02-15-2021, 06:05 PM
UV 199 tubes are not the greatest, even when new. The cathode looses emissions easily, by too high or too low of filament voltage. They often "go to sleep". The GM on them only needs to be around 240 but that is difficult to obtain on many of them. The UV version can be rejuvenated by running the filament at about 5V overnight. Then reset to 3.3V and run them for several hours prior to testing. Most of the filaments will stand up to this and I have had about 50% success in making them usable.
Some of these tubes seem to loose emissions in storage. Makes me wonder about the quality of the vacuum. For the record: UV pin-out IS NOT THE SAME AS UX tubes. If tested as a UX, plate voltage will be applied to the filament - BOOM. You probably know all of this but I thought that I would make sure.
E-Pay listing:
https://www.ebay.com/itm/LOT-OF-7-UV-199...SwRFxgC5iz
But I would not buy them for that price. There are usually more of them listed but not today. A known good one is worth about 20 - 25$. There are brass-base ones also but these are around 50$.I would not use them very often - or at all.
In general a pretty flakey tube. But the UXs are better. You could build an adaptor and use the UXs. They can be as little as $10 ea.
Those subs I showed you guys on my blog using a 3V4 would work well in the front end or as an audio amp (last tube) but might be a little squirrely if used in that radio's IF.
Russ
Do you know if the "catacomb" is in good shape? It is a melt-out and repair job that can be a little difficult.
Some of these tubes seem to loose emissions in storage. Makes me wonder about the quality of the vacuum. For the record: UV pin-out IS NOT THE SAME AS UX tubes. If tested as a UX, plate voltage will be applied to the filament - BOOM. You probably know all of this but I thought that I would make sure.
E-Pay listing:
https://www.ebay.com/itm/LOT-OF-7-UV-199...SwRFxgC5iz
But I would not buy them for that price. There are usually more of them listed but not today. A known good one is worth about 20 - 25$. There are brass-base ones also but these are around 50$.I would not use them very often - or at all.
In general a pretty flakey tube. But the UXs are better. You could build an adaptor and use the UXs. They can be as little as $10 ea.
Those subs I showed you guys on my blog using a 3V4 would work well in the front end or as an audio amp (last tube) but might be a little squirrely if used in that radio's IF.
Russ
Do you know if the "catacomb" is in good shape? It is a melt-out and repair job that can be a little difficult.
