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ID = 19149
United States of America (USA)
Brand: Common type USA tube/semicond.
Tube type:  Double Tetrode   VHF 
Identical to 6C9_Twin-Tetrode
Similar Tubes
Heater different:

Base Noval+1 (10= center pin) = B10G = E10-73
Was used by Radio/TV-reception etc.
Filament Vf 6.3 Volts / If 0.4 Ampere / Indirect / Specified voltage AC/DC

This 6C9 is a VHF twin tetrode; with base E10-73 = B10G = noval base with additional center pin. This base was only used for a few types.
This 6C9 wich we call 6C9_Twin-Tetrode has not to be confused with the 6C9 made by Fivre, a Pentode or the 6C9 from Great Britain, a Triode-Heptode, which we call 6C9_UK.

Text in other languages (may differ)

6C9_Twin-Tetrode: aus Heathkit AJ13
Manfred Rauschen

6c9_sock.png 6C9_Twin-Tetrode: Sylvana Data Sheet
Egon Penker

Just Qvigstad
6C9_Twin-Tetrode: Sylvana Data Sheet
Egon Penker

More ...
Usage in Models 2= 1960?? ; 22= 1962? ; 2= 1962 ; 2= 1963?? ; 42= 1963? ; 4= 1963 ; 1= 1964?? ; 53= 1964? ; 2= 1964 ; 2= 1965?? ; 4= 1965? ; 2= 1966? ; 1= 1967?? ; 1= 1968? ; 1= 1969

Quantity of Models at with this tube (valve, valves, valvola, valvole, válvula, lampe):141

Collection of



Forum contributions about this tube
Threads: 1 | Posts: 2
Hits: 2886     Replies: 1
6C9_Twin-Tetrode Curves
Joe Sousa

Fellow Radiophiles,

The unusual 17C9/6C9 dual VHF tetrode seems to have no published curve traces. I wanted to know what they looked like. These two photos were taken from the TEK575 transistor curve tracer.

Operation under nominal screen operation at 80V:


Operation with reduced screen voltage to see it's effect on the location of the tetrode kink. G2=40V:

This VHF tetrode was used in FM tuner front ends after 1960. The implication is that the noise performance must have been comparable to that of a contemporary triode.

The heater dissipation is 40% higher than that of 12AT7, yet the plate length is about half. The transconductance and capacitances are similar, except for much lower grid-plate capacitance of the 6C9 (0.06pF vs 1.6pF), as expected.

The most common application was as an FM front end was with one tetrode as grounded cathode preamp, driving the other tetrode also with grounded cathode, but configured as self-oscillating additive converter.

While the noise figure of the 6C9 might be comparable to the 12AT7, the expected overall gain as an FM front end should be higher.



Rolf Nickel


Dear Joe,
thank you for presentation of the results from your measurements.
A radio which is equipped with the 6C9 tube can be found here:

Additional information about the 6C9 tube is shown at nj7p:

It is worth mentioning that the 6C9 has 10 pins, No 10 (cathode 1) is located in the centre of the tube base. That means also a special tube holder with ten contacts.
Circuit Description of the KG-50 FM section:
" ...The FM signals presented to the tuner are selected by components in the AM-FM Tuning Assembly. The tube in the Tuning Assembly (6C9) performs three functions: amplification of the desired signal, generation of the oscillator signal and mixing of the FM and oscillator signals to produce the IF frequency signal. The IF frequency in FM operation is 10.7 mc (MHz) rather than 455 kc (kHz) because the conversion of the very high frequency FM signals down to the low frequency of 455 kc would introduce unwanted signal responses and other problems such as drift, etc. Converting to an IF frequency of 10.7 mc eliminates these problems. ..." (Knight Kit Assembly Manual, page 34).
Best regards, Rolf

End of forum contributions about this tube

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