RCA TT-10AH TRANSMITTERS

BACK UP RCA TRASNMITTERS
RCA TT-10AH and RCA TT-25BH

RCA TT-10AH and TT-25BH Transmitters
"Alternate", "Backup"
Picture about 1993

This transmitter is the back up, and is used if the primary fails. This old transmitter was the first model of television transmitter produced by RCA. In fact, this transmitter was originally a monochrome (black and white) transmitter until modified for color.

But do NOT be deceived, this transmitter has advantages:

It has a great picture; almost as good as the primary.

This hardy transmitter tolerates lightning or PGE surges that the solid state primary can not sustain. This transmitter is rugged.

BACK UP RCA TRASNMITTERS
RCA TT-10AH and RCA TT-25BH

Control Module
the two TT-10s

TWO MODULES CONTROL ALL FOUR UNITS:
TT-25 PAA, TT-10 AURAL, TT-10 VISUAL, TT-25 PAB
Module TT-10
Module TT-25

TT-25 PA "A"

AURAL TRANSMITTER

VISUAL TRANSMITTER (DRIVER)

TT-25 PA "B"

Control Module
the two TT-10s
Control outputs...

Reed relays are used for buffering. For added buffering the 12v is floating from an isolated external source. The 5V is always present as it is a system voltage created from the card. It is used for an onboard indicator. The reed relays control yet other larger External System Control Relays. Finally, the External System Control Relays control the equipment. The External System Control Relays and Sensors are located at the equipment.

"You always pass failure on the way to success."
-Mickey Rooney

In the early years, lightning has been a problem with the old system. This approach prevents system solid state damage and system relay contacts fusing together. Equipment will always suffer all kinds of horrendous fates. But the control system must be divorced and immune from external problems.

RULERMAR.GIF, 1 kB

Sensor

SENSOR:
UNUSED AUX CONTACTS ON K1.
The unused contacts are used to indicate the presents of AIR pressure. (Filaments are only assumed). The telemetry contacts are at the left hand side of the relay at the base using a white wire. This relay is located in the aural section: cabinet #5, down below.

Sensor

SENSOR:
UNUSED AUX CONTACTS ON K6.
The unused contacts are used to indicate the presents of AIR pressure and FILAMENTS. The aux telemetry contacts are at the left hand side of the relay at the base using a black wire. This relay is in the visual section: cabinet #6, above.

Sensor

SENSOR:
UNUSED AUX CONTACTS ON K2 OF PAA.
The unused contacts are used to indicate the presents of AIR pressure and FILAMENTS.
PA "A" and PA "B" are identical. PAA K2 is located in CABINET #2, and PAB K2 is located in CABINET #9: both at the top of the cabinet, top row. One can see a red spade on the sense wire. This picture is of PAA.

Sensor

SENSOR:
UNUSED AUX CONTACTS ON K18.
The unused contacts are used to indicate the presents of PLATE HIGH VOLTAGE.
PA "A" and PA "B" are identical. PAA K18 is located in CABINET #2, and PAB K18 is located in CABINET #9: both at the top of the cabinet, top row. One can see a the two red spades on the sense wire. This picture is of PAA. (Part of relay K2 can be seen to the left.) This picture represents two sensor inputs.

Sensor

SENSOR:
UNUSED AUX CONTACTS ON K4.
The unused contacts are used to indicate the presents of AURAL PLATE HIGH VOLTAGE. Technically, this relay is the modulation relay, but the function is to indicate plate volts. This relay is located in cabinet #5.

Sensor

UNUSED AUX CONTACTS ON K4.
The unused contacts are used to indicate the presents of VISUAL PLATE HIGH VOLTAGE. Technically, this relay is the modulation relay, but the function is to indicate plate volts. This relay is located in cabinet #6.

Sensor

Combined-Power-Amp SWR Sensor

Sensor

Combined-Power-Amp Forward Power Sensor

RULERMAR.GIF, 1 kB

control

Commanding controls for the back up transmitter are deceptively simple. Shown in the picture is one of four control pannels. The control pannels are a vertical row manual switches. The simple part: Behind most of the switches are control relays, wired in parallel with the switches.

The bottom button is the OVERLOAD RESET.

The next switch up is the start switch witch turns on blower motors.

The next switch up is the filaments. This switch is left on at all times.

The next switch up is an interlock switch. Switch is left off, and is not remotely controled. It does not have a relay wired in parallel behind the pannel.

The next switch up is the HV PLATES.

There are 3 control relays for each of the four manual control pannels.

In addition, there is the SIDE BAND FILTER room. One control line goes into this room to run the side band filter blowers. This line is activated by the visual driver filament control. With the box switch down, control is automatic. You can manually force the blowers on by throwing the switch up.

Dos computer screen showing the back up transmitter in operation.
Picture about 1994

Old Screens

PIN OUTS, SCHEMATICS

PACKET COMMUNICATION

CognizantWire Systems