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dsavitsk 23rd October 2005 08:22 PM

Difference between Hammond 200 and 300 series
Can anyone comment on the difference between the Hammond 200 and 300 series transformers? I am choosing between them, and they have the exact same specs (same voltage and same current ratings). I will be running them at close to the rated values, and am wondering if moving up to the 300 is worth it. Handmade indicates that the 300 is shielded better and runs cooler. These transformers are to be inside a chassis, so I am not sure how much of a concern that might be. Any thoughts?

Tubelab_com 23rd October 2005 08:55 PM

The 200 series transformers have 115 volt 60Hz primaries, for use on North American current only.

The 300 series have dual tapped primaries and can be used on most power line voltages in the world. Since they are rated for 50Hz use they may run slightly cooler on 60 Hz than the same 200 series part.

I have always used the 200 series parts since they are cheaper, and I am in the USA.

Joel 24th October 2005 01:21 PM

The 300 series definitely throws less of a stray field. I've confirmed this experimentally. If you need to place the tubes close to the transformer, due to a cramped chassis for instance, then a 300 series is a better choice.
They also physically buzz less, so there is less chance of inducing microphonics in certain applications.
It's also been my experience that they run cooler, in general.

So, if price is not an issue, I can't think of a reason to pick a 200 series unit over the 300.


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