Bench Top PS advise

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#41
AkanameJones said:
Hello All,

I didn’t see a post or sticky about it which is kind of surprising-forgive me if I missed it. Anyway, I’m seeking guidance on buying my first PS as I get into building. My primary focus will be (no surprise) power amplifiers. I’ve already determined I’d prefer linear power but that’s about it. Would multiple outputs be very useful? What voltage and amperage do you recommend? What features are make or break for you? As I said, I’m just starting out so I don’t need much but I would also prefer not to outgrow it in a year or two. I don’t have a ton of money to throw at this, but I feel I can go up to $300. Thank you for your help and patience.

-The New Guy
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Follow up post. Thanks for all the information and input guys, this was a very nice welcome to what can be an intimidating community. I pulled the trigger this morning on a very clean HP. 6227B and am very pleased. OK. Sitting down to listen to Wait Wait Don’t Tell Me, drink coffee, and read the manual. Have a great weekend!
 
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#43
rsavas said:
That's funny, because I was testing out the Samuel Groner low noise pre-amp I built recently, it had a spur in the output, I could not figure it out. Jan suggested scope your grounds, PS etc, well it turns out the college project lab supply was the cause. I open it up, a rats nest 🙂 It has lots of 3 terminal regulators in it, wires running everywhere, a bunch of Motorola crow bar chips, scr's, two humming Hammond transformers put me over the edge.
Well one of the other regs that I was not using was oscillating. All the DC voltages were fine until I through a scope on it 🙂 I can confirm that a lm317t makes a clean oscillator in the low MHz's region 🙂
I said screw it, I ain't going to fix the rats nest and bought a HP6227B and 6228B for total ~ $400 CDN landed, just recently, one arrived and the other is on its way for xmas 🙂 I hope it does not need work. Now I do have good PS designs in pcb form that I could have used and it is a much cheaper alternative.
The 6228B is good for testing everything up to +/-50V at 1A, anything above that for an amp can be unregulated since its usually for the output stage. I got the 6227B as well since at times I need more than two supply voltages. Also the DSO will fit nicely on top of the two supplies 🙂
I looked up the datasheets on those HP supplies, check out the prices, Crap our dollar these days is like 70 cents to the USD too. I think it was about the same in the 80's. No damn way I was going to afford one until, I retire and folks do not know their value anymore, do not care or they are almost at scrap level 🙂
I scoped the 6228B outputs, it's clean and stable, on to testing the SG LN pre-amp again. Those damn electronic lamps spray radiation everywhere.
Interesting I found out that the 6227,6228, use a old RCA CA3025 dual differential amp chip which is the TO-5 can version, the CA3054 is the dip-14 version and also M5109P is a version too. Also that the old HP factory in NJ is now a condo or apartment unit, the internet is wonderful for some 🙂
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Right on. I just pulled the trigger on a very clean 6227B. Can you tell me why it is interesting for them to be using the chips you mentioned?
 
#46
While looking at vintage power supplies the Lambda linear supplies are really good and pretty bulletproof. I have 4 hat all are really useful. The Power Designs, Kepko and even Heathkit supplies are also very good. Most of these have really low noise and conservative design.
A real bench supply for a 100W amp should be able to support 200W+ which make it a large and heavy supply. That's why power amps rarely have regulated power supplies, the extra headroom required makes them large heavy and expensive and rarely makes a difference in the output.
 
#47
Built several. My best:
2x MEAN WELL LRS-350-48
2x DPS5005
Totally programmable volts and amps.
 

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