[Elecraft] Hi RF protection mod

[Brian Alsop]

Guys,

Was trying to figure out whether this is necessary. (not a big deal but 
extracting the K3 from the bunch of connection is a pain)

It appears to me that this mod may be needed if one has two radios and 
an A/B switch which has insufficient port to port isolation.

Some hand calcs (assuming an A/B switch with 40db isolation)
A radio running 100 w
B radio attached to the other port

Hand calcs indicate 780 mv possible at the input terminals of B.
S9+60db is 50 mv. It seems like 780mv is high enough to require this 
protection mod.  (when the K3 is transmitting the B radio would also 
need protection.....)

It is not clear at all how the A/B switch isolation is measured and 
whether it is db power or db voltage.  Yes, some A/B switches ground the 
unused ports.  Is that included in the isolation figure quoted?

Does anybody have some quantitative data?

73 de Brian/K3KO
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