[AMPS] Re:Question: input Z on class AB gnd grid pair 4-400 ??

[Jan.E.Holm@telia.se]

With 100W drive and 3kV on a pair of 4-400īs it might
be a problem to get 1500 out, better run 4 kV on plates.
I have a 3 tube 4-400 amp 10 - 160m and it runs excelent.
After 20 years of service it still runs full output and
the tubes wasnīt even new back then, I run slightly less
then 4kV on them and they are GG. If you have the hardware
for a 3 tuber thatīs the way to go.

73, Jim SM2EKM

PS: You can use the same tuned input as a SB-220 (or similar)
    uses and just tweak it.
--------------------------------
>  
> Greetings,
>  
> After digesting the material that I have collected and the responses
> from an earlier post (tnx, Skipp), I think the best way to go for my
> homebrew amp is to run the 4-400's in class AB grounded grid.
>  
> I have dug up a couple of construction articles.  One is from the  
>1982
> ARRL Handbook.  In chapter 6, it describes "An Economy 2-kW  
>Amplifier"
> that uses these tubes grounded grid.  It doesn't, however, have a  
>tuned
> input network.
>  
> I'd like to add one.  But before I do, I need to know what the  
>approx.
> input impedance is for a pair of 4-400's in grounded grid.  If it
> matters any, I plan to run 3000 ~ 3500v on the plates.
>  
> Thanks in advance!
>  
> 73,
> Charlie  N9CO
>  
> --
> FAQ on WWW:               http://www.contesting.com/ampsfaq.html
> Submissions:              amps@contesting.com
> Administrative requests:  amps-REQUEST@contesting.com
> Problems:                 owner-amps@contesting.com
> Search:                   http://www.contesting.com/km9p/search.htm


--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm