>I have an AL80A here which came to me from a handicap ham, no name, before I
>dig into it, I see normal HV, (3500) no plate current on meter , grid mtr.
>shows neg.(?) current .. !! (off scale to left). !! tube out , no mtr.
>readings. !! tube in , as above, !! tube measures no resistance between grid
>and fil. (suspected)on hi res. range. (100k+)
> anyone here that can give me at least an educated guess before I dig into
>it ???
Zero grid-fil resistrance incicates a bent filanment helix touching the
grid. (Photo in September, 1990 *QST*, and on my Web site) Either the
amplifier has been operated aeronautical mobile in an acrobatic airplane
or the filament was bent by EM force as the result of an intermittent
oscillation condition c. 155MHz. However, grid-fil shorted tubes
usually draw high anode current. // Does this AL-80A have
"neutralization" ? What is the measured resistance of the vhf suppressor
resistor?
cheers, Carl
>
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
|