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  #1 (permalink)  
Old 09-30-2018, 9:57 PM
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Default 12v Power Supply Options

I recently installed a mobile HAM radio in my home garage to eavesdrop on some of the local hunters. It's just a cheapo BTech radio. Seems to be receiving great and works for what I wanted a radio for.

However, after a few weeks of this thing sitting here I decided to try and hit some repeaters in my area just to see how far the radio is actually reaching. The problem is that the radio is rebooting each time the mic is keyed. I thought maybe this could be an SWR problem and perhaps maybe the radio had some sort of protection built in. I never checked SWR's. But I checked the voltage at the radio and when I key the mic I'm dropping to 9.xx volts.

The power supply is a $38 Amazon special. Pyramid brand. Rated at 5v. Obviously not the right power supply.

So, what supply do I need? So many options and meters and pretty lights. I don't even know what I need after reading about them. I just want something I plug in, hook up and it works.

Links?
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Old 10-01-2018, 12:19 AM
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A 12v switching power supply will do it. I am not familiar with your radio, but I'm figuring your VHF/UHF radio may pull 15 Amps maximum at full power.

Check this site for a list of various power supplies. If you want a specific recommendation, you should be fine with a Samlex SEC-1223. I have used one for five years with zero trouble. It provided power for a 100 watt radio, so it will handle your 50W max. That model does not have a meter, but they do sell one that has one. I personally never found the need for it.

https://www.universal-radio.com/catalog/hamps.html
I have purchased from Universal Radio with zero problems. You may find what you're looking elsewhere for less or more.

Looks like it is available on Amazon as well, if you prefer them.
https://www.amazon.com/Samlex-SEC-12...eywords=samlex

P.S. Stop trying to transmit using a 5v power supply, that is just foolish. Also, check your SWR. You clearly know what you need to check/do so do it. If you do not have an SWR meter join a club local to you and see if someone can help.
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Old 10-01-2018, 3:27 AM
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The meter is good for wow whiz
Else it's good to see that when you key up the transceiver it's actually drawing power.

I found that a good rule of thumb is indeed to get a PSU that can supply (RF rated radio watts)*2.5 to 3 watts - so a typical 50W radio needs 125W to 150W PSU. But if the radio specs it in the documentation, that's what you should use, but you should add a little margin. If you plan to hook up multiple radios, you should spec to the most number of radios you would expect to transmit together at any one time. Likely this number will be 1, and hence it's okay to use one 150W PSU to power even ten 50W radios - based on the fact that only one will be transmitting at any one time.

I still don't have a real ham rig, still using UHF LMRS radios in the ham bads. My 35W unit seems to work okay with a 60W (rated) PSU but fails with a 40W (rated) PSU, though I'm likely pushing my luck with that 60W'er. My 2W-10W UHF LMRS radio seems to work with that 40W PSU just fine. Both these PSUs are switching PSUs.

On the other hand my 2W-10W UHF LMRS radio does not like being powered by my 2A bench PSU and insists on more current to be able to transmit.

Now whether or not you want to get a linear or a switcher... IMHO it's really dependent on the design of the PSU, there are RF quiet switch mode PSUs out there which will save you power in the long run and your back in the short run.
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Old 10-01-2018, 7:39 AM
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Dont play games with power supplies, invest some money in a Astron30 amp switching power supply with meters on it, it will coast along for years and never know there is a load on it.
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Old 10-01-2018, 9:48 AM
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Something like this?
https://www.dxengineering.com/parts/asr-ss-30
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Old 10-01-2018, 11:43 AM
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Hi Hank
.
You really need a decent power supply, not something Mickey Mouse'd.
.
For my entire laboratory life I insisted on these power supplies:
.
Astron Corporation
.
.
We used them all over the world- from the steamy Central Pacific to the frozen ice fields of the Arctic and Antarctic. I can not recall one ever failing me- which is not the case with other manufacturers- sometimes with **Very** Bad results.
.
Seems my luck always ran to these failures- plural- with switching supplies. After the last such memorable occurence that required a big (expensive $$) Halon fire extinguisher, I have been leery of them. I like the conventional heavy transformer stuff- but what's the saying?
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"Once burned (literally!) twice shy."
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To each their own, but if you decide on a conventional Astron you can save yourself money by not needing to buy a standby fire extinguisher.....smiles
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.
.
Lauri
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__________________________________________________ __________
.
This is all over dramatized, but it doesn't change how I feel about switching supplies- personally of course. Astron makes switching supplies that work just fine.
Save the Hue and Cry, guys-- I know 99% will disagree with me, but you won't change my feelings about this.... and its *Feelings* that we get that are based on experiences, No ? ... like pawing thru the charred remains of a 3 month, $$ project in a cold, cement bunker ... uggggh
.
.

