One power supply, two radios?

[Keith Thompson]

I have a Powerwerx SPS-30DM power supply that I purchased with my Icom IC-7300. It's rated 25A continuous and 28A surge. Voltage can be fixed at 14.1V or varied from 5-16V dc.

This week I added a Yaesu FT-7900R to my station as a base station for 2 meter and 70cm.

Waddaya think? Can I run both radios from the same power supply, assuming I'm not trying to transmit on both simultaneously? Would like to avoid springing for a second power supply if I can.

https://www.gigaparts.com/powerwerx-sps-30dm.html

 

[OldTech03]

I have a Powerwerx SPS-30DM power supply that I purchased with my Icom IC-7300. It's rated 25A continuous and 28A surge. Voltage can be fixed at 14.1V or varied from 5-16V dc.

This week I added a Yaesu FT-7900R to my station as a base station for 2 meter and 70cm.

Waddaya think? Can I run both radios from the same power supply, assuming I'm not trying to transmit on both simultaneously? Would like to avoid springing for a second power supply if I can.

https://www.gigaparts.com/powerwerx-sps-30dm.html

Well, it matters how much power they consume? At idle you can run 15 or 20 of them it's when you transmit that matters. I assume you will not be transmitting on both of them at the same time so as far as the supply handling the load "NO PROBLEM" the real question will be for any cross interference you may or may not experience. Maybe some ferrite cores on the power cords would be a good idea and it may be you will not have any issues at all.

 

[2RT307]

Don't talk on both rigs at the same time.

73,
Brett

 

[Keith Thompson]

Don't talk on both rigs at the same time.

73,
Brett

Nah, don't have that level of concentration any more.

 

[Captain Kilowatt]

Check the manuals and take the max current on tx from one radio and add it to the standby current of the other. If this is less than the total current the PSU an supply you are good.

 

[sunbulls]

That power supply has over current protection and a digital amp meter. Your Icom will draw 21 amps max during transmit (full 100 watts) and your Yaesu 9 amps max (full power on 440). The amp draw during receive on either item is of little consequence. You will be under the limit unless you transmit on both at the same time. The meter will basically tell you how close you are coming to that 25 amp limit. Keep in mind while you’re working repeaters on the Yaesu, use only the power level necessary to achieve full quieting. Another note: Several people have been complaining about that particular power supply producing a 20 volt peak when you first turn it on. Watch you volt meter to see if yours has that effect. I understand that some of the later ones corrected that issue. A 20 volt spike like that could cause damage. In any case, to avoid the problem, make sure that your radios are turned off first before you turn the power supply on.

 

[Captain Kilowatt]

Rx current draw of a selarate radio is not insignificant when the tx approaches the current maximum of a supply and whether current limiting is used or not it is never a good idea to run a PSU at maximum.

 

[sunbulls]

Icom TX is 21 amps max + Yaesu RX is .5 amps = 21.5 amps total
Yaesu TX is 9 amps max + Icom RX is .9 amps = 9.9 amps total
That supply is rated at 25 amps continuous. You have enough headroom for that power supply, especially with SSB where you’re not running 21 amps continuous. If you are running that that many amps continuous for some reason with other modes such as AM or FM, I would strongly suggest reducing the power. Otherwise, I would have a greater fear of damaging the Icom's amplifier, not the power supply. Yes, I would I like to see more headroom, like a 40 amp or greater supply, but you shouldn’t have any problem with what you have. Gotta love a power supply with digital accurate meters like yours. It's like adding eyes to the blind.

 

[Road Squawker]

... edit... Another note: Several people have been complaining about that particular power supply producing a 20 volt peak when you first turn it on. Watch you volt meter to see if yours has that effect. I understand that some of the later ones corrected that issue. A 20 volt spike like that could cause damage. In any case, to avoid the problem, make sure that your radios are turned off first before you turn the power supply on.

Even with the radio turned off, there will still be PS voltage inside the rig.

 

[Beetle]

I Gotta love a power supply with digital accurate meters like yours. It's like adding eyes to the blind.

Quick point: "Digital" does not mean "more accurate than a laboratory standard". Digital meters generally give you more precision than analog meters, but just because something is "digital" doesn't imply anything having to do with accuracy.

 

[fourstringburn]

Can I run both radios from the same power supply

You're fine for the radios with about 4 amps of headroom to spare.

If you start adding accessories like meters, external tuners, etc, then you'll be near the limit.

Go ahead and talk away!

 

[Keith Thompson]

Thanks, guys. I certainly can't imagine a situation where I'd be transmitting on both simultaneously, so it sounds like I'd be okay. Ham Radio Outlet, where I purchased the power supply, had a shelf of around six mobil units hooked into a single SPS-30DM power supply and it ran them all just fine. Of course, no one was transmitting on any of them.

 

[Captain Kilowatt]

Quick point: "Digital" does not mean "more accurate than a laboratory standard". Digital meters generally give you more precision than analog meters, but just because something is "digital" doesn't imply anything having to do with accuracy.

People get accuracy and resolution confused all the time. Digital means bettter resolution maybe down to the last milli-whatever but it could still be waaay off from what the true value is.

 

[sunbulls]

True, they can both be inaccurate. I wasn’t implying that higher resolution corresponded to higher accuracy. All the analog meters, at least the ones I’ve dealt with on these typical supplies are terribly inaccurate compared to my Fluke. Why? Friction and temperature greatly affect moving parts like springs and bearings. It’s no wonder they constantly need zero centering. Zeroing does not compensate for their poor linearity either. Static electricity and surrounding magnetic fields drive them crazy too. One of the few things you need to worry about on a digital meter is its clock frequency. It needs to be stable and on frequency. That’s usually consists of an automated task of accepting or rejecting a completed unit on lab standard during manufacture. Analog meters are typically ±3% accurate. Digital meters are typically ±0.5% accurate, big difference. Those figures are not based on resolution. I can see 13.8 volts on a digital meter from across the room. On an analog meter it looks like something between 12 and 15 volts, provided my sugar level isn’t too low. That’s the type of “eye” resolution I’m talking about.

 

[Beetle]

True, they can both be inaccurate. I wasn’t implying that higher resolution corresponded to higher accuracy. All the analog meters, at least the ones I’ve dealt with on these typical supplies are terribly inaccurate compared to my Fluke. Why? Friction and temperature greatly affect moving parts like springs and bearings. It’s no wonder they constantly need zero centering. Zeroing does not compensate for their poor linearity either. Static electricity and surrounding magnetic fields drive them crazy too. One of the few things you need to worry about on a digital meter is its clock frequency. It needs to be stable and on frequency. That’s usually consists of an automated task of accepting or rejecting a completed unit on lab standard during manufacture. Analog meters are typically ±3% accurate. Digital meters are typically ±0.5% accurate, big difference. Those figures are not based on resolution. I can see 13.8 volts on a digital meter from across the room. On an analog meter it looks like something between 12 and 15 volts, provided my sugar level isn’t too low. That’s the type of “eye” resolution I’m talking about.

You bring up another problem in test equipment specification: "Percent of accuracy". When you say something is "±3% accurate", for example, you're saying that it's ±97% INACCURATE! If I found a meter with that allowable error, I certainly wouldn't keep it around.

The instrument manufacturer (and only the instrument manufacturer) specifies allowable error for his equipment and states it in terms of the percentage of allowable error (generally for analog instruments) or in terms of actual readout for digital.