This cable does not for firmware update use, aftermarket replacement cable compatible with MFJ 20-546, compatible with windows 7 &10, 11.
For these models need use with the stereo/mono adapter. RadioShack: PRO-79 PRO-82 PRO-83 PRO-84 PRO-89 PRO-93 PRO-94 PRO-95 PRO-96 PRO-97 PRO-99 PRO-160 PRO-162 PRO-2051 PRO-2053 PRO-2067 PRO-2096 PRO-433 PRO-528