NC pins on submin tubes

engels · 26th December 2007, 10:23 PM

I'm making a PCB for a preamp with 5719 submin triodes and stumbled upon something very minor. The tube is a triode with 8 pins/legs. A couple of them are non-connected and probably made for a better support only.

The question is - when I solder them, should they remain non connected or sould I tie them to a ground?

What i see inside the tube is that those NC pins go to the first (lower) supporting disk (mica?) and end there.

5719 Sylvania datasheet

dhaen · 26th December 2007, 10:32 PM

Unconnected is the norm;- unless someone can convince us that the 5719 is a special case for some reason....

unclejed613 · 27th December 2007, 03:20 AM

tying them to ground wouldn't hurt anything either if your circuit is operating in the audio range, and like you thought would add mechanical support to the tube.

wa2ise · 29th December 2007, 08:08 PM

I've wired the NC pins (wires) to the nearest neighbor if it is the plate, or the cathode, or the ground side of the heater. A little less capacitence (shouldn't matter in audio work) and it requires a bit less worry about the wire leads shorting to other wire leads, as they are going to the same place.

26th December 2007, 10:23 PM	#1
engels diyAudio Member Join Date: Jan 2007	NC pins on submin tubes I'm making a PCB for a preamp with 5719 submin triodes and stumbled upon something very minor. The tube is a triode with 8 pins/legs. A couple of them are non-connected and probably made for a better support only. The question is - when I solder them, should they remain non connected or sould I tie them to a ground? What i see inside the tube is that those NC pins go to the first (lower) supporting disk (mica?) and end there. 5719 Sylvania datasheet

27th December 2007, 03:20 AM	#3
unclejed613 diyAudio Member Join Date: Dec 2006	tying them to ground wouldn't hurt anything either if your circuit is operating in the audio range, and like you thought would add mechanical support to the tube. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

29th December 2007, 08:08 PM	#4
wa2ise diyAudio Member Join Date: Apr 2005 Location: NJ	I've wired the NC pins (wires) to the nearest neighbor if it is the plate, or the cathode, or the ground side of the heater. A little less capacitence (shouldn't matter in audio work) and it requires a bit less worry about the wire leads shorting to other wire leads, as they are going to the same place. __________________

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26th December 2007, 10:32 PM	#2
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Unconnected is the norm;- unless someone can convince us that the 5719 is a special case for some reason....

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