> center conductor. This design should be ideal for any frequency
> asuming the materials are big enough.
>
> I am planning for a Notch only style duplexer to keep costs down.
> Without design software I cannot acurately predict band pass or
BpBr
> "Q" if the cavities have more than one connector.
>
> Also loop construction ideas are welcome as I currently am planning
> BNCs on the top with 12 ga straight down from the top and soldered
to
> a hole in the side of the can.
>
> I am also considering a Teflon disc at the end of the tuning rod to
> act as a spacer for mechanical stability if the set is lied flat.
>
> On 4/22/05, Mathew Quaife <[EMAIL PROTECTED]> wrote:
> >
> > Yes I agree on that one, I locked them down and one of them
moved on me,
> > check each one indivually.
> >
> > Mathew
> >
> >
> > Dave VanHorn <[EMAIL PROTECTED]> wrote:
> >
> > At 07:22 AM 4/22/2005, Mathew Quaife wrote:
> > >If these are like my TX/RX duplexers, the slighest movement of
the
> > >tuning rods makes a huge difference, especially on the tx
> > >side. retune would be a good idea. Take them slow, they are fun
to
> > >tune. Enjoy!
> >
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