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Type 6CH6 is a video output amplifier used in professional applications for driving TV or radar signals down (fairly) long cables. We did not think that it was much used in domestic sets, however, Wojtek M writes that it was used in the 1955 STC Tymatic clock radio made in Australia.

Thanks to PA3FVQ for some additional information on the 6CH6. This valve was used as the audio output valve in the Rees-Mace receiver AKA the Pye marine receiver AP100339 that was built in the 1950s and extensively used by British and Dutch navies. The question remains as to why the 6CH6 was the valve of choice for this receiver when so many purpose designed audio valves could have been selected.

Sources specifically list it as a video amplifier. Note the high value of gm, necessary in order to obtain reasonable gain and power output with wideband signals, and for correct matching of video into coax cable. TV studio equipment racks used to be full of 6CH6s.

Thanks to John Fielding (ZS5JF) for following information. The 6CH6/EL821/CV2127 was used by KW Electronics as the PA driver valve in the KW2000 series of SSB transceivers. Later versions of the KW2000 used the more popular 6BW6, however like the 12BY7 series all these valves were originally designed for television video amplifier duty.

The valve is pin compatible with the 6BW6 but they have different uses.

Looking along the grid axis it can be seen that the grids pass flat across the cathode.

Here we have another Brimar 6CH6.

The base with connections to the electrodes and the anode with a gap to reveal the grids. The control grid is wound on copper supports.

The grid shape is made clear.

The reverse of the envelope.

The grids and beam plate rods. The notching and peening method of holding the grid wire is clearly shown in this image. Most grids are made this way with first one blade wheel cutting the notch, then the wire is laid into the open notch and the last action is a peening wheel to push the displaced support rod metal back over the wire.

The spot weld holding the base pin extension to the screen grid support rod.

The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 59 mm tall.

References: Data-sheet, ¹⁰⁴⁰, ³⁰⁰², PA3FVQ & John Fielding. Type 6CH6 was first introduced in 1952. See also 1952 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.