[Milsurplus] Sweep Tube Suggestions

[Bruce Gentry]

On 5/13/13 3:29 PM, David Stinson wrote:
> I don't have a "modern" tube manual here.
> Is there a sweep tube that can take up to 1 KV on the plate?
> Odd filament voltage OK but 10-12 VDC would be plus.
> Thanks, D.S.
>
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After a quick look,  the 6LB6 and 6LR6/35LR6 both are rated for 990 
volts supply on the plate. They are  big tubes, used extensively in 25 
inch color consoles. They are too big to fit into most hybrid SSB 
transceivers, so finding them might be realatively easy. I think most 
larger sweep tubes would stand 1000 volts on the plate, there are far 
higher pulses on them from the flyback, often over 5000 volts.  
Accidentally touching the plate cap on one of these operating in a TV 
was extremely painful, leaving a serious burn, and could kill. There 
were serious voltages and currents there. The downside of these tubes  
for audio or linear RF amplification is the design changes they 
underwent in the mid 1970s. Even though not announced in the tube 
manuals, the elements were often re-designed for a "snappy" turn on-turn 
off to improve tube life and efficiency. They were helping owners of 
8-10 year old sets they paid $1200 for get one last hurrah before 
replacing them.

    Bruce, KA2IVY