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Author Topic: Power Supply for TX  (Read 4792 times)

Offline ION Radio

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Power Supply for TX
« on: December 24, 2017, 1303 UTC »
I'm looking to replace a cheap Chinese PSU I've been using to power my Lulu TX. It was good enough I guess to get things started but I recently got a scope and it looks like I get a lot of ripple/noise from my Chinese PSU. Carrier looks terrible on scope and it may be that I don't have my scope settings correct. I'm still learning how to use the scope but I strongly suspect it's the PSU. My audio sounds good on recordings that listeners send with reports, so I don't think the PSU is affecting the audio too badly anyway, but I think I should use a better PSU. I can save the image on the scope, I still have to figure out how to do that, if anyone wants to have a look at what my carrier looks like on the scope with the cheap PSU I can send that to you.

I looked around online for a new PSU but I would like to hear about what other people are using before I spent more money. The Lulu I got from Stretchyman will run from 12-24 volts. I usually stay at 18v (12 watt carrier) so a power supply that is adjustable between 12-24 volts is what I'm looking for. PSUs I see online for Ham radio only go up to 16v. I really don't want to use battery power.

Thanks for any help!
« Last Edit: December 24, 2017, 1322 UTC by ION Radio »
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Offline Stretchyman

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Re: Power Supply for TX
« Reply #1 on: December 24, 2017, 1644 UTC »
Variable PSU is going to be expensive.

Best deal looks to be Chinese SMPSU of 24V @ 5A at around £10, however I've no idea of how good (or bad they are) but have just purhased one to check out and will let you know (if I've not, PM me in a couple of weeks).

Another source of a decent PSU is the LAPTOP bricks as they're 19V @ 6A (120W).

The PSU's I use are all lab PSU's so cant comment on whats available, there's a lot of crap out there!

Str.
'It's better to give than receive' so why Rx when you can Tx!

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Offline ChrisSmolinski

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Re: Power Supply for TX
« Reply #2 on: December 24, 2017, 1722 UTC »
Unfortunately it is not hamfest season (not in this part of the US anyway), but I have often seen nice linear power supplies at them. Many of the 24 volt supplies can be adjusted down via a trimmer pot, not sure if you can get to 18 volts or not, it would depend on the model. There are some well made switching supplies with relatively low noise outputs, Vicor comes to mind. Expensive new, but again pretty cheap at hamfests.

As Stretchyman said, many laptop supplies are around 19 volts, and again, they vary in quality. A genuine name brand supply (say via eBay) is most likely to be low noise, OTOH the Pride of China supplies are almost guaranteed to spew RFI. I ran into that problem when I got a replacement supply for one of the kids' laptops. S9+20 noise over all of 43 and 48 meters. Yuck.

A linear supply is going to be larger and less efficient, but guaranteed to be low noise.
Chris Smolinski
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eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline redhat

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Re: Power Supply for TX
« Reply #3 on: December 26, 2017, 0547 UTC »
I've been using the LRS series supplies from mean well.  They seem to work well enough, a 24V supply should turn down to 20V or so.  Be sure to get one at least 2x your carrier power, 3X is better.

RFI can sometimes cause problems with switchers.  Brute force filtration may be needed in some applications.

+-RH
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Offline ION Radio

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Re: Power Supply for TX
« Reply #4 on: December 27, 2017, 1144 UTC »
Thanks for the input!

-IR
QTH- East of everywhere.
ICOM and 40m Dipole
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Offline Stretchyman

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Re: Power Supply for TX
« Reply #5 on: January 28, 2018, 1735 UTC »
OK, confirmation of cheaply available and compatible PSU for my GaN Tx's.

https://www.ebay.co.uk/itm/DC-3V-5V-12V-24V-36V-48V-Universal-Regulated-Switching-Power-Supply-LED-CCTV-PSU-/151886747221

The PSU has;

JCPOWER JC-120-24 written on label.

24V 5A.

With the PSU at 26V and the Gan LuLu giving a 40 W carrier, no voltage dips were seen at 100% mod.

Caution is advised however as most of the LuLu's I've sold are 10W and ABS MAX voltage is 14V, NOT 24V.

Open the lid, look to see (thru' the hole in the PCB) if the FET has an insulating washer it's ONLY 10W.

OK!

Str.

