GSG 300B with Transcendar OPTs

2nd harmonics for the masses

Still settling in...

Postby EWBrown » Wed Dec 12, 2007 7:13 am

I'm still in the middle of "transitioning" to the new company (still in the old facilities) so I may be a bit slow in replying at times... The network and e-mail are flakey at times, if not suddenly dropping off line altogether.

I like to experiment and try new things, and I have several brands and varieties of 2A3s, and the 2.5VAC filament trannies already on hand.

This project is still evolving, as it exists mostly on paper and in mind, and not yet in the form of solid hardware Yellow_Light_Colorz_PDT_02

Since I've not yet punched or drilled any metal yet, I'm not yet committed to any one concrete design...

The 2A3-40s are very much like 300Bs, and since I recently found that the Trafomatic ST35 power tranny delivers much higher B+ voltage than is healthy for EL84s and 7189s, I'm considering dedicating it to the GSG project, as the additional B+ voltage will be fine for these higher powered tubes, but would still have to be throttled back for 6B4Gs, 6A3s, 6S4S (6C4C) and "traditional" 2A3s.

The Trafomatic power trannie has two 115 VAC primaries, and they operate just fine with the line voltage adjusted down to 115 VAC input, but as I have 123VAC as the "normal" line voltage, I get a B+ of over 410VDC, even with the CL-90 in the primary.

As an aside, John Broskie has the "Aikido" boards and kits for sale at 15% off, I ordered a set of the octal "mono" boards to use as possible drivers for a futureAikido-baseds 2A3 / 6B4G SET project

see http://home.att.net/~abraxasaudio/proje ... 2a3-2.html

The topology of the Aikido is similar to an SRPP / CF design that I tried out a while ago, and with whick I wasn't totally satisfied. The Aikido design havs done it right... The overall voltage gain with a 6SL7 input and 6SN7 output should be around 35 (mu/2). 12AX7 and 6CG7 / 6FQ7
should be about 50.

/ed B in NH
Real Radios Glow in the Dark
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EWBrown
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