[Collins] Re: Orange drops vs the competition

[Bill Abate]

  Dave,

Now test the cap with the megger and see what you get.

73,

Bill

David Knepper wrote:
> Dr. Jerry and all
> 
> I did the test of applying 300 volts to the one end of a "black beauty"
> capacitor that had been removed from my 75A-4 and then measure the voltage
> from the other side.  Guess what they are failed, that is, the leakage was
> over 50 volts.
> 
> I concur with Dr. Jerry that these caps. need to be removed as a matter of
> good preventative maintenance.
> 
> Thank you
> 
> 
> David, W3ST
> Publisher of the Collins Journal
> Secretary to the Collins Radio Association
> To Join the CRA go to www.collinsra.com
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> 
> ----- Original Message -----
> From: "Gerald" <geraldj at ispwest.com>
> To: "David Knepper" <cra at floodcity.net>
> Sent: Tuesday, July 12, 2005 12:31 PM
> Subject: Re: Orange drops vs the competition
> 
> 
> 
>>I specify Vishay Sprague Orange Drops by name (and part number when
>>necessary) because:
>>
>>1. they are American made, I think.
>>
>>2. They are well made.
>>
>>3. They have extended foil for lower inductance than ordinary foil/film
>>capacitors that have only occasional tabs out of the roll for
>>connections.
>>
>>4. I've abused them severely and they come away still not leaking. Back
>>when they were so new they were giving them away as samples, I had one
>>in my pants pocket. It didn't get removed when the pants got washed in
>>mom's Maytag square tub washer, then run through the ringers, rinsed and
>>wrung again, then dried in a high speed electric dryer. It also didn't
>>take on water or get electrically leaky. That's unscientific, but a
>>great deal of concentrated abuse.
>>
>>5. Some of the imported poly capacitors have come with very thin films
>>and leads as thin so they failed from leads breaking off flush with the
>>dipped coating.
>>
>>6. There's no problem fitting Orange Drops in place of Black Beauties
>>because the Orange Drops are smaller. I suppose for appearance, one
>>could wish there was something in an axial lead capacitor with a molded
>>black case (and there was a line of Black Beauties sold for replacements
>>in the 60s that did have a combination of paper and polyester for
>>insulation that don't show the leakage of the all paper/oil molded Black
>>Beauties, but they never seemed to make it to manufacturer's production
>>lines, just as service parts). But one only has to install Orange Drops
>>once. The radio will never need paper capacitors again.
>>
>>7. As for testing, I quit testing after the first couple radios where
>>95% of the capacitors tested leaky. When a screen bypass capacitor drops
>>the screen voltage just 10%, its reduced the plate current and the stage
>>gain by 10%. And in time that extra screen circuit current has added
>>heat to the screen dropping resistor to shift its value higher, adding
>>to the voltage drop. And when a leaky coupling capacitor has reduced the
>>bias on an audio output tube by a volt or two, it has increased the
>>plate current by 15 to 30%, shortening the life of the tube, shortened
>>the life of the output transformer and added scorch to the cabinet above
>>the tube (to say nothing of the operator's fingers doing a tube
>>temperature check). Then a few megohms leakage shunting the AGC line can
>>cause poor AGC and subsequent distortion but won't show up with ordinary
>>voltage checks though the AGC voltage will test low. With the full set
>>of maladies brought on by leaky molded oiled paper capacitors that wreck
>>a radio's performance, replacing ALL them with Orange Drops saves weeks
>>of troubleshooting which won't necessarily show up the individual
>>marginal capacitors. Then getting the old caps out with enough leads to
>>test and put back is very hard on tube sockets and terminal strips. I
>>consider it better to replace after cutting the leads short than to fry
>>sockets, wires, terminal strips and other components trying to salvage
>>the old capacitors.
>>
>>In summary: REPLACE THEM ALL, DON'T CUT CORNERS WITH UNKNOWN PART, DON'T
>>WASTE TIME TESTING.
>>--
>>73, Jerry, K0CQ, Technical Advisor to the CRA
>>All content copyright Dr. Gerald N. Johnson, electrical engineer
>>
> 
> 
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