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829B

Sensibly equivalent to:
3E29 829 C144 CV632 CV2666 QQV07-40
See also:
Olympia Show 1947 - VHF Valve Anode Connector - A Ride Down Memory Lane
    
Extras ▼

 

The 829B American pattern VHF double tetrode is the big brother of the CV788. The American approach to twin VHF transmitting beam tetrodes was to put two separate valves within the single envelope. This design requires external neutralisation capacitances to prevent parasitic oscillations. The European design of a common cathode with independent g1's, a common g2 and single sheet anodes (see QQV03-20 and QQV06-40A) had internal neutralisation and made the 829B and 832 obsolete, as well as offering greater output power.
The wide glass tube envelope has a characteristic bulge of 54 mm diameter that was used for retaining rings.
The RCA logo and Made in USA. The anodes are supported by the top pins as well as the mica discs making for a rigid structure. Note the ceramic insulators for high peak voltage insulation.
The twin anodes and on the glass is the anchor logo of the US Navy.
Here the box anodes with small side flanges are clearly seen.
Seen from the top and looking into one of the beam tetrodes the flat faced with rounded ends of the cathode can be seen with the copper supports of the control grid and the bright supports of the screen grid.
The B7A base pins equi-spaced around the base. For accurate location the index pin has an outer sleeve to increase the diameter.
The wide glass tube envelope is 50 mm in diameter and, excluding the B7A base pins, is 92 mm tall.
References: Datasheet & 1040.

 

Pin Connections
B7A
1
2
3
4
5
6
7
tc
tc
h
g1(2)
g2
k,bp
hct
g1
h
a
a(2)

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
Pdriv
Pdiss
Pout
freq
f.max
6.3
2.25
500
230
-45
230
23
0.9W
40W
83W
200
250
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 18, 2019.
shape:wide.glass.tube construction:all.glass type:double.beam.tetrode age:1940.1950 base:b7a heater:6.3v pins:7 pin:1.h pin:2.g1(2) pin:3.g2 pin:4.k.bp pin:5.hct pin:6.g1 pin:7.h pin:tc.a pin:tc.a(2)
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