Haven't semiconductor switches, caught up with reed relays for this
application by now, or do they "still" provide a lower "on" resistance,
etc. ?



Semiconductor switches have issues with intermodulation, etc. and power
consumption. For wideband RF, you're not going to be using cheap 4066
CMOS muxes.. if you need to handle strong signals, that implies decent
diodes with a fair amount of current.

High quality sealed relays are inexpensive, very reliable, etc.

On Thu, 07 Oct 2010 17:23:15 -0700, Jim Lux wrote:

Haven't semiconductor switches, caught up with reed relays for this
application by now, or do they "still" provide a lower "on" resistance,
etc. ?



Semiconductor switches have issues with intermodulation, etc. and power
consumption. For wideband RF, you're not going to be using cheap 4066
CMOS muxes.. if you need to handle strong signals, that implies decent
diodes with a fair amount of current.

High quality sealed relays are inexpensive, very reliable, etc.

Just a note ...
The signal that will make a switching diode go nonlinear will be Strong
signals (mostly AM/FM/TV) that are not even in the desired band. Several
receiver manufacturers even place a 20db BCB BP filters as the first
thing after the antenna connection and before the attn circuit (also
diode controlled)to prevent these signals from even reaching the first
BPF diode switching network. A bad thing for people interested in BCB-DX.

I think relays in the front end of any RX is a good thing. Relay
reliability has improved allot in the last 30 years too so longevity
should not be an issue in a receiver.