Home ] Up ]






The  RCA TK-21 Camera at SMECC



rca_tk-21-6.jpg (36120 bytes)



rca_tk-21-2.jpg (22044 bytes) rca_tk-21-3.jpg (28268 bytes)


rca_tk-21-4.jpg (16896 bytes) rca_tk-21-5.jpg (15817 bytes)







Aug. 9, 1954  Broadcasting-Telecasting                  Aug. 9, 1954  Broadcasting-Telecasting



• High signal to noise ratio-l00 
to 1 in the final. picture 

• Aperture response correction 

• Excellent resolution-l00% at 
350 lines 

• Low light source requirement 

• Shading controls are not necessary 

• Wide film reproduction range 
and latitude offers possibilities 
for "unattended operation" 

• Small in size; compact in design 

• May be mounted directly to 
projectors or multiplexed 


The ultimate goal in film programming today is to achieve a picture quality which will make it impossible for a television viewer to know whether the program coming into his home is "live" or "on film". Film programs have become direct competition to live presentations. In order to lead the industry movement to top quality film pictures, the RCA Vidicon Film Camera was developed. 

The TK-21 Vidicon Camera is used for finest quality reproduction of motion picture films or slides in a television system. A standard composite video signal output is provided. Because of its small size-only Va cubic foot-the Vidicon Camera can be mounted to advantage directly on either a 16mm or 35mm television film projector such as RCA Types TP-6A TP-16F and TP-35 projectors. An RCA Multiplexer, Type TP-ll, enables a single Vidicon Camera to be used with two 16mm or 35mm film projectors, a 35mm Dual-Disk Slide projector, and a Telop II slide and opaque projector to form a versatile, multi-input film system. 

The Vidicon Camera can be used either directly on a television projector (see picture, upper right) or with a TP·ll Multiplexer (left), 

Mav 1954 


Heart of the Vidicon Camera is the new Type 6326 Vidicon Tube, developed and produced by RCA. Early in the development of this tube, its potential for use in high quality film systems was recognized. The Camera was designed to utilize the unusual capabilities of this tube and with the following criteria in mind: excellent resolution, high signal­to-noise ratio, aperture response correction, high transfer or gamma characteristics, and low light source requirements. 

Excellent Resolution 

The 1-inch Vidicon Tube with a 0.62 inch picture diagonal (3fs" x 112" picture) has a horizontal resolution in excess of 600 lines, with a measured response of 35% at 350 lines compared to zero line number as a base. 

High Signal-to-Noise Ratio 

The signal-to-noise ratio of the system is determined solely by the first few stages of amplification in the video amplifier. Therefore proper design in these stages, especially in the cascode preamplifier, provides a signal-to-noise ratio of 160 to 1. 

Aperture Response Correction 

The vidicon is the first pickup tube that has high enough signal output with low enough inherent noise to use aperture correction effectively without seriously impairing the 
signal-to-noise ratio of the reproduced picture. With this 
excellent signal-to-noise ratio, aperture correction (a scheme for amplifying the high frequencies with respect to the low frequencies without phase distortion) may be added to the signal to compensate for the finite size of the scanning beam. An examination of the amplitude response of the tube shows that to fill the transmitted bandwidth adequately, the response at the higher line numbers can be boosted by a factor of three for a 4.5 mc channel while still maintaining an excellent signal-to-noise ratio in the final picture. 

Shading Controls Are Not Necessary 

Since the Vidicon Tube is essentially an orthicon or low velocity device as far as scanning process is concerned, 

View of the Vidicon Camera with the cover removed. Some video circuitry is located in the camera for adequate preamplification, high peaking and camera blanking. 

Heart of the new Vidicon Camera is the Type 6326 Vidicon tube developed and produced by RCA. 

there is inherently no spurious shading signal developed. 
In the Vidicon Camera no electrical shading cancellation signals are necessary. Hence no shading controls are used nor is edge lighting or any other type of corrective lighting required for flat field. 

