Terry,
Dave, K8CC, is correct. Despite very fast retuning (usually about a second),
the 87A cannot retune fast enough to serve as a shared amp in an SO2R
system. Although there are some indications that the ACOM retunes a tad
faster, it uses a similar stepper motor arrangement and wouldn't work
either.
I used a set of three cascaded TopTen A/B switches driven from the PTT
circuit in my NA relay box to do the switching. As I recall, I had to tell
NA to put in a delay between closing the T/R line and starting RF.
Note that the 87A transmits the low-power output from the transceiver while
retuning, so nothing is lost. But the problem is that at least two letters
are sent at low power before the high power starts (e.g., "WC" at low power
and "1M" at high power.) A lot of stations would be highly confused by that.
But the real problem is that things just happen too fast in SO2R for this
system to work. I always felt the amp was badly lagging my pace.
A solid state amp is more likely to work, but as Dave says, it probably
would have to be driven by the band data output from the transceiver, not RF
sensing like the 87A and ACOM. I know the Yaesu solid state amps use a band
data connection from the transceiver, but I don't know about the ICOM. In
either case, there would have to be band data jacks for both radios, or you
have to develop and elaborate and fast switching system for them.
73, Dick WC1M
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