The 6AK5 is an amplifier pentode that is physically small and the electrode assembly is no more than a 10 mm cube. The use of this device lay in low noise RF amplification at VHF.

Within the box shaped anode can be seen the grid structure. It is hard to see the control grid as it is made of very fine wire and close in to the cathode. The screen grid is a close wound helix of less than 0.5 mm pitch. The suppressor grid is a gentle helix some distance out from grid 2.

The thin glass tube envelope is 18 mm in diameter and excluding the B7G base pins, is 35 mm tall.

References: Datasheet, ³⁰⁰² & ¹⁰⁴⁰ Type 6AK5 was first introduced^¶ in 1942.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	g1	k	h	h	a	g2	k

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.175	180	120	-2	7.2	2.4	0.7M	5.1

Thanks to Frank Philipse for supplying the above PDF datasheet

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