New use for old Motorola AC Adapter

[cpg178]

Have a new XPR4350 coming in today to use as an monitor for a local fire channel, RX ONLY. I realized last minute that I did not have any sort of way to power the radio and found this old Motorola AC adapter I had laying around. With some quick crimping I now have a power supply for my radio. What's interesting is that the multimeter reads 19v DC when it says 13.8. I assume when it is placed under load the voltage will drop.

 

[RFI-EMI-GUY]

The radio should not see over 16.5V ever. I would not chance damaging your radio with that unregulated wall wart. There are better options. Also you need to consider the current draw in receive at full volume.

 

[a417]

unregulated wall wart. There are better options.

emphasis on unregulated.

I did something similar to this many years ago and cooked my Pro95, in fact...it may have been the same wall wart.

 

[cpg178]

The radio should not see over 16.5V ever. I would not chance damaging your radio with that unregulated wall wart. There are better options. Also you need to consider the current draw in receive at full volume.

It is to my understand this was for a Minitor V amplified base after looking up the part number. Is there any reason why Motorola would produce a device that does not output 13.8v as advertised? This is a genuine motorola wall wart

 

[mmckenna]

It is to my understand this was for a Minitor V amplified base after looking up the part number. Is there any reason why Motorola would produce a device that does not output 13.8v as advertised? This is a genuine motorola wall wart

Probably because it had an internal regulator.

Doesn't matter if it says Motorola on it. Motorola has their name on a lot of crap. Doesn't mean it belongs powering up a radio. You really need a well regulated DC power supply. The noise from a cheap wall wart can impact the receiver. As others said, too high a voltage and you'll let the smoke out of your radio.

 

[cpg178]

I guess I am now looking for recommendations for a good power supply just to power this one radio for receive only so don't need anything crazy. I would also prefer to not break the bank

 

[mmckenna]

I guess I am now looking for recommendations for a good power supply just to power this one radio for receive only so don't need anything crazy. I would also prefer to not break the bank

There's suitable stuff on Amazon. Search on 12 volt DC regulated power supply.
I'd recommend something capable of at least 2 amps to power up the radio in RX only mode.

While you are looking, consider your long term needs. If you plan on adding more radios, adding CB, scanner or ham radios down the road, you may want to invest in something with more current capacity.

 

[mmckenna]

Just be aware, people really have their favorites. You can spend a lot of money on a good 12 volt power supply, so take any recommendations with a grain of salt. It's your money…. You're going to get a ton of advice, some of it good, some of it not so good.

 

[cpg178]

Thank you, I figured the amazon offerings would work but wanted a 2nd opinion. I already have a 30 amp supply in my workshop. But this radio is not near that one so unfortunately I can't power it off of that. This supply would only be for this radio so dont need anything crazy and I will never be TXing with this radio at least in the location it is going now. If i was to ever do that I would have it on a beefier supply or in the car which has a fuse block I added wired to the battery

 

[mmckenna]

There are some inexpensive Pyramid 2.5a supplies. Pyramid is not the best name, but for the price and your intended usage, it may be a good option. RX only isn't going to strain the power supply, and you don't need a lot of current. Just make sure you have a fuse on the positive power lead goign to the radio.

Standby for someone to try and tell you that you really need a 75 amp linear power supply for "future use"….

A small switching power supply will work just fine for what you are doing.

 

[cpg178]

Thank you for the advice everyone, I have purchased this and it should be here tomorrow. At my own risk I did connect the radio to the power supply I made so I could measure the voltage and it sits right around 15.9. Higher than it should be but not as high as I was expecting I think it will be alright until I get the pyramid supply tomorrow.

 

[N4KVE]

I have a few of those wall warts. They came with the factory MTS2000 chargers from the early 90’s. Great for charging batteries, nothing else. And yes, with no load I have clocked mine at 18+ volts. And as much as I don’t like Pyramid equipment, I’d use the above PS before the 18+ volt wall wart.