Since you haven't shown the nature of the Source Equipment signal to Q1 (the signal level to both sides of the remote LED), it's not possible to know what the problem is or how to suggest a better way.
Thanks for the reply ronsimpson.
Yes I do know because when I tested the source positive supply pin it was always high.
I am thinking an optocoupler or phototransistor may be a better way of doing this.
What do you think?
As crutschow noted, if you could give us the voltage levels (with respect to ground) on both sides (legs) of the source LEDs for both the working circuit example AND the non-working (LED always ON) circuit example, we will be better able to suggest a solution. These levels should be checked, obviously, when the source LEDs are ON, but it would also be useful to know what they are when the source LEDs are OFF.
These are needed to properly assess the PNPs' base biasing levels.
Connecting the LED of the opto in parallel with the status LED is a bad idea.
If the two LEDs operate at different voltages, then one of them will not operate correctly.
Try connecting the opto in series with the status LED, or simply replace the status LED with the opto.
Also, if I were doing this, I would not run the +5v supply from the "source equipment", out on 100 feet of wire.
I would have a separate supply for the remote LED.
That way there is no possibility of the long leads conducting "noise" back into the source equipment.
We could use the source led and a phototransistor. This way we would be dealing with a known voltage all the time of 5 VDC. The circuit would be very reliable and most likely work in all cases.
In addition, your point about the noise is something I did not think of.
I have done a prelim circuit picture of this above. I picked the R1 value out of the hat. I chose Q1 because I believe it is sensitive to visible light. I added Q2 to boost the output. Did I do good?
In the meantime, does anyone know of any phototransistor examples which would apply?