[Amps] Why are 833s so Expensive

[DAVE WHITE]

The GU81Ms do indeed have a good reputation here in Europe as being a tube that can withstand fearful abuse.  They keep on working long after they should have melted.  I bought a load of these things for about 10 Deutchmarks each 10-12 years ago and never did anything with them (I got some 3CX3000A7s instead), so sold them on to a Tesla Coil builder not too far from here.  I hear the same takes of indestructability and barn door engineering from him too.

I understand that the GU81Ms are good up to about 21MHz but are less efficient above that.  I'd intended to use four of them in a topband amp, so high freqency efficiency wasn't really a design criterion for me.

I hope to hear VK6APK as an S9+ signal on a frequent basis :-)   

BTW Alek, what are your thoughts on the upcoming Ashes series - will you be following it?  Apparently England are rated 11/8 to retain the urn - though I think that's a bit optimistic from our side!

cheers

Dave G0OIL

--- On Mon, 27/9/10, Alek Petkovic <vk6apk at bigpond.com> wrote:

From: Alek Petkovic <vk6apk at bigpond.com>
Subject: Re: [Amps] Why are 833s so Expensive
To: "Roger" <roger at rogerhalstead.com>, amps at contesting.com
Date: Monday, 27 September, 2010, 4:13

Yeah, I've just bought 4 GU81M's and Dr Alex is posting me a pair of 
sockets as I write.

Should be an interesting project. . . . if I can ever find the time.

73, Alek
VK6APK



At 08:28 AM 27/09/2010, Roger wrote:
>Subject pretty much says it all.  833s are running over $125 ($258 for a
>pair) each although they vary from $100 to $200 each on e-bay. I don't
>know if they are selling any, but the price has been that way since last
>spring.
>
>OTOH the RUSSIAN GU-81s (similar to, but not quite as strange looking as
>the 833) are running from $22 to over $100 (typical $35 to $45 USD) plus
>shipping which is roughly $20.  Now there is a monster that will help
>heat the shack with it's warm glow. <:-)) A pair is good for close to
>the legal limit out without forced air.  OTOH they are definitely not
>the first choice for VHF.<:-))  Still, a pair would look great running
>in a glass enclosure.
>
>73
>
>Roger (K8RI)
>_______________________________________________
>Amps mailing list
>Amps at contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>
>=======
>Email scanned by PC Tools - No viruses or spyware found.
>(Email Guard: 7.0.0.18, Virus/Spyware Database: 6.15950)
>http://www.pctools.com/
>=======

 From sunny Binningup, Western Australia

http://www.qrz.com/db/vk6apk
http://www.qrz.com/db/vk6ap 





=======
Email scanned by PC Tools - No viruses or spyware found.
(Email Guard: 7.0.0.18, Virus/Spyware Database: 6.15950)
http://www.pctools.com/
=======
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps