Ham/CB/other transmitter radios... linear vs switching PSU?

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

AHA! I think I found the parts that I need to change to adjust the voltage on the xbox PSU... though the %#&*!@$ stupid @*()$#@(% chip manufacturer of the #($(#@%*#^ supervisory chip did not *(#%$@% clearly specify the %*(%# specifications of the OVP input...GRRR... However it minimally won't cut out under 13.4V so I probably can get it to 13V without modifying the OVP, above that might get into the risky zone depending on how lucky I got with the chip.

The other possibility is to remove the chip, but OCP is also handled by this circuit.

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

Problem with a 12.0V power supply is that the voltage isn't high enough to charge...

I also have a half-made homemade linear using the parts I had on hand. I had it working well with one series pass transistor, alas I wanted to parallel two so it can safely pass 10A+ total. Just don't have enough of the right parts to implement foldback for two transistors.

Yes it was kind of scary shorting the output to test foldback, but it worked when it was just one pass transistor!

[stj]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

that's called "spread spectrum", pc motherboards usually use it too.

[japlytic]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

It may be hard to find in specifications, but frequency jittering (helps reduce EMI) is a good feature to look for in a switching power supply for this application.

[llonen]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

I have used switching PSU's on 100 watt radios in the past, and I have tried the Xbox 360 gig. I don't know while they do seem to work I just don't feel comfortable unless I am using a heavy linear supply of which I have no shortages of. Also I have float charged a bank of lead acid batteries in the past to power my radio equipment, I suppose if I had a real need to use smps then I might get around to feeling differently and I do have a couple of surplus corsair 1200 watt supplies.

That said I know several local radio amateurs who use 50 volt smps supplies for their high power solid state amplifier's either 400 watt or 1 kw amps and they seem to get away with it.

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

Oh this sucks. I have to trick the supervisor circuit too? This thing has OVP/UVP with an internal reference! Grr!!! I guess no battery charging with this...

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

oh weird, I thought it was passively cooled, strange... did not see any fanlike vents. Grr. Oh well.

[stj]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

keep it clean,
they contain a fan and pull air from one end to the other across a huge heatsink.

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

Here we go... I got an 175W Xbox PSU, time to up it to ~13.8V and use it to charge the backup battery and power the shack. Then I can stop using the little 40W switcher...

I wonder if I'll need to add any noise elimination hacks to it... hopefully not.

[redwire]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

A linear PSU is the quietest, great for DX and 6-8 digit multimeters.
But your noise floor is always limited by other interference, usually the neighbor's cheap computer gear.

Any SMPS that passed EMC regulatory like FCC part 15 or EN550xx will have decent filtering and low emissions, i.e. Meanwell 50W PSU.
SMPS wall adapters are ungrounded and less room for filtering components, so not good for radios, I find.

The cheap Ali or eBay PSU's that have never been tested or certified for EMC- they are a crap shoot.
Some have the filter components just jumpered out. You can add a line filter and CM choke on the output though.
The really cheap chinese PSU's I find unstable and make tons more EMC.

[stj]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

well most ps run at 30-80KHz so they are going to be more of a problem for people running in the sw area.

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

Currently I only have 70cm LMRS radios tuned to ham bands, and using SMPS just fine. Almost seems just getting enough watts is sufficient, I'm using a random 12V 40W SMPS PSU that I adjusted to 13.8V on one of my radios - can't seem to hear PSU noise.

That PSU is being shared with the ancient 2m radio... which isn't being used, yet...

My 35W LMRS radio makes the 40W SMPS die on transmit. Well, that figures, so much for radio efficiency

[goontron]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

^ I run my rigs on a pair of Dell Poweredge 2500 PSUs. Works well.

[eccerr0r]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

I was more wondering about people deathly afraid of using SMPS with HF - heard someone mentioned it recently. Yes it's worth experimenting/testing but definitely don't preclude it.

Then there's also the VHF/UHF radios, which seem to be more tolerant of SMPS?

[kc8adu]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

cheap smps always litter the hf spectrum with their wandering birdies.
a surprise is that an xbox 360 supply does well for running 100w hf rigs.
they dont like cap charging inrush so connect then power on.
i have one at the shop running a kenwood ts50 over 3 years.
even with their weight and poor efficiency i prefer an old linear astron.
but if you need something to get on the air with an xbox 360 brick can be free from a dead game.
the older ones are rated for up to 18a.

[stj]

Re: Ham/CB/other transmitter radios... linear vs switching PSU?

switchers must be well filtered - cheap ones arent.
and they need LOTS of output capacitance to keep them stable between RX that is probably only a couple of watts and TX which sure as hell isnt.

[eccerr0r]

Now I don't own any HF gear other than CB, but there still seems to be some arguments against switching PSUs.

Do people still have a good reason to use a linear PSU?

Or is it fully possible to clean up a switching PSU so that it won't interfere a radio?

Now that it seems Yaesu even doles out switching PSUs, is this a sign to start getting rid of linear PSUs?