Charlie's 21AXP22 dud CRT

[cork]

Just received the rebuilt color 21 inch round tube from VDD in Dallas. This is the tube that Charlie supplied to VDD as a rebuildable core. I havn't had time to install it yet, but I though I would pass along how it checks out on the old B & K CRT tester.
The photo below is the lowest emission gun with only something like 4 volts supplied to the heaters. The other guns have slightly higher emission. Of course with 6.3 volts on the heaters emission is higher.

I pass this along only becuase it is interesting to see what a truly new gun acts like. This shows that this tube would look fine with only four volts on the heaters. And if it's anything like a transmitting tube it would be pretty happy on reduced heater voltage and last quite a while until it needed more heater voltage.

The so-called good old tubes (lollipop included) that I have tested have wildly differing emissions between the guns and take several minutes with 6 volts heater voltage applied to crawl out of the "bad" emission zone on the B & K meter. And some of them show the wilting effect; that is the emission will struggle up to the OK region and then slowly fall back to the bad region.

There is none of this nonsense with the VDD rebuild. It's already to go in about 15 seconds.

This B & K CRT tester is nothing too tricky. It applies something like 300 VAC to the CRT control grid through a series R, and the meter measures the rectified current.

Next test for this tube is too see how it works. Just to keep things simple it's going into a CTC-5. I will try to post results if there is any interest.

[Tony V]

Hi Cork,
Its interesting to see how a rebuilt tube reacts to the tester compared to older unbuilt tubes. Thanks for giving us your findings on this as some of us have never had the luxury of owning a freshly rebuilt tube to check this out. Of course you know we are all waiting for you to install the tube so we can see pictures of how well it plays. We can never get tired of seeing too many roundie color tv's play.
-Tony

[Eric H]

Hi Cork,

Isn't this a 21CYP22? it appears to be all glass in the picture, the metal tubes were the 21AXP22 if I'm not mistaken.

Either way a really great thing to have!


Eric

[cork]

Hi Eric,

You're right about the type. It is all glass. VDD had it labeled as a 21FBP22, which is sort o' like a 21FJP22, or a 21CYP22.

Hi Cork, sure am interested in seeing pix of this tube once you have it installed. Your tester is just like the one I picked up recently, although mine is a 445

Anthony