[Elecraft] XV-432 power instability in SSB

[eric norris]

Dear Gangue:

My XV-432 is acting very strangely.  I am working with Gary in support on the problem, but I have to wait for a couple of parts to arrive to run the tests he requested so...I am wondering if anyone has experienced this:

Into a dummy load, used with K3, it works fine on CW.  Puts out 10-20W depending on PWR setting on K3.  When I put the K3 into SSB mode, however, the XV-432 will put out no power on any setting--UNTIL I MOVE the PWR knob.  This is the strange part.  Even if the K3 is set to the minimum pwr setting, .10 mW, the XV-432 puts out no power until I move the PWR setting counterclockwise, that is, as if I am trying to select the a power less than .10 mW.  While the knob is moving the XV-432 will jump in pwr from nothing indicated to 30W (all power LEDs lit) and back down again in roughly 1 Hz cycles.  If I countinue to rapidly move the PWR knob on the K3 back and forth the XV-432 will jump around on power output from 1 to 30 watts.  This is with the K3 showing .10mW the whole time, until I turn the knob clockwise.  Erratic power output occurs at all levels of K3 drive from .10mW to 1.0mW.  

This is completely repeatable.  I have tried changing/rearranging cables.  I am also using an XV-144 that shares the XVTR IN/OUT cables on the back of the K3.  These cables go to a BNC tee and then to each transverter.  I have tried removing the tees, and using the cables stright form the K3 to the XV-432 with no change.  The XV-144 operates fine in all modes even when driving an amplifier to 500w.  Both XV have the bypass cap mod, and the XV-432 has the power module resistor mod.  Again, the XV-432 does not exhibit this behavior in CW mode which I find baffling.  Any ideas?  Thanks.

73 Eric WD6DBM