[Amps] 4CX1500B project

[Bill, W6WRT]

ORIGINAL MESSAGE: 
On Thu, 09 Aug 2012 15:55:21 +0000, Manfred wrote:

>Instead of a simple plain parallel resonant circuit, which would need to 
>be bandswitched, a simpler solution is to include a basic low pass 
>filter section in PI configuration, that cuts above the highest band, 
>and absorb the tube's capacitance in it. Such a basic low pass section, 
>designed to cut off above the 10 meter band, will require about 100pF on 
>each side. So it can be built with the 100pF on the input side but only 
>20pF on the output, and the tube's capacitance will complete it. The 
>result will be low SWR on all bands, without needing a band switch 
>section at the input.

REPLY: 

Thanks, Manfred.  I will have to try that when I get some time. As I mentioned
in another post I had no success trying to broadband the input. Perhaps your
approach is the answer. 

Unfortunately, the amp I built back then has been cannibalized for parts so it's
no longer available to experiment with. 

Someday....

73, Bill W6WRT