>I think the speed you need depends on whether you can get a good early
>'transmit' signal from your exciter
As an alternative, I presently use a CMOS II keyer with an "auxiliary"
open-collector transistor to ensure that the amp is keyed fractionally ahead
of the transceiver. The primary keyer output connects to the transceiver
key jack in a bussed arrangement to all my transceivers. Then, the
auxiliary open collector is run in parallel with the transceiver's external
amp relay or open-collector. In effect, I have a key bus of open-collector
outputs that run into all my amps. With the bussing technique, I do not
need to worry about switching or directing the control of my amps; it's all
automatic and transparent to me and hot-switching is avoided at all keying
speeds. The keyer's auxiliary output ensures that the amp "makes" fast
enough, then the transceiver's own amp key line ensures that the "break" is
adequately long to avoid hot-switching on waveform's trailing edge.
-Paul, W9AC
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|