[Amps] Replace 2x 4-400 with 2x 3-500ZG

[Tony King - W4ZT]

With the increased gain and the plate voltage at 3KV+, you may have to 
provide some bias to keep the idling current low enough with no drive.
73, Tony W4ZT

Peter Voelpel wrote:
> I usually do it the other way round as 4-400G/QB4/1100/RS1002A are more
> rugged then 3-500Z.
> You will get higher amplification, so perhaps 20% more output with the same
> driving power by using 3-500Z.
> But with enough drive I prefer the tetrodes.
> I can do 2,3KW output or even more with the pair of RS1002A in my L4B at
> 4KV, with stiff 3KV they provide 1,8KW at 120W drive and 1,5KW when using
> the original power supply (made for 60Hz). My homebrew P/S is 3-phase.
> The weak point is the bandswitch, it has to be cooled on the high bands, I
> use a good size CPU fan there. If you run a commercial amp that will be no
> issue.
> 
> 73
> Peter, DF3KV
> 
> 
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Posselt Werner
> Sent: Freitag, 2. Juni 2006 10:26
> To: amps at contesting.com
> Subject: [Amps] Replace 2x 4-400 with 2x 3-500ZG
> 
> Hello!
> 
> Is it possible to swap the 4-400s with two 3-500ZG without any further
> modification?
> The tubes are operating in grounded Grid configuration.
> The HV supply is homemade delivering 3,3KV.
> How much increase in power output can I expect?
> 
> Thanks for your answers!
> 
> 73, Werner
>     oe2wpo
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