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75 to 50 ohm minimum loss pad



 
 
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  #1  
Old February 2nd 05, 12:23 AM
J M Noeding
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Default 75 to 50 ohm minimum loss pad

Hi

can't find the notes for a minimum loss pad, anybody who remember the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment

73
Jan-Martin, LA8AK
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm
  #2  
Old February 2nd 05, 12:44 AM
Tim Wescott
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Default

J M Noeding wrote:

Hi

can't find the notes for a minimum loss pad, anybody who remember the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment

Here. Hot out of the math package. Assuming I know what I'm talking
about it's an L with series 43.3 & shunt 86.6 (theoretical). Should be
6dB of attenuation.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
  #3  
Old February 2nd 05, 12:56 AM
John Popelish
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Default

J M Noeding wrote:

Hi

can't find the notes for a minimum loss pad, anybody who remember the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment

73
Jan-Martin, LA8AK
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm


Series resistor on 75 ohm side is 43.3 ohms. Parallel resistor on 50
ohm side is 86.6 ohms.

--
John Popelish
  #4  
Old February 2nd 05, 01:19 AM
Dave Platt
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Default

can't find the notes for a minimum loss pad, anybody who remember the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment


http://www.maxim-ic.com/appnotes.cfm/appnote_number/972

Their calcs yield a design with R1 (in series with the 75-ohm source)
being 43.3 ohms, and R2 (in shunt with the 50-ohm load) being 86.6
ohms.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
  #5  
Old February 2nd 05, 02:06 AM
J M Noeding
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Posts: n/a
Default

On Wed, 02 Feb 2005 00:19:28 -0000, (Dave Platt)
wrote:

can't find the notes for a minimum loss pad, anybody who remember the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment


http://www.maxim-ic.com/appnotes.cfm/appnote_number/972

Their calcs yield a design with R1 (in series with the 75-ohm source)
being 43.3 ohms, and R2 (in shunt with the 50-ohm load) being 86.6
ohms.


thanks to all, I almost remembered it an hour after asking

73,
Jan-Martin
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm
  #6  
Old February 2nd 05, 05:15 AM
Reg Edwards
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Default

Use program PADMATCH for T, Pi, L and minimum loss pads between any pair of
terminating resistances.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........


  #7  
Old February 2nd 05, 09:16 AM
Ian White, G3SEK
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Default

Tim Wescott wrote:
J M Noeding wrote:

Hi
can't find the notes for a minimum loss pad, anybody who remember
the
values? It should be easy to calculate, but I am not in the mood for
doing so at the moment

Here. Hot out of the math package. Assuming I know what I'm talking
about it's an L with series 43.3 & shunt 86.6 (theoretical). Should be
6dB of attenuation.

Faint bells ring... 43 ohms is a standard value, and 86.6 is pretty
close to 100 paralleled by 680.

For testing 75-ohm TVI filters in a 50-ohm system, it's very handy to
make up a pair of those pads as inter-series adaptors.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
 




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