SB-401 Balance modulator diode replacements

[Charles W. Morehouse]

Mike,
1N191 diodes are hard to find.  The substitute is the 1N4148.  Mouser 
has these.  I have used 1N34A diodes in the past.
Get a bunch and match 4 of them.  Luck and 73.
Wayne,
W4GBW

Michael Waldrop wrote:

>Good afternoon everyone,
>   
>  I have an SB-401 that has 2 blown diodes in the balance modulator. The original diodes are
>  color coded Brown/White/Brown which cross references to a 1N191 crystal germanium
>  diode I believe. I have what appears to be some 1N210 crystal diodes. They have clear
>  glass bodies, color bands are "Red/Brown/Black". Cross references that color code 
>  shows them to be 1N210's. Unfortunately, if the color code is correct, a 1N210 doesn't have
>  the PIV and current rating the original Heathkit diodes has; original diodes 90VDC PIV
>  at 500 mils where as the 1N210 has a 45VDC PIV at 27mil current rating. Even if the 
>  210's would work I believe the internal resistance would be too high to work in a 
>  balance modulator.
>   
>  Has anyone ever changed the diodes in the SB-401 and what component number did
>  you use? I'd like to get this fixed but I don't want to install the diodes I have and have
>  them fail.
>   
>  Any suggestions on diode replacements for the balance modulator in the SB-401? Thank
>  you for any help/references/part numbers you can provide.
>   
>  73's
>  Mike
>  W5RKL
>   
>
> 
>  
>

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