[Amps] What to do with tubeless sweep tube FL2000

[Will Matney <craxd1@ezwv.com>]

Well,

The EL509 or EL519 is a 6KG6A, not a 6KD6 or 6LQ6. They are internally wired different than either the 6KD6 or 6LQ6. The 6LQ6 was rated as a 30-35 watt plate dissipation, the 6KD6, 6LF6, 6JS6, 8950 a 40 watt. The 6KG6A was rated about 40 watts with a 700 Vdc plate voltage where the others were ran at 900 Vdc. Svetlana claims that their version will run at 900-1000 Vdc. The 6LQ6's have a smaller anode area than do the 6KD6, 6LF6, 6JS6 and the 6KG6A. Needless to say, the variance in the plate voltage changes the plate impedance to where the Svetlana version does not match the true 6KG6A sweep tube. The actual Russian number for their version is a 6P45. The 6KG6 has a taller envelope than does all the others mentioned because of having two getters suspended over top of the anode. The 8950 is just a 12 volt version of a 6LF6 and can be changed to it by changing the heater pin connections at pins 1 and 12. A 6LB6 can be used to substitute an 8950 this way also. It was my understanding that Yaseu bought out the last stock of the 6JS6 from GE when they ceased operation back in the 80's. Even though the 6KG6A has a nine pin socket, it is wired internally different than a 6LQ6. There was a modification for a Dentron at the Svetlana website at one time that used four 6LQ6's. I've heard a lot of comments about "other" amp builders abusing sweep tubes but the Yaseu, a Dentron, and an Amp Supply model ran them at 1200 Vdc OCV! Talk about running them hot and out of spec! The two BEST tubes made in my opinion was the 6LF6 and the 8950. Two others come in mind that was the utmost best, the 8908 and the M-2057. GE custom made the M-2057 for Majestic Communications using the guts of an 8908. They used extra connections on the grids to drop interelectrode capacitances that the 8908 was guilty of. So, the M-2057 was the 12 pin version of an 8908. The reason I know the full story on the M-2057 is that I was the only one privy to buy them as an OEM besides Majestic, and bought them through Richardson Electronics this way until they ended the tubes in 1989. Back then they were a whopping $15.00 each and I complained about that. Now they're running at $100 - $150 if you can find NOS. The 8950's and the 6LF6's back then were $12.00 each! One last thing, there is available a 40 volt filament version of the 6KG6A which EI manufacturers known as a PL-519. Three of them in series and you can run the heaters off the 120 Vac line or use a dropping resistor for odd numbers. That is a very easy trick to do and saves a filament transformer.

Will

Message: 3
Date: Sat, 26 Jun 2004 15:44:10 -0400
From: "donii@sympatico.ca" <donii@sympatico.ca>
Subject: [Amps] What to do with tubeless sweep tube FL2000
To: amps@contesting.com
Message-ID: <40DDD20A.3070405@sympatico.ca>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Aren't they EL509/6LQ6s rather rather than EL509/6KD6s?  That's what I 
get from the Svetlana site.
73's
VE2FAR

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps