Hi Paul,
For a few months I experimented with a random long wire configured as an inverted L (22m horizontal at about 8 to 9m high with 4m sloping to a 9:1 UnUn on the lawn; UnUn on short wire to ground stake and 10m RG174 feeder back to the shack). Here are the VSWR figures using FT857 with and without a Z11 Pro ATU…
| BAND | ATU | MEASURED VSWR | |||||
|---|---|---|---|---|---|---|---|
| (m) | CW FREQUENCY (kHz) | SSB FREQUENCY (kHz) | |||||
| 160 | 1815 | 1835 | 1845 | 1910 | 1995 | ||
| off | 4.0 | 4.0 | 4.0 | 4.0 | 4.0 | ||
| on | 1.3 | 1.2 | 1.2 | 1.4 | 1.8 | ||
| 80 | 3505 | 3540 | 3580 | 3605 | 3700 | 3795 | |
| off | 5.0 | 6.0 | 7.0 | 7.0 | 8.0 | 8.0 | |
| on | 1.7 | 1.8 | 1.9 | 1.7 | 1.6 | 1.4 | |
| 60 | 5260 | 5300 | 5325 | 5355 | 5375 | 5405 | |
| off | 10.0 | 12.0 | 14.0 | 16.0 | 16.0 | 16.0 | |
| on | 1.3 | 1.5 | 1.6 | 1.8 | 1.9 | 2.2 | |
| 40 | 7005 | 7030 | 7060 | 7100 | 7150 | 7195 | |
| off | 3.0 | 3.0 | 2.8 | 2.6 | 2.6 | 2.5 | |
| on | 2.2 | 2.5 | 2.6 | 2.6 | 2.4 | 2.3 | |
| 30 | 10105 | 10130 | 10145 | ||||
| off | 3.0 | 3.0 | 3.0 | ||||
| on | 1.3 | 1.3 | 1.3 | ||||
| 20 | 14005 | 14050 | 14095 | 14130 | 14200 | 14345 | |
| off | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | |
| on | 1.5 | 1.7 | 1.9 | 1.6 | 1.4 | 1.2 | |
| 17 | 18070 | 18095 | 18115 | 18120 | 18140 | 18165 | |
| off | 2.1 | 2.1 | 2.1 | 2.1 | 2.1 | 2.1 | |
| on | 1.6 | 1.6 | 1.6 | 1.6 | 1.6 | 1.6 | |
| 15 | 21005 | 21070 | 21120 | 21155 | 21300 | 21445 | |
| off | 1.2 | 1.2 | 1.2 | 1.3 | 1.4 | 1.5 | |
| on | 1.2 | 1.1 | 1.1 | 1.1 | 1.2 | 1.4 | |
| 12 | 24895 | 24910 | 24935 | 24945 | 24985 | ||
| off | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | ||
| on | 1.1 | 1.1 | 1.1 | 1.1 | 1.6 | ||
| 10 | 28005 | 28070 | 28190 | 28325 | 29000 | 29695 | |
| off | 1.2 | 1.1 | 1.1 | 1.1 | 1.1 | 1.4 | |
| on | 1.2 | 1.1 | 1.1 | 1.1 | 1.1 | 1.3 | |
| 6 | 50005 | 50050 | 50095 | 50105 | 50200 | 50295 | |
| off | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | |
| on | 1.5 | 1.4 | 1.4 | 1.4 | 1.3 | 1.3 |
I replaced the RLW with a homemade halfwave 80m dipole for portable use (very thin wire, 1:1 balun and 10m RG174 feeder). My KX2 internal ATU flattens the non-ATU VSWR U-shaped curve across the whole band. Here’s the VSWR without ATU …
The 80m dipole also loads well on higher bands using the KX2-ATU and I’ve had good to excellent reports on SOTA summit activation on 60, 40 and 30m as well as 80m using QRP CW.
I adapted my Sotabeams 40/30/20 tri-bander linked dipole adding extensions for 60m. Dependable all-rounder on all those bands with best results compared to the other antennas (except for 80m).
I also have two LNR Precision EFHWs: EFT-MTR 40/30/20 (19.8m long) and EFT-10/20/40 (12.5m long). Excellent VSWR with the KX2 and signal reports but usually not as good as the linked dipole.
In summary, the KX2 ATU loads a wet piece of string but all the above antennas also radiate well.
73 Andy