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Old 14th April 2008, 09:58 PM   #21
coresta is offline coresta  France
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I forgot to say that mine are NOS NIB RAYTHEON from May 22 1944 (US NAVY stamp) . I have 2 LMT , the former "Le Materiel Telephonique" , the french WE subsidiary . The "LMT" logo is written exactly the same as "WE" or "STC"
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Old 17th April 2008, 10:10 PM   #22
coresta is offline coresta  France
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Hi ! Some news : i 've been rectifying the heating ...8000uF +0,39ohms : no more hum i've changed the silver mica cap for ROEDERSTEIN KP1832 (0,075uF/800v) and highs are better now
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Old 25th April 2008, 09:47 AM   #23
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Quote:
Originally posted by coresta
Hello , yes , i'll scan the schematic in a few days : i still have a low hum (on 515 woofers ..) but would like to cancel it . I operate them with 300/0/300 PT / 5R4WG /2x2uF polypro /10Hys /32 uF . There is 325volts on the OT (3,3k primary ) and G2 is tied to A with 47ohms WW. G2 to the center of a 30ohms pot to 750ohms WW (+47uF 63volts) to GND. Heater is fed through 2 WW 0,39ohms resistors to the 6,3Vac . Grid leak res : 255k MF . The red block is a coupling silver mica capacitor 22nF /500v . The input tube : A 10k decoulping resistors goes to 32uF to feed a 6C6 with 80k MF in anode , g2 : 900K MF /0,22uF and Rk : 1,21k MF //47uF tantalum . The Ammeter in cathode goes to 45mA . Silver teflon wiring and iron plate Sound is astonishing for such a low power of 6 watts. Smoth and grainy . Bass is ... good , not so hard as with my 50W OTLs but they would perform for driving a 299/805 combo ! I've build a pair and will modify them for a 423C gas regulator in the 6C6 screen grid . As Tubelabe says , the 307As are worth the effort for the 15 Euros each i found them
Coresta,

Here is the Radiotron 6C6 amp and the link to Joseph Esmilla's site where it is discussed.

Click the image to open in full size.

http://members.myactv.net/~je205d/6c62a3.htm

Look forward to your schematic,

-- josť k.
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Old 3rd May 2008, 09:08 PM   #24
coresta is offline coresta  France
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Wazzat ?
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Old 3rd May 2008, 11:20 PM   #25
wicked1 is offline wicked1  United States
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I wouldn't call the 307a "today's components" since they are no longer built, when 300b's, 2a3's, etc, are.

I wouldn't call them easy to find anymore either. I've been trying to find a pair for months now. Everywhere I check is out of stock, or are charging 60-100 per tube. (while the out of stock places were charging about $15) I did manage to get a pair from 2 different vendors, but each tube was different! now I have 4 tubes w/ different construction! I just want a pair where each tube looks the same, and I want to pay less than 300b prices!!!
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Old 4th May 2008, 01:58 AM   #26
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Let that be a lesson. When you find a good tube, keep your mouth shut The mere mention of certain number depletes stocks and skyrockets prices.
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Old 4th May 2008, 06:20 AM   #27
coresta is offline coresta  France
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yes maybe , so let's close the DIY forums ? i don't have interests in pmillet business , i (almost) never buy any tube charged more than 20 bucks/unit as i still have 12 307a sparelife stock
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Old 1st January 2009, 01:23 AM   #28
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Merry new year!

Just resurrecting an old thread...

I posted some info on the 307A tube, and a push-pull amp design I've been working on for a while:

http://www.pmillett.com/307a_pushpull_amp.htm

Sorry if my site is loading very slowly - a guy at EDN magazine posted a link to my books page and the site has been getting hammered. I might hit 1TB of data transfer this month

Pete
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Old 1st January 2009, 03:07 AM   #29
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Originally posted by pmillett
Merry new year! . . . . . Sorry if my site is loading very slowly - a guy at EDN magazine posted a link to my books page and the site has been getting hammered. I might hit 1TB of data transfer this month . . . . Pete
Ahhh , so that's what happened. I wondered what was up when last night i tried to download the STC file. When it still wasn't finished after half an hour I took a look at the download bar. It read "7 days , x hours etc. remaining" ! Hah ! I got it today in a couple of minutes.

Happy New Year to you too Pete.
Big thanks for all you do, like keeping that site up and running. It's a valuable resource for all of us and it's really appreciated !
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Old 1st January 2009, 09:54 AM   #30
coresta is offline coresta  France
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Happy 2009 to all of you !

A pair of engraved WECo was sold two months ago on ipay . But nothing more different with an RK75

I use mine with G3 tied to cathode , should i try a real full pseudo triode Pete ?

Cheers
Pierre
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