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Old 21st September 2011, 12:10 AM   #1211
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Has anyone used the UTC HA133 transformers in their 26 design? After reading the 121+ pages of this thread in a number of settings I cannot recall if there was someone using it or not. I am looking right now at Kevin Kennedys 26 tube schematic and wondering which taps he used. I know its hard to come up with two HA133's so I am looking toward having something made or substitute something else. I'd welcome any ideas.
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Old 22nd September 2011, 10:47 AM   #1212
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Thanks people I appreciate your willingness to just jump right in there with some input.
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Old 23rd September 2011, 07:44 AM   #1213
regal is offline regal  United States
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Quote:
Originally Posted by 6BG6GA View Post
Thanks people I appreciate your willingness to just jump right in there with some input.
My input would be that the UTC transformer is so hard to come by and expensive why risk it when there are guy's like Bud who can build a transformer that you know the specs of. With the #26 you want to be very careful with the primary you chose due to the high Rp.

Now if you have a pair of UTC-HA133's the spec is:

Primary: 15 kohm 8MA DC

Secondary: 500, 333, 200, 125, or 50 ohm

Max level: +22 dbm

30 – 40 kHz (listed as kc) +/- 1db


But they don't tell you the primary inductance, would be worth a try. But no way I would spend $800 obtaining a pair, you probably would want to parafeed the #26 anyway and these are single feed.
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Old 23rd September 2011, 07:52 AM   #1214
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Hi!

As I mentioned already in this thread: The Lundahl LL1660 works nicely with the 26 in 4.5:1. You can use the PP version which can handle 5mA DC. If you want to be more flexible and also want to experiment with other tubes as well, the 10mA version works too.

If you need other step down ratios, the LL1680 is also an alternative.

Best regards

Thomas
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Old 23rd September 2011, 08:03 AM   #1215
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Hi!

Another alternative which I tried: Tango NP8, but it is not manufactured any more. It was good, but I preferred the LL1660. I'm sure from the current line of ISO Tango there are alternatives available as well. Hashimoto also has a transformer which is suitable. I haven't tried the mentioned UTC, but as the previous poster wrote: depends on the rpimary inductance.

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Old 24th September 2011, 10:54 AM   #1216
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Looks like I will scrap the plate to line transformer on the 26 I wanted to build.
Thanks for your input.
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Old 24th September 2011, 12:21 PM   #1217
mogliaa is online now mogliaa  United Kingdom
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Slowly coming to life. This morning managed to complete the valve board and fitted it in the modular chassis. The board has the two sockets for the 4-pin valve of choice (first one to try will be 26). Also have added the filament bias resistors...
Now will go for the OT board for the LL1660s....

All thanks to Andy Evans who kindly helped me out with some of the parts...
cheers,
Ale
Attached Images
File Type: jpg 26 preamp 2.jpg (57.9 KB, 568 views)
File Type: jpg 26 preamp 1.jpg (57.6 KB, 565 views)
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Old 24th September 2011, 02:54 PM   #1218
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Hi Ale,

looks great! Those black resistors ( I assume filament bias ) Look cool the way they are mounted!

Best regards

Thomas
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Old 24th September 2011, 06:26 PM   #1219
mogliaa is online now mogliaa  United Kingdom
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Quote:
Originally Posted by Vinylsavor View Post
Hi Ale,

looks great! Those black resistors ( I assume filament bias ) Look cool the way they are mounted!

Best regards

Thomas
Hi Thomas,
Thanks! Indeed, those are the filament bias resistors that Andy gave to me. This afternoon managed to complete the second top plate in which I mounted the LL1660 you sold me. See attached.
Just did a simple test with my bench power supply and managed to get Av=3.5 at Va=162V, Vsupply=170V. Ia=5.6mA and Vg=-10.5V

Looking really good. Now need to crack on with the remaining bits and start with the power supply. That will take me some real time...

Thanks
Ale
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File Type: jpg 26 preamp 3.jpg (52.4 KB, 534 views)
File Type: jpg 26 preamp 4.jpg (53.2 KB, 528 views)
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Old 25th September 2011, 12:13 AM   #1220
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by 6BG6GA View Post
Has anyone used the UTC HA133 transformers in their 26 design? After reading the 121+ pages of this thread in a number of settings I cannot recall if there was someone using it or not. I am looking right now at Kevin Kennedys 26 tube schematic and wondering which taps he used. I know its hard to come up with two HA133's so I am looking toward having something made or substitute something else. I'd welcome any ideas.

Just saw your post.. The information you need is here: UTC Data

I wired the primaries in series and configured the output taps for 600 ohms.

Jack Elliano can probably make you suitable plate to line transformers, other candidates would be the Hashimoto 20K part. Look at the Lundahl line as well.. 5:1 ratio is near ideal IMHO.. AE, Trafomatic, or Bartolucci could probably make something nice at a price..

I'm still using the much revised original line stage and getting ready to build the latest version..
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