Now it’s time to adjust the 80 meter coil. The current setting for all three bands are given below
||L / Short
|80m||36cm / 0||4.02||1.40||100 kHz|
|40m||26cm / 7.5||7.04||1.05||274 kHz|
|30m||26cm / 2.5||9.98||1.20||750 kHz|
By decreasing the length of the 80 meter coil I could bring fc down to 3.67 MHz. Unfortunately, this messed up completely the 40 meter settings moving fc down to 6.9 MHz – quite unacceptable for me.
|SWR on 80m and 40m using L80=25cm|
Going back to L80=31cm makes 40 and 30 acceptable, however 80 meter is completely useless:
|SWR on all bands using L80=31cm|
On the other hand, if I stick with L80=36cm, I could try to recover the 40 and 30 meter bands by tuning the 30m coil. This could indeed work out, since L30 did not have any influence on the 80 meter band. In any case, I have to do something about this because as it is now, I have an antenna, which works so-so on all 3 bands, but none of the bands is optimised.
FYI, an index of all SWR graphs can be found here.