Dumb Question

[steveccwohio]

I have a 50 Watt two way radio and want to use it as a base station. Will a 30 amp AC-DC Power Converter work? Thanks in advance

[WRUE951]

5 minutes ago, steveccwohio said:

I have a 50 Watt two way radio and want to use it as a base station. Will I a 30 amp AC-DC Power Converter work? Thanks in advance

a 30 amp Power Supply will be more than enough   -..   Please read this white paper  https://www.buytwowayradios.com/blog/2020/04/choosing-the-right-size-power-supply-for-your-radio.html

[SteveShannon]

7 minutes ago, steveccwohio said:

I have a 50 Watt two way radio and want to use it as a base station. Will a 30 amp AC-DC Power Converter work? Thanks in advance

You can probably get by with a 12-15 amp power supply. My 100 watt ham radio uses 23 amps when I am transmitting at full power. 

[steveccwohio]

Thanks Steve!

[SteveShannon]

12 minutes ago, steveccwohio said:

Thanks Steve!

And it really was not a dumb question!

[WRTC928]

Boy! That was really a dumb question! 

(Just kidding. It wasn't.) 

I don't remember all the calculations now, but when I was looking for a power supply, I calculated that 30 amps would easily power two 50 watt radios. I concluded that I would be running close to the limit if both ran at full power for an extended period, but the probability that I'll ever do that is close to zero. 

Unless you're going for the top-of-the line, a 30 amp power supply can be had for about 1/2 the cost of a 50 amp supply, so I decided to go with the 30 and add another if I was going to exceed 30 amps with multiple radios. I was glad I did, because I can take one PS somewhere else without disconnecting the two radios I have on it at home. I suppose the strategy would be different if you wanted to run a lot of equipment in a place with limited outlets, but two 30s was a better solution for me than a single 50.

[nokones]

Most mobile radios with a RF output power of 50 watts will normally draw between 8-10 amps. I have never seen a 50 watt mobile drawing more than 12 amps in the transmit mode. In the idle mode, usually .6 to .8 amp and in the receive mode another .2 to .4 amp.

[WRTC928]

4 hours ago, nokones said:

Most mobile radios with a RF output power of 50 watts will normally draw between 8-10 amps. I have never seen a 50 watt mobile drawing more than 12 amps in the transmit mode. In the idle mode, usually .6 to .8 amp and in the receive mode another .2 to .4 amp.

Yep. That's how I concluded that I could run two 50 watt radios on one 30 amp power supply. Two radios at full power may draw up to 24-25 amps. Assuming the PS may not be perfect, that's a 5-6 amp safety margin. "In the real world", I doubt I'll ever be transmitting on both units at once, but in the event of a disaster, I suppose it's possible I could have someone else with me, hence the desire to be able to run them both at once. I eventually bought a second power supply for my "travel kit" and because if the one I'm using fails, I can immediately replace it. I have no idea how often a power supply fails, but I don't like the idea of leaving stuff to chance. Probably a residual of 33 years of military service.

[wayoverthere]

10 hours ago, WRTC928 said:

Yep. That's how I concluded that I could run two 50 watt radios on one 30 amp power supply. Two radios at full power may draw up to 24-25 amps. Assuming the PS may not be perfect, that's a 5-6 amp safety margin. "In the real world", I doubt I'll ever be transmitting on both units at once, but in the event of a disaster, I suppose it's possible I could have someone else with me, hence the desire to be able to run them both at once. I eventually bought a second power supply for my "travel kit" and because if the one I'm using fails, I can immediately replace it. I have no idea how often a power supply fails, but I don't like the idea of leaving stuff to chance. Probably a residual of 33 years of military service.

I will mention to watch the specs on the power supplies; many of them advertise based on their "peak" current capability, rather than their "continuous" figure; depending how a particular supply is advertising, that may not provide the safety margin one would hope for.  some of them also vary on much they differ between "peak" and "contiuous" ratings.  25a continuous should be good to run two at the same time with a small safety margin, 30a continuous, a bit more.

case in point, my alinco is sold as a 30a PSU, which is the peak figure; its continuous rating is a bit lower, at 20a.  in the real world, it's going to come down to how it's used, though.  I've had three 45-50 watt radios running off of the one PSU, since, as you mentioned, in the real world it's unlikely you'll be transmitting on more than one radio at a time. each draws less than 1a on receive, and 10-11 amps on full power transmit. (2x vertex vx4200, 1x Btech gmrs50x1). 

[WRTC928]

48 minutes ago, wayoverthere said:

I will mention to watch the specs on the power supplies; many of them advertise based on their "peak" current capability, rather than their "continuous" figure; depending how a particular supply is advertising, that may not provide the safety margin one would hope for.  some of them also vary on much they differ between "peak" and "contiuous" ratings.  25a continuous should be good to run two at the same time with a small safety margin, 30a continuous, a bit more.

case in point, my alinco is sold as a 30a PSU, which is the peak figure; its continuous rating is a bit lower, at 20a.  in the real world, it's going to come down to how it's used, though.  I've had three 45-50 watt radios running off of the one PSU, since, as you mentioned, in the real world it's unlikely you'll be transmitting on more than one radio at a time. each draws less than 1a on receive, and 10-11 amps on full power transmit. (2x vertex vx4200, 1x Btech gmrs50x1). 

