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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: RE: Ah yes - a toroid interstage! posted by andy evans on June 25, 2010 at 06:54:48:
Andy, the 1660 will work fine. The S type has faraday shields 'to improve symmetry at HF' so there is a physical difference between them. The 0.9T is explained to some extent at the top of the data sheet. Its the flux density WRT the amount of DC through the core. That 20mA figure for the xfmr you have is for just one configuration. Have a look at the sheet, take the 10mA type on the sheet, check out AltV, gapped for 18mA. So in that config your 20mA is designed to operate with ~36mADC. If the type 46 is like type 45, that would set up well at 36mA - mu of 3.5 and Rp ~1700, similar in spec to 71A at that point, but with slightly higher gain and at -56V bias you'll be able to swing more volts.
The config. I was meaning is 1:1CT, so 2:1+1, or 4.5:2+2 as they would have it. Primary current WRT to 0.9T and their 20mA figure in this config. is more like 18mA.. if the core saturates at 1.6T.. it'll work fine. For some reason that config isnt on the data sheet - maybe shoot LL an email and ask about it, it can be done. 71A 20mA, Rp 1k8 into 2:1, you're driving the output tube with ~500 ohms. At -40V bias and with mu=3 and into 2:1 you'll get less gain but better drive from the stage, and you can DC heat the thing and filament bias it, 45V supply at 250mA.
What works best is most likely going to depend on your gain structure. But, you have the transformer, its right for both these types, you could do worse that to try it out.
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Follow Ups
- RE: Ah yes - a toroid interstage! - shane. 06/25/1017:15:22 06/25/10 (0)
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