From: cd@notformail.com   
      
   On Tue, 27 Feb 2024 17:57:32 -0500, ehsjr  wrote:   
      
   >On 2/25/2024 1:01 PM, Cursitor Doom wrote:   
   >> So - in the case of a linear power supply - the rectified output of   
   >> the transformer typically goes straight to a big old storage cap for   
   >> smoothing purposes. My question is: how much ripple should I expect to   
   >> see across that cap if all's working well? I have to say I'm seeing a   
   >> *lot* of ripple on this cap in a Marconi RF signal generator and it's   
   >> finding its way to the RF output, which of course should ideally have   
   >> zero ripple on it. The aforementioned cap tests fine WRT ESR and   
   >> capacitance in-circuit, I should add.   
   >>   
   >> Thanks,   
   >> CD.   
   >   
   >   
   >Prior to the regulator circuit, the ripple voltage   
   >depends upon current drawn for a given supply at a   
   >given frequency. The higher the current drawn, the   
   >greater the ripple for your supply.  So one possibility   
   >in your generator is that too much current is being   
   >drawn i.e. a defect in some circuit "downstream" of   
   >the bridge/cap.   
   >   
   >Depending on what follows the diode/capacitor supply you   
   >may have a regulator failure.  Regulators hold the voltage   
   >at some specific value, thus they remove ripple.  Voltage   
   >measurements usually reveal which regulator is failing to   
   >provide the proper output voltage. Again a defect downstream   
   >may pull the voltage down.  Without a manual/schematic its   
   >harder to diagnose - but it is still possible.  And I read   
   >somewhere that manuals are available. See the url posted   
   >below - it may help.   
   >   
   >Next - perhaps the ripple really isn't excessive.  By that   
   >I mean it may be within spec for your generator. You may   
   >find this site helpful:   
   >https://groups.io/g/Marconi-Test-Instruments   
   >   
   >Good luck. Let us know whe you fix it!   
   >Ed   
      
   Many thanks for that, Ed. :)   
      
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