[Amps] 833A GG

[Hsu]

Hi  Mike, Thanks for your very good  and useful information.
   Yes, you are right.I'll not think off this tube.
833C's manufacturer nearby  my home( 300 mtrs apart!)
They made 3-500Z  too, in past two years, Almost all over the  world  3-500C
from this manufacturer.There is a version of rugged 833C, anode diss. and
filament current increase  30%-35% , they renamed it  FU-501
http://hgdzg.com/a/english/Products/blg1/2014/0614/121.html,
  There  is a more powerful triode  FU-605, same as Jananese 6T51
,http://hgdzg.com/a/english/Products/blg1/2014/0613/118.html
the amplification facturer is 48,maybe it is suitable for GG ,its  anode 
diss is 800W.
anode to filament  capacitance is 0.21p, maybe this tube is better?
       73!Hsu


-----原始邮件----- 
From: Mike Waters
Sent: Monday, January 26, 2015 5:01 PM
To: amps at contesting.com
Subject: Re: [Amps] 833A GG

Not recommended for GG on ANY band.. Not enough gain, for one thing; it
would take several hundred watts of drive power to obtain the legal limit.
Another issue is that the feedback capacitance is quite high.

Some tube data sheets I've seen imply that it can be used above 10 meters.
However, you'd almost certainly have to run two in P-P, beside using
neutralization, not to mention careful attention to every last detail such
as layout.

Now, I do know of a guy that did build a working GG 833 amp, but it was a
monoband (75m) amp. His 833 amp used a tuned input and required 600 watts
of drive power, IIRC. But it could put out more than the legal limit, even
by today's standards. I forget whether he used one or two tubes. I forget
his call, but he used to hang out on 3895 in years past. The last I knew,
he (Frank?) listens a lot on 3890 or 3892 at night.

I built a homebrew legal limit amp using two 833Cs in parallel,
swamped-grid-driven. I've used it successfully on 160, 80, and 40. However,
it's kind of touchy on 40; the grid impedance drops too low there, for one
thing (one sign that it needs neutralizing). It's kind of a work in
progress, but it works perfect on 80 and 160. Future plans are to
neutralize it with a tertiary winding in the broadband input matching
transformer connected to the plates through a HV neut cap, and eventually
see if it'll play on 20m.

Details and photos of the 833C amp are on www.w0btu.com if you're
interested.

The graphite plate version of the 833A is actually an 833C, BTW.

73, Mike
www.w0btu.com

From: Hsu <hsu4qro at gmail.com>
> To: <amps at contesting.com>
>
> Date: Mon, 26 Jan 2015 14:13:55 +0800
>
Subject: [Amps] 833A GG
>
Anyone have  experience  about 833 works on GG configurtion?Is it can work
> 10 mtrs?I just contact with the manufacturer, the factory new tube 
> graphite
> anode,only $50/ea, ,dirt cheap
>    Hsu
>
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