Experiments with operating the radio at home continue.
Had a wacky idea to use the anchor in the tree over my balcony as the support for a 20m inverted-V dipole, fed with 300ohm twinlead for multi-band matching. Brainstormed a plan to use a pair of bamboo fishing poles, anchored by pole brackets on the balcony railing, to spread the bottom ends of the dipoles apart and keep them out away from the building.
The signals I got were certainly louder than what I got on the Slinky dipole. Loud enough to hear buzzing and static crashes. I think the static pops were probably from the trees blowing in the wind. Had to experiment with using a mix of noise blanker, attenuator, and turning off the receiver preamp (IPO). At least the high-current area of the antenna, where most of the signal emanates, is at the apex of the V and right at the level of my roofline for better clearance to the East. So there’s that.
Heard 40m surprisingly well. Tried to match the transmitter on 40m, couldn’t get better than 5:1 SWR, so I swapped my DIY 1:1 balun with my DIY 9:1 un-un. The result? Better than 1.5:1. Yes. Even 20m matched OK, enough to trigger my desk lamp with 35W. Twinlead is good about taking up some of the impedance slush of a bad match and not losing much signal in the process, which accounts for how I could match on several bands.
Couldn’t get any QSOs, not even on FT8 (but that’s kinda crowded anyway). I’ll try again later.
This was a proof of concept from existing parts on hand before I wasted any time trying to “build it right” with new parts. It proved it worked better than expected. I guess I’m learning.
I do have some refinements planned:
- Build a proper center insulator for balanced feed (instead of my repurposed Plexiglass insulator with unbalanced SO-239), with UV resistant plastic and weather protection for long-term installation and protection from wind/tree static
- Cut a new 20m dipole and return this one back to the tote in the car
- Build another 9:1 un-un or 1:1 balun for mounting outside next to the balcony door
- Trim the twinlead for slightly longer than 20m resonance so the entire antenna system can match on 40m, and find a way to run it from the balun out to the apex without getting near metal objects or itself. It’s currently 40ft of way-too-long and is probably causing some matching problems on its own
- Make better insulators and clips for the ends of the dipole to attach to the bamboo poles
- Run the dipole legs through the trees without snagging on limbs, in an effort to get them at a more obtuse angle for better SWR and efficiency
- Insulate the dipole ends (the high-voltage section) to prevent arcing to the trees
- Fix the riggings and poles so I can deploy and stow in minutes without snags