Vacuum tubes: Radio tubes, TV tubes, Audio tubes

In the days of tube designed FM radio and TV, there were millions of tubes manufactured to service these components. Now, in modern times these original tubes are coveted due to the small supply of NOS tubes that test well.
NIB (new in box) is what every audiophile wants. It means the tube was originally manufactured in a specialized factory with date codes and has never been used.
NOS (new old stock) is the next gem quality tube. It is an original period tube, but it’s use or non-use can’t be verified. The tube is tested to see if it measures as new. This is why a trustworthy dealer is important.

Re; radio tubes on Ebay. There are still vintage FM radios in collectors and audiophile's homes. Not to mention Ham radio operators and collectors. They need these tubes to keep their gear up and running.

The best vintage tubes were designed for military, they are the highest quality (normally more expensive). So besides radio and tv there are critical military equipment that demands the highest quality tubes, stable, durable etc. I have some NOS japanese tubes from the 70’s, marketed as audio tubes especially for hi-fi audio, the manufacturer guarantee they are low microphonic and low noise (for example NEC 6BQ5 Hi-Fi Green series). As you know there is an amps in TV and Radiolas, so these tubes are audio tubes (fine for your modern high-end amps and phono stages, depends on the type of the tube).

And Russia will be manufacturing tubes for a long time since their military electronics still use tube circuits.

To add to the good comments above, during the many decades in which tube-based radios and TVs were produced countless different tube types came into existence, and were used in countless different radios and TVs. A small fraction of those tube types, but still a significant number of them, are used in today’s high quality audio components.

That tends to be most true in the case of small signal tubes, that are used in preamps and other line-level components. But a number of power tubes that had been used in certain radios are still used in high quality audio power amplifiers. Examples being the types 45 and 2A3, which were used in high end radios of the early to mid 1930s, and the 6L6 which was used in certain radios starting a few years later. Some of those radios, produced by manufacturers such as E. H. Scott (no relation to the hifi manufacturer H. H. Scott, who came later), McMurdo Silver, and Zenith, were quite elaborate and could be considered to be precursors of modern hifi systems.

In many cases the ads you may see offering large quantities of radio and TV tubes come from tube stocks that had belonged to retired or deceased radio and TV service people. Typically most of those tubes would mainly be of interest to antique radio collectors, while a relatively small fraction of them would be of the types that are still used in today’s audio components.

Regards,
-- Al