>
>Hi,
>
>I think the efficiency of my homebrew 6m 8877 amp is
>lower than it should be (currently about 50 %), and am
>looking for some suggestions on how to improve the
>situation.
? What is the resistance of your termination R when measured with a DMM?
>
>The amp runs about 2800 V key down at 1 amp, with 50 mA
>of grid current, into a 50 ohm load. Idling current
>(set with a 12V Zener) is about 75 mA. The plate
>circuit is a Pi-L network patterned after Lauren Libby's
>(W0LD) HR article from July 1986, using a vacuum variable
>tuning capacitor, 3/16" copper tubing for the coil,...
? Due to skin effect, the circumference of conductors needs to be
greater as f increases. IMO, for good tank efficiency, 3/16" tubing is
ok for an 8877 on 160m. For 10m, it is not.
- later, Arliss
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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