Section VIII
A slight adjustment of C-1534 at the bottom of the
d. Substitute Signal Generator SG-13/ARN for the
coarse frequency oscillator should shift all the crystal
SG-1/ARN using the same 6-db pad and adjust the
frequencies so that none will fall outside the +0.0065%
MICROVOLTS dial until the same avc voltage reading
limits. If any crystal still falls outside these limits
is obtained. Adjust METER ZERO. The CARRIER
insert a new crystal to obtain required frequency.
SET control should be adjusted to the red line prior to
this measurement. The MICROVOLTS dial. should
read 1000. `If not, loosen the dial set screws with the
Bristo wrench furnished and reset.
a. Place all covers on the r-f section and tighten all
cover screws securely. This is necessary to prevent
NOTE
r-f leakage during alignment.
The SG-1 microvolt dial is calibrated for use
b. The r-f output is adjusted by comparing it with
with a 6 db pad. The SG-13 microvolt dial is
the output of a Signal Generator SG-l/ARN. Feeda
calibrated for a direct connection between NAV
or GS output connectors and receiver input.
114.9 mc signal from Signal Generator SG-1/ARN
into an ARN/14 navigation receiver with a d-c vacuum
tube voltmeter connected to measure the receiver avc
A 53-ohm 6db pad is used with the SG-13 out-
voltage. Use a 53-ohm 6-db pad in the cable connecting
put cable in this test only to insure proper
the receiver to the SG-1/ARN to keep the standing
termination of the SG-13 in case the receiver
wave ratio low. See figure 8-5 for test connections.
being used does not have exactly 53- ohms
inPut impedance. For this reason, the SG-13
c. Set Signal Generator SG-1/ARN MICROVOLTS
M I C R O V O L T S dial must be set to twice the
dial to 500 microvolt and note avc voltage developed
r e a d i n g of the W-1 microvolt dial during
in the receiver.
this alignment procedure.
38
