3.6M north10.pdf - Dean-O's Toy Box
3.6M north10.pdf - Dean-O's Toy Box
3.6M north10.pdf - Dean-O's Toy Box
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188 High-Power Microwave-Tube Transmitters<br />
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WI characferistlcof crossed-field<br />
amplifier(QK-522 Arnplifron)<br />
b<br />
\<br />
AV/Al =200ohms<br />
(0.128xstatic resistance) \ 1/<br />
I /<br />
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VAcharacferistlc oflhar-<br />
\ 1+~$’!i!liae]<br />
. \ /<br />
. Above-the-kneeregbn of friode \<br />
ortetrodeswitchtube<br />
AWAI-75 kohms<br />
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~ Linearresisfancaload<br />
AV/Al.1583dims<br />
----- ----<br />
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, Operafiig point 50 kV, 32A (1583 ohms)<br />
Cuxka.he regionof trbde Loadiii of line-type<br />
a tefrode switch tube<br />
modulatormatckedto<br />
AWAI -300 OhlS<br />
operating-pointresistance<br />
I<br />
I<br />
.<br />
/<br />
.<br />
/<br />
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o 20 40 80 80 100<br />
voltage (w)<br />
Figure 10-30. Load-line representation of modulator/load interaction.<br />
If one of these devices is used to supplant a vacuum tube as the switch in a<br />
hard-tube modulator, external resistance must be provided to limit current in<br />
case of a shoot-through event. As with a gridded vacuum tube, the Crossatron is<br />
almost always more susceptible to damage than the diode-type microwave tube<br />
it is pulse modulating. For this reason, it determines the magnitude of the series<br />
resistance. The value of this resistance, in turn, often determines the usable<br />
output power from the switch because its resistance value can easily be greater<br />
than the ratio of conduction-tube drop and output current.