The switch mode 5V PS in this computer delivers constant V when
additional USB devices are plugged in because there is a feedback loop
that changes the pulse width of the switch to maintain constant DC
output. Why can't this be done at 3000V?
On Jun 25, 2005, at 1:43 PM, Will Matney wrote:
> Harry,
>
> That much of a voltage drop is ok (3.4 kV to 3 kV), but what were
> mentioning is the chart on their website which shows it having a 1000
> Vdc swing from 0 to 1 ampere. From the knee, it's kind of steep at
> first, then if I remember from 1/2 ampere on or so, the voltage stayed
> around 2800-2500 Vdc from a 3500 Vdc open voltage. I would think that
> one might need to fix that graph if it isn't correct.
>
>
> Best,
>
> Will
>
> ----- Original Message -----
> From: "Harry Brown" <harryhbrown@earthlink.net>
> To: "David Kirkby" <david.kirkby@onetel.net>, "amps@contesting.com"
> <amps@contesting.com>
> Subject: Re: [Amps] HV Switch Mode Power Supplies
> Date: Sat, 25 Jun 2005 07:34:30 -0400
>
>>
>> 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.
>>
>> It uses a switching supply from Watts Unlimited and the total
>> weight of the amp including power supply is 20 pounds.
>>
>> His amp idles at 175 ma. with the plate voltage at 3.4 Kv. At full
>> output, 1.5 KW, the palate current is 3 Kv and the plate current is
>> 850 ma. 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
>> 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
>>>>>>> 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/
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Amps mailing list
>>>>> Amps@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> David Kirkby,
>>> G8WRB
>>>
>>> Please check out http://www.g8wrb.org/
>>> of if you live in Essex http://www.southminster-branch-line.org.uk/
>>>
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>>
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>
>>
>>
>>
>>
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>>
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>
>
> --
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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