[BC] Old tube kW rigs

[John Lyles]

Some of the comparisons of 833A and 4-400A tube rigs here show that we all have diverse opinions. What I offer here is gross simplification, so here goes....There were several variations of tube 1 kW transmitters: the Gates triode boxes, the RCA/Collins/Bauer/McMartian/CCA/Wilkinson/etc tetrode boxes, and stuff that didn't fit into these two categories like the linear amplifiers (RCA and Gates Vanguard), and very old systems like Western Electric (Doherty), older RCA stuff, and whatever I missed.  

The Raytheon RA1000, while it was a quad 833 rig, was completely different in design as it had conventional class B pushpull audio, modulating push-pull RF stages. All the rest used parallel RF tubes, with lower plate impedance as the result. Instead of 807s driving the 833 grids, the big RA1000 had 813s in there. It was overdesigned, no value engineering. The RF circuit was all symmetrical with a variometer for the output link to coax. 

Gates stuck with a design and repackaged it for many years. The basic 833 design that they used was gutless. 

It really makes a difference when hams get these old boxes and try to move them up in frequency. The long straps and wires of the 833 connections, and lack of nearby low L grounding, really limits what can be done with a Gates. Some of the tetrode boxes seem to get pushed to 7 MHz at least.