> BTW, my homebrew project is a pair of relays to switch two
antenna
> connections in the shack. The design bandwidth for these
two antenna
> switches is 1.8 to 450 MHz. A friend with a spectrum
analyzer measured some
> crosstalk between the SO239 connecters and suggested the
toroids be inserted
> in the dc lines to each relay to improve isolation.
Insertion loss was also
> measured to be about 3 dB at 500MHz. This is not
acceptable so I am looking
> for better relays.
Keith,
If you are only switching two ports to a common 500 MHz
should be easy.
In all the switches I've designed, I've NEVER had to bypass
or filter coil leads. That tells me you have a layout or
relay selection problem.
Capacitance across contacts limits port to port in a good
design, and with a wise selection of conventional relays the
system should have less than 1/2 dB loss at the upper end
and a worse case crosstalk about -50dB at the high end.
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|