Q1: It might help some, but it could just as well hurt the tubes. All tubes are rated for a specific filament voltage. All voltage variations, both above and below, specified voltage cause issues. It is my understanding that indirectly heated tube (as are in all the Drakes) are more tolerant of slight voltage variations. Other here have more background and will hopefully comment.
Q2: The bias you adjust on the Drakes is just on the finals. It is adjusted to make the final tubes amplify in a linear fashion. Bias is a compromise, more bias generally makes the amplification more linear (less distortion) but less efficient, while less bias make the amplification more efficient and less linear (more distortion). In the case of the Drakes, it is important to adjust the bias to the value that Drake engineered. Anything outside of that value will either cause more "splatter" (distortion) or shorten tube life. 73, Ron WD8SBB --- On Fri, 11/11/11, Michael A. Kelly <[email protected]> wrote: From: Michael A. Kelly <[email protected]> Subject: [Drakelist] Bias Adjustment on TR4CW To: [email protected] Date: Friday, November 11, 2011, 9:53 PM Question 1: Would tube life be extended if I ran my TR4Cw at 108-110 Volts AC instead of 120VAC? (All of the 21 tubes, not just the transmitting tubes?) I have access to a variac and could do it easily. Has anyone else done this? Obviously output would suffer a bit, but I typically run 90-100 watts maximum anyway. Aside from less possible total power output, is there a downside here? Question 2: When you adjust the PA Bias to 0.1 what exactly is that doing, decreasing the voltage similar to a variac? Does it affect all tubes, or just the finals? If so, again, why not turn it down to say 0.009 instead of 0.1 and again extend tube life? Thanks, Michael Kelly N4MAK _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
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