6DQ6 Generic

The 6DQ6A is a top-cap beam pentode designed for service as a line output valve in black and white television horizontal stages. (see also 6CM5)

Bottom view. NJ7P Database

The “beam” bit indicates that it is a pentode, but with beam-forming plates instead of a conventional spiral grid.

These were designed for use as horzontal output valves for service in larger screen 21 and 23-inch black and white television sets. This explains the odd very high peak voltage rating on the anode, several kilovolts, of little interest in audio applications.

Electronics Australia remarked that they have a “similar” plate characteristic to the 6CA7/EL34 for audio service but hard data is scarce.

From their switching background have a higher gain than most with respect to screen grid voltage which must be firm to achieve full output power in audio service.

Unlike the 6CA7/EL34, the 6DQ6A tends to fail gracefully with its emission dropping gradually over time.

Please note a critical difference between the 6DQ6, 6DQ6-A and the 6DQ6-B versions; the latter had higher anode power rating than the former, 15 watts upgraded to 18 watts. Note that as designed even the 40 watt Playmaster 116 requires the 6DQ6-B version.

Beam Pentode
Plate Voltage ................................. 770 Volts
Grid No. 2 Voltage ............................ 200 Volts
Plate Dissipation ............................. 18 Watts
Grid No. 2 Dissipation ........................ 3.5 Watts

Typical application in class AB₁ push-pull.

Click for full size 150k jpg

See also Goldentone and Playmaster 116/7.

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Audio Service

New: 30/9/08

Okay, this is something I said I wouldn't do - put a PDF on the site. Jason Boyd sent the PDF file
Operating conditions for the 6DQ6A as a class AB1 audio power amplifier; originally from Radiotronics March 1982.

Note that these tables do not include the set of conditions used by EA for the Playmaster 116/7, nor most of the Goldentones as far as I can see, but they help to expand our view of this widely used bottle.

I strongly suspect that he picked this up from David Crittle's Retrovox site, but it's only 70kb and it's worth mirroring because it's just about the only data anywhere on this valve in this service.

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