STA LEVEL - TURRET BOARS LAYOUT

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Deepdark

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Joined
May 19, 2013
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Location
Quebec, Canada
Hi

Jst wanted to share with you my turret layout for a STA Level. For those ineterested in this project and like to build on turret board, it could be nice to use this layout. Anyway, enjoy it :) let me know if you got some ideas or see any mistakes

Looking at the transformers, the original specs appear to be something like 1:10 (input) and output something like 8K:600!??

Possible alternative:

1:1 (10K:10K), 1:4 or 1:5 in input (600:10 or 15K) should work fine, resulting in better and less sensitive input control (Cinemag, Edcor, and other brands should have these values). Dripp uses Sowter 9062 1:4+4. Don't know how it is wired, though. Probably 1:8

4:1 in output (something like 10K:600) should be enough. Drip uses Sowter 9185 8K:150 (7.3:1).

I guess with a lower ration there is no need for the input pad!?

Any thought about the transformers options/alternative. I'm I correct?

I was asking myself about something on the 1960 schematic. They strapped a 200K resistor across the secondary of the iinput transformer. They didn't do that in the previous schematic. Is it a kind of load for the input? They strapped it just before the dual 100K pot.

;D
 

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power board and meter/switch board.

Concerning the power board, I forgot to put the C13 cap (Between the CT of the filament and HT). The power transformer hookup isn't drawn. Just strap the 5V tap on pin 2 and 8 of the 5Y3, pin 4 and 6 to the 500V.
Depending on the size of the C12's caps, they could have to be install out the board.
 

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For the ground, probably a ground wire like the original will work great. Or we could give some ground points, like on the LA2A, a try.
 
Deepdark said:
Hi

Jst wanted to share with you my turret layout for a STA Level. For those ineterested in this project and like to build on turret board, it could be nice to use this layout. Anyway, enjoy it :) let me know if you got some ideas or see any mistakes

;D

Thanks! - this looks great

Gustav
 
This is awesome! Thank you for sharing it. I'm looking at doing a PTP version of this and wondering if you tested out your layout yet? I'm curious about the transformer substitutions you mentioned in your first post as well? It would definitely be nice to see if Edcor's could be subbed with good results 8)
 
I'm looking at this as well, any feedback you can share will be greatly appreciated!

Regards,

Pierre
 
Hi. I hadn't had time to build it yet. Looking at the transformer, the easiest path would be to take the sowter one. I don't know if edcor has something that could fit. Probably they have something. Another way would be to Ask Cinemag / Jensen / Lundahl / Carnhill if they have some transformers that could fit the design. Since this circuit require a couple of tube (including one that is pretty expensive), transformers, etc. It will end up being a little expensive for me now.
 
From my personal experience edcors look cheap until you order them, the shipping cost eat up what look like savings.  In the end if you figure the total cost of the project i'm not sure the amount you save will be that significant...just my humble opinion that is....

Regards,

Pierre
 
Yes, you could use a high Z 1:1-1:3 input here, the circuit has a very large pad on it which could be left out in that case.    Gates used anything from 5K to 8K on the output primary, depending on era.  BTW I have a lovely set of suitable RCA transformers in the BM, for anyone wanting to build a pair with proper vintage iron. 
 
Yes edcor's shipping fees are a little expensive, so not that cheap at the end. I have little experience with their products sor i couldn't gave Any advice on them. I saw your BM Emrr, really nice stuff there. There is probably a couple of utc that could work, too.
 
Certainly there are some other UTC that would work.  Lots of choices.  Gates used a lot of Triad and ADC in that era.  The Edcor in my experience don't have as flat a low end, so they could require a tweak in the NFB to compensate. 
 
And i forgot oep. They have some nice transformer and not that expensive :) maybe they have something that could work. I dont know about the capacitance need in this circuit. Is it negligeable or not...
 
Nice info! I have a couple random Oep's laying around. I agree about Edcor's high shipping cost . It's still a significant savings for us folks here in the states compared to Sowter.  Obviously the vintage iron would be great.

I'm half tempted to try the PTP layout… I just finished a PTP Redd 47 which turned out nicely.
 
If your in the states, then cinemag would be the way to go if they have such transformers ratio. You could ask him :)  You can try your oep, too. If the ratio are ok, then give them a chance.

Since it's not a very complicated design, a p2p should be easy enought to do :)
 
The design wasn't that hard to do :) just follow the schematic and put component in the most convenient way. I could have use a 25 position 2 rows turret instead of a 20, thought. Anyway. I could also redraw the psu to make it simpler. Just a few ideas :)
 
Here is a list of possible transformers. None have been tested in the unit, though.

Input:

cinemag CMLI 10/600 wired backward
Edcor xsm 600/10k
Edcor xsm 600/15k
Sowter 9062 (1:4+4)
Sowter 9820
Sowter 8540
Utc a24 wired backward
Oep a262a3e
Carnhill CA-VTB2318
 
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