Need an operating manual for a Cobra MR F75 VHF Marine Radio

https://www.manualslib.com/manual/468424/Cobra-Marine-Mr-F75-D.html

you'll need a filter capacitor in the power line to the radio. wiring varies according the the individual unit, but typically one side to power, the other to ground.

Do you have it set on low power? There is a power setting in the menu that will fix that problem.

Try resetting the radio per the user manual by doing a setup procedure as described on page 28. This may clear up the problem. User manual here: https://www.cobra.com/sites/default/files/manuals/MRF75D%20-%20ENGLISH_0.pdf

restore.

your input to radio crystal is out

link below.

Link:

Before changing out the radio try the radio on a ANTENNA RADIO TESTER or try it on a different antenna. Good luck.

http://www.cobra.com/downloads/manuals/MRF75_manual-Eng.pdf.

Check your microphone by swapping with another duplicate. If no differance, you will need a SWR meter (standing wave ratio) to find the culprit. It attaches in line of the coax and determinds power out and reflected power. The reading should be 25 watts foward and max of 1 reflected.