Radar System Engineering

466 THE RECEIVING S YSTEAf—RADAR RECEIVERS [SEC. 12.10
necessary for the reception of the 0.5-psec pulses employed by the system,
to allow for tolerances in the adjustment of the AI’C unit and in t,he manufacture
of the i-f strip as well as for a slight spread in the frequencies of
beacons. The voltage gain between the grid of the first tube and the
plate of the sixth is about 30,000.
The seventh tube is a plate detector, which gives 10-db gain as well
as a somewhat larger power output than could have been obtained from a
diode detector of the same bandwidth. This advantage, ho,.vever, is
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FIG, 12.19 .—AN/APS-lO receiver; top and bottom views.
accompanied by three disadvantages. First, this detector is not St,rictly
linear, a difficulty that is not too serious since this system is not intended
to be operated in situations where interference is to be encountered.
Second, with certain detector tubes there is some “ blackout effect”-
that is, the sensitivity does not recover immediately after the transmitted
pulse or after other very strong signals. Third, care must be employed
in t,he design of the power supply to reduce plate-supply ripple because
such ripple is amplified by the entire video amplifier. The detector has
an output test point for convenience in checking the pass band.
The last tube is a cathode follower which supplies negative video