[Amps] Transformer choice

[Ulf (SM0NOR)]

I actually think the quote was for class 105, which is 40 ambient+55 rise+10 hot spot.


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On 4 mar 2013, at 21:57, "Carl" <km1h at jeremy.mv.com> wrote:

> 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 at sm0nor.com>
> To: <amps at 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 at sm0nor.com
> 
> 
> 
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