Pictured above is the small, compact Vidicon Camera. 
High Transfer or Gamma Characteristic 

The gamma or transfer' characteristics, which is inherent in the vidicon surface itself, has a log-log slope of 0.65 when signal output current is plotted against light on the photo­conductive surface. The slope is practically constant over a wide film contrast range, resulting in more realistic film reproduction than ever before possible. 

Low Light Source Requirements 

light source requirements under favorable conditions, using commercially available lenses, average 300 foot-candles, measured at the film gate. When the vidicon camera is mounted on a projector for direct projection, appreciably less than full lamp voltage is needed. This lower light requirement permits reduced voltage operation of the projector lamp, thereby prolonging its life. Multiplexer operation will require more light due to multiplexing light losses; although full voltage illumination is still in excess of operating requirements. 

"Unattended Operation" Possibilities 

The Vidicon Camera offers unusually attractive possibilities for unattended operation. Tests with a wide range of film material have shown that it is practically unnecessary to ride video gain. Black level control is inherent in the vidicon tube giving an absolue black reference, and shading controls are not necessary. From a day to day opera- 

The remote control panel for the Vidicon Camera Chain is conveniently located in the recessed portion of a standard console housing beneath a TM·6B Master Monitor. 

MI-26085-B   WP-33B 14 POWER SUPPLY  






Block diagram showing rack space requirements of Vidicon Film Chain. 
Vidicon power supplies and amplifier units are rack mounted for ease of maintenance and performance checks. 

tional basis, only two variables require adjustment. These are the wall focus, which determines electrical scanning beam focus and hence picture resolution, and beam bias which controls the number of electrons available for discharging the target. 

RCA Vidicon Film Camera Equipment is designed to meet the requirements of any size television station. The Vidicon Camera itself may be mounted directly on either a 16mm or 35mm projector or integrated into an optical multiplexing system. The Vidicon Camera Chain consists of the 

camera connected by a standard 24 conductor camera cable to the camera control chassis and deflection chassis which may be located up to 200 feet from the camera. 

All control circuits are rack mounted for better servicability, ease of maintenance and performance checks, and to reduce the heat dissipated at the operating position. 
Only the remote control panel, which contains the operating circuits, is located in the console housing. This panel 
uses only doc control voltages and can be placed up to 200 feet from the camera control and deflection chassis. 
The control panel is designed to mount in the recessed portion of a standard RCA Console Housing associated with the TM-6B Master Monitor. The camera control and 

.•••. The Vidicon deflection chassis. 

.•••. The Vidicon processing amplifier. 
camera deflection chassis occupy only 31 V2 inches of rack space. 

All tube circuitry for deflection of the vidicon tube is located in the deflection chassis-none in the camera. Deflection voltage is generated in the rack-mounted deflection chassis and delivered to the camera via the camera cable. 
Because of its high frequency spectrum, horizontal deflection is carried through the camera cable on a coaxial line. 
The horizontal deflection yoke is arranged in a constant resistance network at the camera to provide proper termination for the coaxial line. Since the frequency spectrum of the vertical deflection circuit is much lower than that of the horizontal, vertical deflection is carried over un­shielded leads in the camera cable. 

Some Video circuitry is located in the camera for adequate preamplification, high peaking, camera blanking, and a feedback pair for driving the video output coaxial line 

to the camera control unit. Although negative film is not recommended for best results, a polarity switch is located on the remote control panel so that negative film can be used when the situation demands. In the camera control chassis, blanking is added, black level is set, aperture correction is introduced and sync addition is provided if required. An output amplifier capable of driving three 75-ohm lines with sending and receiving end terminations is also included in the camera control chassis. For reasons of multiplexing, both horizontal and vertical deflection reversing switches are included. 

SIZE, VERTICAL CENTERING. A meter is used on the panel 
to monitor signal electrode voltage and beam current for 
the vidicon. Zero adjustment is provided for this meter. 


Power Requirements (Vidicon Chain): 

Line Rating 105-125 volts, 50/60 cycle, single phase 

Power _ 535 watls 

Current _ 6 amps. 

