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Reviews For: Pyramid PS-53KX Power Supply

Category: Power Supplies

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Review Summary For : Pyramid PS-53KX Power Supply
Reviews: 14MSRP: 257.00
53 amps peak, 12-15 VDC power supply w/thermal and overvoltage protection.
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
KB1KVL Rating: 2015-03-22
Review Update Time Owned: more than 12 months.
This is an update from 2006. It is now 2015 and as stated before, this is not the PS-53KX, but the PS-52KX. My review before stated that I had no problems up to that point.

I have now owned that power supply 14 years with one problem. The fan bearings got noisy. I replaced the fan with one at the local electronics store for $20-$25. After 15 years service for as many hours in a day I use it, it owes me nothing. Would I recommend it to a friend or relative? You bet I would!
N8FVJ Rating: 2014-11-04
Not so good Time Owned: 0 to 3 months.
Transformer operates hot with no load. Possibly a 100 volt primary design vs 120 volt or operating near saturated core to get every amp with less voltage drop (no reserve). Cheap capacitor bank pushing the capacitors way beyond recommended ripple current even at 50% duty.

Get an Astron.........
KA2LIM Rating: 2014-05-03
Leaves a lot to be desired Time Owned: more than 12 months.
Transformer is robust. The rest of the circutry is junk. We have had to re-build 4 of these units with heavier components and only then will they work. The circut board that is in these things must have been designed by someone on dope.- pure crap! do not buy....
KB2TEK Rating: 2011-04-08
Pyramid PS86 Time Owned: 0 to 3 months.
Trust me people of God Pyramid Power Supply.
Junk and they will not make good on anything.
And this one almost burn our house down. ANd there was no load at all, not even 4 amps drawing on a 86 amps poweer supply. 16 days old they would make good on it
KC8UIO Rating: 2011-04-03
Great PS for 99 bucks! Time Owned: 0 to 3 months.
If you don't like it, you could go buy a Tripp-Lite equivalent for 250 bucks.

Don't try to get 60 amps out of it; it says, "50 AMPS."

The PS-52KX is very close to this model.
W6EM Rating: 2009-11-02
Needs Rework....... Time Owned: more than 12 months.
I did 3/4 of what WB4FUR did to my PS-52KX, and I'm not finished.

The ballast resistors, if 0.1 ohm units are used, limits the current to just about 5 amperes per transistor. 8 times 5 is 40 amps. Better to reduce them somewhat to about .08 to be able to realize the 52 amps.

And, the jumper from the junction of all of the emitter wires terminates in one No. 12 going to the red terminal. Imagine how hot a No. 12 wire will get with upwards of 50 amps on it.

The crowbar circuits in this and another Pyramid I have leave a lot to be desired. Traces won't handle short circuit currents well above the rated currents of the supplies. Get bigger SCRs and wire them so they can take probably more than 100 amps for a few milliseconds til a real fuse blows, not the board trace.

I'm going to use an SCR rated for about 40 amps continuous with an I squared t of about 1600 since it has to last long enough to open the AC line fuse.

One of the reasons Astrons last is that they have transient overvoltage protection on the LM723 regulator and Pyramid doesn't. The 723s will pop just above 40 volts, so if their inputs aren't clamped with a zener, well....... Also, Astron uses a TVSS on the transformer too.

AI3I Rating: 2009-10-26
As the numerical rating says... "Needs Help" Time Owned: 0 to 3 months.
I too have one for repeater service, and fortunately, it was shut off before it had a chance to do any damage. I had a small short (my error) and instead of the supply shutting off, it took out the regulator and decided to soar to 24-25 VDC as well. While I agree that it was poorly designed, I concur with WB4FUR and his remarks about this supply having great potential. I fully anticipate rehabilitating mine and also want to go on the record-- beware if you purchase this unit and intend on using it with any expensive equipment, especially repeaters. Best of luck!
KG8FV Rating: 2009-05-09
Poor quality Time Owned: more than 12 months.
This power supply is not made for repeater use! BEWARE! use a ASTRON instead!. The rectifiers are 35 amps so giving you a 70 amp surge well at 50 amps you only have 20 amp lea way. Mine blew up went 24 dc and ran away! blew up my controller. I got the supply fixed ran 5 month and went out again! this time around I'm going to put in the TWO 50 AMP rectifiers!. So we can get more backup. But this thing is just for normal use it would probably be ok but in a repeater environment no way!
KE7FFM Rating: 2009-05-02
10 years and going strong! Time Owned: more than 12 months.
10years with the ps-52kx. i have charged car battereis to run ham gear. I have shorted the output manytimes,, and abused in about eery way possible. still going strong, no repairs so far !!
also, when checking for ripple the scope trace looks clean, even after ten years of rough service. are many componets undersize? i ouwl think so, and yet I have ran mine at full output current for long time periods, and given it a workout on a daily basis. If this one quits, I'll rebuild it or buy a new one in a minute!
last poster must be an engineer, there never happy unless they make their own!!
WB4FUR Rating: 2008-05-12
Piece of junk, but can be made better Time Owned: 0 to 3 months.
All: I purchased one of these at a hamfest in non-working condition. Opening the case and studying the schematic shows why.

The power transformer sure appears to be something that would deliver the goods. Heavy iron. I don't know if it would get to 50A continuous or not, but there's at least hope. Grade: B

The rectifiers are 35-ampere bridge rectifiers. Diodes in parallel. If there's any mismatch in the diodes, one winds up taking all the current, and it fails. That's what had happened in mine. Grade: F

The pass transistors are mounted on good heatsinks, cooled with a small fan. Collectors are bonded together with metal straps. Unclear if they can dissipate the heat under full load, but there's hope. Individual emitter connections to a common point. Grade: B

NO CURRENT-BALANCING EMITTER RESISTORS. Worst possible design decision. Grade: F-----...

Electrolytics are small, PC-board mount devices, with small-gauge wire connecting rectifiers, caps, and rest of circuit. Grade: D-

Crowbar SCR is small, 16-ampere unit. Could not possibly handle crowbar current more than once! SCR is PC-board mounted (HOW did they expect it to handle the current????). Grade: F-----...

If you own one of these, you could bring it to being a first-rate supply as follows:

a. Replace the rectifiers with stud-mount, 85-ampere units (Mouser has them). I did this; took a few minutes with a drill to enlarge the mounting holes for the original rectifiers.

b. Replace the electrolytics with large, PC-grade caps, and run heavy-gauge (10 AWG or better) from the two diodes to the caps, and from the caps to the pass transistor collectors. You need the large caps to be able to land heavy-gauge wire.

c. Install 0.1 ohm emitter resistors on each of the 8 pass transistors. I was going to use cased wirewounds that would mount against the heat sinks (again from Mouser). Install 16 AWG wire from each transistor to a common point.

d. Install the largest stud-mount SCR you can put in. I was aiming at a 135-ampere device. Bond it to the output terminals, and reference it back to the PC board.

e. Install a real meter shunt (another wirewound resistor mounted to the bottom of the case, suitably sized to drive the ammeter with an adjustment pot).

f. Complete installation of heavy-gauge wire everywhere in the DC power circuits between rectifiers, capacitor, pass transistors, SCR, and output terminals. Consider putting larger output terminals on rear of case.

As you can see, it really IS possible to make this supply a silk purse instead of a sow's ear; however, it's not clear to me that it's worth doing. You are talking somewhere between $50-$75 worth of parts to do a creditable job, and somewhere around 6-8 hours of labor. If your time is valuable to you, you'd be better off buying a new supply (or a used one) from somewhere else.