You got me intrigued. If the balun in the DB4/8 does not pass L-VHF, then how would I got CH4 from the DB8e OK?
And BTW., Yes, I did rezero the tuner every time; and I really mean everytime, even after a small direction change. I had formed a routine to follow exactly each test: Disconnect the cable from the TV; start a scan; then go on to move/reset/swap the antenna; come back to check the TV and confirm that it finished scanning with 'No signal' and no channel logged; reconnect the cable; start a new scan.
Anyway, I did all the DB mod tests with my own curiosity too. Before getting the 751, I thought about combining in a dipole (and I was going to ask: a vertical dipole would be omni-directional, right? It would be much easier to setup). But as of now, there is no need for all that since the 751 handles it all for me nicely -if I am giving up the N/NE-channels dream.
