On Wed, 31 Jan 2007 18:40:56 -1000, wrote:

works on one 75 where the VSWR is 1.3:1 and the bandwidth is 85 khz
for the 2:1 points.

On 40 meters the VSWR is over 10:1

it looks like this

|
|
| abot 56 ft high
|
|
|
|

feed here has 2 loading coils

|
___________|____________ both sides approx 17 ft
|

base insulator here

_|_ base mount

ground

feed point impedance is supposed to be very low - maybe 12 ohms

Which gives rise to the question, where did the match at 75 meters
come from? I suspect it comes from the added loading.

Next question, why does it have the high mismatch for 40 meters. The
same suspicion follows logically (as the harmonic relationships follow
logically).

With loading resonance is not length, it is the combination of all
elements. What appears to be a normal (good) 75 meter operation
should also appear to be normal (poor) 40 meter operation. At 75
meters, the antenna is normally Low-Z. At 40 meters, the antenna is
normally Hi-Z. Your SWR measurement confirms the sense of "normal" in
both bands.

73's
Richard Clark, KB7QHC