Total posts : 45366
..the hypothesis I made months ago, that the 5K unit is going to have a wee bit of a problem reaching it’s sweet spot when connected up to anything else other than the simple wire..
As I said in a previous post, the AMT5000 was designed and verified to cover the frequency range of 1350 kHz to 1700 kHz for all antennas with capacitance in the range of 19pF to 37pF.
Per FCC rules, the absolute maximum height is 3 meters (118 in.).
#22 wire (118 in. length supplied with kit)
minimum length=108 in., C=19pF
maximum length=226 in., C=37pF
102″ CB whip, OD=.2 in.
length=102 in., C=24.46pF
1/2″ Copper Pipe OD=.625 in.
minimum length=56 in., C=19pF
maximum length=132 in., C=37pF
3/4″ Copper Pipe OD=.875 in.
minimum length=50 in., C=19pF
maximum length=120 in., C=37pF
Antennas with less than 19pF capacitance will shift the tuning range upward. Antennas with more than 37pF capacitance will shift the tuning range downward.
The tuning range of 1350 kHz to 1700 kHz was chosen because of better antenna efficiency at the high end of the band.
The capacitance range was chosen to include the most common Part 15 antenna element types.
Widening the tuning range and capacitance range significantly would necessitate a toroid with many more taps and/or a larger trimmer capacitor, both of which would reduce tuning network efficiency.