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Old 22nd February 2005, 11:36 AM   #1
gianis is offline gianis  Greece
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Default 7241 tube

I found some of these tubes : [ 7241 tung-sol] , I want informations , data, etc, abaut these. thanks
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Old 22nd February 2005, 11:40 AM   #2
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Old 22nd February 2005, 11:42 AM   #3
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Horrible, horrible, horrible things.

Only capable of passing 1200mA, and 100W anode dissipation at 67 ohms ra. Horrible for OTLs.

You MUST send them to me for safe disposal, or even better send me some 7242s if you have any

Seriously, though, if you have enough, you could probably make quite a nice OTL. Datasheet here.
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Old 22nd February 2005, 12:03 PM   #4
gianis is offline gianis  Greece
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Default 7241 tube

I have 9 of them [ from old military stock] are these tubes good for SE topology?? I have no expiriance with OTL amplifiers. Thanks
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Old 22nd February 2005, 12:14 PM   #5
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Because of the valve's characteristics, you'll need a low turns ratio transformer capable of handling quite a large DC current, but yes, they will work for SE amplifiers. With the large Pa rating, I would imagine quite a lot of power would be available - probably >20W, but you'll have to keep an eye on the bulb temperature (not literally, of course )
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Old 22nd February 2005, 12:19 PM   #6
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I probably should add that the high input capacitance (I can't find a value for this, but it's going to be pretty large), and low m will make the output stage a devil to drive, but it's nothing that can't be overcome
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Old 22nd February 2005, 01:06 PM   #7
panos29 is offline panos29  Greece
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Default Excellent tube!

Geiasoy Gianni!

What a wonderfull tube this is! I never imagined you could find such tubes locally! Anyway such a tube is supernice for OTL as proposed allready but also can be used in SE. It would be very interesting to try wind your own transformer as the primary resistance is too low thus too easy to make! I am sure its going to be very hard to drive such beast, but as already stated, nothing is impossible.

If you like any help you can call me at 6977744232

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Panos
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Old 22nd February 2005, 08:20 PM   #8
gianis is offline gianis  Greece
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Default 7241

Thanks for the responses,, i`ll try to build something with these tubes [ i hope so] its difficult but i`ll try it..Thanks, Gianis
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Old 23rd February 2005, 04:23 AM   #9
jlsem is offline jlsem  United States
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A 500 ohm output transformer that can handle 400 ma. standing DC current is an awful lot of work for 18 watts.

CAUTION: Don't be misled by other parties on this forum. All tubes designated for proper disposal are to be referred to me first.

John
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Old 23rd February 2005, 04:28 AM   #10
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Agreed that the OPT will be a lot of work, and perhaps I should add that current sharing between the three cathodes within the envelope might be a concern - so individual cathode resistors would be preferable if cathode bias is used.

But not agreed that valves should be referred to John before proper disposal!
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