Yes, good point. Something to be aware of.

[LeoG]

21 hours ago, WRTC928 said:

Yep. That's how I concluded that I could run two 50 watt radios on one 30 amp power supply. Two radios at full power may draw up to 24-25 amps. Assuming the PS may not be perfect, that's a 5-6 amp safety margin. "In the real world", I doubt I'll ever be transmitting on both units at once, but in the event of a disaster, I suppose it's possible I could have someone else with me, hence the desire to be able to run them both at once. I eventually bought a second power supply for my "travel kit" and because if the one I'm using fails, I can immediately replace it. I have no idea how often a power supply fails, but I don't like the idea of leaving stuff to chance. Probably a residual of 33 years of military service.

Talking on my landline phone I've had my cell phone ring and need to pick it up because it was important.  So one on each ear.

I'm sure that can happen with radio.

[LeoG]

10 hours ago, wayoverthere said:

I will mention to watch the specs on the power supplies; many of them advertise based on their "peak" current capability, rather than their "continuous" figure; depending how a particular supply is advertising, that may not provide the safety margin one would hope for.  some of them also vary on much they differ between "peak" and "contiuous" ratings.  25a continuous should be good to run two at the same time with a small safety margin, 30a continuous, a bit more.

case in point, my alinco is sold as a 30a PSU, which is the peak figure; its continuous rating is a bit lower, at 20a.  in the real world, it's going to come down to how it's used, though.  I've had three 45-50 watt radios running off of the one PSU, since, as you mentioned, in the real world it's unlikely you'll be transmitting on more than one radio at a time. each draws less than 1a on receive, and 10-11 amps on full power transmit. (2x vertex vx4200, 1x Btech gmrs50x1). 

Yup.  I bought a 7 amp power supply for my 20 watt only to find out it was 4.5 amps continuous which is what the unit drew on transmit.  Still worked but I had it overheat and trip on two occasions when I got jabber jawing.  I have a 30 amp now which is 25 amp continuous.

[WRTC928]

26 minutes ago, LeoG said:

Talking on my landline phone I've had my cell phone ring and need to pick it up because it was important.  So one on each ear.

I'm sure that can happen with radio.

It could happen, which is why I wanted a PS that could handle both at once. The probability of that going on for a protracted period is near zero, though, which is why I was comfortable with one that has a fairly slim safety margin with both units running. I now have a second power supply and a few batteries, so I can quickly switch one radio to another source of power, should that become necessary.

[LeoG]

I have 4 LiFePO4 batteries at my disposal too.  One is dedicated to a winch but can easily be removed.  The other 3 are just sitting there waiting.  They have bluetooth BMSs so I can check on the state of charge when I'm near them.  So far they've been keeping well at about 99%.  I expected them to self discharge faster but they aren't.

[WRTC928]

33 minutes ago, LeoG said:

I have 4 LiFePO4 batteries at my disposal too.  One is dedicated to a winch but can easily be removed.  The other 3 are just sitting there waiting.  They have bluetooth BMSs so I can check on the state of charge when I'm near them.  So far they've been keeping well at about 99%.  I expected them to self discharge faster but they aren't.

I've never had LiFePO4 batteries until recently, and I have been pleasantly surprised how well they hold their charge. I have one in my mobile repeater kit and one in the shack to power the radio in the event of storms or power loss. Considering how little they weigh and how well they perform, they're a good investment, IMO.

[LeoG]

I picked up 4 of them over a short period of time.  I have a bench power supply that I charged them with and kept the voltage below top charge.  Then bumped it up a bit and watched it hit 100%.   BMS shut things down which was cool.  I also have a bunch of solar panels and two charge controllers in case SHTF.  I can pull them out and hook them up to my 3KW inverter I have in the truck and power some of my house.

[GreggInFL]

On 11/11/2025 at 11:22 AM, WRTC928 said:

Yep. That's how I concluded that I could run two 50 watt radios on one 30 amp power supply. Two radios at full power may draw up to 24-25 amps. Assuming the PS may not be perfect, that's a 5-6 amp safety margin. "In the real world", I doubt I'll ever be transmitting on both units at once, but in the event of a disaster, I suppose it's possible I could have someone else with me, hence the desire to be able to run them both at once. I eventually bought a second power supply for my "travel kit" and because if the one I'm using fails, I can immediately replace it. I have no idea how often a power supply fails, but I don't like the idea of leaving stuff to chance. Probably a residual of 33 years of military service.

"Reliability through redundancy."