Tuesday, June 21, 2022

Thinking of Buying an EV? Watch Out for QRM

(Photo by Mariordo/Wikimedia Commons)
If high gas prices and/or environmental concerns have you considering the purchase of an electric vehicle (EV), here’s one more consideration to include in your decision-making: Will you be able to operate a mobile HF ham rig without debilitating interference from the car itself? Radio World magazine reports that the subject of electromagnetic interference (EMI) from EVs was a forum topic at June’s conference of the Audio Engineering Society.

RW reports that interference to analog AM signals is so bad in some vehicles that the manufacturers are not including AM radios with their cars, opting only for FM and digital, both of which are more resistant to electrical noise. Such noise would likely be broadbanded enough to seriously degrade analog SSB and CW signals on the HF bands as well. VHF/UHF FM is less likely to be affected.

Apparently, not all EVs are created equal in this regard. One of the AES forum speakers on the subject was Xperi Corp. communications system engineer Pooja Nair, who wrote in a previous RW commentary (<https://tinyurl.com/yckay4fk>) that “EMI can be suppressed in EVs using well-known mitigation techniques such as shielding cables and electric motors, installing filters and carefully locating electrical components within the vehicle. Within receivers, EMI can be limited by isolating and shielding antenna and RF sections, filtering connections and carefully grounding and placing receiver components.” Some manufacturers, Nair writes, do work hard to mitigate EMI while others take the easier path of leaving out the AM radio.

Takeaway for hams who operate HF mobile and are considering an EV purchase: Do your homework. Find out the steps taken by the manufacturer of each vehicle you’re considering to control EMI within the vehicle. Step 1: Does the car include an AM radio?