[NLRS] Using a Sequencer on 10 GHz

[jcplatt1 at mmm.com]

Hi Mel.  Sounds like it should work.  I assume that your ALC voltage is
externally generated and that you are inject that into the IF rig to
control how much output power it generates.  Does - 4 volts REALLY give you
ZERO watts out ?   If so, good news.   The "critical" time constant, if
there is one, would be that state between when you toggle the T/R microwave
relay and when you activate the 3 watt amp .... I think that is State 1 and
2 in your write-up.   When changing from receive to transmit you want to
give that T/R relay enough time to switch over to transmit without any
relay bounce before you allow the amplifier to conduct RF.  In opposite,
you want that amplifier to stop conducting RF well before you then set the
T/R relay back to receive ... this will best protect the receiver's RF
front end.   A time constant of 50 to 100 ms may be good here, perhaps
favoring the 100 ms (and more will not hurt anything).

I have often wondered about how fast the 24 vdc SMA relays activate when
using the DEM design 12vdc stacked capacitor circuit.   Just listening to
them they don't seem to "snap" audibly like they do when you drive them
with 24vdc continuously.   I suspect, but don't know, that their switching
times may be a little slower so using a longer time constant isn't a bad
idea .... don't know this for a fact, but just something I wonder about.
Perhaps someone has measured relay response time as a function of driver
circuits (hey ... maybe there is a paper here ! )

73, Jon
W0ZQ