EL84 Marconi Osram MOV N709 British Made 6BQ5 rare valves etched code on glass rx1 B made at Blackburn

Description

The Marconi Osram N709 is a special version of the Mullard EL84 having a single-ended construction and a B9A noval base.
With the maximum anode dissipation rating of 12 watts and a mutual conductance of over 11 mA/V a signal of very small amplitude is sufficient for full drive an amplifier. The Mullard EL84 GEC (N709) has been designed to satisfy demands in high fidelity in amplifier or receiver operation. To meet the requirements for high fidelity it is desirable to increase the available audio output power from the amplifier and hence decrease the distortion present at a given output, this is what the EL84 does.
This section shows various type of UK made EL84

The Marconi N709  EL84 shown here are by far the rarest and the best Marconi N709  EL84 ever made.

They all have early code on glass that is rx1 B made at Blackburn

Holy Grail of audio valves

The  Marconi N709  you see here have been tested at 6.3 Volts filament with both Anode and Screen at 250 Volts and negative grid of 7.3.

Marconi N709 have been tested with AVO 163 with current of : 49mA; 49mA; 47.5mA; 48mA matched quartet 100% emission