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Re: [Amps] 833A GG

To: "Fuqua, Bill L" <wlfuqu00@uky.edu>, "Hsu" <hsu4qro@gmail.com>, "Mike Waters" <mikewate@gmail.com>
Subject: Re: [Amps] 833A GG
From: "Carl" <km1h@jeremy.qozzy.com>
Date: Mon, 26 Jan 2015 14:59:45 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Heck I had a pair of 100TH's on 6M in the early 60's but no matter what I did with the bias or drive could I get high output and no splatter at the same time. At 3KV they glowed nice. Shortly after that National sold me a NCL-2000 prototype for $20 (standard employee price for a lot of no production items) which I converted to 6 and still use.

I believe the Orr amp was a 304TH. I built one for G&G but looking at the output with the 60's era spectrum analyzer at National I decided Id likely get lynched if I put it on the air.

Never used a 833 at RF, just audio once to a 4-1000A in the 70's. These days the AM guys still salivate over them and lots of 1KW BCB rigs converted to 160/75 use a pair at RF and audio.

Back in the early 60's Sam Harris, W1FZJ/W1BU, used a S Line and 30L1 to drive a pair of 750TL's on 75 to a Lazy aimed at EU and VK/ZL. I never saw the power output but the PS was 7500V and the tubes glowed white on voice peaks. Signal reports of 20-30 over to VK/ZL were common

Carl
KM1H



--------------------------------------------------
From: "Fuqua, Bill L" <wlfuqu00@uky.edu>
Sent: Monday, January 26, 2015 10:46 AM
To: "Hsu" <hsu4qro@gmail.com>; "Mike Waters" <mikewate@gmail.com>
Cc: <amps@contesting.com>
Subject: Re: [Amps] 833A GG

You know, I ran a pair of 250THs grounded grid back in the 60's driven by a pair of 6146Bs at 1kW plate input power. That was before I knew that you could not do it. I wonder if it I could do it again knowing it will not work. Hi Hi they have a mu of 37. In one of the Radio Handbooks by Bill Orr, there is an example of a GG 304TL. It did require 200 Watts drive
for 900 Watts output, but back then the tubes were very cheap.
But as far as the 833, I see no advantage of running them in GG due to the grid plate capacitance. Either a single or two in push pull would be better. I am not aware of any hams getting good results on 10 meters however. Some have been
built for 80-20 meters but the output drops a bit on 20.
73
Bill wa4lav

________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Hsu [hsu4qro@gmail.com]
Sent: Monday, January 26, 2015 5:44 AM
To: Mike Waters
Cc: amps@contesting.com
Subject: Re: [Amps] 833A GG

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@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@gmail.com>
To: <amps@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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