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Walking on the Moon

Need A 13.8v 20 amp PSU


Stargazer33
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Hi, I'm in the final stages of designing my new power distribution hub after the psu in my old one died on me.

I am going for a different design with the distribution box mounted on the mount, over the polar finder hole. My intention is to then have a totally separate bench power supply running power to my distribution box and then on to the mount, DSLR, USB hub, dew heater tapes etc.

The thing is I'm having trouble finding the right bench PSU. I want 13.8v to properly power the mount and all the tech I will be running is close to 20 amps with a bit to spare.

Can anyone recommend a bench PSU with these specs? I can't afford to go much more than £60-£70, which I  know isn't going to get me much, as long as it's reliable.

I intend to post my build when I start. Thanks for any suggestions!

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Thanks Souls! Both of those look good. I was looking at ham radio power supplies because of the low noise, but as soon as you read one bad review it kind of puts a doubt in your mind. ?

John; a little above my preferred spend, but a personal recommendation is worth its weight. Can I ask how long you have had your power supplies and how long do you run them for during a session?

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No Prob Bryan,

I previously owned the 8A Nevada's but it wasn't enough to power my laptop and all my kit when slewing, so I purchased the first Nevada PSW-30 last October and when the seeing is good in the winter I will run it from just before it gets dark until 3 or 4 in the morning, so 12 hours at a time, last night it was running from 20:00 until 04:35 this morning, not one single problem or failure with them.

I was watching the output graphs etc from my Pegasus Ultimate Power Box last night and it was so stable I would have paid 3 times the price to get that quality of supply.

One feeds my equipment and was drawing a max of just under 3A last night and the other runs my laptop as that has every energy saving option switched off and runs an i7 16GB 17" screen with a 2TB HDD, 4 USB 3.0's as well so the last thing I want is for their to be a loss of power to one that affects the imaging.

Hope that helps.

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No worries Bryan. I know exactly what you mean.

I wouldn't be advocating a switching PS but if i were to suggest you anything, it would be a linear PS which is cleaner power.

Also, there's another company called Fusion who makes switching PSU. They're supposed to be good too.

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Thanks again John! That does sound pretty good. I think my set-up might draw a bit more than 3 amps though! I'll be running my mount, focuser, 2 dew heater tapes & USB hub - running two cameras. I think the mount on it's own draws nearly 3 amps when slewing, but that will obviously only be for short periods.

As my road tax isn't due 'til October (thought it was due 01 September) I will have a think about getting one of those. Mind you with all these darn potholes I'm thinking about withholding my road fund payment 'til they fix some of them, properly, and not just drop a lump of quick set tarmac in the hole!!!

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Hi souls, thanks! I have read a bit on the discussion between switching and linear PSU. I did think that the switching PSUs used for ham radio would be better on noise as they are all quoted as having very low RFI. I guess the linear ones are a lot more expensive. I'll have a look into them though.

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8 hours ago, Stargazer33 said:

Hi souls, thanks! I have read a bit on the discussion between switching and linear PSU. I did think that the switching PSUs used for ham radio would be better on noise as they are all quoted as having very low RFI. I guess the linear ones are a lot more expensive. I'll have a look into them though.

I had a thread going on not too long ago which was very well explained by the pros here the difference between a switching and linear PSU. I ended up with the linear QJE brand which as you rightly pointed was expensive.

I have also found out another PSU for you https://www.rothervalleyoptics.co.uk/mercury-138v-15a-bench-top-power-supply-unit.html not sure if 15A is going to be enough?

Hope this helps.

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Just bought this: http://www.nevadaradio.co.uk/used-equipment/nevada-ps-30m--b-grade-model-

Spent more than I intended, but then isn't that always the case! ??????

Now I can get on with my new power distribution hub. I will be using a lot of parts from my old one so you will excuse me if I hope it's cloudy for the next couple of weeks, 'til I finish! ?

Build to follow in a new thread.

Thanks to souls & John for your thoughts and guidance. ?

