[Keith-Snook.info]


~ Component Information ~


Information on obsolete components and some other stuff not readily available — For additional information on other BBC registered and coded equipment — Click here



Registered Designs and coded equipment — 1963 — Volume 2 [ BBC designed ] components

Section A1 —Attenuators — Fixed — Unmounted
Type
Input R
Ω
Required Load Ω
Output R
Ω
Required Source Ω
Attenuation
Remarks
FO/1P1
600
600
600
600
2dB
Square Network
in 6 pin Jones plug
FO/2P1
600
600
600
600
4dB
"
FO/3P1
600
600
600
600
6dB
"
FO/4P1
600
600
600
600
8dB
"
FO/5P1
600
600
600
600
10dB
"
FO/6P1
600
600
600
600
0dB
"



Section A2 — Attenuators — Variable — Unmounted

Code letters have the following significance:-

First prefix — P — indicates a potentiometer or variable attenuator of commercial design and manufacture

First prefix — B — indicates a potentiometer or variable attenuator of BBC design usually based on wafer switches

Next prefix leters

A = Ladder Network

B = Bridge Network — Bridged-T -H etc. and lattice

F = Normal potentiometer — requiring Load — reverse or feedback

H = H — Network

U = U — Network = 3 Arm balanced L — Network

L = L — Network

N = Normal potentiometer working into valve grid [ high impedance load ]

0 = Square Network

P = PI — Network

T = T — Network

Z = Series resistance

Combinations of the above letters indicate a multiple type of attenuator e.g. NF indicates an attenuator with a normal section and a feedback section — NN indicates two separate potentiometers i.e. a stereo control

following the / in the code The number indicates the design number of its class — The suffix letter if any represents the mechanical arrangement and a final number [ if any ] is the mechanical design serial number — Attenuators fitted with special noise free contacts are indicated by a final suffix letter — S

Thus PT/12B3 is decoded to :-

P = potentiometer or variable resistor of commercial design — T = Based on a T Network — 12 = design serial number for T class Networks — B = assembly type — 3 = design serial number for PT/12B class attenuators denoting certain details like spindle design - detents - switch etc.

Type
Input R
Ω
Required Load Ω
Output R
Ω
Required Source
Ω
Attenuation dB
No. Studs
Remarks
Stud No.
Loss
/step
Total loss
BB/1Y1
600
600
600
600
1
1.96
8
Transmitter
Control Rooms

Balanced H—Bridge

Wafer Switch

2
1.60
3
1.35
4
1.05
5
0.84
6
0.57
7
0.30
8
0

BB/1Y2
600
600
600
600
"
"
"
BB/1Y1 with longer spindle

BB/2Y1
600
600
600
600
0
0
9
Transmitter equipment Balanced H—Bridge Wafer Switch
0 - 8
0.5
8
4

BB/5Y1
600
600
600
600
1
20
11
DRD/1 Balanced H- Bridge Wafer Switch
1 - 11
2
11
0

BB/6Y1
600
600
600
600
1
0
11
Balanced control panel
No.81 Balanced H-Bridge
Wafer Switch
1 - 11
4
11
40

Type
Input R
Ω
Required LoadΩ
Output R
Ω
Required Source
Ω
Attenuation dB
No. Studs
Remarks
Stud No.
Loss
/step
Total loss
BBB/1Y1
600
600
600
600
Echo
Echo Mixer

Switch Panel No.49

Two Ganged

H- Bridge

Wafer Switch

1
2
12
3
7.5
4
3.5
5 - 9
0
Direct
1-5
0
6
3.5
7
7.5
8
12
9

BBB/35Y1
600
600
600
600
"
"
"
Small version BBB/1Y1

BTT/1Y1
300 +
300 +
300 +
300 +
Direct
5 + 5
Type A
Studio Equipment

Mark V11

Double Bridged T
Wafer Switch

300
300
300
300
1 -4
0
5
Echo
1
2
12
3
8
4 - 5
0

BTT/3Y1
600 +
600 +
600 +
600 +
Direct
9
Type B

Studio Equipment

Double Bridged T
Wafer Switch

600
600
600
600
0 - 4
0
5
3.5
6
7.5
7
12
8
Echo
0
1
12
2
7.5
3
3.5
4 - 8
0

Type
Input R
Ω
Required LoadΩ
Output R
Ω
Required Source
Ω
Attenuation dB
No. Studs
Remarks
Stud No.
Loss
/step
Total loss




QUAD Hi Fi Valve data Sheets QUAD Hi-Fi Buy Beer Button Valve Audio Articles Valves for Sale