6DQ6B - 6DQ6B

Professional HF 5000W Transmitter
5000W amplifier
vista ampliada amp. RF
6000W of audio
RF stage partial arm
Output Networks

6DQ & B is a directed beam power pentode . Its high plate current for "zero" polarization of the control grid and low grid 2 or screen voltages make it suitable for television receivers with low plate voltages. It differs from the 6DQ6A version in that it has a higher maximum plate current for null polarization and higher plate dissipation. The 6DQ6B replaces the 6DQ6A, but the converse is not possible.

Its filament voltage is 6.3V +/- 0.6V. It works both as a pulse and linear amplifier as well as audio outputs in class A, AB1 and AB2 and transmission modulators up to class B.

In class S PWM modulators developed by LU8EHA for radio amateurs in 1978 based on the Sinclair X-20 amplifier as a generator and similar configuration to the Harris MW10A transmitter.

Also in linear radio frequencies and class C transmission amplifiers, achieving much higher performance than their transmission counterparts and up to frequencies of 50 MHz. It is connected according to EIA 6AM socket, with octal socket and socket for connection of the plate.


The 6DQ6B valve is the receive version of the 6146. It does not have the same robustness as its transmission relative, and it exceeds it in several performances. However, the basic construction of the board and its average characteristics are very similar.

Maximum design values ​​as horizontal amplifier

  • Filament voltage: 6.3 V +/- 0.6 V, 1.2 A.
  • DC voltage of the plate source (boost plus source voltage): 770 V.
  • Plate positive pulse peak value voltage: 6,500 V.
  • Plate negative pulse peak value voltage: 1,500 V.
  • Screen voltage: 220 V.
  • Grid 1 negative peak voltage: 330 V.
  • Plate dissipation: 18 W.
  • Screen dissipation: 3.6 W.
  • Continuous cathode current: 175 mA.
  • Cathode peak current: 610 mA.
  • Filament to cathode tension:
    • Positive filament with respect to cathode:
      • In direct current: 100 V.
      • Continuous current plus peak: 200V.
    • Negative filament with respect to cathode:
      • Continuous current plus peak: 200V.
  • Grid resistance 1: 1 megohm.
  • Ampoule temperature at hottest point: 220 ° C.

Average characteristics for amplifier and symmetric class AB1

  • As amplifier:
    • Plate voltage: 250 V.
    • Display voltage: 150 V.
    • Grid voltage 1: -22.5 V.
    • Plate resistance: 18,000 ohms, approximately.
    • Transconductancia 7,3 mA/V.
    • Board current: 65 mA.
    • Display current: 1.8 mA.
    • Approximate grid 1 voltage for 1.0 mA: -42 V.
    • Triode magnification factor: 4.4.
  • With null polarization:
    • Plate voltage: 60 V.
    • Display voltage: 150 V.
    • Grid voltage 1, no more than 2 seconds: 0 V.
    • Board current: 345 mA.
    • Display current: 27 mA.


  • As a class AB1 symmetric amplifier: (For 20 W no-load plate dissipation, 25 W maximum plate dissipation, regulated sources, fixed bias, zero magnetizing current (perfect balance of quiescent currents), low leakage inductance and paired valves)
    • Plate voltage: 560 V.
    • screen voltage: 175 V.
    • Grid voltage 1: -38V.
    • Board current without signal: 38 mA.
    • Display current without signal: 1.3 mA.
    • Board current with maximum signal: 118 mA.
    • Display current with maximum signal: 7 mA.
    • Plate power: 23 W.
    • Display power: 1.1 W.
    • Plate-to-plate load impedance: 5,600 ohms.
    • Average total output power: 86 W.
    • Total harmonic distortion: 5%.
    • Yield: 65%.
    • Plate peak current: 360 mA.
    • Minimum plate voltage: 55 V.
    • Signal voltage in grid 1, peak to peak. 76 V.
  • How to class C modulated RF amplifier
  • Plate voltage: 800V
  • Screen Drop Resistance: 60000 OHM 10W
  • G1 voltage: -120V. 60V 30000 OHM exhaust resistor, 60V zenner.
  • Plate current: 125 mA
  • G1 current: 2 mA
  • RF load impedance: 3500 OHM
  • Modulation impedance: 6000 OHM
  • Input power: 100W.
  • Output power 90W
  • Yield: 90%


  • As a horizontal television output amplifier.
  • As a linear amplifier in 80m and 40m amateur radio bands.
  • As an output pair on electric guitar amplifiers [ 2 ] or audio equipment.
  • In high power Short Wave transmitters with 48 valves in parallel.
  • In PWM Modulators.
  • In class C broadcasting amplifiers with 16 or 24 6DQ6B tubes modulated in class B by the same tubes.

Equivalences and replacements

The 6DQ6A has an equivalent or replacement in the 6CU6, the same in the 6GW6. The 6BQ6B exceeds the performance of a 6CU6. In some uses, a possible replacement for the 6DQ6B is the 6FH6 valve , although it has somewhat lower plate dissipation and less transconductance. In extreme applications or being strict as to look for an equal or superior and compatible valve, the 6DQ6B valve has no replacement.

The 6DQ6 was born as a replacement for the 6CM5 / EL36 for monochrome television receivers with 23-inch tubes. Later revisions 6DQ6A and 6DQ6B improved upon the original design. The move to solid-state technology in television quickly took 6DQ6 out of production. Its use in musical instrument and audio amplifiers is not very popular. They were especially used in Australia, Germany and Argentina. A valve highly prized for its excellent transient response. Radio amateurs look for them for being cheap and of very good performance in all bands including the 6-meter band.