Sidekick control box modification

Preface-Addendum:
      Try this mod at your own risk,
      no, nothing bad will happen to you or your radio,
      but after trying it for awhile,
      I find the action a bit jerky when trying to 'jog' the antenna into fine-final tune.
      If the up/down button is pressed very quickly to move the tune slightly,
      the radio goes in and out of tune very fast too,
      so you don't really know if the tuning is correct.
      I'm now thinking of using the toggle switch to put the radio into tune mode,
      so it can be set to tune, jogged, then taken out of tune.
      Yeah, it's a bit more work, but trying to 'catch' the quick tune just isn't working as well as I hoped.
      (see the bottom addendum)

The control box that comes with the stock High Sierra Sidekick Antenna
has an up / down control and a lamp to indicate the antenna has hit the end of the travel.

To find the correct tuning for the antenna,
first the antenna is raised or lowered until the background noise or a QSO is heard the loudest and the s-meter peaks, then the '706 is put into the RTTY or CW mode and the power is lowered to L.
The radio is keyed and the raise/lower button is again activated until the SWR is at the minimum.
Now the '706 is return to the sideband function, and the power is raised to what's needed.

Master Po, It is too bad that the builtin tune function can not be activated by the antenna control.

Aahhhhhh ! ! !
But it can Grasshopper !
When is the bird that flys around the swimming fish,
and the gonkulator is intermodulated with the . . .

OK OK,
get to the good stuff Po !!

Hah yes impatient one . . .

High Sierra has a new controller box, the I-Box,
that will activate the '706 Tune function (low power, CW)
whenever the up/down control is activated.
The I-Box and Antenna can be purchased as a package (the I-tenna) and that is a great idea.
But I purchased the antenna second hand and already have the standard control box.
The I-Box is available separately,
but at $110, and then I still have the original to throw in the junk box,
a yankee-ham idea was needed.

Tooling around the net gathered the requirements for the '706 tune control from G4FZN,
showing that the tune function is activated by "grounding' the antenna tuner port pin 1.
Chris used a 10K resistor to 'ground' pin 1 to pin 4 using a transistor.

Armed with that and a non-polarized low current relay,
we too can 'ground' pin 1 whenever the up/down switch is activated.

In the original box, the power from the cigarette lighter and fuse
goes through the current limiting / end-of-travel lamp,
Then to a double pole, double throw momentary, center off, reversing switch,
then on to the motor to run it up (+) or down (-).

By adding a relay across the output line, we have an activation control anytime the motor is run (up or down).
The added switch in series with the relay coil lets us tune the antenna 'by-ear' without having to transmit.
The 10K was used by Chris and works, but others have just grounded pin 1.
In practice, we actually used two 4.7K resistors in series, one in the control box, and one at the plug by the radio.
Why ?
Just in case a voltage gets onto the line, it won't (shouldn't) hurt the radio.

The wire from the front mounted control head and the radio is just a small (18 AWG) speaker wire pair the I had.
The additional 47K resistor is mounted in the connector at the radio side, this tells the '706 that a tuner is connected,
and to accept the 'Tune Control' signal from the relay.

There isn't alot of detail added here for the operation and actual control levels of the Tuner Control port.
This is discussed in the '706 tune control from G4FZN article, and others on the net.

The switches, relay and resistors used were junk-box parts.
There is nothing critical about them (except to make them fit in the box).
Radio Shack and others have suitable small relays and switches.
The relay has to have a non-polarized coil, but can have multiple contacts, but we're only using one NO set.
If you have any questions, contact me via my call sign at the arrl dot net, email forwarding address.

This is a view inside the control box, lots a room for the mods.
Notice the lamp/resistor in series with the + lead and the cross wired up/down switch.


This is the modified control box.
The relay is glued to the corner of the box with it's leads up (dead-bug style), lower left corner.
The series (tx-disable-while-tuning) switch
is mounted through a new hole drill between the up/down switch and the lamp.
The yellow wires are the added relay-coil activation connections.
The output (10K to ground) wires are snaked through the stock strain relief
to a small in-line connector (not shown) and back to the 4-pin Molex connector of the radio.

Take care when soldering in the small box. There is lots of room, but when you stick a hot iron down in between the wires, you don't want to lose too much of the insulation.
Fortunately I didn't do too much damage and photo-shop won't let you see it.

In operation, we generally tune 'by-ear' with the tune control relay shut off.
By listening for the most signal or peaking an existing QSO, a close match is attained.
Then the switch to enable the '706 tune control is set,
and the radio will transmit at 10W CW signal whenever the up/down motor control is pressed,
and the built-in SWR meter is watched to enhance the tuning.
Be sure to set the radio to a non-used area of the band, especially if you re-tuned by ear on a QSO, so as not to cause interferance.

addendum: The relay idea works similar to the I-Box, with the semi-automatic tuning,
But wait . . . it can be cheaper (and easier) still ! !
Instead of the relay controlling the grounding of pin 1,
why not just let the switch that we added do it?
By having the switch start the tuning mode (10W-CW),
then operate the up/down switch, you can find the match and when found,
just flip the new switch off.
So, just wire the toggle switch in, instead of the relay contact.
Keep the two resistors of course, but eliminate the complexity of the relay.
Not quite as automatic, still easier than switching modes, lowering power etc by hand.

Now . . . how about a double-pole double-throw center-off toggle and we can have BOTH ! !
Manual and semi-automatic hhuummmmm . . .
But that's going even more complex and we haven't tried it . . . yet . . .

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