Buffer Capacitors in Car Radios

If you have worked on tube type car radios or mobile transmitters that used vibrators, you are aware of the high voltage rating of the buffer capacitor.

What many folks are unaware of is:
It is recommended that anytime the vibrator is replaced, the buffer capacitor also be replaced.
 There is a lot of argument on this but right from the manufacturers data they tell you to do this.
 Why?
Well a bad or marginally bad buffer capacitor can cause the vibrator points to fail.

How do you choose the correct buffer capacitor?

 It works like this- set up an experiment with a car radio and have several different values of buffer capacitors handy.
 Sub each capacitor in and watch the DC current draw of the radio. You will find one value (Typically the original value) results in a reduced draw from the power supply or battery.
 That is the correct value to use, per the manufacturer's guidelines.

Yes, you can substitute values, but at the cost of higher current draw, and likely premature vibrator failure. Vibrators are not "cheap" no matter how you look at it. last I saw point type contact vibrators they started at $35.00 and went up to over $100.00 for certain ones.