On 11/1/20 10:12 PM, HexAndFlex via groups.io wrote:
Get yourself an antenna tuning unit (ATU). If doing receive only you will need a manual type as the automatic ones need a few watts of tx power to detect a bad match.
At low frequencies on receive, the mismatch may not hurt you all that much - the input Z of the receiver probably isn't all that closely controlled. The noise figure of most HF receivers isn't all that hot either, since the dominant limit on received SNR is the atmospheric and environmental noise.
Easy test - if you connect the antenna, does the noise go up? If so, then you're fine.
You can use the VNA to help tune to a particular frequency. The closer the original match is to the outside of the Smith chart the harder it is to match and the narrower any tuning will be.
Btw, hugging the outside of the Smith chart does NOT indicate loss. It indicates reflection. Loss tends to make the match look better than it really is.
