power supply question

[matty909]

i was looking at getting a Kenwood tk-880 mobile radio and wanted to ask what amp power supply would be best for both tx/rx without having issues

 

[KK4JUG]

You're asking about a power supply so I assume you are shooting for a base installation. That radio only draws 8A on transmit so almost any standard ham 12 volt power supply would work, To be on the safe side, however, I'd get at least a 12A power supply.

For mobile installation, you don't need a power supply.

 

[matty909]

You're asking about a power supply so I assume you are shooting for a base installation. That radio only draws 8A on transmit so almost any standard ham 12 volt power supply would work, To be on the safe side, however, I'd get at least a 12A power supply.

For mobile installation, you don't need a power supply.

yes that is correct. would there be a difference for the power supply amps if the radio is a 25W or 45W? (just want to get a better understanding)

 

[KK4JUG]

Check the specs on the radio. Look for amperage draw on transmit then go from there. Whatever the draw, add about 15-20% for the power supply.

 

[matty909]

so a Astron SL-11R 13.8V 7A (11A 50% Duty) should be fine for a 25W

 

[KK4JUG]

so a Astron SL-11R 13.8V 7A (11A 50% Duty) should be fine for a 25W

I haven't look at those specs for that power supply but if those are the numbers, it should work.

 

[alcahuete]

so a Astron SL-11R 13.8V 7A (11A 50% Duty) should be fine for a 25W

If it's only 7A continuous, I would not go with that power supply, personally.

 

[KK4JUG]

If it's only 7A continuous, I would not go with that power supply, personally.

The more I think about it, the more I think you're right. The power supply has 11A capability but I suspect that may be like the surge when using a portable generator. It's not the kind of numbers you can count on.

A 12 or 15 amp (continuous) power supply would be the better option. It's a little more money but it's the safer choice.

 

[KX0Z]

Astron RS-12 or RS-20.

 

[w2xq]

I would go with at least a 20a Astron, but...

If you are thinking of adding more equipment--say, an HF transceiver and accessories--soon perhaps buy a larger Astron at the outset. A 35a or 50a Astron may very well be a worthwhile investment to take care of present and future toys.

 

[KX0Z]

^^^^^<<< this.

 

[mmckenna]

The TK-880 comes in two models, the "H" and non-H.
The non-H are 25 watt radios.
The H models are 40 watts.

Per the service manual, the 25 watt models will pull 7 amps while transmitting.
The 40 watt manual will pull 11 amps while transmitting.

Since each radio is different, I'd give that a ± 10%.

You'll need a power supply capable of running 11amps at least. It's sometimes shown as "ICS" or Intermittent Communications Service, which means the power supply will happily run 11amps for "a while". Since commercial radios usually aren't used for long winded conversations, that usually translates into some duty cycle somewhere along the lines of a minute or so transmitting followed by a few minutes of not transmitting.

As others have said, it's -really- a good idea to up your power supply a bit and not run it on the ragged edge all the time. It also gives you the option of adding additional radios down the road.

A 15 amp power supply is pretty good for one radio, maybe a second one as long as you don't transmit with both at the same time. If you plan on adding several more radios in the future, or running something like an HF rig, getting something in the 25-30 amp range can be a good idea.

But for one radio, a 15 amp supply is plenty. You can go larger, it won't hurt, but if you are not going to use that excess capacity, it might be a waste of money.

 

[iMONITOR]

yes that is correct. would there be a difference for the power supply amps if the radio is a 25W or 45W? (just want to get a better understanding)

KENWOOD KPS-15 12vdc 23a

https://www.universal-radio.com/catalog/hamps/4273.html

 

[KK4JUG]

The TK-880 comes in two models, the "H" and non-H.
The non-H are 25 watt radios.
The H models are 40 watts.

Per the service manual, the 25 watt models will pull 7 amps while transmitting.
The 40 watt manual will pull 11 amps while transmitting.

Since each radio is different, I'd give that a ± 10%.

You'll need a power supply capable of running 11amps at least. It's sometimes shown as "ICS" or Intermittent Communications Service, which means the power supply will happily run 11amps for "a while". Since commercial radios usually aren't used for long winded conversations, that usually translates into some duty cycle somewhere along the lines of a minute or so transmitting followed by a few minutes of not transmitting.

As others have said, it's -really- a good idea to up your power supply a bit and not run it on the ragged edge all the time. It also gives you the option of adding additional radios down the road.

A 15 amp power supply is pretty good for one radio, maybe a second one as long as you don't transmit with both at the same time. If you plan on adding several more radios in the future, or running something like an HF rig, getting something in the 25-30 amp range can be a good idea.

But for one radio, a 15 amp supply is plenty. You can go larger, it won't hurt, but if you are not going to use that excess capacity, it might be a waste of money.

mmckenna is one of the participants in this form that knows his stuff and give consistently accurate information. Do what he says.