Last month I posed a question about using these relays for RF switching even
though they are not specifically rated for that purpose.
The general consensus of the replies was that they would be OK although there
was some fairly convincing anecdotal evidence that contact resistance would
increase with time especially on the 'receive' contacts.
I have done a fair bit more research looking at the websites of all the vacuum
relay manufacturers and elsewhere and I am now convinced that they _can_ be
used for rf switching. The contacts are made of tungsten compared with copper
for normal rf vacuum relays, which means that they have a slightly higher
resistance which in turn reduces their power handling capability. However, that
power handling capability is still 5 kW in 50 Ohms...
The relays that _cannot_ be used at rf are the gas filled versions as the rf
will ionise the gas with bad results!
I actually cannot work out why the contact resistance of a vacuum relay should
ever change if it is not hot switched or overheated - there cannot by
definition be any oxidation in a vacuum.
In case anyone else is interested I got the relays from:
http://apexelectronic.com/Rf.htm
He gave me a discount because I bought 8 of them, but even his one off price is
pretty good. (I have no connection with Apex Electronic but it was a pleasure
to deal with them.)
73 Roger
VE3ZI
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