[SCCC] Portable Laptop for Field Use with KX3

[Steve]

At 05:34 PM 11/1/2020, Bruce Horn wrote:
>Hi,
>
>Looks like there are 12V to 19V DC-DC converters available for 
>powering laptops. Here's a recent review of one:

Sometimes, I take my old Sony Vaio laptop (a W7 survivor with just a 
300 GB HD) out to the garage to do things while puttering around. I 
have a bunch of comm and ham band receivers out there running off a 
wire strung through the garage rafters for an antenna and there's 
nothing that irks me moren hearing computer or switching power supply 
noise while monitoring the bands. I quickly found my laptop's 19V 
brick was noisier than heck, as were several old surplus Compaq 
laptop supplies I had (slightly quieter).

So I made a little cable for external power to plug into a shop power 
supply. Unfortunately, I forgot the shop supply was a switcher, and 
the worst noise offender of anything else I have, including my MFJ 75 
amp, 12V switching power supply (which is absolutely horrible, 
especially when I'm on 160m with birdies sweeping up and down the 
band all night). It took me a few weeks to find and buy a 5 amp 18V 
transformer but as soon as I came across it, I built a good ole 
fashioned regulated (with an old but still-working, 
what-must-be-the-world's-absolutely-last-remaining, LM323K regulator 
IC) analog power supply, complete with meters and a cuppla other 
bells and whistles. It turns out that when my laptop's battery is 
partly-depleted, it'll take all of 3+ amps to run the machine and its 
battery charger. Once it's charged, it drops back to 2.5 amps with 
once-a second peaks to 3 amps. The internal battery charger, itself, 
doesn't seem to create extra noise. I still have a bit of noise from 
the laptop (mostly when scrolling) but not much. The 
30-some-feet-long radio antenna wire is only 3 or so feet away so 
that's not too bad.

I recently got an Instek low-voltage tracking variable, regulated 
triple power supply from KM6Z; but it can only provide exactly 3 amps 
before it goes into current-limiting.

SteveH K0XP