Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- Ron -
Wayne's suggestion to "turn the bias to where the plate meter just barely moves" doesn't result in Class C operation. True Class C operation require the grid be biased "several times cutoff voltage". The only "benefit" with this setting is the reduction in "idling current" between elements of CW. There is no real gain in the "class efficiency" of the stage. It DOES however definitely move the operating point of the final tubes out of the linear range which will certainly mess up a SSB signal! :-)
73, Garey - K4OAH Atlanta
Drake C-Line Service Manual <http://hr99.home.mindspring.com/R-4C_Servicez/>
Ron Wagner wrote:
Ron Wagner <[EMAIL PROTECTED]> made an utterence to the drakelist gang
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The bias voltage is used in other places on the rig besides just the finals. That said, have a look at the "drake mods" article written by VE3EFJ http://www.dproducts.be/drake_museum/Drakemods.htm select the PDF version and look for bias. The 5 or so hit will be the CW discussion.
He discusses backing down the bias provided that you are only running CW. Keep in mind that the 6JB6s are a small linear amp, and adjusting then out of linear will effect you CW note. Might get the FCC looking your way, or at least a few fellow ham unhappy with your key clicks.
73, Ron
On Sun, 13 Feb 2005, F3WT wrote:
I run only CW and would like to bias for class C operation those finals as
I did once for my home - made CW Xmter which has a couple of 807's.
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