1976 Rediffusion MK1 CH2213

 redmk1 Rediffusion MK.1 Series Chassis – Hybrid

Model: CH2213

Year: 11th October1976 ( stamped in the cabinet)

System: Cable Wired System TD70 5.9MHz
Input : TD90 5.9MHz/8.9MHz
Frequencies: TD90 5.9 MHz (offset)

Original List Price : Not Applicable: Cable Rental set. Identical UHF (CU2213) set was £347.00

Technical Specifications

V500 PL509 Line Output
V501 PY500 Efficiency Diode

Transistors: 47

S.F. Board
TR100 BF148 S.F emitter follower
TR101 BC148 1st S.F. feedback pair
TR102 BC148  “”
TR103 BC148 Luminance S.F.
TR104 BC148  feedback pair
TR105 BC148 Luminance emitter follower and sync amp
TR106 BC148 Chrominance S.F.
TR107 BC148 feedback pair
TR108 BC148 A.G.C. amplifier

Decoder Panel
TR200 BC1489 Luminance Delay Line Driver
TR201 BC148 Luminance emitter follower
TR202 BC194 Gain controlled amplifier
TR204 BF194 2nd chrominance amplifier
TR205 BF194 3rd chrominance amplifier
TR206 BC108 PAL delay line driver
TR297 BC147 7.8KHz identification amplifier
TR208 BC147 R-Y chrominance emitter follower
TR209 BC148  Burst Amplifier
TR210 BC157 “”
TR211 BC148 D.C. amplifier
TR212 BC147 Sub-carrier oscillator
TR213 BC148 Sub-carrier driver
TR214 BF197 B-Y amplifier
TR214 BF197 G-Y amplifier
TR216 BF197 R-Y amplifier

RGB Drive Amplifier panel
TR300 BC147 Red amp emitter follower
TR301 BF337 Red output amplifier
TR302 BC147 Green amp emitter follower
TR303 BF337 Green output amplifier
TR304 BC147 Blue amp emitter follower
TR305 BF337 Blue output amplifier
TR306 BC148 Beam current limiter
TR307 BC148 Brightness pulse generator

TimeBase Panel
TR400 BC158 Sync generator
TR401 BC147 Line sync generator
TR402 BC149 Line oscillator
TR403 “”
TR404 BF337 Line driver
TR405 BC158 Field oscillator
TR406 BC107B Field driver
TR407 BC148 Field oscillator
TR408 BF337 Line & Field blanking

TR600 2N3055 Field output

Convergence Panel
TR700 AC128 Line convergence clamp
TR701 AC128 Field convergence clamp

Diodes: 45

S.F. Panel
D100 DK13 A.G.C.diodes
D101 DK13 “”
D102 HG50008 Lumimance
D103 HG5008 “”
D104 BA155 A.G.C. rectifier
D105 HG5008 chrominance detectors
D106 HG5008 “”

Decoder Panel
D200 OA90 Burst isolating diode
D201 AA143 Saturation control
D202 BA155 PAL switch
D203 BA155 “”
D204 1N4148 Phase detector
D205 1N4148 “”
D206 1N4148 A.G.C. oscillator
D207 BA102 Oscillator control
D208 OA90 7.8KHz restorer
D209 OA90 B-Y demodulator
D210 OA90 “”
D211 OA90 R-Y demodulator
D212 OA90 “”
D213 1N4148 Pulse shaping
D214 HG5008 Threshold diode
D215 1N4148 A.C.C. restorer diode

RGB Drive Amplifier Panel
D300 BA145 Red clamp
D301 BA145 Green clamp
D302 Ba145 Blue clamp
D303 BA145 Pulse limiter
D304 Ba145 Pulse DC restorer
D305 BA148 Red amp protection
D306 BA148 Green amp protection
D307 BA148 Blue amp protection

Timebase Panel
D400 BA514 Line Flywheel
D401 BA154 “”
D402 HS9078 Field oscillator
D403 HS9078 Field timing
D404 HG5008 Field discharge
D405 BA145 Blanking DC restorer
D406 HG5008 Protection diode
D407 BA145 Negative line rectifier
D408 BA145 Protection diode
D409 1N4148 Protection diode

