[Amps] Transformer choice

[Jim Garland]

Hi Ulf,
To me the choice depends on how much you trust Company B. If Company B can be trusted to meet their quoted specifications (2000VA with 2.5% voltage drop at full load), then I'd go with them. As you note, 11 kilo is as big or bigger than the transformers in many ham-rated commercial amps of the same power rating.  If you're planning on heavy contest use, or RTTY service, then Company A is probably the better choice, but for routine ham operation I'd think Company B makes mores sense, considering the large price differential. An interesting choice.
73,
Jim W8ZR


> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Ulf (SM0NOR)
> Sent: Monday, March 04, 2013 4:29 AM
> To: amps at contesting.com
> 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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