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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176 High-Power Microwave-Tube Transmitters<br />
0 -20 40 -60 -60 -1oo -120 -140 -16a<br />
Grid VOl@E ~<br />
Figure 10-20. Transfer characteristic for S94000E tetrode showing “projected” cutofi<br />
.<br />
S94000E has an anode-hold-off voltage rating of 200 kV and a maximum peakanode<br />
current of 125A. (We will later see that peak-anode current is virtually the<br />
same as the peak-cathode current.) The 4CPW1OOOKB has an anode-voltage<br />
rating of 175 kV and a peak-anode-current rating of 75 A. Both tube types<br />
evolved from high-power RF amplifier forebears. Like most tubes intended for<br />
high-voltage hold-off capability, they differ from their predecessors in the spacing<br />
between anode and screen grid. Consequently the slope of their diode, or<br />
virtual-cathode, lines also differ.<br />
The 4CPW1OOOKB is a radial-beam, external-anode tetrode of more-or-less<br />
conventional geometry. It descended from the 4CW250000 and was intended<br />
primarily as a megawatt-class RF amplifier in the HF band. Its anode is capable<br />
of 1 MW of average dissipation— which is what the “1OOOK“ in its type designation<br />
refers to-giving it extended capability for linear voltage nqydation and<br />
waveform shaping.<br />
The S94000E, by comparison, is literally inside out, as shown in Fig. 10-18. It<br />
is a radial-beam tube, but its cylindrically shaped anode is on the inside of the<br />
tube rather than the outside. Around the outer periphery is a circular array of<br />
“unitized” electron guns, which are shown conceptually in the figure. Each gun<br />
has its own central cathode bar, grid box, and screen box. The grid and scxeen<br />
boxes are solid on three sides. The sides facing the anode are open, except for the<br />
very fine wires stretched across them that are the actual control and screen ~ids.