[Amps] Transformer choice

[Ulf (SM0NOR)]

No one mentioned CCS here, Carl. I was into "ham specs" already from the beginning. This particular project calls for a certain level of mobility. Compromise is fine..

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

> I would not consider 11 kg to be close to a 2kVA CCS transformer. The AL-1200/1500/82 Dahl is 15 kg and that is ICAS (2570V/800ma) and a C Core yet it still has to be derated for RTTY, etc.
> 
> A stock SB-220 transformer is close to 11 kg and its rated at 600VA.
> 
> Also remember those ratings are DC input power, not RF out. Add 15-20% to the weight for E-I construction.
> 
> Carl
> KM1H
> 
> 
> 
> 
> 
> ----- Original Message ----- From: "Jim Garland" <4cx250b at miamioh.edu>
> To: "'Ulf (SM0NOR)'" <ulf at sm0nor.com>; <amps at contesting.com>
> Sent: Monday, March 04, 2013 7:55 AM
> Subject: Re: [Amps] Transformer choice
> 
> 
>> 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
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>> 
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