Help with my Regulated Power Supply Pls..

colin55 said:

The only thing I can suggest at the moment is to put a bridge on the output of the transformer, by connecting the two outer leads to the AC points on the bridge. The 0v wire (the centre-tap) goes no-where.
Try this for a few minutes and see if it cures the problem. This will create additional heat in the 2N3055 but will be ok for 30 seconds.

Click to expand...

This is very helpful Mr. Colin, one thing i was afraid of is that is it possible that if the regulator will be damaged (due to short circuit,excessive heat etc..), the unregulated part of 18-20vdc will go directly to the transceiver? I don`t have any overvoltage protection for this diagram..

Your transceiver should operate properly on 12V. Try it for a while with this setting, which gives you 1.8 volts more for the regulators to do their job. If the hum is reduced, good. As was offered before, check to see if your LM317 is capable of delivering 1.5A with the heatsink that you're using. If it's LM317T it should be. If it is, disconnect the 2N3055. It is costing you overhead voltage and its emitter follower response is letting hum through.

If your transceiver is satisfactory on 12V (it's like running on the battery with ignition off) you should have no hum.

Thanks guys! i`ll let you know if i have done this already, another question of mine is that when i connected the dc tester at the power supply and when the transceiver is transmitting on 5 watts (maximum power ouput for an ICOM 0-2N) i noticed the voltmeter is dropping almost 1++ voltage. Anyweiz i`ll just fix this up first using your ideas maybe the dropping of voltage be answered too.

73`s

DW9HRV
Davao City, Philippines

good idea

Dear Colin,
this is a great idea (of winding additional turns)to increase secondary voltage using the same setup.
thanks for the idea.
Prash.