[hpsdr] LPU mod.

[Henry Vredegoor]

Hi All,

For those who want a LINEAR high(er) power supply solution:

As an in-between-in-between PSU solution / modification of the LPU, one 
could add an external series regulating high power transistor on a 
(large-) heat sink ?
Collector to the +V input into the LPU, Base to the output of U2 (+5 
Volt), Emitter to +5 Volt input of Atlas

To compensate for the increased output voltage of now 5.7 Volts (added 
0.7 Volts of the base-emitter junction of this series regulating pass 
transistor) one could connect the GND pin of U2 to the junction of a 
small signal diode (kathode), e.g. a 1N4148, and a say 1 KOhm resistor, 
connected between the GND rail (anode of 1N4148) and the -12 Volt rail 
(1 KOhm resistor)
In this way the GND pin of U2 would now be on negative 0.7 Volt and the 
output of U2 will now be +4.3 Volts.
Together with the extra 0.7 volts from the base-emitter of the external 
series regulating high power transistor, the output of the LPU will now 
be +5 Volts again.

I think this should work this way.
Maybe others can comment on this.

However I have not tried this myself (yet), so you are on your own and 
doing this at your own risk!

Henry - PA0HJA.