I agree generally with these comments, except that my experience with
CdAg contacts on receiving hasn't been that bad, provided that the
application exercises the relays occasionally. Thus, using them as,
e.g., an outdoor antenna switch where the antenna isn't regularly
switched, and where there are large temperature fluctuations, can
definitely lead to receive problems. At one point I thought about
using a small dc bias current through relay contacts, but found it
wasn't necessary.
With two relays in an amplifier, and maybe 5-8 relays in a switch, and
thousands of amplifiers and antenna relays sold, and with Internet where
even 1-2% failures creates a lifelong firestorm of "what they did wrong" by
critical experts (who probably see less than one or two units a month
instead of samples out of thousands), the perspective changes.
:)
The relays have to be gold flash, because silver has sulfidation issues. The
contacts generally have to be small, or must have pretty high operating
power for the relay size to allow high spring pressure.
This is all summarized, including links to outside relay information, at:
http://www.w8ji.com/relay_cleaning_and_life.htm
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