Ian says:
> that the contacts heat up, loosen/corrode, and fail as the years go by
I think Ian has a point here. Leaving out any surmise about parasitics, the
costs of switches are such that a number of amps are somewhat marginally rated
in that area. Some commercial transmitters that I've worked on used an extra
phenolic wafer with a very small tongue on the rotor; when the switch was
turned, before the main contacts opened and could arc, the phenolic wafer
contacts opened and that switched off the PA. That doesn't get by burn ups
caused by too high an SWR, mistuning, etc., but it can help. Another tx I saw
had an arrangement that you had to push the knob in before you could turn it,
and this shut off the PA.
73
Peter G3RZP
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|