40 Meter Quarter Wave Vertical/75 Meter Inverted L

[AJ1G]

The 75/80 meter inverted L is up a running.  Did it all yesterday in the sub-freezing cold snap so was confident it would work well.  Final configuration ended up being  sloping inverted L with the extension off the top of the 40 meter vertical running down at about a 45 degree angle to the west.  The original plan to run horizontally to the southwest supported by the neighbor’s tree has been put on hold for the time being,  will reguire a significant effort clearing tree branches over the run.  Did some researching into using a sloped L section and figured it was worth a try.

Initially tested using just the 12 elevated 40 meter radials.  Got it resonated mid- band near the DX window with a minimum SWR of about 2:1, expected it would be somewhat high due to probable feed point impedance around 30 ohms at resonance.  Saw that I had room to extend at least 3 of the forty meter radials to 1/4 wave plus for 75 meters, did that and left the remaining 40 meter radials still part of the elevated counterpoise.

Resulting SWR after extending the 3 radials actually went up slightly.  Figured that was likely due to further reduction of the feed point impedance.  Tried to improve match at the feed point with a shunt cap of 500 pf, what I use for matching my mobile Hamsticks on 80 and 40 meters.  The shunt cap brought in a near 1:1 match at around 3700 kHz.  Pruned off about 20 inches from the ZL section and brought the 1:1 match point up to 3790 kHz in the DX window. Will do more tweaking and will end up with segments and jumpers  at the end of the L section for best matches at the AM window, DX window, and CW end of band.

Initial results working across the pond very encouraging- many boy are you loud vs normal, what did you? comments. 😁😁😁 Haven’t done any Antenna A Antenna B comparisons vs the inverted V, but significant improvement apparent in received DX signal levels.

[AJ1G]

Did some antenna  A to B comparisons of the inverted L vs the inverted V with some of the relatively far off early AM AM gang on 3885 around 6 AM this morning, L was down at least an S unit from the V out to Kentucky and down to the Atlanta area.  Then went down to the DX window to try for VK6APZ near Perth, but he was a no-show.  However, Pat, KK6ZM on the Pacific at Cape Disappointment WA gave me a 59 on the inverted L, said it was at least nominally up to 10 dB better out there than than the inverted V.  He was received on my end very loud on receive using the L essentially no copy on the V. So it looks like a keeper for long haul use on 75.  Going to make up an extension for the L section tonight to get it matched down at the low end of the 80 meter CW band and do some A to B checks using the Reverse Beacon Network CW skimmers.

Update at 2205Z 17 Feb...just got through to VK6APZ on 3790 on the long path just before local sunset here , he was solid 57 58 on the inverted L, down in the weeds on the inverted V. Gave me a 56, similar to reports to other East Coast stations.

[KK4YY]

Looks like you're getting more low-angle radiation from the inverted L at 8+33 feet than the inverted V dipole at 43 feet. Might be a good DX antenna for those of us (most of us) that can't get a dipole up at 100 feet. I think you're on to something. Well done!