LOPT Panel / EHT Tower
D500 BA148 Line shift rectifier

Power Supply
D600 BY127 H.T. rectifier
D601 TRC100P L.T. rectifier
D602 TRC100P “”
D603 BA148 Field pulse limiter

CRT: 22″ Mullard A56 120X

General Information:

In the collection I already have the UHF version of this set, namely the CU2213. This CH2213, the wired chassis of this Rediffusion MK1, came into my possession as just a cabinet and CRT. Thankfully I managed to marry it back with the original wired chassis to make a complete set. The Mullard A56 120X CRT appears to be brand spanking new. I put it on the CRT tester and each gun (R,G,B) tested 100% with perfect synchronous tracking.

All that remains now is to track down a Rediffusion  Frequency translator box, or more commonly known as a “Tele-Box”.

The Wired MK1 CH2213

1976 Rediffusion MK1 CH2213 11976 Rediffusion MK1 CH2213 2 1976 Rediffusion MK1 CH2213 3 1976 Rediffusion MK1 CH2213 4 1976 Rediffusion MK1 CH2213 5 1976 Rediffusion MK1 CH2213 6

February 2017

Finally managed to track down a couple of Frequency Translators albeit working condition unknown. If there are any problems with either, from two I should be able to make one good working unit. Thanks to Rob ( Guest who contacted me) who provided the circuit data for the translator and other very useful MKI data, all of which is now stored in the members only Data library, should other members with MKI sets require it.

1976 Rediffusion MK1 CH2213 7

This Rediffusion  Frequency Translator “Tele-box” box, allowed a wired set such as this to be used on UHF for normal TV reception. This device takes a UHF TV signal and converts it to the Rediffusion cable TV standard.

The repair can be followed here in this blog.

The Frequency Translator

1976 Rediffusion MK1 CH2213 8

Box 1

The box on the right is in much better original condition, its also appears to be an earlier version, the assumption being wood boxes before molded plastic cabinets . This unit rather than being housed in a plastic cabinet is all wood construction, including the lid. I intend to use this one in for the MKI CH2213. I’ve no idea if it works but as stated above, the other box will serve as spares should the need arise.

1976 Rediffusion MK1 CH2213 9 1976 Rediffusion MK1 CH2213 10 1976 Rediffusion MK1 CH2213 11 1976 Rediffusion MK1 CH2213 12 1976 Rediffusion MK1 CH2213 131976 Rediffusion MK1 CH2213 14 1976 Rediffusion MK1 CH2213 15

Box 2

As mentioned above this next one had been got at, an additional tuner, speaker and knob out the front being added. Along the back were RCA and DIN outputs along with an extra switch. This unit was housed in an all plastic cabinet, it also had the wired connection cable plug removed along with the original mains flex. This box will be used for spares.

1976 Rediffusion MK1 CH2213 16 1976 Rediffusion MK1 CH2213 171976 Rediffusion MK1 CH2213 18 1976 Rediffusion MK1 CH2213 19 1976 Rediffusion MK1 CH2213 20


This afternoon I got ‘Box one’ up onto the bench, the first thing to do was free the tuner as it was seized. After a lot of fiddling and trying to figure out how it worked, success, channels could now be changed without jamming and importantly now one can be selected and tuned.

Now time to feed in a grey-scale from the PM5518T to the Frequency Translators RF input. I hooked up the scope to the base of TR1, nearest easy access was R20. Looks like this one is a ready for service.

1976 Rediffusion MK1 CH2213 21 1976 Rediffusion MK1 CH2213 22


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3 years ago

Our firm rented out a few of these under the brand name “BWE President”. They were bought from ERD in Gloucester. Picture quality was good. The most common fault as I remember was tripler failure. The raster correction transductor sometimes used to fail intermittently, causing bottom cramping of the raster. We also had to replace the 2N3055 field output transistor occasionally. The triplers were less likely to fail if the HT voltage was reduced by a few volts.

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