The PC86 is a purpose designed UHF oscillator triode for television reception. At UHF a coaxial design would normally be used but by connecting the electrodes to several pins the manufacturers achieve the desired result without the complications, and cost, of a disc seal valve and its mounting.
In this other PC86 the gettering is largely missing as the valve is possible 'soft' ie a poor vacuum. This gives a chance to see the construction of the getter holder disc.
The getter material would have been deposited in the holes in the top disc and fired during final pumping.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
References: Datasheet & 1040. Type PC86 was first introduced in 1962.