Rectifier - TV Line Scan Boost ·Rectifier
1BH2 is a directly heated half-wave high-voltage flyback rectifier for television CRT anode supplies. It uses a 1.25 V, 0.2 A filament, 9RG basing with solder lugs and a top-cap anode, and is rated for 18 kV peak inverse voltage in pulsed service.
The 1BH2 is a directly heated, half-wave vacuum rectifier intended for high-voltage pulse service in television receivers. It rectifies the flyback pulses from the horizontal scanning system to supply the high-voltage anode of a cathode-ray picture tube. RCA (1968) and Sylvania (1970) both document this application.
The tube is a filamentary diode with 9RG basing, a miniature nine-pin button base, solder lugs on filament pins 1 and 5, and a high-voltage top-cap anode. The solder lugs permit filament connections without an ordinary tube socket. Sylvania identifies the base as E9-99 and the top cap as C1-45. The filament is the electron-emitting cathode, so this is a directly heated rectifier.
The filament operates at 1.25 V and 0.200 A. Sylvania specifies a permissible filament voltage range of 1.05–1.45 V. Both references give a peak inverse plate voltage rating of 18,000 V, peak plate current of 45 mA, and average plate current of 0.5 mA under the stated television pulse conditions. The instantaneous forward tube voltage drop is 80 V at 7 mA plate current. Sylvania gives a plate-to-filament capacitance of 1.0 pF.
The ratings apply to a 525-line, 30-frame television scanning system. The voltage pulse duty cycle must not exceed 15% of one horizontal scanning cycle, approximately 10 microseconds. RCA further specifies that the DC component of the inverse plate voltage must not exceed 15,000 V. These pulsed ratings must not be treated as continuous DC operating ratings.
The very high operating voltages can produce X-radiation. Sylvania explicitly warns that prolonged close exposure can be hazardous without adequate shielding, and that television shielding components must be restored to their intended positions before operation. High-voltage insulation and discharge precautions are essential when servicing the circuit.
This description synthesizes the 1968 RCA RC26 and 1970 Sylvania Technical Manual entries for the 1BH2. Their stated primary rectifier ratings agree.
General specifications
Properties common to every published source and operating point.
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
1 physical section, each with unique specifications.
Section 0
Half-wave TV flyback high-voltage rectifier; 80 V forward drop at 7 mA; 525-line/30-frame pulsed service, maximum 15% horizontal duty cycle. RCA DC component of inverse voltage <=15 kV. Plate-to-filament capacitance 1.0 pF (Sylvania). Filament 1.25 V, 0.2 A.
Source-dependent data
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.
Data set 01
Published operating points and test conditions from this source.
Filament Voltage
1.25 V
Tube Voltage Drop
80 V
Instantaneous at plate current 7 mA
Filament Current
200 mA
Maximum Peak Inverse Voltage
18000 V
Maximum Peak Plate Current
45 mA
Maximum Average Plate Current
0.5 mA
Data set 02
Published operating points and test conditions from this source.
Filament Current
200 mA
Tube Voltage Drop
80 V
Instantaneous at plate current 7 mA
PlateFilamentCapacitance
1 pF
Filament Voltage
1.25 V
Maximum Peak Inverse Voltage
18000 V
Maximum Peak Plate Current
45 mA
Maximum Average Plate Current
0.5 mA