[R-390] 26Z5W replacement

[Bob Camp]

Hi

If you want to "improve" things - put a couple of 1N4007's in series in each leg. The voltage rating will go up and you *might* improve the reliability. The modest voltage drop will be in the "right" direction. Total cost - diodes are cheap ….

Is it worth it? Well, first diodes in series don't always add, but mostly they do. Second, you already are "good" for 1KV (1N4007). A line spike at 2X is pretty common. At 4X not quite so common. At 8X fairly rare for something wide enough to get through the line filter and transformer inductance. How many radios with solid state diodes show up with blown diodes?… 

Bob

On Sep 16, 2013, at 7:15 AM, Charles Steinmetz <csteinmetz at yandex.com> wrote:

> Roy wrote:
> 
>> There is of course at least one other option:  Change the rectifier tubes to another type, the 12BW4.
> 
> I was discussing the problem of voltage rise at turn-on or during standby operation if the 26Z5s are replaced with SS diodes.  The 12BW4 is no different from the 26Z5 in this regard, so in this context it is not another option -- it is the same option.
> 
> Note that some people have reported clearance problems using 12BW4s, which are about 1/2" taller than 26Z5s.
> 
> Best regards,
> 
> Charles
> 
> 
> 
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