[TowerTalk] 80M Doublet Issues

[Tony]

All:

I built an 80 meter doublet using W8JI's antenna length and feed line 
guidelines which appear in DX Engineering's documentation. 
http://static.dxengineering.com/global/images/chartsguides/c/choosing-the-correct-balun.pdf

They are:

Antenna Length: 110 feet
300 Ohm LL : 62 feet

I'm also using a short (12') run of coax that goes to a 1:1 
DXE-BAL050-H10-AT current balun that's grounded.

The problem I have is that after gradually trimming both the antenna 
length (110 ft to 100 ft) and feed line to get the antenna to tune more 
easily on 30 meters, the SWR is now much higher on 80 meters.

It's now 18:1 on most of 80 and decreases to about 10:1 on the upper 
edge of 75 meters. I'm also using an auto-tuner which doesn't care for 
anything above 10:1, especially when running the amp. On 40 meters the 
average SWR is 4:1 and about 8:1 on 30 meters.

My question is: Is it best to go back and start with a 110 or 120 foot 
dipole and carefully trim the ladder line to find a happy medium between 
80 and 30 meters? Or should I accept the fact that you can't have it 
both ways?

Thanks

73, Tony