Author Topic: Proven Ham radio Power Supply 13.8V 25-30A  (Read 6635 times)

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Offline HoracioDosTopic starter

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Proven Ham radio Power Supply 13.8V 25-30A
« on: October 26, 2021, 01:50:05 pm »
Hello.
I need to power a ICOM7100 and I can't find a linear power supply where I live, I only find cheap switching power supply from China and I don't want to spend time trying to filter the noise. So I need to build a linear one. Does anybody have a proven and simple design? I just want to build one and go.
Thanks in advanced
 

Offline BeBuLamar

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #1 on: October 26, 2021, 04:23:17 pm »
25-30A linear is going to be very big. You need a transformer that can handle that kind of current also very large capacitor.
 
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Offline CJay

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #2 on: October 26, 2021, 05:06:43 pm »
Oldie but a good one, look for PW Marchwell or take a look at the Astron schematics for ideas.
 
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Offline Manul

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #3 on: October 26, 2021, 06:52:41 pm »
Is this peak or continuous current? If you want cheap, hacked-together supply, you might be able to use car battery and a linear charger attached to it. Both are widely available. Lead battery will provide huge peak currents and good ripple filtering. 5 or even 10A linear chargers are available. There is also a benefit, that radio can be used for up to a few hours under blackout.
 
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Offline HoracioDosTopic starter

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #4 on: October 26, 2021, 07:28:18 pm »
Hello Manul
25A continuous current @100W. I'm sure I will not have to worry about noise. LOL. If I get a 12V 30A battery and a floating charger I could start from there. As I'm getting my license I only do RX, So I only need 5A.  I must connect RF ground as usual. Thanks! 
« Last Edit: October 26, 2021, 07:51:04 pm by HoracioDos »
 

Offline Manul

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #5 on: October 26, 2021, 08:08:58 pm »
69W for RX? That seems like a lot.

And what would be typical duty cycle when both TX and RX? 10A charger might be enough to keep battery from draining down in practical usage scenario, the only way to know for sure is to measure real world average current.
 

Offline BrokenYugo

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #6 on: October 26, 2021, 08:18:22 pm »
Are those those cheap surplus 12V server supplies quiet enough? Some are easily modified to output 13-14V, power tends to fall in the 750 to 1500 watt range. 
 

Offline HoracioDosTopic starter

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #7 on: October 26, 2021, 09:43:40 pm »
Hello.
I'm listening WFM radio now and transmitter is taking 0.625A
 

Offline edtyler

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #8 on: October 26, 2021, 11:20:30 pm »
Have a look at the Astron linear supplies. Very reliable, easy to repair and relatively inexpensive used. I have three RS-50A supplies. One powers a IC-7300, FT-8800 and Flex-6600 simultaneously (Only one transmitting at a time).

The only issue is high standby current and lower efficiency than switching supplies at low currents.
 
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Offline johnboxall

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #9 on: October 26, 2021, 11:35:05 pm »
If you're happy to build it yourself, consider the VK Powermaster. Example - http://www.philipstorr.id.au/radio/seven/vkpower/VK%20Powermaster%2084.pdf
 
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Offline richard.cs

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #10 on: October 27, 2021, 08:52:46 am »
A warning if you go to build something - older designs with 2N3055 transistors as the pass elements can often be unstable with modern transistors. This is easy to fix if it happens, just something to check for. It's because the 2N3055 specification is very broad with no upper limit on Ft, so much faster transistors made on modern processes can still meet the specification of and be sold as 2N3055.
 
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Offline radiolistener

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #11 on: October 27, 2021, 08:57:25 am »
Here is 13.8 V / 50 Amps PSU:



Tr1 should have 20 V no-load voltage and 16 V under 50 Amps load (after rectifier and capacitor).
Tr2 should have 24 V 0.5 Amps (after rectifier and capacitor).

here is description in Russian: http://www.ra4a.ru/publ/bloki_pitanija_i_zu/1/12-1-0-838


Be careful with high currents, it can make fire and burns!
 
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Offline Psi

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #12 on: October 27, 2021, 09:01:01 am »
Wouldn't be that hard to rip the HV winding from a microwave oven transformer and add your own windings to give 13.8V at 30A.
They normally do over 1kW,  for you 13.8V @ 30A is only 414W.
Granted, they don't normally run continuous and sometimes have a fan on them, but you only need 400W.


There's lots of DIY guides for turning microwave oven transformers into spot welders at ~2V or so
Just need ~7x as many turns.
« Last Edit: October 27, 2021, 09:04:22 am by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)
 
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Offline richard.cs

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #13 on: October 27, 2021, 09:14:11 am »
Microwave oven transformers are a bit short on primary turns so run at very high flux densities, especially at light loads (which in a microwave is fine because they never have light loads). I don't think I would use one in this application, it'll run pretty hot even off load.
 

Offline HB9EVI

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #14 on: October 27, 2021, 09:50:32 am »
I almost entirely use Meanwell PSUs, high power linear power supplies are a pita; it's not worth bothering with them
in my Shack for my TS-2000X I use this:

https://www.mouser.ch/ProductDetail/MEAN-WELL/RSP-320-135?qs=%2Fha2pyFadujFkvpksmE%2F%252Bx4juEINt6RZLAjLGiMQXJJ4RgS82SPwTQ%3D%3D

even if it's not declared as 25A continuous, it never let me down on my activities; and it delivers a very clean voltage; so no need for external filtering.
 
