Motorola VPN1022A Power supply question

[cahighwayman22]

Anyone happen too have a schematic of the Motorola 15Amp Base station Power supply? VPN1022A. What I am trying too do is lower the voltage too about 14VDC rather than having 15VDC when the Radio that I have hooked too it is idle. Any suggestions?

Trevor KI6KGN

[Will]

True 15 volts IS a bit too high, 13.5 is about right for most radios.

Not sure who made that one, do you have a photo?

[cahighwayman22]

It's Motorola made. look up the model # and that'll be the pic.

Trevor KI6KGN

[Will]

On that one you have to 'pad' a resistor in the regulator section on the rectangle circuit board. I have the road map somewhere.

You should replace the axial leaded capacitor, 100 uf 25 volts, when you are in there. These power supplies are old.

[RFguy]

I thought the VPN 1022 had a voltage pot on the circuit board. I will have to open one of mine to confirm.

[cahighwayman22]

Anyone still have a schematic of this supply? Btw I bought a TPN1154A not sure what the difference is, but it's (the TPN1154A) set for 13.8V, I just would like to bring the other one down to about 14V.

Trevor KI6KGN

[cahighwayman22]

Btw the model # of the first supply (the one I want to bring down to 13.8V) is a TPN1136A.

[jackhackett]

As far as I can tell the difference between the 1154 and 1136 is the filter cap and output transistors, rest of the schematic looks the same.

If you PM me your email I can send you the 1154 schematic.

[Will]

Btw the model # of the first supply (the one I want to bring down to 13.8V) is a TPN1136A.

Pad R9 with a 10 K resistor in parallel. Replace C2 the 100 uF axial leaded.

[cahighwayman22]

As far as I can tell the difference between the 1154 and 1136 is the filter cap and output transistors, rest of the schematic looks the same.

If you PM me your email I can send you the 1154 schematic.

PM sent.