DB 4076 duplexer jumper lengths info

[DAL-COM]

I had to call DB products (Andrew) to get jumper cable lengths for a DB4076 duplexer, 3-cavity type. (It had a GE part number but they assured me it was a 4076). I am posting them for general interest as they are definitely not the "half-wave or multiple thereof" that some people claim. Nor are they "quarter-wave or multiple thereof". These lengths are "cut lengths" for RG-142.

High freq Pass side, cavity-cavity=6inch, cavity-tee=9inch
Low freq Pass side, cavity-cavity=11inch, cavity-tee=10inch.

In this case there was only one highpass cavity.

I think there are no rules for jumper lengths, it all depends on the design of the loops inside the cavities.
BTW these are "series resonant" loops so the transfer function shows 2 notches with a pass between them. Apologies to our Canadian readers for the inches.

[mancow]

I know it's an ancient topic but I have one of these that's missing some cables. Does anyone know how critical the measurements are. I messed up and made one cable 1" too long and another 1/2" long.

[Jim202]

I had to call DB products (Andrew) to get jumper cable lengths for a DB4076 duplexer, 3-cavity type. (It had a GE part number but they assured me it was a 4076). I am posting them for general interest as they are definitely not the "half-wave or multiple thereof" that some people claim. Nor are they "quarter-wave or multiple thereof". These lengths are "cut lengths" for RG-142.

High freq Pass side, cavity-cavity=6inch, cavity-tee=9inch
Low freq Pass side, cavity-cavity=11inch, cavity-tee=10inch.

In this case there was only one highpass cavity.

I think there are no rules for jumper lengths, it all depends on the design of the loops inside the cavities.
BTW these are "series resonant" loops so the transfer function shows 2 notches with a pass between them. Apologies to our Canadian readers for the inches.

It would help if you posted what frequency these lengths are for. As you change to different frequencies, theses lengths do change. One set of lengths will not cover the entire commercial band or the ham band.

Jim

[mancow]

444.1 repeater out, 449.100 repeater input

I never could find a formula for it. It's obviously not 1/4 wavelength. I wonder how much "wigggle room" the is to work with when it comes to length of those jumpers?