Harry Brown wrote:
> Here's some more info on a "real" application of the Watts Unlimited
> power supply.
>
> At the VHF Dinner at Dayton this year, K5AND gave a talk on a 6 Meter
> amp he designed using an 8877 for DXpedition purposes.
>
Did he make measurements of IMD?
> It uses a switching supply from Watts Unlimited and the total weight of
> the amp including power supply is 20 pounds.
I'm surprised the amp did not weigh more than that, but anyway, that is
not the main issue.
> His amp idles at 175 ma. with the plate voltage at 3.4 Kv.
The graph of regulation (which does not state if this is typical, or
guaranteed), says it would be about 3.3 kV, so not much difference there.
> At full
> output, 1.5 KW, the palate current is 3 Kv and the plate current is 850
> ma.
Well the graph at
http://wattsunlimited.com/_wsn/page3.html
says it will be about 2.6kV at that current.
But the graph looks odd anyway. They show ouput power linearly
increasing with output current, whereas voltage drops dramatically with
increasing current, especially between 100 and 400mA, where it changes
from about 3600 to 2800V
I'd personally not buy something like that without seeing some
guaranteed specifications - including load reguation and noise.
The specs are
http://wattsunlimited.com/_wsn/page2.html
are poor, both in the way presented and their values.
So the voltage swing is not all that terrible when compared to
> conventional power supplies. When the amp is not on, the power supply is
> keyed off.
>
> 73, Harry, W3IIT
I can't help feeling that is poorly designed. As I said earlier,
designing that sort of thing is not trivual, but to me at least that is
poorly designed.
> I
> At 01:16 AM 6/25/2005 +0100, David Kirkby wrote:
>
>> Will Matney wrote:
>> > David,
>> >
>> > You are correct on the regulation. A regular transformer type power
>> supply when designed right will have a regulation somewherre around
>> 11-14%. In the case of the switching supply, it looks like 30-35%.
>> 1000 kV drop over 1 amp is a good bit of sag.
>> >
>> > Best,
>> >
>> > Will
>>
>> I would have thought that cause serious non-linearity problems on SSB.
>>
>>
>> Having gone to a switch mode design, I would have thought they used some
>> feedback to keep the voltage constant. But it seems not. Given the line
>> voltage will probably sag too at 2.5kV, you can rekon on over a kV drop
>> in practice.
>>
>> I assume you mean 1kV sag, or 1000V, and not 1000kV !! Reminds me of a
>> lecturer I know who got fed up with the cleaners moving his equipment
>> that worked from 12V. So he decided to put a sign on it
>>
>> "Danger, 1200000 uV"
>>
>> Apparently nobody touched it any more.
>>
>> >
>> > ----- Original Message -----
>> > From: "David Kirkby" <david.kirkby@onetel.net>
>> > To: "amps@contesting.com" <amps@contesting.com>
>> > Subject: Re: [Amps] HV Switch Mode Power Supplies
>> > Date: Fri, 24 Jun 2005 00:39:13 +0100
>> >
>> >
>> >>Steve Thompson wrote:
>> >>
>> >>>Winfried Kriegl wrote:
>> >>>
>> >>>
>> >>>>http://www.wattsunlimited.com <http://www.wattsunlimited.com/>
>> >>>>have a 2500W SMPS. Works fine.
>> >>>
>> >>>Looks very nice.
>> >>
>> >>But look at the regulation (or lack of).
>> >>
>> >>http://wattsunlimited.com/_wsn/page3.html
>> >>
>> >>
>> >>--
>> >>David Kirkby,
>> >>G8WRB
>> >>
>> >>Please check out http://www.g8wrb.org/
>> >>of if you live in Essex http://www.southminster-branch-line.org.uk/
>> >>
>> >>
>> >>_______________________________________________
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>> >
>> >
>>
>>
>> --
>> David Kirkby,
>> G8WRB
>>
>> Please check out http://www.g8wrb.org/
>> of if you live in Essex http://www.southminster-branch-line.org.uk/
>>
>>
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--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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