Also look for the kind to finals tune up procedure in the list archives. Best way I have ever found to tune up a set of twins. BTW found that it was originally published in Ham Radio magazine. Boy do I wished we had that type magazine back.
73, Ron WD8SBB --- On Thu, 10/7/10, Garey Barrell <[email protected]> wrote: From: Garey Barrell <[email protected]> Subject: Re: [Drakelist] bias adjustment To: "drakelist" <[email protected]> Date: Thursday, October 7, 2010, 6:17 PM Jim - Generally not a good idea. This pops up every once in a while. The concept is that the PA stage is a LINEAR amplifier, and the BIAS current is set for the most linear operation. Just as an extreme example, you COULD crank the bias up way past cut-off (zero bias current), and run the PA as Class C if you had enough drive. But then you're into the clicks, harmonics and even spurs that come along with Class C. The Drake PA is operated in Class AB1, for the cleanest amplification possible. Best to run it that way. Idle current is only drawn 'between dots' and briefly waiting for the VOX to drop out. Not significant. Run the tubes as designed, and they will last many years. Spend five minutes tuning up into the 'wrong' or 'no' antenna and reach for your wallet!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-B, C-Line& TR-4/C Service Supplement CDs <www.k4oah.com> [email protected] wrote: > Greetings to the group, > After all the posts lately about the care and feeding of the 6JB6 finals I > have what may be a dumb question .....but here she goes. > I have a T4XC that I use exclusively on CW. I think I recall some while back > that someone said the idle current could be reduced > from the standard .07 A level if the transmitter was only being used on CW. > Is that true and if so what level would be appropriate ? > My T4XC looks to have original Sylvania finals and they seem healthy as I get > about 140w out on 20m if I run it full out. > I never run it over 100w and have a fan sucking air up from the cage. But if > I could perhaps get longer life from the tubes by > running less idle current then I might ought to try it. Is this a good idea > or maybe not ? thanks for any thoughts Jim N5KY > _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
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