Batboard

CABLES RUNNING FROM THE TX AND RX RADIOS IN A GR500 TO THE DUPLEXER, DO THEY HAVE TO BE THE SAME IN LENGTH ? I WOULD LIKE TO USE RG 142 CABLE ALL THE WAY AROUND.

Aesthetically, they'll probably look better if they're of equal length. Realistically, it probably doesn't matter much. Since the receive and transmit frequencies differ by some amount, the cables should also be slightly different in length, but not enough to be noticeable.

Some duplexers also contain coax inside them, so theoretically you'd need to factor that length into your equation as well. It's just not worth the effort.

If everything is very well matched and is 50 ohms, use the shortest length you can get away with and still have room to maintain the equipment.

Whether you want multiples of 1/4 wave (1/4, 3/4, 5/4, 7/4, ...) or multiples of 1/2 wave (1/2, 1, 1-1/2, ...) was debated here some time ago. Do a search for "duplexer cable" and read some of the posts.

Bob M.

[quote="kcbooboo"]Aesthetically, they'll probably look better if they're of equal length. Realistically, it probably doesn't matter much.
Bob M.[/quote]

That statement is about as far from the real world as you can get. The length of the cables between the cans IS IMPORTANT. It will effect the ability of the duplexer to provide the needed isolation if you go changing the lengths. They are frequency dependent.

If you move the operating frequency of the duplexer very far, you will have to also change the cable lengths. The lengths of cable between the duplexer and the radio are not effected by the frequency.

Make sure that what ever cable you use is double shielded or of a "Heliax" type cable.

Jim

Original poster was asking about the radio-duplexer cables. These shouldn't matter, as kcbooboo stated. As Jim202 stated, the can-to-can duplexer jumpers DO matter.