Hey Ray,
VHF and UHF guys use this sort of thing all the time to get there
GaAs fet preamps "outta the way" of the 8877 amp. They call It
a Sequencer, Its in most of the handbooks and you can buy kit versions
from DEMI. Down East Microwave Inc.
http://www.downeastmicrowave.com/PDF/trs.PDF 8 channels in 4 steps the preform step 1 to 4 with PTT and
steps 4 to 1 when PTT drops. Timing is set with a cap and they
work well.
It uses an LM324 to fire the relays in sequence.
/Dan