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Old 7th January 2004, 05:38 PM   #1
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Default Anyone tried this at home?

Wanna try this nice piece of Russian-art,It's stamped RK-71....but believe it's a GK71,when I am correct.Looks a lot like a 813 too.
Anyone familiar with this tubie?
Sure would help me:-))
Thanks in forward!
Arthur.
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File Type: jpg resize of crop phto0006.jpg (9.7 KB, 870 views)
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Old 8th January 2004, 12:37 AM   #2
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Hi,

Quote:
but believe it's a GK71,when I am correct.Looks a lot like a 813 too.
It is a GK71 but that tube isn't a 813.

Like most of those big bottles it's a transmitting tube, in casu a tetrode.

If you have a few spares they're certainly worth building with.
Love those graphite anodes...

Cheers,
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Old 8th January 2004, 01:31 AM   #3
316a is offline 316a  England
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Default Re: Anyone tried this at home?

Quote:
Originally posted by universum
Wanna try this nice piece of Russian-art,It's stamped RK-71....but believe it's a GK71,when I am correct.Looks a lot like a 813 too.
Anyone familiar with this tubie?
Sure would help me:-))
Thanks in forward!
Arthur.

These valves look super-beefy and are on my 'to do' list ! Lit up with the lights off , very impressive looking . I estimate trioded Ra to be about 1.5k if the mug1g2/transconductance specs are anything to go by . After trying various triode strapped pentodes and tetrodes with anode voltages way over the g2 limit , 700V should be handled easily triode-strapped . I have built sockets already from teflon septars and will plot curves on the tester up to 400V , should give a good idea if my Ra guestimate is correct . One point to note : the heater requirements are a little on the 'nasty' side and will require DC for SE usage (20V heaters) , I doubt a hum pot and AC heating will be quiet enough . I'll post the triode test results once I've completed what's currently on the bench

316a
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Old 8th January 2004, 07:13 AM   #4
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Default graphite

Quote:
Originally posted by fdegrove
Hi,



It is a GK71 but that tube isn't a 813.

Like most of those big bottles it's a transmitting tube, in casu a tetrode.

If you have a few spares they're certainly worth building with.
Love those graphite anodes...

Cheers,

Hi Frank,

That's what i thought too:-)
Would be a shame to leave them laying around...I have three of them left(gave two away to a friend),sure like the white filements once lit up looks like a bulb(no orange glow here:-))what a light!!
What should i put in front of these biggies?
I was thinking of an El-84 followed by an EL-34 and the the GK-71,but maybe I should stick to DHT's?Suggestions?
Thanks in forward!
Cheers:-))
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Old 8th January 2004, 07:29 AM   #5
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Default Re: Re: Anyone tried this at home?

Quote:
Originally posted by 316a



These valves look super-beefy and are on my 'to do' list ! Lit up with the lights off , very impressive looking . I estimate trioded Ra to be about 1.5k if the mug1g2/transconductance specs are anything to go by . After trying various triode strapped pentodes and tetrodes with anode voltages way over the g2 limit , 700V should be handled easily triode-strapped . I have built sockets already from teflon septars and will plot curves on the tester up to 400V , should give a good idea if my Ra guestimate is correct . One point to note : the heater requirements are a little on the 'nasty' side and will require DC for SE usage (20V heaters) , I doubt a hum pot and AC heating will be quiet enough . I'll post the triode test results once I've completed what's currently on the bench

316a
According to the specs the limit on g2 is 400 volt,so wanna be a bit on the save side,you really think they can handle up to 700 Volts?Was thinking of triode strapping and put an el-84 an EL-34 in front..(triode mode too:-)
Wanna try AC on the heaters too,if that doesn't work i can go to DC later:-)But I am very curious how your testresults develop:-)
Please keep me posted:-)
Let there be light!(can read my paper next to it:-))orange?...nah white!

Thank you all for your replies!
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Old 8th January 2004, 07:53 AM   #6
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Here is a little bit of information, if you don't already have it.

just a couple graphs and some ratings.



Seems like an intresting tube.. cheap, powerful.. cool looking.
Damn heavy on the heater though! 60w.

edit: bah! forgot the link. Here it is.

http://www.qrz.ru/reference/tubes2/type2/gk71.shtml
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Old 8th January 2004, 08:59 AM   #7
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colt45 thanks...didn't have them with the graphs....only the russian keeps hunting me:-))
for those who like the glow see attachment...sure keeps me warm in winternights:-)
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Old 8th January 2004, 12:13 PM   #8
316a is offline 316a  England
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Default Re: Re: Re: Anyone tried this at home?

Quote:
Originally posted by universum

According to the specs the limit on g2 is 400 volt,so wanna be a bit on the save side,you really think they can handle up to 700 Volts?
YES Here's my prototype teflon socket


Did you use clip leads to light yours up ?

316a

http://www.auction.2y.net/user/bigdaddy/gk71skt.jpg
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Old 8th January 2004, 02:33 PM   #9
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Default Re: Re: Re: Re: Anyone tried this at home?

[QUOTE]Originally posted by 316a
[B]

YES Here's my prototype teflon socket

WOW looking great!Did you make them yourself?Looks prof to me.

Don't have one:-(or two...do you sell?


Did you use clip leads to light yours up ?

Yes i did..whehehe,on 12 volt dc...only for the picture...

Well it's gonna be a while when i start the project,working on other amps that must be done first,then the nicer things..

What are you planning to make?
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Old 8th January 2004, 02:55 PM   #10
316a is offline 316a  England
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Default Re: Re: Re: Re: Re: Anyone tried this at home?

[QUOTE]Originally posted by universum
[B]
Quote:
Originally posted by 316a


YES Here's my prototype teflon socket

WOW looking great!Did you make them yourself?Looks prof to me.

Don't have one:-(or two...do you sell?


Did you use clip leads to light yours up ?

Yes i did..whehehe,on 12 volt dc...only for the picture...

Well it's gonna be a while when i start the project,working on other amps that must be done first,then the nicer things..

What are you planning to make?
12V DC ! Thats a bit wimpy . The things look far more impressive with 20V on them . The sockets are adapted from teflon septars . The contacts are removed and the holes opened up . I then insert bullet crimp shells inside the holes and use a slice of teflon with a nut and bolt to retain the contacts . Topcaps can be made from terminal blocks withe the connectors removed . I just drill out a slice of 1" teflon bar and push the teflon on to the connector once its screwed on to the topcap . None are for sale , you have to make them yourself but I do have a fair quantity of the septar sockets in stock in case you are interested in making some yourself . I should really get busy with the triode curves now......

316a
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