Why won't my LDG 1000ProII auto tune in the lower 80m band?
Although my 1000ProII often fails to tune as accurately as my Z100-A, it usually brings the SWR down below 2:1 without the need to manually push the L or C buttons (which can often further reduce the SWR by a good margin). However, I just ran into a situation where my 1000ProII completely fails to obtain an acceptable sub-2:1 tune (even when the 1.7:1 max option is set). After recently changing the connectivity to my 80m OCFD antenna, I am forcing "full" tunes ("long" button press) to re-populate the tuner memory with valid settings, but the SWR in low 80m is usually now worse than the bypass SWR!
Strangely, my feed line SWR in low 80m is completely reasonable for auto tuning (under 2.88:1) and significantly lower than realized in the higher portions of the 80m band, which DO auto tune successfully. (See the attached SWR plot taken at the end of the coax in my shack.)
This problem popped-up after I took action to correct coax shield common mode current problems from my N9SAB OCFD, which DJ0IP says is problematic of all 80m OCFD antennas, so I wound and installed an exact copy of the Guanella choke section used in DJ0IP's highly rated B10 hybrid balun from his "Battle of the Baluns" test:
After attaching my tiny new choke onto the SO-239 connector of my antenna's 4:1 Ruthroff balun, SWR sweeps across all bands became invariant with coax feed length and position (excess coax placed either on the roof or on the ground, etc.). Although the antenna also now functions better, as revealed in my regularly scheduled nets and QSOs, the SWR plots are also now completely different and all bands need to be re-tuned--preferably auto-tuned.
Unfortunately, my 1000ProII now completely fails to auto-tune in my favorite and most often used digital frequencies between 3.5 and 4.0 MHz. Manual L and C button adjustments do not help. I eventually discovered the High/Low Relay manual adjustment in the "Advanced" section of the manual, which enabled me to successfully complete L and C push button adjustments and save them to memory for future auto-tuning (fingers crossed--the tuner really needs an "always use memory settings" switch feature, because it will sometimes do an auto-tune that ends up being inferior to a stored settings tune).
My IC-7100 significantly reduces power to well below 100W after a 1000ProII auto tune. I upgraded to the 1000ProII from my LDG Z100-A to eliminate the Z100-A 30W digital mode limitation and help with my topographically challenging Idaho QTH. My entire system is currently 100W max, but maybe there will be a Mercury IIIS amp and other upgrades in my future too, so I went for the LDG flagship model.
Hopefully this post may prove to be useful to others and perhaps some group members will reply with their ideas or answers too.
73 and thanks!
Cal -- AD8Q
