~ 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 Bridged - H 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
P/17B		300		300				14	P/17M with single pole switch on stud 0 only
P/17C		300		300				14	P/17M with single pole switch on stud 13 only
P/17M		300		300	0		∞	14	Unbalanced series fader for microphones. Panel No. 38A on TD/3702 series desks. Supercedes P/17 , P17B and P17/C ~ C.O. switch on studs 0 or 13
					1		38
					2		30.1
					4		18.5
					6		11.2
					8		6.3
					10		3.5
					13		0

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