Changes in force: C#2 C#4, C#5 and C#6
TM 11-6625-496-45
C6
HEADQUARTERS
Change
DEPARTMENT OF THE ARMY
Washington, DC, 12 March 1980
No. 6
General Support and Depot Maintenance Manual
Including Repair Parts and Special Tools Lists
TEST SETS, RADIO AN/VRM-1 AND AN/VRM-1A
(NSN 6625-00-892-5542)
TM 11-6625-496-45, 3 July 1962, is changed as follows:
The title of the manual is changed to read as shown above.
Page 2. paragraph 1, subparagraph c is supersed-
current. Actual current measurements arc in excess
ed as follows:
of 400 ma when tested at 28.6 volts dc. Therefore,
c. Report of errors, omissions, and recommenda-
CR7901 is now type 1N4383 (NSN 5961-00-765-
tions for improving this publication by the in-
6578) which is a l-ampere device. This will result in
dividual user is encouraged. Reports should be sub-
a reduced statbilization period.
mitted on DA Form 2028 (Recommended Changes
(c) Resistor R790S (figs. 17 and 55) has been
to Publications and Blank Forms) and fowarded
changed from 475 ohms (fig. 39.1) to 402 ohms
direct to Commander, US Army (communications
(NSN 5805-00-818-5548) (fig 39.2) This allows the
and Electronics Material Readiness Command,
midpoint trigger leve1 for selector switch positions 9
ATTN: DRSEL-ME-MQ. Fort Monmouth, NJ
and 14 to be set closer to the median value for trig-
07703.
gering. This action provides a more optimized
Paragraph ld, subparagraph (5) is added after
operating point. Switch position 14 must be set near
subparagraph (4). Add the following sub-
the lower limit to maintain switch position 9 value
below the operating limit.
paragraphs:
(5) The TS-1777A/VRC displayed a problem of
(d) The TS-1777A/VRC exhibited problems
long warmup voltage data drift. When the CO/NO-
in sensitivity caused by lack of adjustment
CO test voltage levels are set at the time the set is
capabilities for positions 2 and 19 of the selector
first turned on, it seeks a new set of test trigger
switch. Fixed resistors R7902 (position 2) and R7919
voltage levels after approximately 30 minutes. This
(position 19) (fig. 11). respectively. have been
condition has been alleviated by the fol1owing
replaced with variable resistor R7902 in series with
changes, The changes have been incorporated in the
fixed-film resistor R7923 and variable resistor
TS-1777A/VRC starting with serial number 602 and
R7919 in series with fixed-film resistor R7922 (fig.
higher under Contract No. DAAB05-73-C-1632
11.1). Resistors R7922 and R7923 prevent
(1973) and succeeding contracts.
overheating of transistors Q7802, Q7803, and
associated components if the variable resistors arc
and resistor R7901 (figs. 14 and 54) is reduced
by
set for minimum resistance. The minimum
the application of a silicon heat sink compound
resistance setting of R7902 and R7919 results in the
(Dow Corning No. 340) between the mating sur-
full input signal level of 20 volts applied to the base
faces.
of Q7802, which is in the full input signal level of 20
(b) Diode CR7901 (figs. 14 and 54), type
volts applied to the base of Q7802, which is in excess
1N645, is rated at 400 milliamperes (ma) maximum
of the normal trigger voltage of 2.6 volts. The resul -
