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Looking around at mono band antennas and also having tried a few one thing stood out . They all ( or most ) relied on "tuning" a counterpoise and /or adjusting whip length, this could be fine in one qth but then you could find your vswr high in another especially if the counterpoise used was lay on the ground and not a true tuned c/poise suspended off the ground.I set about making a set of monoband antennas that required no or little tuning in the field and if any was needed it could be done at the antenna via a small trimmer cap on the matching box and more importantly ( for me) using a single length counterpoise for all the seperate antennas as im making a set and no messing around up and down with the whip to fine tune. The one below is my 30m version and just needs a banana socket fitting to accomodate a banana plug for the c/poise. I tuned this antenna in the clear and the vswr results seem repeatable as long as i'm in the clear.
The matching box
Below you can see the matching box. You can see the small hole in the side of the case to accomodate the screw for the trimmer capacitor inside the unit. This is used for any fine tuning to initially tune the antenna. I have found this useful if i have tried it for example in my home where the vswr rises slightly so i can fine tune it . I have found once tuned in the clear it requires no further tuning again as long as its used in the clear.
Schematic
The antenna was tuned using a 30 foot counterpoise wire on the radio. This same wire was used when i made the 20m version and also whilst working out the turns needed for all bands up to 6m.
core winding info
The core windings required for each band are as follows using T68-2 core using 24 swg.
30M , 35 turns/20m , 23 turns / 17m , 14 turns /15m , 12 turns / 10m , 7 turns and 10m , 5 turns.. all turns close wound.. T50-2 core can also be used but windings will vary slightly , an extra + or - one or two turns gets very near the same inductance as the T68 but this will need to be experimented with. Using a T50 would allow enough room for a switch and my next build is to see if i can tap the core for 2 bands per unit but room on the smaller T50 would only allow this on the higher bands.
3 finished antennas for 30,20 and 17m . Would like to do some side by side RX tests and also some tests using these versus a commercial miracle whip.
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![match2[1].gif](images/match2[1].gif)
