[Amps] Class C amp for RTTY contesting...

[Robert Chudek - KØRC]

Thanks Tom, Bob, and Michael...

I learned a few things today! My gut feeling was if this was a good idea, 
someone would already be marketing a high efficiency power amp to the RTTY 
guys!

So the idea of running a hefty tube conservatively in continuous RTTY duty 
service still makes the most sense.

73 de Bob - KØRC in MN


----- Original Message ----- 
From: "Tom W8JI" <w8ji at w8ji.com>
To: "Robert Chudek - KØRC" <k0rc at pclink.com>; <amps at contesting.com>
Sent: Thursday, November 02, 2006 6:39 PM
Subject: Re: [Amps] Class C amp for RTTY contesting...


>I have a few questions about this idea:
> What would be needed to convert a "traditional" linear (AL-1200, AL-1500, 
> L-4B, TL-922, etc) to strictly Class C operation?>>
>
> Too much work.
>
> Is there a specific tube (or tube series) that would be more efficient 
> when run in this class?>>
>
> Yes, a low mu grid driven triode with very high peak emission current.
> You want a tube that can produce very high current pulses (very low anode 
> to cathode "on" resistance) without damaging the tube. You want a switch, 
> not a linear tube.
>
> What efficiency could be expected?>>
>
> If you play your cards right, about 90% or more. The theoretical limit is 
> right at 100%. RCA made a BC transmitter that ran in the lower 90% range. 
> It was a low mu triode with third harmonic resonators in the anode and 
> grid. We had one at WSPD that had a very slight metering error in three of 
> the meters, and it calculated to be 102% efficiency. :-)
>
> Class AB at the edge of B can be over 70% in theory. As I recall about 
> 75%.
>
> Does Class C provide more/less gain (drive power) to obtain 1500 Watts 
> output?>>
>
> Generally speaking less gain.
>
> Don't try to run CW through it though!
>
> 73 Tom
>
>