Hi All,
I had reported previously that my despite adding the W8JI
key-click modification to my FT1000MP MK V it was still
clicking on the leading edge character and also on intra-
word leading character (e.g. first character after a word
space). W8JI suggested this was caused by ALC action
and that it might be mitigated by pre-biasing the external
ALC input with a DC power supply and indeed this turned
out to be the case (~ -3.5V on 160 meters). The external
supply was not a good solution, however, as the
adjustment was way too touchy to be useful in practice
and the optimum setpoint drifted as the rig warmed up
during long transmit intervals.
Tonight I decided to get more familar with rigs ALC circuit
in hopes that I might be able to figure out a better fix. In
doing so, the first thing I stumbled on to is the Mark V's
TX IF gain hidden menu ("9-2"). This is a scrolling menu
that provides a drive level preset for each amateur band
(-018 for 160, -035 for 80, -070 for 40, etc). The preset
ranges from "0" to "15" with "0" being minimum TX IF gain
and "15" being maximum TX IF gain. My rig (as received
from the previous owner) was set to between "6" and "7"
for each of the 10 bands segments except for "-290" (the
29.0 MHz segment of 10 meters) which was set to "8".
Dropping this setting from "7" to "2" for the 160 meter
segment (e.g. "-018" segment) completely eliminates the
leading edge clicks even when using VOX for the initial RX
to TX changeover yet still provides enough excess TX IF
gain to sustain some ALC action (about 1/3 scale) at 200
watts output. I haven't tried this adjustment on the other
bands, but presumeably results will be similar. Seems
that the Mark V does have a drive control after all. Its just
in a hidden menu instead of on the front-panel - Doh!
73 de Mike W4EF............
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|