I was working with a End-Fed antenna. I simply fit the antenna wire into available space so the antenna was effectively a random length. A rough calculation showed that the antenna wire was about 92 feet long. The feed-point, which is at ground level, is connected to a 4 foot long ground rod and a choke balun made with 7-8 turns of RG-8x. While this length might not be optimum, I was curious as to what bands it would be usable on.

I have two antenna tuners, a Dentron Jr Monitor and a MFJ 941D. But both tuners are T-Type tuners. T-Type tuners are a C_Ser-L_Par-C_Ser configuration. T-Type tuners work great, but may not be the best choice when working with a End-Fed antenna.

This tuner was initially designed so that the configuration can be switched easily between L, PI, and T configurations. I was going to just use a rotary switch but then realized that, using movable plugs/jacks gave be more flexibility. The jumpers can then be configured to provide several other configurations. And even some configurations that are useless.

The front panel of the tuner is pretty straight forward. Capacitor C1 is on the lower/left, the switch for the Inductor L1 is in the upper/center, and capacitor C2 is on the lower/right. That's all there is so I don't think that a drawing is needed. But the rear panel might need a little more explanation.

On the right is a scaled drawing of the rear panel. The rear panel is 5-7/8" wide by 4-3/8" high. On the lower/right is a SO-239 connector for Input from a transceiver. On the lower/left is a SO-239 connector for the Output to an antenna. Between those connectors are two Ground terminals. Directly above the Output connector is a binding post for a End-Fed Wire. While it is not shown on the physical diagram, the binding post is wired directly to the center conductor of the Output SO-239. This is then routed out the grommet labeled RF Out and terminated into a Pin Plugs.

The upper/right contains the configuration jacks/plugs. The Pin Jacks, labeled J1 through J15 are used to set the configuration. Directly below those Pin Jacks are five rubber grommets labeled L In/C1 Rot, C1 Sta, L Out, RF Out, C2 Sta, respectively. The configuration wires exit the chassis through the grommets and are terminated with Pin Plugs. The rubber grommets are simply to protect the wires. configuration plugs. For any particular configuration, these Pin Plugs will only be plugged into the Pin Jacks directly above them. For example, the Pin Plug comming from the grommet labeled, L In/C1 Rot will only be plugged into J1, J2, or J3.

The wiring shown on the drawing is actually on the inside of the chassis. The colors are just for clarity. But this gives a good idea of the internal wiring.

There is nothing critical about the pysical layout. I just used the space available. The Jack/Plug Matrix is spaced 7/8", down from the top, and 1" in from the right. The Jacks/Plugs are then spaced 1/2" from each other, vertically and horizontally.

The labels on the right (L, PI, and T) make for easy switching between the three main types of tuners. If you move ALL of the Pin Plugs to the Pin Jacks in in any one of those rows, the tuner type listed by that label will be realized.

The original idea came from http://www.qsl.net/sv1bsx/tuner/tuner.html. The original contained a switch that allowed you to quickly change the configuration. But I was working with a partially built home brew tuner that I purchased at a ham fest. The tuner had all of the hardware mounted, but was just never finished. What was really nice was that the tuning capacitors were already mounted on ceramic insulators and isolated from ground. It appears that it was originally meant to be a T-Type tuner.

Below is the schematic for the Multi Tuner. Initially, the drawing simply shows the internal wiring of the tuner. On the upper/right of the drawing is a table with six interactive buttons. Clicking on any of those buttons, except "Clear", will show the necessary jumpers required for that particular configuration. The upper/left side of the drawing will then show you a small schematic of the configuration.