Hi Ardee.
I have no personal experience with these tubes, but see them for sale on eBay. The ones pictured for sale by sellers from various countries appear to have a getter disc mounted inside just below the top cap. But these have no flashing on the glass that I can see. I have also seen websites with pictures of power supplies that used these tubes and they do have dark getter flashings.
Perhaps there was a quanity of 6D22Ss that were never exposed to an RF source to flash the getter. Maybe the factory's RF bombarder was not working for a period of time. Maybe they felt the vacuum was sufficient and could survive without a getter. Maybe they were in a hurry and just didn't flash it to save time and money. Who knows?
Also possible, but unlikely, there is a bunch of defective tubes with bad seals that have leaked. Have you powered up your filaments to see how they light? If they light dimly and/or smoke, they have air in them. Perhaps give that a try and let us know.
Sometimes a tube's plate, when made of tantalum or carbon, will act as a getter when hot. But that almost always applies to transmitting tubes. Not receiving tubes such as these.
Victor
I have no personal experience with these tubes, but see them for sale on eBay. The ones pictured for sale by sellers from various countries appear to have a getter disc mounted inside just below the top cap. But these have no flashing on the glass that I can see. I have also seen websites with pictures of power supplies that used these tubes and they do have dark getter flashings.
Perhaps there was a quanity of 6D22Ss that were never exposed to an RF source to flash the getter. Maybe the factory's RF bombarder was not working for a period of time. Maybe they felt the vacuum was sufficient and could survive without a getter. Maybe they were in a hurry and just didn't flash it to save time and money. Who knows?
Also possible, but unlikely, there is a bunch of defective tubes with bad seals that have leaked. Have you powered up your filaments to see how they light? If they light dimly and/or smoke, they have air in them. Perhaps give that a try and let us know.
Sometimes a tube's plate, when made of tantalum or carbon, will act as a getter when hot. But that almost always applies to transmitting tubes. Not receiving tubes such as these.
Victor
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