[Amps] Transformer choice

[Carl]

You sure did mention "continuous" twice and you also asked for feedback.

Transformers should always be specified at CCS when ordering as reputable 
manufacturers do not work with  ICAS, IVS, or other ham versions of ratings. 
What it is capable of in ham use is up to the individual.

I dont see either one of those quotes being capable of 2.5-3% regulation at 
twice CCS with any sane value of filter C

Carl
KM1H



----- Original Message ----- 
From: "Ulf (SM0NOR)" <ulf at sm0nor.com>
To: "Carl" <km1h at jeremy.mv.com>
Cc: "Jim Garland" <4cx250b at miamioh.edu>; <amps at contesting.com>
Sent: Monday, March 04, 2013 5:13 PM
Subject: Re: [Amps] Transformer choice


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..

Sent from a wireless device of an unrevealed brand.

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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