Over on QRPer.com, I just published a post on portable power that was The Spectrum Monitor magazine’s April 2021 cover article.
This article is essentially an overview of a few different types of rechargeable batteries including pros and cons of each chemistry.
While this article focuses on use in ham radio field applications, it also applies to anyone powering receivers–especially those without an internal power supply–in the field.
Yesterday, a weather front moved through the area that dropped temperatures from an unseasonably high of 50F to 25F in the space of a couple of hours. Fronts like this always equate to high winds here at our altitude. This time, it packed a little snow as well.
Last night, around 22:00 local, our power went out due to a fallen tree further down the road.
Here at SWLing Post HQ, we don’t panic about power outages. As I’ve mentioned before, our refrigerator, freezer and some of our home lighting is solar-powered and off-grid–we also rely on passive solar heating and a good wood stove to keep us warm and cozy.
Without fail, I always use power outages as an excuse to play radio on battery power.
This morning, the uBITX V6 transceiver was already hooked up to a LiFePo battery on my desktop, so I simply turned it on and started tuning around the 40 meter band, where I had recently logged a few POTA contacts. Problem was, the band was absolutely dead, save a couple weak stations. After thinking about it a few seconds (keep in mind this was pre-coffee) I put on my boots and coat, walked outside and confirmed my suspicions: the antenna feedline had become detached from my external ATU box.
The winds were strong enough last night, that the ladder line pulled itself out of the banana connector jacks on the side of the ATU box. This happens quite often during periods of high winds and is a bit annoying. Of course, I could secure the feedline in such a way that it would easily survive high winds without disconnecting, but frankly this is an intentional design choice. You see, when a black bear walks into my feedline, it easily disconnects before the bear gets tangled, up, frustrated and yanks my antenna out of the tree!
Trust me on this: bears and antennas don’t mix. I speak from experience.
After re-connecting the antenna, I fired up my portable alcohol stove (the one you might have seen in this post), boiled water, and made a fresh cup of coffee to take back to the shack.
I turned on the uBITX once again and found that the 40 meter band was chock-full of strong signals.
It’s time to go chase a few more parks today and plot my next POTA activation.
Frankly, I’m in no hurry for the power to be restored. It’s a wonderful excuse to play radio.
Readers: Anyone else enjoy radio time when the grid goes down? Please comment!
Please consider supporting us via Patreon or our Coffee Fund!
Your support makes articles like this one possible. Thank you!
Many thanks to SWLing Post contributor, Adam, who writes:
Hi Thomas I enjoy reading your blog and often when I put a question in Google yours is the first on the list so I wonder if you’d mind if I ask you a question about the Sony SW35.
I’m interested to try powering it from a power bank but I have no idea what DC plug to buy for it as I bought it second-hand without an adaptor.
I thought about taking a couple of wires out of the battery compartment but it wouldn’t look as nice so any help you could give me would be much appreciated.
Great question, Adam!
You can certainly find a DC plug that will work with the ICF-SW35. I believe this same plug was used with a number of Sony Walkman type players back in the day. You might be able to find one at the local charity/thrift shop in their power cord jumble.
I do know that the coaxial type plug needs to have positive tip polarity (click here to read about this in the owner’s manual) and the radio requires 4.5 VDC . The OEM power adapter (Model AC-E45HG) provided 700 mAh, but I don’t know what the ‘SW35 actually requires (other than something equal to or less than 700 mAh).
One option would be to find a 12VDC to 4.5 VDC converter like the Sony DCC-E345 and plug it into a 12VDC source (there are a number of high capacity 12V battery packs on the market).
Of course, you could also build your own external source by purchasing an appropriately sized external battery holder. I would use a D cell holder (I assume one to hold 3 cells at 1.5VDC x 3 = 4.5 VDC) which would provide much better capacity than a AA cell holder. (Something like this.)
I haven’t been able to determine the +/- voltage tolerance of the ICF-SW35, so I would keep the supply voltage figure at or below 4.5 volts.
One crucial number I’m missing is the coaxial plug size. I can’t seem to find a spec for OEM Sony AC-E45HG. I hope a reader might be able to help us here.
Post readers: Can anyone confirm the DC plug size for the Sony ICF-SW35? If you have any other advice or tips for Adam, please comment!