The knob you just mentioned is for the adjustment of the Decision Height ,   I already knew about that DH adjustment knob,  but the radar altimeter displayed on the right side of the EFIS across from the DH display has no knob for adjustment,  it was the radar altimeter not having an adjustment knob that I raised for question.

Forgive me, I misunderstood; I don't know what you are trying to do with the RA, I've never seen one you can adjust from inside the cockpit. Could you link me to any photos that show an RA with what you mean?

One example would be the piper navajo,   some of those have a radar altimeter with an adjustment knob,  I do not have a close up photo of the gauge with the knob but if you google the cockpit of the navajo you can see it,  not all navajos have them though,  and they could be hard to find or locate,   many fighter aircraft have them and the DCS Blackshark attack helicopter has one that can be adjusted. 

Isn't the adjustment knob found on smaller aircrafts RA just to be able to set the bug for an accurate decision height? What else would you need to adjust? The RA is not dependant on BARO like the main ALT, is it?

One example would be the piper navajo,   some of those have a radar altimeter with an adjustment knob,  I do not have a close up photo of the gauge with the knob but if you google the cockpit of the navajo you can see it,  not all navajos have them though,  and they could be hard to find or locate,   many fighter aircraft have them and the DCS Blackshark attack helicopter has one that can be adjusted. 

I haven't played the game for a while, but according to my DCS Blackshark manual the Radio Altimeter has a knob to adjust the low altitude warning (equivalent to setting DH) and a test button. Just like a civilian RA. No adjustment. Pictures of Navajo panels I looked at online only show a DH setting knob. I can't see any other adjustment, nor is there any reason to adjust a radio altimeter.

 

What exactly do you think needs to be adjusted?