Electronic – DC Barrel + Battery schematic

General electronics handling precautions should be observed:

• Once exposed the elastomeric structure is a good capacitor and can accumulate static charge. Ground yourself prior to working with the parts to avoid an ESD event which could damage the onboard IC's inputs. Maintain grounding. Avoid working in a carpeted area. Etc...

• Wash your hands with soap (and rinse thoroughly) and then isopropyl alcohol to remove contaminants. Even so, avoid contact with the connector's and pcb's electrical contact area.

• An oxidation layer will form over time and alter the contact impedance. Therefore, you should minimize the exposure time and work in as dry a room as possible. That's a practical recommendation that deserves some qualification:

  • As @embedded.kyle very keenly and correctly notes (Thanks Kyle!): "There are certain ranges of humidity that strike a good compromise between the increased risk of oxidation and the increased risk of static buildup. Humidity below 40% starts to increase the risk of static generation. NASA-STD-8739.7 recommends between 40% and 60% humidity. ANSI/ESD S20.20-1999 and MIL-STD-1695 are a bit more relaxed at 30% to 70%."

  • If you are serious about long-term reliability, you should adhere to these climate control standards. For a hobbyist-grade project, I recommend working in "as dry a room possible" given that, in the US at least, natural weather patterns are more likely to leave you too humid than too dry and static control techniques can mitigate the risk, whereas there is little you can do on the other end of the spectrum.

Tips on alignment:

• Elastomeric's are typically classified into two categories, those with contacts substantially smaller than the PCB pads (very tolerant of alignment error), and those approximately the same size (alignment sensitive). Unfortunately, for LCD applications, the latter type is the most common since the manufacturer needs the connector density to increase the communication bandwidth to the display.

• Alignment can be extremely challenging. Rely on the original alignment mechanism if possible. If you can avoid breaking the original contact seal, all the better (then you won't have to re-align it). Some devices have clips and other apparatus to assist alignment (although this is becoming increasingly rare in my experience).

• If you must reattach, fashioning a makeshift pick-and-place machine out of a mill (CNC or otherwise) and an eye-dropper or baby bulb (hand operated vacuum pump) that you tape to the chuck (or head) can give you the precision you need to re-align. Use of a dissecting microscope or loops is also helpful as it improves your mechanical acuity.

But above all, may you have GOOD LUCK! =)

This means I should be able to use my existing USB car charger that outputs 5V/2A and my existing USB charging hub at home, right?

No. The VX-8R series radios require 11-14 V DC (Negative Ground, EXT DC jack) input to charge ("Operating with Charging" pg 166 of the Operating Manual). Take note of the PA-48B charger:

Can I literally just chop off the integrated cord that runs out of the car charger and solder a full-size USB connector to the end and call it good?

No. Not only does your device not support 5V charging, but it is also not a qualified USB device and can neither negotiate power delivery nor respond to different chargers.

If I connect this new USB connector to a battery (such as one used to recharge a dying cell phone) is there any possible problem with this increased output wattage connected to a battery instead of to an actual continuous DC power source?

Since your device **cannot* be charged by 5V from USB, a cheap lithium battery pack for USB phone charging is not appropriate.

However, for continued operation at high power, you could use an external 12V lead-acid battery (car, motorcycle, marine) connected with the correct polarity to a barrel jack to supply external power such that your radio will operate in high-power mode. When using such a battery, be sure to use fuses to reduce the possible damage from the high-current capability of a lead-acid battery.