What problem may occur if your transmitter is operated without its cover or other shielding in place?

The metal case or shielding of a transmitter acts as a Faraday cage, containing stray radio frequency (RF) energy generated by internal circuits. When a transmitter is operated with its cover removed, this stray RF energy can easily escape the chassis and act like an unintended antenna. These escaping signals are known as spurious emissions. Because they bypass the transmitter's final filtering stages, they can cause harmful interference to nearby electronic devices and other radio communication services operating on completely different frequencies. Operating without the cover does not generally cause chirpy signals, which are typically related to power supply or oscillator stability issues, nor does it cause a weak signal or excessive current draw directly.