I nput Signals: 

Horizontal Drive .4 volts peak-to-peak at 15,750 cps 

Vertical Drive .4 volts peak-to-peak at 60 cps 

Mixed Sync 4 volts peak-to-peak at Standard RETMA Signal 

Mixed Blanking .4 volts peak-to-peak at Standard RETMA Signal 

Output Signal: 

Picture Output # L .. _ Picture with optional sync, 1.4 volts 

Picture Output #2 Picture with optional sync, 1.4 volts 

Picture Output #3 _ 1.0 volt video-no sync 

Frequency Response Essentiaily flat to 8.0 megacycles 

Input Impedance for Driving Pulses High 

Input Impedance for Sync __ 1000 ohms 

Input Impedance for Blanking __ ._ _ 1000 ohms 

Tube Complement: 

Vidicon Camera 


I RCA 6326 Vidicon 
2 RCA 6BQ7-A 

I 417-A 

I RCA 12B4 

I RCA 12AT7 

Control Chassis 

4 RCA 6AU6 
I RCA 6U8 

6 RCA 6BQ7A 
2 RCA 6AL5 


2 6BX7GT 

I RCA 12AT7 

I RCA 6X4 


Deflection Chassis 


.4 RCA 12AT7 
2 RCA 12AU7 


2 RCA 12AX7 
I RCA 5963 

I RCA 12BH7 

The Vidicon Camera in multiplexed 
use. It is shown here mounted' on 
a TP-ll Multiplexer and used with 
two RCA TP-16 Film Projectors and 
a 2 ·X 2 dual-disk slide projector. 


Camera. ._._. __ ._ __ . 41/211 X 61/2'1 X 9" 

Control Chassis 

Width .. __ . _ .. _ _ _ .. .__ 1911 

Height............................................ 191/4" 


Camera . 7 Ibs. 

Control Chassis _ 30 Ibs. 

Deflection Chassis 231/2 Ibs. 

Remote Control Panel .4 lbs. 

Deflection Chassis 

121/4 " 

Equipment Supplied 


Quantity Description 

I Vidicon Camera . MI-26021 

1 Vidicon Tube Type 6326.......................... ..MI-26671 

1 Vidicon Control Chassis .MI-26061 

1 Vidicon Deflection Chassis .MI-26081 

1 Vidicon Remote Control Panel. MI-26241 

2 WP-33B Power Supply MI·26085-B 

1 TM-6B Master Monitor MI-26136-A 

Kinescope Tube RCA 10SP4 (for Master Monitor) MI-26655 

CRO Tube RCA 5UP1 (For Master Monitor) MI-26665 

Blower (For Master Monitor) MI-26579-8 

Console Housing (For Master Monitor 

and Control Panel) . MI-26266-B 

Camera Cable, 50 Feet with Connectors 

(MI-26759-23 and MI-26759-24) MI-26725-A 10 
The Vidicon Multiplexer, Type TP-ll



The Vidicon Multiplexer, Type TP-ll, is designed as an integral part of RCA's superior Vidicon film reproduction system. It is used in the system to enable a single vidicon camera to handle signals from two 16mm or 35mm slide projectors, one 2 x 2 dual-disk projector, and a Telop opaque and slide projector. For compactness and extra convenience, the vidicon camera mount and an adjustable 2 x 2 slide projector shelf are built into the unit. Precision optics maintain the "live" picture quality and "realism" of the vidicon film reproduction. 


The TP-ll Vidicon Multiplexer employs a pair of semi­
mirrors for transmitting and reflecting the proper amount 


• Four inputs-two movie projectors, one 2x2 slide projector, one opaque projector 

• Vidicon camera .and 2x2 slide projector mount directly to multiplexer 

• Precision optics, coated lenses 

• Rugged construction for stability of 

• Light-tight and dust-free 

• Remote control of opaque projector 
changeover mechanism of light through the optical system onto the photoconductive surface of the vidicon camera tube. The use of mirrors permits the permanent arrangement of the film equipment for maximum program efficiency. Either of the two movie projectors or the 2 x 2 slide projector may be switched on or off electrically while the mirrors remain in a fixed position. The opaque projector is accommodated by utilizing a remotely controlled moving mirror assembly. 

