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!
I think the solution is quite easy: Get an USB power bank, an USB cable and an appropriate power plug. Those are standard items. If the 5 V of USB worry you, get a rectifier diode like an 1N4001 or so.
A new pack of 1.5 V cells will give you nearly 5 V. The Sony engineers should have taken this in account so this should not be a problem. But you might use the diode to drop 0.6 V or so.
Now do:
* See what plug of the power bank is the 5 V output.
* Cut the plug of the USB cable *not* to be entered into the power bank.
* Slide the sleve of the power plug for the radio over the cable so you can latertwist it on the plug.
* Remove 2 cm of the cable isolation.
* Locate the red and black wires.
* Cut back the typically white wires.
* Locate the ring on the diode housing.
* Cut the wire on this side of the diode to 3 mm.
* Solder this tip to the inner soldering slug of the plug.
* Cut the other lead down to 3 mm.
* Solder the red wire toe the tip.
* isolate your last soldering with duct tape or so.
* Solder the black wire to the outer soldering slug of the plug.
* Zwist the sleve onto the plug.
* Plug the USB cable into the power bank.
* Measure that the outside of the radio power plug is negative and the inside positive. Typically you will measure a bit less that 5 V.
* Push the plug into the power socket of the radio set.
* Enjoy!
The only possible problem: The battery in the power bank provides 3.7 to 4.2 V. Therefore the powerbank must contain a switching regulator. This might create some RFI. Then try another power bank. If that dows not help: Get a ferrite ring and pull the power cable through the ferrite ring several times.