Radar System Engineering

572 PRIME POWER SUPPLIES FOR RADAR [SEC. 14.6
Maximum frequency at 28.5 volts, ~ load, 35,000 ft, – 15”C,
Leland PE-218-C
GE PE-218-D
485 CpS
458 CpS
Minimum frequency at 28.5 volts, full load, sea level, –35”C,
Leland PE-218-C
GE PE-218-D
401 Cps
392 CpS
The variation in frequency caused by change in input voltage and in
temperature is indicated in the following table.
TABLE 14.4.—CHANGES IN FBEQUENCY OF IiWERTERS WITH TEMPERATURE AND
VOLTAGE
Frequency, cps
Input
Temperature,
voltage ‘c Leland GE Co.
PE-218-G PE-218-D
26
29
Over-all regulation
–45
+25
+55
– 45
+25
+55
373 379
396 396
406 398
411 404
443 423
449 428
Leland
GE Co,
I PE-21&C I PE218-D
In cps
76
In per cent 17,0 i :.5
I
All data were taken at sea level and with full rated load on inverter.
The GE PE-218-D unit has a compensating resistor in series with the
field which accounts for its slightly better regulation. It also has an
adjustable resist or which allows the frequency to be varied over a range
of approximately 40 cps. These inverters are show-n in Figs. 14.16
and 14.17.
In most radar applications, such a range in frequency is not objectionable.
Certain indicator and computing circuits, however, require much
closer regulation of the order of +2* per cent. Good speed regulation
also considerably reduces the problem of voltage regulation. In accordance
with the need for better speed characteristics of inverters, the latest
Army-Navy specifications (AN-I-1O) stipulate the following frequency
limits: For all voltages between 26 and 29 volts and at any load from
~ to full, the allowed frequency limits for a temperature range of – 10”C