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Old 16th November 2007, 05:19 PM   #1
zxx123 is offline zxx123  United States
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Default Hail to Vintage Power Transformer & Choke?

Everybody seems to give glory to vintage output transformers.
How about Vintage Power Transformer & Choke?
Are they worth to have such hail?
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Old 16th November 2007, 05:43 PM   #2
kevinkr is offline kevinkr  United States
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Not really, and if rusty your find may run a lot hotter than it should due to increased core losses. They are usually a lot noisier in the magnetic domain which may be a problem if other magnetics are nearby.

Use them if you can get them at reasonable prices, but do not pay more for these than comparable new production..

Hermetically sealed and potted transformers are the exception. I always use these when suitable and I can my hands on one at a fair price.

Another issue with vintage power transformers is that the primaries are usually wound for 110V, 115V, or 117V. Nominal line voltage is now 120V and is usually significantly higher than this except during peak hours. (Mine is 123 - 125V even during peak and I live in a big city. My previous home in a rural community was as high as 132V off peak - finally got the power company to change the taps after many heated discussions with the plant engineer. )
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Old 16th November 2007, 06:21 PM   #3
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Default Re: Hail to Vintage Power Transformer & Choke?

Quote:
Originally posted by zxx123
Everybody seems to give glory to vintage output transformers.
How about Vintage Power Transformer & Choke?
Are they worth to have such hail?
Maybe. If they're not poofed or show other signs of abuse, and you can get 'em cheap, then they may be useful. However, like kevinkr said, watch out for higher than expected voltages (a problem I actually had when using a "vintage" power xfmr). Also, if you're going to use these with a solid state power supply, it's important to keep the first filter capacitor small, certainly not over 47uF at the most. Even though the silicon diodes can source much bigger surge currents, the secondary of the xfmr may not handle that so gracefully ( ). These vintage xfmrs weren't designed with big surge currents in mind.
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Old 16th November 2007, 06:46 PM   #4
zxx123 is offline zxx123  United States
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Default thanks....

thank you!

@how about choke?
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Old 16th November 2007, 09:03 PM   #5
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I think zxx123 may be taking about for old NOS WE output transformers going for $600 each on ebay. I have seen some old junk go for huge money on ebay, i always figured it was collectors.

Edit: A choke is a choke, all a better (Ni lam) choke will do is be smaller and lighter.
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Old 16th November 2007, 10:13 PM   #6
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Quote:
Originally posted by ak_47_boy
I think zxx123 may be taking about for old NOS WE output transformers going for $600 each on ebay.
That's just plain nuckin' futz. You can get new Lundahl's for less than that. Click the image to open in full size.
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Old 17th November 2007, 01:35 AM   #7
w5jag is offline w5jag  United States
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I like old power transformers for several reasons. I go to a lot of hamfests and I can get them for a few bucks, often never used. The older transformers can have multiple high voltage secondaries, making them more versatile to me. Most are the drop in or through chassis mount, and, while that does not seem popular nowadays, I prefer it - it makes a lower profile project, sinks heat better, and seems to be more structurally rigid after installation.

The downside is that they often need to be cleaned up and painted, and they are invariably made for lower line voltages than we see today. If this is a problem, they can be bucked back down. I don't bother with that and just accept that the filament voltage may be a bit high. In practice, I haven't found it a problem. Yet. One thing I don't like is that the older trannies usually have a solid core filament secondary that can be difficult to solder to.

The only new transformers I've used seem small for their current ratings and run really hot . I don't like that.

I have old audio output transformers, but haven't used them. I use new transformers for output.

Win W5JAG
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Old 17th November 2007, 05:10 AM   #8
zxx123 is offline zxx123  United States
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Quote:
Originally posted by ak_47_boy
I think zxx123 may be taking about for old NOS WE output transformers going for $600 each on ebay. I have seen some old junk go for huge money on ebay, i always figured it was collectors.

Edit: A choke is a choke, all a better (Ni lam) choke will do is be smaller and lighter.
Man, I am not a big fan of $XXX NOS things. Thanks for advice about choke anyway. Ya, choke is choke.

However, in terms of impedence, modern power transformer may have benefit with new material and technology, I guess.
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Old 17th November 2007, 01:20 PM   #9
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Hi zxx123

In 'Valve Amplifiers' (third edition) Morgan Jones describes some 'bad' experience with vintage iron: chokes that lost inductance (or at least had less than specified), raatling, etc. Therefore he recommends to use new stuff!

Erik
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Old 17th November 2007, 01:31 PM   #10
SY is offline SY  United States
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Quote:
Originally posted by Miles Prower


That's just plain nuckin' futz. You can get new Lundahl's for less than that. Click the image to open in full size.

More than that, new transformers well outperform the vintage stuff. Materials and processes in manufacturing have made one or two advances since 1950, computer design techniques are quite sophisticated and have greatly refined the folk wisdom, and there are still lots of specialty houses that take real care in using these advances to make excellent products.
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