Samlex PST-120-12: Slick little pure-sine wave inverter

[FreeLancer]

This is an oddball inverter, about the size of a couple of old Reader's Digest magazines and limited to a single two-prong AC receptacle and 0.5A USB output, but it has some interesting features that might fit an off-grid niche for some use cases. 

At a bit over $100 it's certainly not cheap, especially when compared to what's available in modified-sine wave units of similar power output, but it connects easily to DC sources with the standard ham radio powerpole configuration and works great with battery packs (like 12V Bioenno LiFePO4) that come wired that way.  A high quality cord, with ferrite bead winding, that fits a standard cigarette lighter receptacle is included for those that aren't interested in rolling their own powerpole cords.

I used it the last two nights to run a CPAP machine off my 20Ah Bioeeno battery, which has a similar desktop footprint.  Monitoring the battery load via a Watt's Up meter, I found that the inverter drew just under 0.25A by itself and ran cool and quiet under the less than 2A peak load of the CPAP machine.  My CPAP's power consumption fluctuates dramatically with the cycle of respiration, going to nothing on inspiration and averaging under 1A (CPAP and inverter combined) overall, such that 18 hours of sleep over two nights consumed less than 14Ah.  Online reviewers have mentioned that this unit puts out much less RF noise than other Samlex PSW inverters, at near-touching proximity, but I haven't tested that yet.




Here's the Samlex spec sheet:  http://www.samlexamerica.com/documents/product-specs/12001-PST-120-12-1116.pdf

[Alan Georges]

That is impressive.  My big question was about RFI, but I think a review over on Amazon answered it:

This is a better than average inverter. I bought it to use to power my laptop for mobile operation of ham radio. The most important characteristic of an inverter is how much (or how little) radio noise it generates. When used in a vehicle, the inverter is very close to antennas so any noise will overpower radio signals and make the radio useless. While this unit is not perfectly quiet, it's quiet enough that the noise it does produce can be suppressed by winding both the AC and DC cables through ferrite cores.

I've had this unit for a couple of years, and find it to be quite reliable. A colleague bought a larger model in this product series, and it's far to noisy to use around radios.

Thanks for posting this, FL.

[FreeLancer]

Apparently Samlex engineered this inverter to meet UL60601 hospital standards for microcurrent and RF interference with critical life support telemetry electronics.  That's doesn't come cheap and probably explains the higher price, even compared to the other small Samlex PSW units.

[Alan Georges]

Ah, that explains everything about this inverter, FL.  Definitely a cut above the usual consumer grade gear.  Got to get one now.