|Basic shack supply, but has lots of potential
||Time Owned: more than 12 months.
|I wonder if Jaycar dumbed down the construction of their MP3099 in later days of distribution? My MP3099 certainly ain't the same as the one VK2MMM describes!|
*It's a linear supply. That alone makes it highly prized in my shack. So disappointed with the high failure rate of switch mode supplies and their RF interference, despite claims to the contrary.
*No fan, convection cooled - silent!
*There's loads of room inside to perform 'go better' mods.
*Very beefy iron core transformer
*The blurb says it is fully protected. Oh really? I can't see any over-voltage protection in case one of the series pass transistors goes short circuit (by far the most common failure mode) - how does 20 volts up the date of your radio sound? Yeah, didn't think so.
*6 x 4700uF capacitors gives around 28200uF total. Not really enough in my opinion.
*6 x 2N3055 pass transistors for 30 ampere @ 5 amps per device? That doesn't leave much margin for reliability. I'd de-rate this supply to 25A (peak) for longer life.
*I only counted 14 diodes for the bridge rectifier.
*Lacking in attention to detail with the internal construction quality - wiring looms that were too tight for effective servicing, wiring looms pinched under PCBs, wiring looms that rub on sharp edges of heatsinks, stripped threads on screws used to mount active devices to heatsinks, causing poor heat transfer due to the loose screws.
*The mains power switch has a neon light inside, which gets hot, which over time makes the plastic brittle - which could in turn become a safety hazard if the switch crumbles at your fingertip, exposing you to lethal mains voltages.
*Being convection cooled means it does get hot, fast.
The good news: there's lots of room to fix these problems! At a minimum, you'd want to:
1) Add a overvoltage crowbar circuit and fuse to ensure your equipment is over-current and over-voltage protected in the event of a failure
2) add some protective edging over sharp edges of heatsinks & protruding case screws where wiring looms pass.
3) Replace the 4700uF caps with 10000uF caps. Much better!
4) Replace the mains switch with one that doesn't have a neon bulb integrated into it. Add a LED to the front panel if you want to have a visual indication.
And optionally, with this much room, you could also add:
Current shunt and current meter
Temperature controlled cooling fans
Front panel indications of: mains supply healthy, regulator circuit healthy, output healthy.
More output terminals
When buying this, think of it as a half-finished power supply. In it's basic form, it does work, but I have serious doubts as to it's long term reliability and performance. With the 'go better' mods, it brings this supply up to scratch - and makes for a nice little weekend project. At the asking price (AUD $229) you get a decent launch pad for a good power supply, if you're prepared to put a little bit of work into it. Either that, or fork out another $100 on top of that to get a very well made power supply from the outset.
If the power supply had all the issues sorted out from the factory, it would have scored a 4/5 from me.
|Great Linear Supply
||Time Owned: 0 to 3 months.
|This 30A / 32A surge supply is nicely constructed and performs well. The internals are wired with heavy (4AWG) cabling where needed, and the capacitor board and regulator board are easy to remove if servicing is needed. The transformer is huge, and thus the supply weighs a tonne, but thats to be expected with a supply like this. The manufacturer were good enough to include a schematic so troubleshooting the supply is a no brainer.|
Two banana screw lugs are available for equipment hookup, and a nice green backlighted switch tells you the supply is live.
This supply is ideal for modding. Theres room in the case for a shunt and meter for amps measuring, and you could desolder the trimpot and replace it with a regular pot, and volt meter to turn this beast into a 30A regulated variable supply.
I had the top off first thing before I powered it up. Very well constructed. The bridge rectifier is 28 1N5402's in parallel, and the filter caps 6 4700uf 40 caps, totaling ~70,000 uf.
Regulator PCB uses all descrete components that are easy to source.
Accidentally forgetting to put my rig on low power with the linear turned on, the supply didnt complain at all while drawing 25 amps (10 for the rig, 20 for the linear).