Anyone Recognise this transformer? Yet Another One - Sorry!

Hi guys,

I have a couple of these:



Does anyone recognise it? It says AF Transformer Type 210 on it.

I know that resistance values are almost useless, but the primary has a 25 Ohm resistance and the secondary has a 2.2 KOhm resistance.

I assume this is probably a big step up transformer then? Any potential uses?

Any help is greatly appreciated.

Roddy

[quote author="rodabod"]I know that resistance values are almost useless[/quote]
Hold on there, Bald Eagle...

As a starting rule of thumb in the past, I've started from the 'guesstimate' that DC resistance often is in the order of 10% of the AF impedance for many transformers. That would indicate a 250Ω - 22kΩ transformer, probably about an 8:1 voltage ratio tranny (the rule of thumb would suggest closer to a 9:1 ratio, but common sense suggests that 8 is a more common number than 9) so let's guess at an 8:1 step-up mic input transformer.

With that in mind, I'd say it's utterly useless.

I insist that you box all the examples that you have up and send them to myself or CJ, who will dispose of them properly, by the time-honoured ritual of throwing them in a box with a power supply, a follower circuit, then putting the box on eBay and using the words "Vintage Mic Pre, not Neve/API/SSL/Avalon" in the listing title.

Rest assured, your transformers will be properly recycled with us.

Keef

To get the turns ratio you can stuff a sine wave into one side & measure it on the other side. The impedance ration is simply the square of the turns ratio.

I think I`ve got a few similar looking transformers somewhere.

Yes, mines got type AF5201 cat no. P373 d7668. ratio 1:10 primary 600ohms

[quote author="Rob Flinn"]To get the turns ratio you can stuff a sine wave into one side & measure it on the other side. The impedance ration is simply the square of the turns ratio.

I think I`ve got a few similar looking transformers somewhere.

Yes, mines got type AF5201 cat no. P373 d7668. ratio 1:10 primary 600ohms[/quote]

Cheers Rob, that's really handy. I assume you hav eprobably not used yours - I wonder if they are any good? Thanks for advise on calculatig ratios - I'm too cheap to buy a sig. gen. but I may look into using my soundcard.

[quote author="SSLtech"]
I insist that you box all the examples that you have up and send them to myself or CJ, who will dispose of them properly, by the time-honoured ritual of throwing them in a box with a power supply, a follower circuit, then putting the box on eBay and using the words "Vintage Mic Pre, not Neve/API/SSL/Avalon" in the listing title.
[/quote]

Hahaha.... Still, its not as bad as buying some vintage knobs and putting them on an empty rack case - sold as seen.

It really is unbelievable how much crap you get on Ebay. Has anyone seen the "Roberts Radio With Mic Pre" - a modded Roberts radio. Bet that sounds good!