At 05:43 PM 11/25/04, VA3EXT wrote:
>I wondered if anyone could give me some ideas on co-phasing two
>Sinclair SRL-210C4 repeater antennas together.
>
>They both have 50ohm impeadence.
>
>I think you would just use odd 1/4 wave electrical harness between the
>two. I know how to calculate the lenght of the coax.
Correct, but be sure to use 75 ohm coax. The odd 1/4 wave of 75 ohm will
transform the antennas' impedance from 50 ohms to 100 ohms. Putting the two
in parallel with a T gets you back to 50 ohms.
>I have one top mounted with 1/4 wave spacing from the mast on my 200'
>tower that enhances the gain the way the dipole face, north. I have
>another 1/2 wave spacing from the mast and want extra gain twards the
>east-west which I would mount on the side of the tower below the
>other.
>
>How far apart should the bottom element of the first antenna and the
>top element of the second antenna?
I'm not sure, but my guess would be to use the same spacing as between the
elements on the individual antennas. With your varying dipole orientation
and distance from the tower you'll probably get an interesting pattern.
Roger Grady K9OPO
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