Saturday, May 27, 2006

Home Brew Balanced Tuner

See comments at the bottom of this page for more information about this project.
Inductors are in parallel- The box is an un used fire alarm control panel from my work.

The fire alarm control panel made a nice enclosure.

The plexiglass viewing lid from the FACP makes it nice to see the relays as they are picked. The choke is under the round, white plastic lid. I power the relays with 24vdc.

Left to right: Inductors, 16 position cap switch, C1 and C2

This tuner was not only a fun project, but it is a very usefull tool in my shack. The design is not mine. WA7NAN suggested the layout and componets. I was able to cobble it together. The inductors and one of the Caps are from Ten Tec - The other cap is from my junk Box.
I used a diode matrix to switch in 16 different values of capacitance from the 4 door knob caps. This really give a lot of lattitude to the tuner. The Balun, or actually it's a choke, is on the transmitter side of the circuit - so it does not deal with the huge mismatchs that other designs face with the balun on the antenna side.
I use a 160 meter dipole and an 80 meter delta loop with 450 ohm ladder line. An external relay picks the feed line to connect to the tuner. I use an AL-572 - and have never had any arching or smoke at any frequency.


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