OEP A262A2E

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ruffrecords

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Nov 10, 2006
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The OEP A262A2E is a small 150:600 ohm input transformer with split winding so it can be wired 600:2400 if you wish. I have not paid this transformer any attention until I saw it used as an OUTPUT transformer wired 2400:600 in a 500 series all tube mic pre  by gemini86 (Rodney) here:

https://groupdiy.com/index.php?topic=51020.msg647656#msg647656

The A262A2E is specified to 100mW at 300Hz which is +20dBm - quite respectable, but only 1mW at 30Hz which is 0dBm - not so good. So I thought it was worth buying one an putting it through its paces. It arrived yesterday. All I have tine to do was measure the inductance at 100Hz with the windings in series (2400;600). Primary was about 10H and the secondary was about 2.5H. Perhaps not as high as they should b but, if the core is all iron, the inductance will rise at lower frequencies to the LF response might be OK. Tonight I will have a go at measuring its frequency response at 0dBu. Then I will move on to distortion.

Cheers

ian
 

ruffrecords

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Location
Norfolk - UK
I made some further tests tonight.

1. Frequency response at 0dBu and +18dBu in is pretty flat from 20Hz to 40KHz when output is unloaded.

2. With 600 ohm load the response at bothe levels is -1.25dB at 20Hz and -1.25dB at 20KHz

3. IKHz 3H distortion at 0dBu in was 0.0057%. with output unloaded. At +18dBu in it was 0.17%

4. At 0dBu input, distortion was measured from 100Hz down to 10Hz. At 100Hz it was 0.051%, at 40Hz it was 0.11%, at 20Hz it was 0.23% and at 10Hz it was 0.8%

I then tries to measure the low frequency distortion with an input level of +18dBu (+12dBu output). However it rose to 2.14% at 40Hz and to 14.6% at 32Hz. Clearly it was not going to reach down to 20Hz at this level. Instead I increased the 20Hz level in 1dB steps from 0dBu. At +9dBu input (+3dBu output) it reached 1.09%. It reached 2,76% at +11dBu input (+5dBu output).

Conclusion, low frequency distortion performance makes it unsuitable as an output transformer at levels significantly above 0dBu output.

A pity because it is a nice small low cost transformer.

Cheers

Ian
 

Whoops

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May 9, 2008
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5,438
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Portugal
Thank you so much Ian

Some people seem to like this transformer for it's more lo-fi/distortion characteristics.

It's inexpensive so you get what you pay for here
 

vinyvamos

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Jul 15, 2014
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78
Location
East Iceland
I have been meaning to buy a few from this OEP range as I am curious. Thanks for the test data Ian. I must say their datasheets are well detailed which is great. It bugs me when distortion and inductance measurements are not published
 

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