RE: What if.......

Posted by Stuben (A) on December 30, 2014 at 12:16:16

In Reply to: RE: What if....... posted by vinnie2 on December 30, 2014 at 06:21:22:

Vinnie,

For the CF implementation, instead of going to ground after your output tube bias resister, connect it to the top of the secondary winding of you OPT and make sure the OPT secondary is grounded.

Obviously, if you triode strap, no need...unless later you want more power and you're curious :> )

I have never found a site that totally explains IT implementation. Maybe some of more senior members know of a site.

If you want to use an IT, you have to be aware of the Rp of the driver as you implement. You want your IT primary impedance to be at least 4x your Rp.

primary impedance (R) = 2 x pi x L x F

http://www.lundahl.se/pdfs/datash/1692A.pdf - I used this IT for my SE builds. You can go 125 Henries and 35 Henries on the primaries
You can also gap these for more current. I had mine gapped for 25 mA.

The original Sakuma design triode strapped the driver EL84 to get the lowest Rp of 1525 ohm which is the only practical way to drive the primaries of an IT with an EL84. We can assume that you want to go down to 30 hz...

A 1:1 ratio IT is the best place to start. If you step for more gain the Rp of your driver will need to go lower because of the reflected impedance into the secondaries. Because you are running at 1520 ohms you probably have some wiggle room.

What I have found using Lundahl ITs...wire all of your primaries in series to get as much inductance out of your primaries as you can. Run your current as high as your gap permits. Stick with 1:1 until you get used to using these puppies.

Stuben

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Follow Ups Full Thread

Topic - What if....... - vinnie2 17:54:55 12/29/14 (28)

RE: What if....... - D Mike 04:43:26 12/31/14 (3)

RE: What if....... - vinnie2 05:33:24 12/31/14 (0)

RE: What if....... - D Mike 04:46:47 12/31/14 (1)

RE: What if....... - vinnie2 05:35:36 12/31/14 (0)

RE: What if....... - TomWh 18:49:24 12/30/14 (1)

RE: What if....... - vinnie2 04:22:04 12/31/14 (0)

There is this - Chip647 08:28:59 12/30/14 (2)

RE: There is this - vinnie2 10:14:14 12/30/14 (1)

RE: There is this - Chip647 05:23:18 12/31/14 (0)

RE: What if....... - Stuben 06:12:08 12/30/14 (8)

RE: What if....... - vinnie2 06:21:22 12/30/14 (7)

RE: What if....... - Stuben 12/30/1412:16:16 12/30/14 (6)

RE: What if....... - vinnie2 13:57:16 12/30/14 (5)

RE: What if....... - Stuben 07:57:35 12/31/14 (4)

RE: What if....... - vinnie2 10:18:40 12/31/14 (2)

RE: What if....... - Stuben 12:21:49 12/31/14 (1)

RE: What if....... - vinnie2 14:28:27 12/31/14 (0)

RE: What if....... - Stuben 08:02:29 12/31/14 (0)

RE: What if....... - Chip647 05:22:49 12/30/14 (9)

RE: What if....... - vinnie2 06:16:32 12/30/14 (8)

RE: What if....... - Chip647 07:53:56 12/30/14 (1)

RE: What if....... - vinnie2 10:04:01 12/30/14 (0)

RE: What if....... - rage 07:12:09 12/30/14 (3)

RE: What if....... - vinnie2 05:36:57 12/31/14 (0)

RE: What if....... - Chip647 08:20:19 12/30/14 (1)

RE: What if....... - rage 12:43:11 12/30/14 (0)

RE: What if....... - Garg0yle 06:28:24 12/30/14 (1)

RE: What if....... - vinnie2 10:05:34 12/30/14 (0)

Follow Ups

RE: What if....... - Stuben 12/30/1412:16:16 12/30/14 (6)

RE: What if....... - vinnie2 13:57:16 12/30/14 (5)

RE: What if....... - Stuben 07:57:35 12/31/14 (4)

RE: What if....... - vinnie2 10:18:40 12/31/14 (2)

RE: What if....... - Stuben 12:21:49 12/31/14 (1)

RE: What if....... - vinnie2 14:28:27 12/31/14 (0)

RE: What if....... - Stuben 08:02:29 12/31/14 (0)

RE: What if.......

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