7A-25Z

Sharp Cutoff Pentode. Runs off 12.6v±10% AC or DC volts
Primarily used in video amplifiers for TVs. Features high transconductance, high power sensitivity, and low interelectrode capacitances. It can deliver relatively large output voltages with low values of plate-supply voltage and plate load resistance.

Designed to function as a combined detector, amplifier and automatic volume control tube.
MFR: RCA, GE, Tung Sol, Triad, Delco, Sylvania, Chief, Realistic, Brimar
SKU: 12AT6
New old stock * No longer available for export.

Designed to be used as an output amplifier primarily in automobile receivers and in AC-operated receivers
New old stock * No longer available for export.
MFR: Westinghouse
Made in Japan
SKU: 12AQ5-JAPAN-WH

UA78H12ASC Transistor, MFR: ASC  No longer available for Export, (NOS)

New Old Stock * No longer available for export
MFR: Unknown

SKU: 12AX7A-UN

No manufacturer label on tube

Designed to be used as a high gain voltage amplifier and a cathode type phase inverter
New old stock * No longer available for export.
MFR: International Servicemaster
Made in Japan
SKU: 12DW7-IEC

New Old Stock * No longer available for export
MFR: National
SKU: 7025/12AX7A-NAT

Designed to be used in electronic computer applications and other On/Off applications.
New old stock * No longer available for export.
MFR: 6829
SKU: 12AV7

The ECC 803S (ECC803S) Telefunken Gold Pin High Mu Twin Triode tube is RARE and difficult to find.  The ECC803S is a very low noise, special quality 12AX7, made with the old-style Telefunken German precision. These have the ultra wide bandwidth of the Telefunken ECC803s, but also have nicely matched internal triodes, gold pins, and have been carefully factory-screened for low noise. 

New Old Stock * New In the Box * No longer available for export
MFR: Telefunken
Made in West Germany
SKU: ECC803S-WG