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860

Sensibly equivalent to:
CV640 VT-17
See also:
Barkhausen-Kurz (B-K) Mode Oscillators
    
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The 860 is a magnificent specimen, it also carries the USA service code of VT-17. The anode is brought out at the bottom of the picture. The control grid is connected at the left and the filament plus screen grid is connected to the base at the right.
The screen grid is a massive cage and the anode quite short in relation to the screen. The filament is a course helix with the control grid surrounding it. The frequency of operation was in the HF range and amateur practice pushed this to 60 MHz. The small anode does not suggest high power dissipation, but was in fact rated at 100 Watts. The screen grid dissipation was 10 Watts. The output power in CW service was 150 Watts and in AM (phone) operation this reduced to 100 Watts. The anode maximum voltage was 3 kV. The filament ran at 10 V and 3 A.
The VT17 was also used as a BK oscillator.
This valve was mainly used in the latter half of the 1930s but were made up until the end of WWII (1945).
The central sphere is 87 mm in diameter, and excluding the base pins is 203 mm tall.
References: Datasheet.

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Pdiss
10.0
3.0
2,000
100W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated December05, 2012.
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