Total posts : 45366
I see in the pictures that a choke is present in the ground wire just below the transmitter. http://krocksradioone.com/imageweb/AMT5KBalconysetupcloseviewchokeongroundline.jpg. This was a surprise to me because it wasn’t mentioned previously.
The presence of the ground choke can be a reason for tuning problems. As I pointed out in a previous thread, a ground choke will detune a transmitter. The choke inductance adds to the loading coil inductance causing the total tuning inductance to increase. This will detune the transmitter. To get things tuned back to resonance, the loading coil tap must be adjusted to reduce the loading coil inductance by the value of the choke inductance.
If the choke inductance is relatively high, you will run out of taps at the low-inductance end of the loading coil resulting in not being able to tune to a frequency at the upper limit of the transmitter’s specified tuning range.
A ground choke is not recommended for the AMT5000, or any other transmitter for that matter.