[AMRadio] Amplifier with input drive to screen grid

Bill Fondren bill.fondren at sbcglobal.net
Tue May 23 08:43:55 EDT 2006

I recently traded for a linear that has a strange input circuit, at least to me.  The amp is built in a 18 " Bud rack mount cabinet weighting about 150 lbs.  To heavy for 1 person to handle so I deceided to split the RF deck from the power supply and put it in a taller cabinet along with the exciter.  No info was with the unit.  I have used it a couple of times and it works fine .  It uses a pair of 813's in parallel.  I started to draw out the circuit finding that the drive goes to a tuned circuit and then to the sceen grids of the 813's.  The control grids are connected together and go to a 10K resistor, the grid current meter and then to grd.  No connection to the drive circuit at all other than the interelectrode cap. I guess.  The plate circuit seems to be normal.  Just wondering if any one has seen something like this before.      Bill     K5PML

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