'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

Offline Azimuth Coordinator

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Re: Power Supply for TX
« Reply #6 on: January 30, 2018, 0009 UTC »
I'm not a big fan of Switching power supplies for rf applications for a few dollars more...

https://www.ebay.com/itm/POWER-SUPPLY-15V-5-5A-LAMBDA-LDS-X-15-47-63Hz-EXCEPTIONAL-REGULATION-NOS/322445608094?epid=734586403&hash=item4b1341849e:g:Ov4AAOSwB-1Yv57S

or you can just build your own..
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Offline redhat

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Re: Power Supply for TX
« Reply #7 on: January 30, 2018, 0102 UTC »
I have good luck with Mean Well (they meant well...) supplies.  You can get them off the shelf anywhere.  If you want something built a little better, TDK Lambda makes good stuff too with a little better ripple performance.

I don't know why anyone would take a chance on a no-name chinesium wonder.

+-RH
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Please send QSL's and reception reports to xfmshortwave [at] proton [d0t] me

Offline Pigmeat

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Re: Power Supply for TX
« Reply #8 on: January 30, 2018, 0143 UTC »
You said it Redhat. I've heard so many horror stories about Chinese electronics and parts, it's tough to pull the trigger on them.

I'm a hamfest man when it comes to power supplies. You can stock up on ferrite cores/chokes to tame possible problems while you're there and come out with plenty of money left over. When it craps out, and it will, someone will buy it to either try their hand at fixing it, or for parts and a pre-drilled box. It's hamfest recycling at work.

Offline ChrisSmolinski

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Re: Power Supply for TX
« Reply #9 on: January 30, 2018, 1454 UTC »
Yes, you can get good deals on nice linear supplies at hamfests. Lambda and Power One are names to look for. Every so often a decent adjustable benchtop supply will turn up as well.

It's possible to make quality switching supplies, at a former job we used Vicor, their stuff was good, and we never had issues even though we used them in industrial process control applications where we were taking sensitive measurements. I've seen Vicor supplies turn up now and then at hamfests.

When I bought my GPS reference (used, a pull from a cell phone tower installation), it came with a Pride of China supply. That thing generated all sorts of RFI, including junk right on top of the 518 kHz NAVTEX frequency. I found a Power One linear supply with the appropriate outputs (5 and 12 volts), and it's been great since, no RFI at all.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Pigmeat

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Re: Power Supply for TX
« Reply #10 on: January 31, 2018, 0225 UTC »
BTW, if you're not a hamfest vet avoid anything with a cut cord, unless you're looking for parts and a box. The cut cord means it's shot. Sniff for ozone if the cord hasn't been cut, that's a telltale sign, as are black scorch marks from arcing when you open the the box and any obviously blown parts.

90% of people at hamfests are straight shooters, it's the other 10% you've got to watch.

Offline redhat

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Re: Power Supply for TX
« Reply #11 on: February 01, 2018, 1918 UTC »
But then again your dealing with hams, most of which these days don't know how to fix anything (appliance operators).

+-RH
Somewhere under the stars...
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Please send QSL's and reception reports to xfmshortwave [at] proton [d0t] me

Offline ThElectriCat

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Re: Power Supply for TX
« Reply #12 on: February 02, 2018, 0034 UTC »
If you want a used one,  I agree with the eBay/ hamfest idea, but also advise you to acquire a linear power supply rather than switchmode.

if you want to buy a new one, I wholeheartedly recommend Astron power supplies, I have one rated for 20 amps at 12 volts, and it will gladly provide its maximum power with almost no ripple day in and day out
In another life, I could have been a telephone engineer.

Offline ION Radio

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Re: Power Supply for TX
« Reply #13 on: February 02, 2018, 1046 UTC »
If you want a used one,  I agree with the eBay/ hamfest idea, but also advise you to acquire a linear power supply rather than switchmode.

if you want to buy a new one, I wholeheartedly recommend Astron power supplies, I have one rated for 20 amps at 12 volts, and it will gladly provide its maximum power with almost no ripple day in and day out

A linear PSU is what I think I will eventually get, Astron has great reviews.


Thanks ALL!

-IR
QTH- East of everywhere.
ICOM and 40m Dipole
ionradioshortwave@gmail.com

Offline ChrisSmolinski

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Re: Power Supply for TX
« Reply #14 on: February 02, 2018, 1219 UTC »
Astron makes great power supplies. I have one I bought back in the 90s, and it still works. The only thing I had to recently was replace the lighted power switch.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

 

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