The equipment is mounted on a rigid pedestal which is provided with two adjustable supporting shelves for leveling the vidicon camera and the slide projector. The semi-mirrors and field lens are mounted on an adjustable optical bench plate. The complete optical system is covered so that 
it is light-tight and dust-free. The rugged construction of the entire unit assures stability of operation. 

Closeup of the optical system of the TP-ll Vidicon Multiplexer. The optical system is completely covered by a housing to keep it light­tight and dust-free. 


Length 635/8" 

Height 56" 

Width 18" 

Optical Center Above Floor .48" 

Weight 148 Ibs. 

Equipment Supplied 

The following items are supplied as part of the Vidicon Multiplexer, 

Vidicon Multiplexer MI·26328 

Projector Support Shelf and necessary hardware 

2 Semi-Mirrors 

1 First Surface Mirror 

3 Mirror Pad Assemblies 
2 x 2 Test Plate 

Field Lens Aperture Test Plate 
Field Lens Image Size Test Plate 
Vidicon Camera Lens 

Block diagram .showing optical alignment of components of a Vidicon Film System 
incorporating the TP·ll Vidicon Multiplexer. 

16MM OR 35MM 


\ ~LENS(I) 

-----------~~----U-----/f---- :':~~~: 


701 I. 401 P ~---FIELD ~ENS(lt) 

I . ~ . 

. ~"4RST ~S:::E-------- 








rca_tk7.jpg (136994 bytes)   rca_tk8.jpg (143064 bytes)



rca_tk9.jpg (132904 bytes)   rca_tk10.jpg (121139 bytes)


rca_tk11.jpg (132248 bytes) rca_tk14.jpg (126685 bytes)


rca_tk15.jpg (118175 bytes)  rca_tk17.jpg (109859 bytes)






RCA BROADCAST NEWS Vol 78 Mar April 1954

From the Sharpe Collection at SMECC



rca_1954-tk21-2.gif (703831 bytes)  rca_1954-tk213.gif (336480 bytes)


rca_1954-tk21-4.gif (327857 bytes)  rca_1954-tk21-5.gif (325912 bytes)


rca_1954-tk21-6.gif (370891 bytes)  rca_1954-tk21-7.gif (370200 bytes)







Feb 1957 - RCA BROADCAST NEWS                Feb 1957 - RCA BROADCAST NEWS




Feb 1957 - RCA BROADCAST NEWS                    Feb 1957 - RCA BROADCAST NEWS




Feb 1957 - RCA BROADCAST NEWS                      Feb 1957 - RCA BROADCAST NEWS




Feb 1957 - RCA BROADCAST NEWS                  Feb 1957 - RCA BROADCAST NEWS





There were some instances where the TK-21 was used as a studio camera.

Notably, Ch8, WMTW had a TK21 atop Mt. Washington (6288 feet) at their transmitter site.
Marty Engstrom, aka "Marty on the Mountain" - (He wrote a book by that name as well).


Marty was a classic native Down-Easter. He did the weather report atop the mountain for many years.
Most of that time the camera used was a TK-21 with a more sensitive 7735 vidicon for live pickup.

The normal tube would have been a 7038 for film use.
The 7038 had a bit more lag to reduce film flicker, and less sensitivity.

The Woonsocket Museum of Broadcast Technology now has Marty's weather cam.

There were also some early film islands that had "balop" (telop?) windows, and their mirrors or prisms would enable the vidicon camera to see a small fixed tabletop stage for shooting products or signs. I suspect they needed a fair amount of light.

I would have liked to see one working. Would also like to know the origin of the word "balop".

Pete Fasciano
It's short for one of those wonderful turn of the 18th century items...

Ted Langdell









Everyday we rescue items you see on these pages!
What do you have hiding in a closet or garage?
What could you add to the museum displays or the library?



DONATE! Click the Button Below!

Thank you very much!


Material © SMECC 2007 or by other owners 

Contact Information for
Southwest Museum of Engineering,
Communications and Computation 

Talk to us!
Let us know what needs preserving!


Postal address 
smecc.org - Admin. 
Coury House / SMECC 
5802 W. Palmaire Ave 
Glendale, AZ 85301 

Electronic mail 
General Information: info@smecc.org