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Old November 30th 03, 03:04 AM
J M Noeding
 
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Default Building a psu for linear amplifier

Hi

planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

73, Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
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Old November 30th 03, 03:19 AM
John Popelish
 
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J M Noeding wrote:

Hi

planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

73, Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
--
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I think this slide applies to 60 Hz power.
http://hyperphysics.phy-astr.gsu.edu...ic/rectct.html
--
John Popelish
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Old November 30th 03, 03:19 AM
John Popelish
 
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J M Noeding wrote:

Hi

planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

73, Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
--
remove ,xnd to reply (Spam precaution!)


I think this slide applies to 60 Hz power.
http://hyperphysics.phy-astr.gsu.edu...ic/rectct.html
--
John Popelish
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Old November 30th 03, 04:54 AM
Reg Edwards
 
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Default

Ripple voltage across smoothing capacitors can be calculated from the amount
by which they discharge, at the DC load current, during the time of a
half-cycle of the power supply frequency.

For half-wave rectification, ie., a single diode plus capacitor, the
capacitors are charged up once per cycle and the capacitor discharges into
the DC load during the period of a whole AC cycle.

---------------------------


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Old November 30th 03, 04:54 AM
Reg Edwards
 
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Default

Ripple voltage across smoothing capacitors can be calculated from the amount
by which they discharge, at the DC load current, during the time of a
half-cycle of the power supply frequency.

For half-wave rectification, ie., a single diode plus capacitor, the
capacitors are charged up once per cycle and the capacitor discharges into
the DC load during the period of a whole AC cycle.

---------------------------




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Old November 30th 03, 01:03 PM
J M Noeding
 
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Default

On Sun, 30 Nov 2003 02:19:14 GMT, John Popelish
wrote:


planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

73, Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
--
remove ,xnd to reply (Spam precaution!)


I think this slide applies to 60 Hz power.
http://hyperphysics.phy-astr.gsu.edu...ic/rectct.html
--
John Popelish


thanks,
very basic, but it may be a good reply, and as quoted "They can be
modified to 50 Hz by examination of the expressions."

suppose R = U/I for this expression?

Jan-Martin
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Old November 30th 03, 01:03 PM
J M Noeding
 
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On Sun, 30 Nov 2003 02:19:14 GMT, John Popelish
wrote:


planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

73, Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
--
remove ,xnd to reply (Spam precaution!)


I think this slide applies to 60 Hz power.
http://hyperphysics.phy-astr.gsu.edu...ic/rectct.html
--
John Popelish


thanks,
very basic, but it may be a good reply, and as quoted "They can be
modified to 50 Hz by examination of the expressions."

suppose R = U/I for this expression?

Jan-Martin
--
remove ,xnd to reply (Spam precaution!)
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Old November 30th 03, 03:43 PM
Frank Dinger
 
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It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

=====
As a rule of thumb not less than 2000 microFarad per ampere
Hence for a 20 Amperes supply a total of 40KmicroFarad or more.

Frank GM0CSZ / KN6WH


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Old November 30th 03, 03:43 PM
Frank Dinger
 
Posts: n/a
Default

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?

=====
As a rule of thumb not less than 2000 microFarad per ampere
Hence for a 20 Amperes supply a total of 40KmicroFarad or more.

Frank GM0CSZ / KN6WH


  #10   Report Post  
Old November 30th 03, 08:59 PM
Ian White, G3SEK
 
Posts: n/a
Default

J M Noeding wrote:
Hi

planning a power supply for NEC 36284 150W 2m linear amplifier with
2SC3286, see http://home.online.no/~la8ak/images/nec36284c.gif

It is only a simple psu, but using a 24VAC transformer
[http://home.online.no/~la8ak/images/4ua3.gif)

Wonder what size capacitors I should use to keep ripple minimum above
+24V?


Work it out for sure, using Duncan Munro's PSU Designer program. Follow
the link from the 'In Practice' pages:
http://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#psud


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek
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