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2 hours ago, Stargazer33 said:

Just bought this: http://www.nevadaradio.co.uk/used-equipment/nevada-ps-30m--b-grade-model-

Spent more than I intended, but then isn't that always the case! ??????

Now I can get on with my new power distribution hub. I will be using a lot of parts from my old one so you will excuse me if I hope it's cloudy for the next couple of weeks, 'til I finish! ?

Build to follow in a new thread.

Thanks to souls & John for your thoughts and guidance. ?

Good man, you won't be disappointed with Nevada. They're great company. Enjoy you PSU experience mate and you're welcome? 

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7 hours ago, Stargazer33 said:

Just bought this: http://www.nevadaradio.co.uk/used-equipment/nevada-ps-30m--b-grade-model-

Spent more than I intended, but then isn't that always the case! ??????

Now I can get on with my new power distribution hub. I will be using a lot of parts from my old one so you will excuse me if I hope it's cloudy for the next couple of weeks, 'til I finish! ?

Build to follow in a new thread.

Thanks to souls & John for your thoughts and guidance. ?

If you can cancel that one then do so as it is no where near as stable as the one I bought and the price is £5 cheaper

I looked at both and the one I bought is so stable and weighs a 1/4 of the weight.

Here's the spec: -

It is also engineered to minimize the switching noise specifically for amateur radio use. If minor noise does occur it can be eliminated with the Noise-Offset function. Includes pre-set voltage and back lit meter as standard.

Nevada PSW-30

  • Description: Input Voltage: 240 VAC
  • Output Voltage: 9-15 VDC adjustable or 13.8 VDC fixed
  • Output Current: 25 A continuous, 30 A surge.
  • Output Voltage Regulation: Less that 2%
  • Ripple: Less that 80mV p-p at rated load.
  • Front Power Connectors: 10A cigarette lighter plug + pair 3A push-in terminals
  • Rear Power Connectors : 2  x large 25-30A Red/Black binding posts
  • Controls: Voltage/Amperage meter switch (front), power
  • switch (front), Noise Offset control (front), Variable/13.8V
  • Fixed voltage switch (back)
  • Weight: 2.3 kg / 5 lbs
  • Size :190mm W x 69mm H x 181mm D (7.5 in x 2.7 in x 7.1 in)
  • Warranty - 2 years

I think its Helen in the Office at Nevada and she is really helpful.

The one you have bought really does struggle when a heavy load is put on it, although it will handle it, it isn't as efficient.

Edited by Jkulin
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Thanks John. I knew I would make the wrong decision! If I had the choice of one I would still pick the wrong one!

Anyway, the PSU arrived today and I've powered up the mount from the 10 amp max ouput cigar lighter socket at 13.8v and slewing in both alt and dec barely caused the amp meter needle to flicker and the CGEM is supposed to draw upto 3.2 amps.

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On 26/08/2018 at 15:14, Stargazer33 said:

Just bought this: http://www.nevadaradio.co.uk/used-equipment/nevada-ps-30m--b-grade-model-

Spent more than I intended, but then isn't that always the case! ??????

Now I can get on with my new power distribution hub. I will be using a lot of parts from my old one so you will excuse me if I hope it's cloudy for the next couple of weeks, 'til I finish! ?

Build to follow in a new thread.

Thanks to souls & John for your thoughts and guidance. ?

I have the same power supply and it has never let me down. Running all of my gear and LED Observatory lights without problem.

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Question - must the voltage be 13.8v, or would 12v be enough if it doesn't dip under load?

A half-decent PC PSU would be well able to consistently deliver >20A at 12v, and generally low RFI given the use inside the PC case faraday cage. Also those PSUs should maintain 12V under load.

It may be a cheaper option if you're willing to solder a few connections for the power plugs. This is definitely the route I'm taking to power items if/when I get myself any permanent observing area.

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I was running 22m of 2.0mm cable and although the PSU was easily handling the A requirements the voltage dropped to under 12v when under heavy slewing, so I made up new 22m cables with 2.5mm thickness and gave the mount it's own feed from the 10A power socket at the front and the V never dropped below 13.1 the whole of Wednesday night ?

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