[Boatanchors] Reforming caps

[Jim Wilhite]

I purchased a NC 183D some years back that had the original 
multi-section cap in it.  I decided that it be best to do as you 
have and reform the caps before turning it on.  I have a Sprague 
TO-6 and disconnected the leads to the cap then attached the cap 
checker.  The caps formed quite nicely so I re-attached the wires 
and used it.

About a year later I decided (for reasons unknown) to check the cap 
again.  That time it was very leaky.  The electrolyte in old caps 
were already partially dry when I got the receiver and with the heat 
of operation they dried more.  So it would be good to check them 
after you operate the rig for a while.  It may not take long for 
them to become leaky again.

Jim/W5JO


----- Original Message ----- 
From: "Barrie Smith" <barrie at centric.net>



> I'd like to thank everyone that answered my question regarding 
> reforming caps.
>
> I finally got four done with my terrible old lashup.  All drew 
> less than 40 microamps at close to full rated voltage, so I's say 
> they are still good.
>
> This contraption that I built for the purpose, probably twenty 
> years ago, certainly needs some re-engineering!
>
> For starters, the voltage is read on the output side of the 
> current-limiting resistor, which must be a very high value, 
> ohms-wise, because the voltage at the cap rises very, very slowly. 
> At one point last evening I came back to see 450 volts on a 400 
> volt cap.
>
> I'll install a switch so that I can set the voltage on the input 
> side of the current-limiting resistor first.  Then I can set the 
> switch to monitor the actual voltage on the cap.
>
> Anothe real problem is that when I'm finished with a cap it's 
> fully-charged. The only way it's going to discharge is back 
> through the high-value current-limiting resistor, which takes 2 
> hours to go from 400 volts to 175 volts.
>
> I need yet another switch so that when I'm finished, and the 
> tester power supply is shut off, I can switch a 5000 ohm resistor 
> into the circuit to act as a more rapid bleeder.
>
> Again, thanks!
>
> 73, Barrie, W7ALW