If. Rejection

e. Apply this if. test signal to the test

set.

f. Increase the signal generator level

c o n t r o l setting to produce a full-scale

meter indication. The ratio of the two sig-

nal generator output level control settings

in db (in this procedure and that in c above)

m u s t meet the requirements of the fol-

lowing chart:

e. A f t e r d e t e r m i n i n g t h e i m a g e f r e -

quency for the frequency under test, apply

this frequency from the tuning unit signal

generator to the test set.

f. Increase the tuning unit signal gener-

g. R e p e a t t h e p r o c e d u r e s g i v e n i n c

ator level control setting to produce a full-

through f above at the middle and highest

scale panel meter indication. The ratio of

frequency points of each band for all tuning

the two signal generator output level con-

units.

trol settings in db (in this procedure and

t h a t in c above) must meet the require-

109. Rf Intermodulation

ments of the following chart:

The rf intermodulation test concerns the

r e s p o n s e of the test set to the intermod-

ulation components that are generated

a h e a d of the if. amplifier in each tuning

u n i t . The response is measured with the

test set receiving high-intensity broadband

i n t e r f e r e n c e signals from the self-con-

tained impulse generator. No signal gener-

ator is required. Make the test as follows:

a. Rotate the SIGNAL ATTENUATOR DB

g. R e p e a t t h e p r o c e d u r e s g i v e n i n c

control to the 0 CW ONLY position.

through f above at the middle and highest

b. S e t t h e c a l i b r a t i o n s w i t c h t o t h e

frequency points of each band for all tuning

SHUNT CAL position.

units.

c. Set the function switch to the PULSE

PEAK position.

108. If. Rejection

d. Set the TUNING control and the fre-

a. With a tuning unit plugged into the

quency dial of the tuning unit under test to

tuning unit compartment, connect the ap-

t h e lowest frequency of the lowest band.

e. With the IMPULSE GENERATOR DB

p l i c a b l e signal generator for the tuning

u n i t under test as directed in paragraph

A B O V E 1 V/MC switch at its OFF po-

105a.

sition, vary the tuning unit GAIN control

to produce a zero db indication on the upper

b. Set the AN/URM-85 front-panel con-

scale of the panel meter.

trols as directed in paragraph 105b.

c. Repeat the procedure given in para-

f. Set the IMPULSE GENERATOR DB

A B O V E 1V/MC at ON and adjust the

graph 107c.

i m p u l s e generator coarse and fine output

d. Retune the signal generator to the

c o n t r o l s to produce a 2-db deflection on

i n t e r m e d i a t e frequency of each band, as

the panel meter. Record the settings of the

listed in the chart in paragraph 107d.

224