.

Last edited by Lauri-Coyote; 10-01-2018 at 12:02 PM..
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Old 10-01-2018, 12:44 PM
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Thanks for your help. I've ordered an Astron SS-30.
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Old 10-01-2018, 12:46 PM
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I've had charred remains of switching PSUs too but it hasn't stopped me from using them, just need to carefully select the good ones. I just like them because of them staying relatively cool and not being backbreaking to move them, especially when dealing with hundreds of watts.

Offtopic but slightly relevant - I have an ancient SCR based variable bench PSU 0-18V 0-15A CC/CV (but I don't use it on my radios). It overshoots pretty badly during a large negative di/dt. I wonder if I should design/add a clamp circuit to quash the overshoots and how badly it will interact with its regulator...

(and my spare parts bin is screaming at me to design/build a linear PSU, only because they are collected parts (big heavy transformer, bridge rectifier, 2N3771s, paint can sized capacitors, LM723s, etc., etc.) that may never get used by themselves... uugghh)
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Old 10-04-2018, 9:39 PM
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I have Astron RS-35M and Astron SS-30M. The RS-35M is in the shack. Rock steady. I do not care for the connections in the SS-30M. For an easy portable supply I got the Powerwerx SS-30DV. I did modify the Astron SS-30M to have Anderson Power Pole connectors in the back. Good luck!

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Old 10-07-2018, 12:55 PM
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It's self protect mode in under voltage,most of these are knock offs of older Yaesu equipment ,i have a big Rs 50 linear supply that's variable and once in awhile my dog will will turn the voltage down and I will key up and reboot ,i added the bb 30 m problem solved ,i have enough batteries to run several months continously at 200 watts ,if powersupply isnt sufficient it automaticly brings the batteries online .yes thats an excessive amount of power on tap but the batteries are free ,so why not ?

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Old 10-07-2018, 1:15 PM
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You have been given some good feedback. But the real bottom line here is to sit back and really decide just what your long range plans are.

Then look at the radio or radios you want to use and check the specifications. Pay close attention to the transmit current. You need to have a power supply that has the ability to supply more current than the radio needs in transmit.

So if the radio will draw say 10 amps in transmit, I would suggest that you obtain a power supply with at least 15 amps of continuous ability. Now if your going to have multiple radios connected, then look at the receive current requirements and add up the number of radios with that current draw. Then add the transmit current draw of the highest power radio. Don't forget to add a buffer in the total current draw.

If you have no plans for any 100 watt radios, there is no need to go the route of obtaining a 30 or 35 amp bench supply.

I like to have meters on my power supplies. That way I can see what is going on in both receive and transmit modes with the radios connected. Gives you a good indication of a pending problem or if the supply has rolled over on you.

Good luck on your endeavor.
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Old 10-07-2018, 2:46 PM
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Switching supplies are cheaper but tend to make noise on HF,all of mine are linear and some have been on continuously for 17 years,the light in the switch is starting to twinkle,i have tried some switching for "light duty" they all failed and so help God, i have 30 years experience and guys senior to me could not fix them so they ran ,if you can afford linear supply I would reccomend them they work and when they don't you rebuild the damn thing and it runs another 20 trouble free years .if you send me a PM I can give you a candy store that sells used units that are good and serviceable it's ham owned so your not getting screwed ,he gets the old Sherman tank Kenwood,Icom and such when guys trade in there entire station.my rule of thumb has always been plan for the station of your dreams ,so down the road when you get there you don't have to buy new gear ,when I became a ham I couldnt afford a dual band all mode ,but i planned for needing to power multiple 100 watt output rigs ,30 years later I have four or five radios in every room of the house (it just kinda happens over time)between the best of old school rigs you keep because you love them and the new school SDR based gear ,unless you get ruthless and ditch the old everytime you get something new! I buy radios the same way with features and capabilities I don't "use " ,so when boredom hits and you want a challenge ,it's only a twist of the knob or button press away ,it's a method of future proofing your investments .

