Don, If the PA amp is tube type, just take the audio off the plates of the audio output tubes, and interface the the amp to the grids of the 833's with high voltage transistor emitter followers. This is what John WA5BXO created, and W5OMR does well with his Titanic. I think John can give you the link to the circuit. It is pretty simple, and high performance.
If the audio amp is solid state, then you need a step up transformer with a secondary center tapped winding of suitable turns ratio. Load the secondary so that the amp sees the proper load impedance. This arrangement will work with a tube amp as well, but I personally don't like cascading transformers. In either case if the PA amp has 4, 8, and 16 ohm outputs (some solid state amps do) AC ground the 4 ohm tap, and you have 180 degree opposing audio at the common, and 16 ohm taps. The problem here is that 833's need a hell of a lot of grid swing, and this scenario when driven to maximum level (16 ohm swamping resistor across transformer entire secondary winding) will only provide about 40 volts RMS, or 56 volts peak grid to grid (E^2/R=W; so at 100 watts into 16 ohms you get 40 volts rms). This might do for a pair of high mu triodes AB2, but not 833's. Regards, Jim Candela WD5JKO --- Don Moore R Moore <[EMAIL PROTECTED]> wrote: > I have a older BC 1F series gates transmitter. I > would like to do away > with the 845 driver tubes and drive the 833's with a > 100 watt PA amp. > Does anybody have any Ideas what I would need to > match the amp to the > driver transformer of the 833's. > Don Moore > W5FFK > ______________________________________________________________ > AMRadio mailing list > Home: > http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net >
