[TowerTalk] Coax Impact on Receive Performance

[Jim Brown]

On 3/23/2021 11:30 AM, Jim Miller wrote:
> In my opinion the difference between connected and disconnected of only 2db
> shows that you are marginal and likely impacting your RX performance.

For this sort of evaluation to be meaningful, the RX input should be 
terminated in 50 ohms. Ideally, we would like to see at least 10 dB 
difference.  Does that radio have a preamp? If so, it should probably be 
switched on for weak signals on 20M.

Loss in 350 ft of LMR400 calcs to 1.6 dB on 20M. LDF4-50 (1/2-in) would 
reduce the line loss by about 0.9 dB, LDF5-50 (7/8-in) buys you another 
0.3 dB.

73, Jim K9YC