[HAM] Recapping

[David Anderson]

Hi Mike,

I might be able to help you with some real-world experimenting I've 
done.

What I found, on a CV-era generator was that the filters on tones 55-91 
peaked anywhere from 92 to 116 nanofarads (.092 - .116uF). Using a 
decade capacitor, I could adjust the value in 1nF steps. You could also 
move the decade capacitor about a 5nF range without getting a 
measurable change in output using a standard digital multimeter. In 
other words, you might peak a tone at 4.7 millivolts at 103nF, but it 
would read 4.7mV from 101 to 105nF.

This is just speculation, but based on those findings, perhaps Hammond 
sorted the caps into 4 bins, say: 95-100nF, 101-105nF, 106-110nF, and 
111-115nF. Perhaps they peaked the filter with their own decade 
capacitor setup and then grabbed a cap from the bin with a close-enough 
value.

I also have another generator I recapped years ago with a set of caps 
all at one value. (Its caps had melted to blobs of goo.) I found that 
peaking the filters with my decade capacitor gave a smoother output 
curve than using caps all of one value.

It's certainly heartening to hear that someone like Alan Young was so 
generous about sharing his experience. It's an excellent example of 
graciousness and magnanimity that should speak to all of us.

David Anderson

On Sunday, December 3, 2006, at 08:11  AM, mike p wrote:

> Mike,  I am hoping you'll write a little more on a very simple question
> here.    I know what youre saying about the caps having a stamped 
> nominal
> and of course variations in actual measurments.   --  But when you 
> find that
> your  .105 caps read in the .300's  and your  .255 caps read in the 
> .600's
> to .800's   wouldn't replacment with today's caps get you back 90% of 
> the
> way  ???      Some people would be happy to get their poor sounding 
> hammond
> back on track even if it isn't as precise as it could be .
>
> You stated that you never said there were 4 bins of caps at the 
> factory ,  I
> never said you did... But I did ask the question ( which never got
> answered )  What was the range of the caps to choose from at the 
> factory
> ....  for .105 nom caps,  were their bins of  .103 .104. 105 .106  
> etc.   or
> were they .105 .110.  120. 170 ?   What do you think their values 
> ranged
> from ...  ?   Thats all I wanna know,  gotta admit I hit the delete 
> button
> alot on this subject during the past 8 years .  Mike P