[Amps] What to do with tubeless sweep tube FL2000 ?

Bill Fuqua wlfuqu00 at uky.edu
Mon Jun 28 11:42:27 EDT 2004

In fact you could bias the grids for AB1 and cathode feed (4) 4x150A or 
4cx250b and get extremely low distortion due to the very low grid current 
drawn. But you will need bias supplies. And reduce filament voltage from 
6.3 to 6.0 volts.  4CX150A and 4CX250B have the same electrical 
characteristics but the 150s are much cheaper.  Keeping the plate supply 
voltage the same prevents having to go to greater spacing it plate tuning 
capacitor, changing out parts such as bypass capacitors and plate coupling 
capacitor and modifying power supply to doubler and adding more 
electrolytic capacitors.
    Grid driven would allow you to use QRP rig as exciter.

Bill wa4lav

At 09:16 AM 6/28/2004 -0400, Val" , <Amps at contesting.com> wrote:
>Maybe go to (4) 837's or modified 1625's. Not as much power ( they were 
>really pushing the sweep tubes anyway).
>Look at the LA-400 amplifier made by P&H on bama.sbc.edu. ( no www). 1200 
>volts is just about right. Or you could run
>tetrodes (4) 4x150A  and get more power (AB1=620w, AB2=850w) than a pair 
>of G17B's and the 4x150A tubes can be gotten cheap. The sockets with out 
>built-in by-pass capacitors are fairly cheap ( buy surplus T-195 modulator 
>tube assemblies possibly from Fair Radio).
>Bill wa4lav

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