Em87/ em84

Dagwood · 3rd March 2010, 01:15 PM

Hi

Could anyone confirm if these 2 are interchangable?

EM87 @ The National Valve Museum

EM84 @ The National Valve Museum

Thanks

TheGimp · 3rd March 2010, 01:55 PM

Looking at the data sheets it looks like the EM87 may be more sensitive since it's grid voltage is specified as -15max vs -22max for the EM84. The EM84 also has a lower Anode Current and dissipation but it is close. So, they may or may not be interchangable. It will be very dependant on the circuit.

Which do you have currently? Ie are you trying to sub an EM84 for an EM87 or sub an EM87 for an EM84?

Is it used as an FM tuning indicator?

It is probably relativy easy to change the circuit to make a swap, but it would be easiest if you could find design examples of both to see the differences in bias and possibly load resistance.

Dagwood · 3rd March 2010, 02:26 PM

Hi TheGimp

I actually have a 6E2 (no datasheet) used for line level display which I have been told is the same as the EM87? I can get my hands on a EM84 easier that the EM87 so hoped that the difference in the Anode Current would be within the tolerance?

I'm new to all this and am very grateful of any advice.

3rd March 2010, 01:15 PM	#1
Dagwood diyAudio Member Join Date: Feb 2010 Location: North of Auckland	Em87/ em84 Hi Could anyone confirm if these 2 are interchangable? EM87 @ The National Valve Museum EM84 @ The National Valve Museum Thanks

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3rd March 2010, 01:55 PM	#2
TheGimp diyAudio Member Join Date: Aug 2009 Location: Johnson City, TN	Looking at the data sheets it looks like the EM87 may be more sensitive since it's grid voltage is specified as -15max vs -22max for the EM84. The EM84 also has a lower Anode Current and dissipation but it is close. So, they may or may not be interchangable. It will be very dependant on the circuit. Which do you have currently? Ie are you trying to sub an EM84 for an EM87 or sub an EM87 for an EM84? Is it used as an FM tuning indicator? It is probably relativy easy to change the circuit to make a swap, but it would be easiest if you could find design examples of both to see the differences in bias and possibly load resistance.

3rd March 2010, 02:26 PM	#3
Dagwood diyAudio Member Join Date: Feb 2010 Location: North of Auckland	Hi TheGimp I actually have a 6E2 (no datasheet) used for line level display which I have been told is the same as the EM87? I can get my hands on a EM84 easier that the EM87 so hoped that the difference in the Anode Current would be within the tolerance? I'm new to all this and am very grateful of any advice.

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