[37-670]

A friend of mine in Canada is into designing and building tube amps using pre-octal triodes. In payment for a really neat Canadian Stromberg-Carlson 694 table radio he scored for me, I have been rounding-up 10's and 10Y's (military VT-25's) for him.
My Triplett 3444 gm tester, plus a couple Triplett emission testers I have, show different plate and bias settings for 10 and 10Y tubes. I assume the 10Y will take a higher plate voltage and have a higher RMS wattage in an output circuit. Am I correct in this assumption?
It would seem that the obvious place to go for this information would be a tube manual, but my RCA manuals make no mention of the 10Y. Any help you can render would be greatly appreciated.
By the way, those 7.5-volt tungsten heaters really light up a room!

[codefox1]

Check out this website

http://www.nj7p.org/Tube.php

THe 10 an 10Y appear to be different animals. Hope this helps

[37-670]

Thanks Codefox1. What a great site. Never knew it existed until now. Looks like I should be going for 10Y's.

[exray]

I believe there's also a "10 Special". It was used primarily as a transmitting tube in the 20s and 30s.

Found a picture of mine, can't find the tube

[attachment=0]

[Doug Houston]

I'm using a 10Y (VT25) in a Brunswick P-10 Panatrope (Phonograph), in place of a regular 10; possibly the original one. From all I'd ever read, the 10Y is simply an upgrade of the 10, and has the same characteristics as the original 10. It also has a micanol base, as the 10 was a popular oscillator with the hams i n the twenties. It was also the master oscillator in the BC-191 and BC 375 transmitters of WW II. The most refined version of the tube is the 210T, which has a ceramic base, and was designed for higher power transmitting service.

Now that you know this, leave a few of these tubes for those of us who have early Radiolas and record layers, please.

[Jayce]

I used to have a Radiola 41 that was supposed to use a 10, but the cost of getting a 10 for it was rather prohibitive. Later on I got a nice Zenith 34P with a good 10 in it that I shared between the two radios for a while until I sold the Radiola. I've never, ever run across a used or NOS 10 or it's variants around here. I rarely play my Zenith because of the expense of that one tube.

[37-670]

I wound up buying five 10's -- two N.O.S. RCA VT-25's, a no-brander N.O.S. (allegedly) from a tube dealer, an Arcturus that tests super high for Gm on my Triplett 3444 and a bad "Aristocrat" (most likely rebranded; never heard of the name). Except for the no-brander, all came off eBay sites. There are, or were, a couple sellers peddling pairs of Sylvania VT-25's on eBay. Haven't checked lately as I am done buying 10's, so rest easy lovers of old radios and ham gear.
It turns out that data shown on <!-- w --><a class="postlink" href="http://www.nj7p.org/Tube.php">www.nj7p.org/Tube.php</a><!-- w --> for the 10Y was not entirely accurate. There was a printing error in an old tube manual showing 13 watts RMS output, where it should have been 1.3 watts -- same as the 10. The site continued this error.
Once again, this was a one-time deal. A trade for a Model 694 Canadian Stromberg-Carlson. There is nothing not to like about this 1947 table radio; nine tubes including push-pull 6L6's and a tuning eye, an 8" PM speaker and a hefty power transformer meant to operate on both 60 and 25-cycle current. No FM band, but there is an RCA phono jack on the rear apron of the chassis in which I plug my little Sony ST80W tuner so I can listen to FM (standard broadcast stations in my neck of the woods -- Wyoming -- have, without exception, wretched programming).
Thanks for everyone's input.
Eric Strasen