[Boatanchors] Identity of plugin solid state rectifier replacementt

[Glenn Little WB4UIV]

Might be a good idea to fuse both inputs to the rectifier.
Could save a transformer.
I would use a pigtail fuse of good quality as you will be using it 
above the rated voltage rating.
I would place sleeving over the fuse.
If the fuse blows, it will create a plasma within the fuse.
I ceramic, sand filled, fuse would offer the best protection, but 
this is marginal.
It will be a crap shoot as to the transformer protection with this 
fuse, but, it will offer a small amount of protection.

A fuse on the primary, properly selected, would probably offer the 
best protection.

Do some research on fuses and give it your best shot.

You could place a protection relay in the primary of the transformer.
Use the voltage drop across a resistor between the diode and the 
filter capacitor.
If the diode should short, the current into the capacitor as well as 
through the resistor will increase.
This will cause a voltage drop across the resistor to energize a 
latching relay.
This would open the input to the transformer.
For this to work, you will have to control the inrush current into 
the capacitor at turnon.
A step start circuit will control the inrush and greatly limit the 
surge at turnon.
This will help prevent the lights dimming and may save a few switches.

73
Glenn
WB4UIV




At 10:18 PM 12/27/2012, Jim Wilhite wrote:
>John if you plan to use that device I suggest you check it first.  I 
>have seen some of them open and one or two shorted which does not 
>bode well for your transformer.
>
>Use a 9 volt battery and your digital multimeter to see if it 
>conducts and you see the expected voltage drop.  If there isn't any 
>voltage drop then it is shorted, if there is no forward voltage at 
>all it is open, naturally.  If I am not mistaken that has only one 
>diode on each input so be sure to check them both.
>
>Might save you some grief.  I lost a transformer to one of them 
>working for a while then shorting one leg.  I suggest you check carefully.
>
>Jim
>W5JO
>----- Original Message -----
>>A google search reveals that this is a 1N1239.
>>A search for 1N1239 shows that this is a solid state replacement for a 5R4.
>>This appears to have been for an FAA project.
>
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