[Collins] 30L-1 Electrolytics

[Carl]

The key to long life is to completely read the cap specs. Most include 
expected life at rated temperature.

Ive used CDE 381LX series for decades in amp repair work with zero failures.

The Sprague ATOM's were leaky from new in comparison and are useful only in 
a "correct" restoration.

I wouldnt deviate too much from the factory C since the surge current can 
annoy switches and marginal transformers unless a step start is added. 
Considering that the tolerance of those old caps and Atom's is mostly on the 
high side the 20uF or so total is sufficient at the low current involved in 
that amp.

Carl
KM1H


----- Original Message ----- 
From: "Dr. Gerald N. Johnson" <geraldj at weather.net>
To: <collins at mailman.qth.net>
Sent: Thursday, January 19, 2012 12:48 PM
Subject: Re: [Collins] 30L-1 Electrolytics


> Look at Mouser catalog pages 823 to 826. One of the limits is ripple
> current and the more compact the capacitor the less surface area it has
> to dissipate heat from the ripple current. The higher capacitance part
> will make the peak ripple currents larger (though the time shorter) and
> I see in Cornell Dubilier that the 105 C rated caps have a lower ripple
> current rating than the 85C even though some of the high temperature
> caps are titled "high ripple current" their ripple current ratings are
> lower.
>
> The Vishay/Sprague axial lead Atoms on page 865 I like for vintage
> repairs because they have the surface area to dissipate heat like the
> originals and Sprague was a favored vender half a century ago.
>
> Larger capacitors will improve the voltage regulation, at the cost of
> higher peak currents the original rectifiers may not be able to handle,
> at the cost of a greater capacitor temperature rise, and difficulty
> fitting into the volume available.
>
> The upgrade boards have been created because the caps to upgrade the
> original boards don't exist.
>
> 73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.
>
> On 1/19/2012 10:46 AM, Byron Tatum wrote:
>> Hello-
>>      Can someone recommend to me a good replacement electrolytic for the 
>> 30L-1
>> 100 uFD @ 450 VDC ones? I do not wish to replace the existing PC board 
>> with one
>> of the upgrade boards at this time.
>>      I was looking at the axial lead capacitors (Mouser, Newark) and 
>> there are
>> not many offered above 100 uFD. I am wanting to use higher capacity ones 
>> such as
>> 220 ufd. Is it necessary to use radial lead units on the existing board?
>>
>>      Any advice appreciated.
>>                                  Thanks, Byron WA5THJ
>>
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