[Heathkit] Source for 125 uf 450V electrolytics?

[jeremy-ca]

CHEAP rarely means good. While the cheap import electrolytics will work OK 
in a basic receiver or transmitter power supply they can be quite dangerous 
in a series string HV supply, especially a half wave doubler as used in many 
amps.
The failure mode is excessive heat from a high internal dissapation factor 
(ESR). They go with a bang and often take the xfmr with them. Good caps are 
those designed for industrial duty switching supplies.

United has a decent snap-in style in their 105*C KMH series. Personally I 
prefer Cornell Dublier made in USA 105*C 381LX series, available at Mouser, 
and have been using them for about 10 years now for my own use and repairs 
of customer amps. They have the lowest leakage/best ESR of any Ive evaluated 
in the affordable product range. They also have better than advertised 
tolerance and balance very well with 100K resistors thereby saving 
additional heat and xfmr draw. The 330 mF/450V fits right into the SB220/221 
mounting blocks and noticably improves regulation on  SSB. They or the 
220/270 mF versions will adapt to the SB200/201 without drilling any new 
holes in the PC board. Dont try and save a few pennies with the 85*C 
version.

Carl
KM1H


----- Original Message ----- 
From: "David Thompson" <thompson at mindspring.com>
To: <boatanchors at mailman.qth.net>; <heathkit at mailman.qth.net>; 
<national at mailman.qth.net>; <hammarlund at mailman.qth.net>; 
<hallicrafters at mailman.qth.net>
Sent: Saturday, February 03, 2007 7:22 PM
Subject: Re: [Heathkit] Source for 125 uf 450V electrolytics?


>I got a set of 120uF 450V caps on the internet for a mere song.  I blew a
> cap in my Dentron DTR 2000L with an 8877 final.  When you blow one its 
> good
> practice to replace them all (8 in my case).
>
> My originals (actual 2nd set) are 4" tall.  These new ones are very short
> and thin. About 1/4 the original size.  I find
> about the same type of capacitor in the Newark Catalog under United
> Chemi-con.  These are for a printed circuit board which the Dentron has. 
> My
> catalog is several years old so assume they run about $12.00 now.  Newark
> has several different brands.
>
> 73 Dave K4JRB
>
>
>
> _______________________________________________
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
> $$ See the vintage area on the HCI web site - http://www.w9wze.org $$
> Heathkit mailing list
> Heathkit at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/heathkit
>