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Re: [Amps] Transformer choice

To: "Ulf \(SM0NOR\)" <ulf@sm0nor.com>, <amps@contesting.com>
Subject: Re: [Amps] Transformer choice
From: "Carl" <km1h@jeremy.mv.com>
Date: Mon, 4 Mar 2013 15:57:41 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
A 105C rise is not what I consider a good transformer, ask what the magnetizing current is.

Carl
KM1H


----- Original Message ----- From: "Ulf (SM0NOR)" <ulf@sm0nor.com>
To: <amps@contesting.com>
Sent: Monday, March 04, 2013 6:28 AM
Subject: [Amps] Transformer choice


Hi Guys,
I'm looking for some feedback on two transformer offers I have. I'm intending to build a table top amp, so I'm accepting some compromises regarding the transformer. I have made inquiries to a couple of winders and I have boiled them down to 2 offers. I was asking for 2000 Volts @1A =2000VA (+ G1 and G2 windings). I'm targeting to get 2200-2400 watts output in PEP service and about 1K in continuos service.

Both companies claim 2000VA but at different core weights

Company A:
17 Kilo toroid, D=200 mm, H=110. About 3% voltage drop at full load. Max temp rise = 105C over 40C ambient. DC resistance, about 25 ohms.
Price: €480

Company B:
11 kilo toroid, D=180 mm, H=85mm. About 2,5% voltage drop at full load. Can't, or don't want to specify other data.
Price: €195

So what are your reflections? The A is obviously a the better choice. They are serious and they offer detailed specs, exact delivery times etc. But all comes at a premium price. Company B is smaller and they obviously compromises with their specifications, but the price is a lot lower and so is the weight.

Now, I don't expect the cheaper and smaller core to do wonders. The bigger one will for sure be more rugged and closer to "true 2000VA", especially if I run it in true continuous mode. I'm inclined to go for the the bigger one, because I want the best. But OTOH, I don't want to waste money because of a "feeling". Perhaps the smaller one will be enough given the table-top size/PEP service I'm targeting? After all, it matches what's inside most commercial amps in this category.

I'm happy for any feedback...



73's

Ulf (SM0NOR)
ulf@sm0nor.com



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