Radar System Engineering

SEC.105] MAGNETRON CHARACTERISTICS 343
appreciable numbers and thus constitute well-tested designs. Fixedfrequency
tubes are indicated by a dot and tunable tubes by a line whose
length shows the tuning range. Whenever possible the magnetrons are
identified by their RMA type numbers.
The values of pulse power given in thk chart are conservative ones
corresponding to reliable operating conditions. Pulse powers considerably
in excess of those given for the highest power tubes have been
FIG. 10.19.—An array of anode blocks showing the effect of wavelength and pulse
power output. Top row—10 cm, pulsepower 2500to 0.1 kw; secondrow—3 cm, pulse
power600to 0,025kw; single block—1.25cm, 80 kw.
observed. At 3000 Me/see, for example, 4500 kw have been obtained
from the HP1OV, and the British report 3700 kw peak at an average
power level of 5 kw from a similar tube, the BM735.
The general rule that maximum pulse power is proportional to wavelength
squared is illustrated by the falling-off of power at high frequencies.
Exceptions to this rule are the magnetrons in the 20- to 30-cm range,
whose pulse power output is not as high as might be expected. This
particular situation resulted from a lack of need for very high powers in
this wavelength range.
Figure 10.19 illustrates the effects of wavelength and power output on
the design of anode blocks. In the top row, from left to right, are 10-cm
anode blocks for magnetrons with pulse power outputs of 2500, 1000,”
250, 5, and 0.1 kw. The reduction in anode diameter with pulse power
is evident. In the second row are 3-cm anode blocks with pulse power