I think you've hit the important points. Biggest mistake I see newbies make when tuning up amplifiers is watching output and plate current while ignoring grid current, and cooking grids. I watch outp
Normally, the tuning shaft/screw/plunger is at chassis ground, and the fixed piece of the capacitor is the "hot" side, so I don't see the issue. Of course, which is grounded and which is floating is
VY1JA: I'd use 3-500ZGs and not 3-400Zs in a new construction amp, since 3-400Zs are obsolete (unless you just happen to have some new ones). Even if building for the zero-bias 3-400s, leave sufficie
I agree the "flapper" tuning cap works quite well in lieu of a small value vacuum variable; but its adjustment is quite critical, and if a flapper is used it should be with a gear reduction or some o
Conrad, If you ever visit the U.S., come to Los Angeles and I'll take you to the local monthly ham radio swap meet (flea market). You will think you've died and gone to heaven....all sorts of vacuum
I think it's not a matter of "should" or "should not," but most appliances having such a control are labeled "100" when the plates are fully UN-meshed (minimum capacitance), by convention. WB2WIK/6 "
Wait a second, here. You mean, a tuning knob diameter of 1.75000" is not really required to achieve maximum output power? Holy smokes, maybe I can put some of those other knobs I've been saving to us
You might try a 1N3306B from R.F. Parts: 7.5V, 50W stud mount, $13.95/each. WB2WIK/6 "Success is the ability to go from failure to failure with no loss of enthusiasm." -Winston Churchill
Cheaper, probably, but I can't see why they'd be more rugged. A 3A epi rectifier should have about a 150A top 300A surge rating, and so does a 7.5V 50W zener. (Actually a good 50W stud zener is proba
Hi Rich, Re: Power zener surge current ratings.... You normally won't find the surge rating for a zener on a data sheet, since a single-die zener isn't normally tested under surge conditions, it's ch
[Steve Katz] Indeed. A modern-day SB-200 for only four times the price, what a deal. But, it has a front-panel "SWR" meter, and a built-in receiving preamp! Neat. -WB2WIK/6
[Steve Katz] For Rich's info, Diodes Inc is on Hillcrest Blvd in Westlake Blvd, about 10 miles from your home. I know them well. They're not a manufacturer, but a large franchised reseller of mostly
The electronic bias switch circuit may cause additional IMD during soft syllables, but in normal Ameritron amplifiers it does not cause any hot switching of T-R relays because the amplifier remains "