Tnx Bob.... got it.? ?Into a 50 ohm DL..... swr is 1:1? ? regardless of coax length.? My guess is since the C1 and C2 caps in the tuned inputs are fixed...and only the coil is adjustable, there is no real way to adjust it correctly.? It's probably off a tiny bit, and enough such that it's not 50 ohms + zero reactance.? Then when the cable length is changed, the values used on the tuned input are even more outa whack.??
On my hb tube amps, I use a manually tuned, PI tuned input, with a tapped coil, and a pair of broadcast caps.? ( both padded on 160m only).? Coax length is a non issue.?
?
On the next manually tuned, tuned input,? I'm going to use a 0 -? 4.4 uh? roller coil (8 ga wire used)..and a pair of broadcast caps? ( padded on 160m).? ?Then I can vary the loaded Q between extremes, on each band..... which is more of an experiment to see the effects on? IMD? vs loaded Q, and some other tests.?
?
Years ago, I used a pair of Arco trimmer caps ( padded on the lower bands) and a T-50 coil...... one assy for each band.? Simple tweak for flat swr. Again, cable length did not enter the equation.?
