The VT26A (later renamed the CV1568) is a directly heated HF RF power triode. The VT in the designation indicates an RAF specification. Although designated as an HF device the upper working frequency is only 7.5 MHz.
The Type designation and maker are etched into the glass. The 12 - 100 indicates a 12 V filament (thoriated tungsten)
The bright anode is held securely by bands around the pinch stem. The insulators are ceramic as this is a high voltage valve.
Side view of the anode with the control grid winding extending above and below the anode.
The Air Ministry Crown logo on the envelope. Within the two tension springs hold the top of the thoriated tungsten filament.
A closer view of the filament loops held within the hooks of the springs.
A slightly different angle showing the spring construction and grid wires.
Looking up from the pinch, note the method of attachment to the supports held in the glass pinch.
The wide glass tube envelope is 58 mm in diameter and, excluding the L4 base pins, is 175 mm tall.
