Tubes are cheap but not even my son who travels all over Eastern Europe cant
find cheap sockets.
Carl
KM1H
----- Original Message -----
From: "Fuqua, Bill L" <wlfuqu00@uky.edu>
To: "Roger (K8RI)" <k8ri@rogerhalstead.com>; <amps@contesting.com>
Sent: Monday, February 27, 2012 4:08 PM
Subject: Re: [Amps] 833A/GU-48 x4 Amp support
> My vote is for the GU-81 grounded grid. Looks like folks have been runing
> them that way.
> Where can I get some cheap? Sounds like a good project.
> 73
> Bill wa4lav
>
> ________________________________________
> From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf
> Of Roger (K8RI) [k8ri@rogerhalstead.com]
> Sent: Monday, February 27, 2012 3:34 PM
> To: amps@contesting.com
> Subject: Re: [Amps] 833A/GU-48 x4 Amp support
>
> On 2/27/2012 3:03 AM, Fuqua, Bill L wrote:
>> I believe he wants 4 glowing plates. Larger the better.
>> 4x 250th would work but a bit expensive compared to the Russan 833.
>> I once ran 2x 250th in grounded grid driven by a pair of 6146Bs on 20
>> meters.
>> So 4 should work.
>
> The GU-81 is, or was, very popular in Europe, particularly running a
> pair of them. I think you'll find it's a Pentode, not a Tetrode. Of
> course it still requires the same power supplies as a Tetrode as the
> suppressor is grounded. They are rated to 50 Mhz but at substantially
> reduced power. Dr Alex http://www.nd2x.net/ur4ll.html lists a pair of
> them running 3KW without forced air.
> http://www.nd2x.net/ur4ll/gu81-skem.gif Nice thing about them is they
> can be run without forced air. Other than the two connectors on top, to
> me they don't look much like an 833. The audio guys have pushed the
> price of 833s well out of reason as far as I'm concerned.
>
> I should have picked a few more up when they were running less than
> $20USD each. The ones I purchased were $18 each. Now they are averaging
> more than twice that and the sockets are running close to $50 each.
> (Prices vary widely) I've often thought I'd like to build monobanders
> for 160, 75, and 40. *Apparently* they are a tube that can be "abused"
> and run well beyond its official ratings. I have no idea as to it's IM
> characteristics, but I did hear a couple groups using a pair of them as
> drivers. <:-))
>
> OTOH getting four of the rather massive graphite plates to run a
> substantial glow might be pushing a fair amount of power out.
>
>
> 73
>
> Roger (K8RI)
>>
>> 73
>> Bill wa4lav
>
>
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