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3NF

 
See also:
Loewe Multi Valve Repair Policy
    
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Loewe produced the 3NF multi valve to avoid excessive taxes levied on the number of valves in a set. The three triodes and associated passive components sealed into the envelope are used to make a complete radio with a minimum of external components. The 3NF was the first integrated circuit. The passive components (resistors and capacitors) were sealed in glass tubes prior to final assembly.
The identification panel printed on the glass.
The passive components are near the base with the triodes above. The outside triodes are mounted horizontally and the third triode is placed vertically between them.
The base pins are set in Bakelite and there are three location pins that fit the bayonet holder in one orientation only. The points scrape along the base contacts when inserted and the location pins sliding into their slots maintain the required contact pressure.
One of the side triodes. The thoriated tungsten filament is a single strand with a helical grid around it.
The The tungsten filament is held in a fold of the support. The anode is a folded cylinder with two supports. All the electrodes for the triode are fixed to an intermediate glass rod. Clearly the individual triodes are assembled before the complete valve is fabricated.
Two resistors with a capacitor in the centre.
The OE333 receiver that the 3NF was designed for. We have a complete receiver in the museum but the condition is not as good as this image.
The wide glass tube envelope is 46 mm in diameter, and excluding the base pins is 154 mm tall.
Reference: Data-sheet. Type 3NF was first introduced in 1926.

 

Pin Connections
1
2
3
4
5
6
g2(1)
f-
a(2)
a(1)
f+
g1

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
4.0
0.34
90-200
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated August 29, 2021.
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