RCA BTA-250M Instructions Manual page 22

OPERATION
To energize the BTA-250M transmitter, close the
FILAMENT breaker switch. After the time delay
relay has operated, approximately 30 seconds delay,
place the PA, MOD, and PLATE switches in the
ON
position. The transmitter is now ready for normal
operation.
To shut down the transmitter, open the FILA-
MENT and PLATE switches. Future applications of
power may be made by simply closing these two
switches.
During operation it is well to check the filament
voltage occasionally on the panel meter, and to ad-
just the FILAMENT control as necessary to compen-
sate for any line voltage fluctuations.
Increased tube
life will result by operating all tubes at their rated
filament values.
Overloads may trip the PA or the MOD breakers
individually, requiring manual reclosing after the
difficulty has been remedied.
MAINTENANCE
To insure continuous and reliable operation it is
recommended that a definite maintenance schedule
be established.
It is particularly important that the
entire transmitter be kept free from dust and exces-
sive moisture.
Special care should be observed in
the case of all insulators to avoid high resistance
leaks.
A small electric hand blower may be used
advantageously to blow dust from inaccessible
places.
ically for poor contacts and loosened connections.
As far as possible, tube failures should be antici-
pated by keeping a log of tube life and replacing
tubes before actual breakdown.
The appearance of the transmitter and its compo-
nents may be kept like new by the judicious appli-
cation of the matching lacquers which are included
as part of this equipment.
As an aid in servicing, Table 7 lists typical volt-
The transmitter should also be inspected period-
ages at the tube sockets.
TABLE 7
TYPICAL TUBE SOCKET VOLTAGES
' Fi'ame"t
'
Tube
Tube
Symbol Function
~___
Volts
Pin
DC No.
----
Vl Oscillator 807
cap 4 20
225
3
- 2
~___~
VlOl
Buffer/
807
Driver
cap 4 42
530
3
-75 2
245 l-5
~___
345 l-5
Volts
AC
6.3
6.3
V104,S 1st AF 807 cap 240 4 36 3
9 2
V106,7
Modulator
813 cap 1,515 - - 4
-80 3
___ ___
V108,9 Rectifier 866/366A cap 1,840AC - - -
- -
335 l-7
______
240 l-5
10
6.3
All voltages except filament voltages are measured to ground, using a high-resistance voltmeter
22