On Wed, 16 Nov 2005, ne1s wrote:
On the Ranger accessory plug are available LV B+ (~300V), HV B+, and each
secondary lead from the mod tranny. You can simply rewire a new plug to hook
the "bottom" of the mod xfmr secondary to LV B+, or, you can do as I did:
mount the plug in an aluminum minibox along with a SPDT switch rated for the
voltages involved to switch the bottom of the mod xfmr secondary between LVB+
and HV B+. The entire minibox assembly splugs into the acessory plug on the
back of the Ranger. Make sure you ground the minibox to the ground pin on the
accessory plug, for safety's sake.
Works FB, got the idea of using the LV B+ from Timtron.
Ranger puts out ~12-15W of carrier when running the PA on LV B+, perfect for
driving an amp, and no power wasted in a big honking resistor.
73,
-Larry/NE1S
For my Ranger / amp situation, I originally looked at doing exactly
this. I have a couple of reservations - first is that the LV Supply will
have to stand the additonal load over the long haul, and second that I'd
really rather the mod section be running at "10 on the knob".
Also, the resistor, if variable (even the 'slider' type) allows one to
adjust the output as needs be - I want to run RTTY which is even more
severe than AM in terms of overall duty cycle , and I want to spare my old
amp (an Ameritron AL-80) as much as possible.
Then again, I have the schematics for the "attenuator" as Johnson called
it - to go between the Ranger output and linear input.
And of course there a lots of topologies that will accomplish the task of
lowering the output of a tetrode or beam-power RF section without
upsetting the relative current balances.
Mebbe I oughta should by a junker Ranger... Just In Case... ;}
Cheers
John KB6SCO
