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7. TUBES
LED graphs, advanced adjustments of the BIAS setting
There is an upper adjustment limit to the "high" BIAS setting, which is indicated by the green and
LEDs lighting up at the same time, and a lower limit to the "low setting, where the yellow -
and green LEDs light up. The lower limit should be used with "smaller" output tubes such as the KT
88, 6550, EL 34. The upper value, which provides a higher BIAS current for the output tubes, can be
used with the KT 120, KT 150 and KT 170 in both positions of the power selector.
The BIAS LOW setting corresponds to the plate current of 33mA.
The BIAS HIGH setting corresponds to the plate current of 40mA.
LED graphs
The crossover setting yellow / green or green / red is an adjustment with a very high precision. Small
changes in the brightness of the LEDs are normal due to the long time drift of the tubes or the mains
voltage.
Summary of Contents for MRE 220 SE
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