i've been awol for a while. i lost my password and only just know found it again. (doh!)
i've been awol for a while. i lost my password and only just know found it again. (doh!)
i've heard of people here doing various things to tune a 3m antenna but i havent seen anyone talk building making a full on t-network antenna tuner. as i understand it t-networks work great at lots of different impedances and at frequencies. have you guys experimented with this already? is it a dead end?
heres a few links i just found on the topic of matching networks in case anyone is curious:
http://www.qsl.net/vk3jeg/atu.html
http://www.k7mem.150m.com/Electronic_Notebook/antennas/end_fed_ant.html
http://fermi.la.asu.edu/w9cf/tuner/tuner.html
i recently acquired a bunch of variable capacitors so i am tempted to trying this out.
think hamiltons use a T-network the coil being a toroid and the cap being a trimmer
Antenna matching is physics, but in practice, it's more like an art form. Matching networks have been around a long time. The only caveat for what we do with such low power is that we need to avoid unnecessary resistance and losses in the unit, so component sizes and values become more critical.
Having said that, the worst that can happen is that your efforts might fail ... but that rarely stops most of is from experimenting ... when we have time 😉
Here's a page that's kind of on point, titled ANTENNA TUNERS AND LOADING COILS
http://hlrinternational.tripod.com/id14.html
The Rangemaster has the secondary winding of an RF transformer, which serves as the loading coil, tuned to resonance with a trimmer cap across the terminals of the coil. I would not call that a T-network.
a t-network has two tuning capacitors. i guess the advantage of the t-network is that it can handle a wider range of impedances. but maybe that isn't so important in a part15 situation.
The Rangemaster coarse tuning is done by selecting taps on the secondary winding of the RF transformer, and fine tuning is done by the trimmer cap in parallel with the secondary winding.