[Amps] Grid current protection HELP

TexasRF at aol.com TexasRF at aol.com
Mon Feb 13 18:30:35 PST 2012

Rick, that address: members.cruzio.com/~k6xx/radio/76a_prot.pdf  
does not work for me. Is something missing?
Gerals K5GW
In a message dated 2/13/2012 6:59:20 P.M. Central Standard Time,  
n6pe at yahoo.com writes:

Hi  all,

A while back K6XX published an article that can be found at  
It is a simple  opticoupler that triggers a 555 timer base on the voltage 
drop across a  resistor.
I built the circuit but only connected pin 2 to the 100k resistor  from the 
It has different levels of working with different  connections I have 
tried. Grounding the relay jack will key Q1 if the output  is low, but it starts 
high. At one point I could vary the voltage in to the  opticoupler and 
trigger the 555. Also, the time delay worked too. Now I can't  get it to do much 
hi hi I need to start over.

I'm a tube and voltage  guy and almost nothing I've built SS except for a 
160 meter surface mount SDR  and my copy of the Alpha 78 QSK board has worked 
first time out hi  hi

Can someone look at the schematic and let me know what the problem  is, IE 
correct it? 
I can see the trigger tied to B+ and do not think that  is correct.  
I assumed pin 4 needed to go to B+, maybe not.

I  made a PCB and it is a pain makeing changes and cutting foil.

Please,  any help from you solid state guys? My 8874s need you. K6XX does 
not  respond.


Rick,  N6PE


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