I added a chassis view of the Ugly amp. to my Web site. Warning. This
is a high-res JPEG file, so it takes a while to download. However, you
can pretty much see what's what. The grid roller coil [from Collins ant.
tuner/available for $10 from Fair Radio] is just below the grid terminal
on the socket (center, lower). The filament transformer is on the upper
right. The 0mA grid bias supply is between the socket and the fil.
trans. The shiny dark object below the bias supply is the multiplier
resistor for the 0-10kV anode-potential position on the multimeter. The
filament V rheostat is on the lower left. During the Great Debate,
there were many stern warnings from critics of "The Nearly Perfect
Amplifier" (Jan., 1994 *QST*) - to the effect that manufacturers don't
use rheostats to control filament voltage (as per the article) because
rheostats simply do not last in this application. The rheostat still
works after a dozen years of service.
The large shiny surface with four holes on the socket is one of the two
filament/cathode collets. The other filament/cathode collet lies just
behind. Please note the large collection of multiple-value, HV, disc
ceramic capacitors that are bypassing both collets. Multiple disc-cer.
capacitors are needed because they must bypass 6A-peak of RF to chassis
gnd over a wide range of frequencies, with little reactance. . . .
One should keep in mind that above its self-resonant frequency, a
capacitor looks like an inductor. For example, your typical 0.01uF
disc-ceramic universal "bypass" capacitor looks like an inductor on 20m -
10m.
cheers
- Rich..., 805.386.3734, www.vcnet.com/measures.
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