The One Quick Switch
Extend Battery Power!
An Adapter for the Z-11 QRP Auto Tuner
By Richard Morrow, K5CNF

ithin the world of the QRP backpacker or the HF backpacker, battery weight and life is of prime importance. Anything that can be done to conserve battery life and to reduce the weight that is in the backpack holds great interest for those who pursue this aspect of amateur radio. For those who are not aware of this amateur radio amateur activity, there are a considerable number of hams that like to backpack their gear. They enjoy camping and radio operating in inaccessible places and operate with battery power from these remote locations. There is a SIG for HFPack on Yahoo (HFPack), and the group has a considerable membership. Radios being used range anywhere from surplus military radios to the commercial radios. For example, some backpackers use such equipment as the PRC-74 series and the PRC-104, which are man-pack carried and cover the HF bands, with SSB, CW and data capabilities.  At the commercial end of the scale, there are rigs like the Yaesu FT-817, the SGC-2020, and others, not to mention a wide variety of commercial kits and homebuilt equipment.

The weight factor is getting a lot of consideration by the many operators who backpack. Speaking from military experience, the lighter the load you carry, the happier you will be at the end of the day. Many of the HF pack group members are using the Yaesu FT-817 and the LDG Z-11 QRP automatic tuner.

Since my primary concern was not backpack operation, but operating in emergency conditions, such as in the aftermath of hurricanes and other such disasters, I was also concerned about the battery life of the power supplies for my portable equipment. I knew that the SGC-2020 would work on eight to ten D-cell batteries if I reduced the power to 1 watt, a level that will allow CW or SSB for a few days. My other battery-powered box is the Z-11 autotuner. Now I know that the Z-11 does not draw much current at rest (none if the power switch is off) and I had a small Radio Shack battery holder for eight AA batteries that was to power the Z-11 in case of an emergency situation. Since there is no way to tell how long any such emergency might need to be endured, I became concerned as to how long the Z-11 battery operation would last. The 2020 transceiver was not a concern on battery life, since I had a way to charge the D cells and the 12-volt car batteries. I have a patch cord that would allow the Z-11 to run off of the same power supply as the 2020, but I still wanted to limit the total power drain as much as I could. So I started a search to find a way to reduce the total power drain.

THE ONE QUICK SWITCH
After some looking around and checking specifications on different devices, I located a plug-in modification for the Z-11 that would cut the power drain down to nothing between tune cycles without having to turn the Z-11 off and on. This device is a little PC board for the Z-11 called the "One Quick Switch" that is made by W4RT Electronics. A few e-mails and five days later, a package with the One Quick Switch (OQS) inside arrived at my house.

The switch was well packed and came with excellent instructions, complete with photographs and detailed information on how to install the little board in the Z-11. All one needs to do is to simply follow the directions and refer to the pictures for the correct position of the little board when installing it.

Now A VERY IMPORTANT POINT:
Before you order your OQS, you must first must open the Z-11, look at the CPU and determine the version, which is located on a label right on top of the CPU chip. If you built your Z-11 from a kit, you may have that information written down somewhere. You MUST have V1.4 to be compatible with the OQS.  Older CPU versions do not allow proper operation because they expect the carrier to be present when the Z-11 Tune button is pressed. The version V1.4 CPU includes a timing delay before the carrier presence is tested. This allows time for the One Quick Switch to activate the Z-11 and for the One Touch Tune to place the FT-817 in a carrier generation condition.. There is an exchange program with W4RT Electronics that allows you to send in the CPU if it is not the V1.4, and they will send you the correct CPU. I had to take advantage of this service as I had the V1.3 chip. I received the replacement chip within a week of requesting it.

EASY TO INSTALL
Installation instructions are not needed for the new chip, as the socket for this chip is well marked as to the correct orientation of the chip. But, use care when installing the new CPU and do not use too much pressure to push the chip into the socket. If the CPU seems to be hard to press into the socket, then double check to make sure that the chip is orientated correctly. It is possible to break the chip and/or the board if you use too much pressure to insert the chip into the socket.  Hence, care is imperative.

Photo 1 shows the top of the little board and Photo 2 is of the bottom of the board.

Photo 1 - Top of Daughter Board

Photo 2 - Bottom of Daughter Board

You must disconnect the Z-11 from all external cables and remove the case. Now you are ready to begin the modification process. Photo 3 shows the interior of the Z-11 before conversion and reveals the area where the modification is performed. You can see that the CPU I had clearly is a V1.3 and required the exchange. Also, the ribbon cable that connects the front panel is shown and must be unplugged from the main board.

Photo 3 - Interior before conversion showing CPU

After I received the V1.4 replacement CPU chip, I continued the simple conversion. Following the instructions step by step, I finished the job within about 2 minutes. Photo 4 shows the little daughter board that is installed in place of the front panel cable before the cable is reinstalled on the daughter board.

Photo 4 - Conversion made showing daughter Board installed but not cabled yet

Photo 5 displays the completed installation before replacing the case. One can see the front panel cable is reinstalled on the daughter board.

Photo 5 - Conversion made showing daughter Board installed & with cable attached

After the conversion is completed, the Z-11 still operates in the normal manner as when operating from a fixed station power supply with the Z-11 power switch in the normal "on" position. The difference in operation becomes evident when switching to battery power. When using battery mode, the Z-11 remains turned off. When tuning is needed, the transmitter is keyed up, the tune button is pressed on the front panel of the Z-11 and the button is held down until the Z-11 wakes up. It then does the required antenna tuning and turns right back off as soon as tuning is completed. It will take about one half to one second before the Z-11 comes to life and the relays start buzzing. When this happens, just immediately lift the finger off the tune button. Once the Z-11 finishes tuning, it turns itself off until you need it again. It’s that simple and of course, obviously, this little gadget will help to greatly extend the battery life.

As one can readily realize, the One Quick Switch is a clever, useful and even essential accessory for the Z-11. If using something like the 2020 or other similar transmitter, the modification would be well worth consideration for your Z-11. The construction is first class and it is made here in the U.S.A. My questions via Email were answered very quickly, and as far as I am concerned, customer service is excellent.  The price is $39.95 plus shipping & handling.

If you have the FT-817 portable, there is a W4RT Electronics module, One-Touch Tune, that allows one button tuning by turning on the Z-11 and keying up the FT-817 in the proper sequence to allow the Z-11 to do the tuning and turn off when done, and also un-keys the FT-817. There is also a kit for the FT-100/D that allows one touch tuning. -30-

 ~ antenneX ~ July 2002 Online Issue #63 ~

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