Topband: What have I done?

[Carl Braun]

I have revised my question to correct the length of the antenna in question


Topbanders

In the past, I've posted some questions related to making my 80 meter verticals (64' tall ground mounted) work on different bands.  The pair is spaced at ¼ wl on 80m and then I switch in base loading to resonate the same pair on 160m which are then effectively spaced at 1/8 wl.   Now I want to make them work on 40m which would have them resonate as ½ or 5/8 wl and would have an effective spacing at ½ wl.

So this is what I did...I installed an L network off of the vertical effectively tuning a 64' stick of aluminum to 7.050.  It took me a couple of tries as the first 1500pF (monster) variable capacitor wouldn't get down low enough to get me flat.  I had another 50-150pF Johnson variable cap available so I tried that and got the antenna to tune to 46 ohms at j+0.    Inside the shack I see 1.0:1 Vswr from 7.000 to 7.290...wow!

I measured the cap and it came to 70pf.  My cheapie Chinese meter doesn't register anything on the L scale but I have 7 turns on a 3 ½" inductor. The full coil is 33 uH at 25 turns so I estimate 8-12 uH of inductance.

But what have I done? Have I resonated a ½ wl antenna or have I resonated something else like a 5/8 wl antenna with the added inductance?

I plan on treating them as ½ wl spaced phased verticals on 40 and feeding them with equal lengths of ¾ wl feedlines for broadside phasing and then adding an additional 2/4 wl to get my 180 degree shift for end fire.

Please share your comments.

thanks

Carl de AG6X