Mic Kaczmarczik's TubeInformation - The Blue Guitar

is of considerable importance in many applications. In use, valves build
up a resistive layer between the metallic cathode and its emissive
coating. As this resistive layer appears in the cathode circuit, it
results in a negative feedback condition giving the valve a reduced
performance figure due to the loss of slope. The growth of this
interface impedance is more likely to occur where valves are used with
very low cathode current or in cut-off condition for long periods.
This also applies where valves are required to give high pulse
current after a long period of low current operation. To overcome this
problem Brimar Long-Life valve types incorporate new cathode alloys
which, as well as giving increased strength at working temperatures,
virtually eliminate cathode interface growth.
I have a few of the special quality flying lead CV4035=12AX7
and CV4069=12AU7.
Regards,
Brendan Biever
tekman@execpc.com
(414) 208-0353 (phone/fax)
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