Galaxy Saturn Base - 12vdc connector

[jrd426]

Hi guys, as many of you familiar with this old base radio there was no provision on the back of the radio to use it with a external power supply. Yet they added a connection for a external freq counter (works when radio is in tx only). Personally i would have preferred a connector on the rear to run 12vdc direct with a power supply. I know this beast is wont be run in a mobile but having the flexibility to run it with a power supply would have been good imo. So im considering adding a 12v connection on the rear (considering. My question if i go ahead with it is this. Where would be the best place to connect the 12v leads to the radio which then would terminate on a male 3 pin connector installed on the rear panel to axcept a typical 3 wire fused power cord ? Im assuming the connection would be done on the board in the same location as the power feed from the internal power supply. Looking for input / confirmation and thoughts from you's on this.
73's
Jeff

 

[Dmans]

Im assuming the connection would be done on the board in the same location as the power feed from the internal power supply.

A rear panel "AC/DC" switch would protect your external supply from damage when on the A/C supply. Or a big fat diode(s)???

73
David

 

[jrd426]

I like the idea of a switch to toggle the 2 different sources. Similar to what is done on many base cb's. Thx for the input

 

[Transresistor]

If memory serves me correctly you should have a voltage regulator transistor on the back left corner of the radio. The DC(B+) comes off the emitter of that transistor and goes to the on/off switch on the front of the radio. The B+ comes out of the front switch and goes back to the radio board and turns on the radio. The easiest place to put the switch is on the back of the radio(think before you make the hole location clearances and ease of access). You need a minimum of a 10 amp SPDT or DPDT toggle switch. A 15 amp or 20 amp rated switch would be so much more the merrier. The wire from TR603 (the regulator transistor on the back) I believe is yellow. One should not assume that to be the case as someone could have had other ideas. If you use a voltmeter and check the DC on the two transistor pins/wires, one should be about 24-26 volts and one about 14 volts DC. The lower voltage of the two should be the wire you want to remove from the transistor and wire it to the middle of the switch. One side of the switch will go to the transistor pin you removed the wire from and the other side of the switch will go to the 12V+ of the 3-pin chassis socket. I would recommend using a DPDT switch, although you only need an SPDT switch, and connect the two switch poles together thus doubling the current handling capacity of the switch and hopefully make it last much longer.

 

[jrd426]

If memory serves me correctly you should have a voltage regulator transistor on the back left corner of the radio. The DC(B+) comes off the emitter of that transistor and goes to the on/off switch on the front of the radio. The B+ comes out of the front switch and goes back to the radio board and turns on the radio. The easiest place to put the switch is on the back of the radio(think before you make the hole location clearances and ease of access). You need a minimum of a 10 amp SPDT or DPDT toggle switch. A 15 amp or 20 amp rated switch would be so much more the merrier. The wire from TR603 (the regulator transistor on the back) I believe is yellow. One should not assume that to be the case as someone could have had other ideas. If you use a voltmeter and check the DC on the two transistor pins/wires, one should be about 24-26 volts and one about 14 volts DC. The lower voltage of the two should be the wire you want to remove from the transistor and wire it to the middle of the switch. One side of the switch will go to the transistor pin you removed the wire from and the other side of the switch will go to the 12V+ of the 3-pin chassis socket. I would recommend using a DPDT switch, although you only need an SPDT switch, and connect the two switch poles together thus doubling the current handling capacity of the switch and hopefully make it last much longer.

Thank you for the info. Much appreciated Transresistor!