[hpsdr] Demeter PSU design

[Phil Harman]

Hi Jeroen,

Understood,  I'll see what I can do in the near future to do this test.

>
> One more thing, on one of the boards a LT3080 is used. If I'm correct it
> is used with a gyrator like circuit in series. Is the schematic where it
> is used somewhere online?
>

Yes, it is used with a Miller capacitor multiplier circuit on the Phoenix 
local oscillator. I'll ask Richard, VK6BRO, to upload the latest circuit to 
the Wiki.

73's Phil...VK6APH


----- Original Message ----- 
From: "Jeroen Bastemeijer" <J.Bastemeijer at TUDelft.nl>
To: "Phil Harman" <phil at pharman.org>; "HPSDR" <hpsdr at hpsdr.org>
Sent: Tuesday, July 01, 2008 11:36 PM
Subject: Re: [hpsdr] Demeter PSU design


> Dear Phil, Graham and others,
>
> Thank you for all the E-mails with regard to the Tiny Demeter design! I
> will read them and respond to them in the coming days.
>
> Phil, at this moment I'm very curious about the performance of Mercury!
> I would like to give you the following suggestion for doing more
> "scientific" noise measurements on Mercury. It is possible to do these
> experiments with a simple setup.
>
> What you need:
> * Power supply (which you already have)
> * Signal generator
> * Toroid or transformer with two coils (primary and secondary)
>
> The transformer is the most tricky part: with succes I used a, so
> called, common mode choke. These kind of chokes can usually be found in
> the input-filter of switching power supplies. So, if you have an
> old/defective computer power supply there is probably one in there. The
> common mode choke is basically in series with the mains connection. It
> passes the mains-power but it represents a short for "RF"-common mode
> signals on the power line and vice-versa.
> These chokes have a pretty high power handling capabillity and they have
> two sets of windings (ratio 1:1). The higher the current handling
> capabillity, the better.
>
> For the measuremnts you can put one side, let's call it the primary, in
> series with the power supply line (e.g. the 5 Volt line). The secondary
> winding can be connected to the signal generator. In this way it is
> possible to inject an AC-voltage on the power supply line. The generator
> will be  loaded with the circuit as well, so, when you turn up the
> output level of the generator, a much smaller waveform will be present
> on the power supply (due to the 50 Ohm internal resistance of the
> generator). By adjusting the frequency, amplitude and the waveform you
> could see if there is any influence on the performance of Mercury.
>
> Hope you are willing to do these tests, this will help us enormously in
> determening the finals specs for (Tiny) Demeter.
>
> One more thing, on one of the boards a LT3080 is used. If I'm correct it
> is used with a gyrator like circuit in series. Is the schematic where it
> is used somewhere online?
>
> Thank you, 73 Jeroen PE1RGE
>
> Hope you are willing
>
> Phil Harman schreef:
>>
>>>
>>> Do you have any means to test the sensitivity of the HPSDR and/or
>>> Mercury for noise on the supply lines? Especially for "high frequency"
>>> noise (at the switching frequency (and harmonics) of a swicther) on the
>>> +5 Volt and the -12Volt rail?
>>>
>>
>> Nothing beyond using it to power Mercury and looking at the bandscope
>> - not very scientific I'm afraid!
>>
>> I think the picoPSU will be a good test and we should be able to try
>> that in the next few days.
>>
>> 73's Phil...VK6APH
>>
>>
>>
>
> -- 
> Ing. Jeroen Bastemeijer
>
> Delft University of Technology
> Department of Electrical Engineering
> Electronic Instrumentation Laboratory
> Mekelweg 4, Room 13.090
> 2628 CD Delft
> The Netherlands
>
> Phone: +31.15.27.86542
> Fax: +31.15.27.85755
> E-mail: J.Bastemeijer at TUDelft.nl
> GPS: Lat N52.00002 Lon E4.37157 Alt 46.2m
>


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