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Offline radiolistener

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #15 on: October 27, 2021, 10:01:12 am »
I almost entirely use Meanwell PSUs, high power linear power supplies are a pita; it's not worth bothering with them
in my Shack for my TS-2000X I use this:

Many ham amateurs using Meanwell PSU for transmitters in my location. It's easy to detect them by high background noise when they TX :)

It works, but it is very unpleasant to hear that noise.
 

Offline richard.cs

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #16 on: October 27, 2021, 10:19:16 am »
If you're going to build one I quite like this design with the pass transistor collector common with the negative output. It gives you low dropout without an auxiliary transformer and also eases the heatsinking.
https://ludens.cl/Electron/Ps20/Ps20.html

Manfred also has a low-noise switching design for the ambitious builder:
https://ludens.cl/Electron/PS40/PS40.html
 
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Offline Psi

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #17 on: October 27, 2021, 11:13:35 am »
I have a 40A meanwell psu running the 14 meters of LED strip around the ceiling of the bedroom.
If the lights are on the FM radio is jammed all to hell.
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline HB9EVI

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #18 on: October 27, 2021, 11:14:38 am »
Many ham amateurs using Meanwell PSU for transmitters in my location. It's easy to detect them by high background noise when they TX :)

It works, but it is very unpleasant to hear that noise.

do you have some hard facts for that? I know that Meanwell is often first choice in the ham domain, also by some very picky operators, who are fond of and engaged for their clean signals; so it'd surprise me
 

Offline radiolistener

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #19 on: October 27, 2021, 12:57:06 pm »
do you have some hard facts for that?

Yes, I hear this noise with my own ears. One time one of these amateur with Meanwell PSU got linear one for a short period of time. And when he tried to work with linear PSU, I notice very well that background noise disappears. The test was very impressive because the difference was just amazing. The sound of his station with linear PSU became crystal clear. With Meanwell PSU it was unpleasantly noisy.

Also he reported that he got much less noise floor with linear PSU and can listen much more weak stations, which is under the noise with Meanwell PSU. Before that case he advertised Meanwell PSU for TRX, but after that he is not so happy with it anymore :)

I know that Meanwell is often first choice in the ham domain

Yes, exactly. As I said above, many ham amateurs in my location using Meanwell PSU. But it doesn't means that this is better choice. This is just a cheap, lightweight and compact compromise. But it affects your receiver sensitivity and add noise on TX.


Some time ago I also tried to use Chinese SMPS for my QRP TRX. Cheap, small and nice... But later when I compared it with linear one, I never use SMPS for radio anymore. Because SMPS produce a lot of noise.
« Last Edit: October 27, 2021, 01:17:21 pm by radiolistener »
 

Offline CJay

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #20 on: October 27, 2021, 07:38:01 pm »
I almost entirely use Meanwell PSUs, high power linear power supplies are a pita; it's not worth bothering with them
in my Shack for my TS-2000X I use this:

Many ham amateurs using Meanwell PSU for transmitters in my location. It's easy to detect them by high background noise when they TX :)

It works, but it is very unpleasant to hear that noise.

I proved this to a couple of hams at my club by monitoring the TX fundamental of a 6M transverter with a spectrum analyser and switching between one such "quality" SMPSU and linear PSU, the noise was obvious and quite unpleasant.

I don't doubt it could be improved and filtered but it would take a lot of effort.
« Last Edit: October 27, 2021, 07:50:46 pm by CJay »
 
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Offline David Hess

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #21 on: October 27, 2021, 07:56:17 pm »
I also recommend checking the schematics for the various Astron linear power supplies which show how it is done with 2N3055s power transistors and a 723 regulator.

I have also done it using a PNP power transistor boosted LM317 with the board mounted directly to the large electrolytic input capacitors.  The example below shows how this is done and is better than what I did at the time.

In either case, plan on using more than one power transistor in parallel to get sufficient power dissipation capability.
 
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Offline m3vuv

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #22 on: October 30, 2021, 06:53:55 am »
To me having a smps in the shack is like having dracula in charge of the bloodbank,dont go there!!!
« Last Edit: October 30, 2021, 06:55:28 am by m3vuv »
 

Offline David Hess

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #23 on: October 30, 2021, 09:49:49 pm »
To me having a smps in the shack is like having dracula in charge of the bloodbank,dont go there!!!

A switching power supply may be quiet enough to power radio equipment, however it is difficult to know ahead of time and without testing.
 

Offline radiolistener

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Re: Proven Ham radio Power Supply 13.8V 25-30A
« Reply #24 on: October 31, 2021, 09:43:20 am »
it depends on equipment sensitivity. But anyway good SMPS with low noise requires expensive filtering and shielding measures, so they are more complicated and much more expensive than linear one. So, it can make sense if there is very high power (for example 10-100 kW and above) and linear PSU will needs very expensive transformer.
« Last Edit: October 31, 2021, 09:46:48 am by radiolistener »
 


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