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Old 10-07-2018, 5:25 PM
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I agree with everything said here, all true. Except it was true 30 years ago and today the art of designing and building a switching power supply today probably exceeds the MTBF of analog linear supplies of 30yrs ago. Modern switchers are very RF quiet and can be extremely reliable.


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Switching supplies are cheaper but tend to make noise on HF,all of mine are linear and some have been on continuously for 17 years,the light in the switch is starting to twinkle,i have tried some switching for "light duty" they all failed and so help God, i have 30 years experience and guys senior to me could not fix them so they ran ,if you can afford linear supply I would reccomend them they work and when they don't you rebuild the damn thing and it runs another 20 trouble free years .if you send me a PM I can give you a candy store that sells used units that are good and serviceable it's ham owned so your not getting screwed ,he gets the old Sherman tank Kenwood,Icom and such when guys trade in there entire station.my rule of thumb has always been plan for the station of your dreams ,so down the road when you get there you don't have to buy new gear ,when I became a ham I couldnt afford a dual band all mode ,but i planned for needing to power multiple 100 watt output rigs ,30 years later I have four or five radios in every room of the house (it just kinda happens over time)between the best of old school rigs you keep because you love them and the new school SDR based gear ,unless you get ruthless and ditch the old everytime you get something new! I buy radios the same way with features and capabilities I don't "use " ,so when boredom hits and you want a challenge ,it's only a twist of the knob or button press away ,it's a method of future proofing your investments .

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Old 10-07-2018, 7:22 PM
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Prcguy I am always willing to try again ,any ones you reccomend ? My kitchen could use a new power supply ,something I could mount under the cabinets would be awesome!

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Old 10-07-2018, 9:24 PM
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I have several from Astron including the SS-18, SS-25 and SS-30 series with some running continuous 24/7 for over 20 years with no problems or RFI. I just acquired a Powerwerx SS-30DV and its also RFI free and Elecraft sells this one so it has to be good quality. There are others that are known to be low RFI and good quality but I forget the brands and model #s.

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Prcguy I am always willing to try again ,any ones you reccomend ? My kitchen could use a new power supply ,something I could mount under the cabinets would be awesome!

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Old 10-08-2018, 4:56 PM
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Default Switchers vs Linear

I agree with Laurie: nothing beats Big Iron Transformers and Big Bad Capacitors for a quiet, reliable power supply. But practically speaking, switchers are where it's at.

Remember that all things are engineered to produce the specified result at the lowest possible cost. Most COTS switchers are designed to provide best performance at rated output, because that is the first and primary specification most of us consider when reading the spec sheet. But, a switcher may be very 'quiet' when loaded to 10 amps, yet be very VERY noisy when only loaded to only 100 mA.

You have to read the specs carefully.
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Old 10-09-2018, 12:54 PM
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Quote:
Originally Posted by prcguy View Post
I just acquired a Powerwerx SS-30DV and its also RFI free and Elecraft sells this one so it has to be good quality.
I have an SS-30DV and it works well for me, but I noticed some noise on 6m when that model is turned on. Nothing massive, but it did raise the noise floor. It's more of my toolbox power supply for temporary projects. Hmm...I received some 43 and 31 beads yesterday. Time to test a few loops through the core.

Let me know if you observe anything around 6m with yours. Maybe mine is just a little wonky.
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Old 10-09-2018, 1:04 PM
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1hank1 are you a licensed ham operator? Some of your words make me question. Sorry if wrong.
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