Strange indeed Bill! I don't mean to be descending but have you checked to see if you wearing your wife's glasses instead of yours. HIHI
It is possible to drive the screens instead of the control grids as a class B zeros bias circuit however it would require neutralizing to work properly. Most folks would opt for the grounded grid configuration where neutralizing is generally not required. I can't see where the meter in the grid circuit would ever show much current unless the rig was once a grounded grid and then was converted to screen driven and they just didn't change the grid meter. Even so 10K in series with the grid meter and no by pass - it just don't make sense to me. John, WA5BXO -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Fondren Sent: Tuesday, May 23, 2006 7:44 AM To: AMRadio@mailman.qth.net Subject: [AMRadio] Amplifier with input drive to screen grid 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 ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb