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UHF Remote Dual 2 If you’re looking for a mains “switch” which can be operated from some distance away, this low-cost, simple project could be just what you want. With a UHF remote control and two switched “channels”, it needs very little power thanks to the use of latching relays. T here are countless applications – especially with colder weather coming on – where it would be nice to turn mains devices on and off remotely. Imagine being able to switch something on and off without having to go close to it – outside in the wind and rain, for example. Imagine being able to control two devices, completely independently. You’re imagining exactly what this device does. It has an IEC mains input connector (so uses a standard IEC power cable) and two standard 3-pin mains sockets, into which any mains devices (up to 2300W total) can be plugged and controlled. It’s housed in a standard plastic case with the only other control an on/off switch. The number of channels you construct is optional. The prototype was made with two channels but if your application only needs one channel, you simply leave a relay and a few other components out. It’s a true remote “switch” – you press one button on the pre-built UHF remote control keyring transmitter to turn one of the relays on, then press another to turn it off. The transmitter has four buttons on it, therefore it can control two channels. It has a nominal range of up to about 80 metres, perhaps more and this should be more than enough for most applications. But this range can be significantly extended with an optional module, which we will look at a little later. And speaking of relays, they’re not your garden-variety types. Each has a contact rating of 80A – much more than is available from a standard power outlet (10A). But more importantly, they’re latching relays which only require a short-term power pulse to turn them on or off. The advantage of this is that once actuated, no power is required to keep the relay “pulled in” – so you don’t waste a lot of power if something needs to be left on for a length of time. We explain how latching relays work in a separate panel. Like the transmitter, the UHF receiver module is pre-built, thus avoiding any setup problems. How it works The UHF keyring transmitter has four pushbuttons, labelled A, B, C and D. When any of these are pressed, a pulse train is sent to the receiver module, it is decoded and the corresponding receiver output will go high. While the pulse train is sent while ever the transmitter button is pressed the The three main components of our UHF Mains switch: (left) the UHF receiver module, already attached to the main PC board and (right) the UHF transmitter module with its case behind. 80  Silicon Chip siliconchip.com.au 30V Power Switch By Ross Tester Design by Branco Justic# receiver circuit only needs a very short “high” to actuate the relay.   When the receiver output goes high, a time-delay circuit comprising a 10μF capacitor and 22kΩ resistor feeds a pulse of around 50ms to the gate of the Mosfet connected to it. This momentarily turns the Mosfet on, grounding the end of the latching relay to which it is connected. Each end of latching relay is also connected to 12V via a 47Ω 1W resistor, so when a Mosfet is turned on, the coil is energised. You might think that a 1W resistor is not enough in this application but it hardly raises a sweat, due to the fact that the turn-on and turn-off pulses are so short. Note that a Mosfet is connected to each end of the latching relay and only one of the two Mosfets will have any effect at any given time, depending on which way the latching relay is set. If, for example, the latching relay is in the “off” position and button “A” is pressed, the Mosfet will enable current siliconchip.com.au to flow through the relay coil and it will pull the relay into the “on” position, where it will stay. Further pressing of the “A” button will have no effect. However, pressing button “B” turns the Mosfet on connected to the opposite end of the latching relay, so current flows through the coil in the opposite direction. This causes the relay to switch over to the “off” position and stay there – and again, further pressing of button “B” will have no effect. Transmitter buttons “C” and “D” and the second relay operate in exactly the same way. The circuit is powered by a halfwave rectifier (D1 and C1) circuit running from an on-board 9V AC transformer. This transformer has a split primary and can therefore be connected for 230V or 115V operation. For 230V operation the transformer primaries are connected in series; for 115V they would be connected in parallel. The circuit can also be powered from 12V DC via a pair of terminals or, as we have done, 12V DC can be taken out from this point to power a LED (inside the on/off switch). A second diode (D2) isolates the 12V supply, which powers the latching relays, from the 5V supply, which powers the UHF receiver module. This is to ensure that the module always has enough power to operate even when the relay coils are actuated. Normal (standby) current is around 14mA but for the 50ms or so that the relays are being powered, the current rises to around 600mA. One thing we haven’t mentioned is that the UHF receiver must be “trained” to recognise the specific transmitter you are using, otherwise they won’t work together. We’ll do this as part of the testing procedure a little later. Construction With the exception of the mains input/output sockets and the power switch/LED, all components mount on a double-sided PC board coded K231A # Oatley Electronics Pty Ltd May 2009  81 REG1 78L05, 7805 +5V ANTENNA WIRE 173mm LONG OUT IN GND D2 1N4001 A K 1000 F 16V 10 F +12V 2200 F 16V A  10 F 22k Q1-4: STU432S MOSFETS 10 F D 22k D0 S 47  1W S 47  1W Q4 10 F G 22k C B RLY1* 80A D RLY2* 80A K 7805 A SC 2009 78L05 IN GND OUT IN STU432S D GND G OUT S 2-CHANNEL UHF MAINS SWITCH and measuring 79 x 73mm. The entire project is housed in a standard all-plastic utility box measuring 95 x 157 x 53mm. It’s a fairly tight fit in this box but it will all go in, as our photos show. As normal, make sure your PC board is up to scratch – there should be no shorted or broken tracks. They’re unlikely these days but it pays to check. The first thing to do before starting construction is to carefully remove the braided output leads from the two latching relays. Unfortunately, they are not insulated nor are the really long enough to do much with. We cut them very close to the relay terminals with sharp sidecutters, then (later) used the remaining copper braid as a handy solder point for the mains wiring. We also found it necessary to bend the right-angle terminals back about 45° so the board would easily fit into the case later on. Take care when cutting these off and bending because the terminals are relatively easy to damage. That done, you can now proceed 82  Silicon Chip 230V AC INPUT MAINS OUTLET 1 N A E MAINS OUTLET 2 N A #LED1 AND ITS SERIES RESISTOR ARE INSIDE CASE OF POWER SWITCH S1 1N4001 E N LINK B-C FOR 230V * BOTH RELAYS ARE LATCHING TYPES Q3 G D1 47  1W S D G GND 47  1W S Q2 22k A +12V D G 10 F IEC INPUT SOCKET S1# D A Q1 UHF D2 RX MODULE 9V AC K #OPTIONAL D3 A K T1 POWER Rs # LED1 # V+ D1 1N4001 E Fig.1: the UHF receiver module D0-D3 outputs go high as buttons A-D on the transmitter module are pressed. These in turn control Mosfets which can energise the coils of latching relays RLY1 or RLY2. If the contacts are closed, they will open and if open, they will close. to assemble the PC board. Start with the resistors and small capacitors (watch polarity – all the electrolytic are polarised) then the diodes and 5V regulator. While the regulator is specified as a 78L05, we used a standard 7805 – either may be supplied in the kit and both are fine. The UHF receiver module plugs into a 9-pin header socket mounted on the top side of the PC board – solder the socket in now but don’t plug in the module yet. Also solder in the three 2-way terminal blocks (it snaps together to form one 6-way). Make sure the wire connection side goes towards the edge of the PC board. Solder the two larger capacitors (2200μF and 1000μF) and the power transformer in at the same time. The two capacitors are a fairly tight fit and may need a bit of juggling to place alongside the power transformer. The transformer will only go in one way – the primaries towards the edge of the PC board. When the transformer is soldered in, it’s a really good idea to glue a strip of insulating plastic over the top of the transformer primary solder connections – just in case! The last components on this side of the PC board are the two latching relays. These have three pins to solder in – two connect to the coil but one is for stability only. You should have only four components left – the Mosfets. These are very small – in fact, they’re surface-mount devices but fortunately the spacing is quite wide so these should present no problems in soldering. The close-up photo shows best how these devices are mounted. Use a clean hot iron but don’t keep apply heat for any longer than necessary. Finally, solder a 173mm length of thin insulated hookup wire to the “antenna” position on the UHF module and then plug the module into its header-pin socket on the PC board. Training and testing It’s easiest to check the project before mounting it in its box – and it’s quite safe to do so because we will check it with a 12V DC power supply. And while we’re about it, we will “train” the receiver to work with siliconchip.com.au # – 4x STU432S MOSFETS SOLDERED ON UNDERSIDE OF PCB * --- KST-RX902A UHF RECEIVER MOUNTED ABOVE TOP SIDE OF PCB 1000 F + GND c 22k 22k S G # D D # D 5x10 F S G # G + * + D + C T1 + B REGNAD LAHTAEL EGATLOV A + TP CS VT D3 D2 D1 D0 +5V – 22k 22k T1 PRIMARY CONNECTIONS D AND A; LINK B AND C 12VDC REG1 2x 7805 47  1W + + D1 D2 2200 F S G S # D 2x 47  1W K231A RLY1 JMX-94F-A-Z RLY2 JMX-94F-A-Z Fig.2: the component layout for the double-sided PC board, complete with the pre-built UHF receiver module which mounts on a header pin socket above the board. Compare this with the same-size photo at right and the completed project wiring diagram overleaf (Fig.3). The terminals pointing down need to be bent to the left at about 45°. your transmitter. Before doing so, however, it’s wise to give the board a thorough examination, checking for bad solder joints, misplaced or mis-oriented components, etc. In fact, it’s even better to have a second person do this for you because you’re likely to see what you want to see! If satisfied everything is correct, connect a 12V battery or power supply to the upper two terminals on the terminal block (+ towards the edge of the PC board). There is a white pushbutton on the UHF module – push it and hold it down until the red LED on the UHF module goes out. Now press button “A” on the keyring transmitter until the red LED flashes. Your keyring transmitter is now matched to your receiver. When you press button A or C on the transmitter two things should happen: (1), you should see the red “acknowledge” LED on the UHF receiver module flash, and (2) you should hear a quite distinct “thunk” from one or other of the relays as it switches over. Pressing the B or D buttons should achieve exactly the same result as the relay releases. If you connect a multimeter (low Ohms range) across one of the relay contacts, you should be able to confirm it closes and opens as you press buttons A then B. If it doesn’t, try buttons C and D – you might be across the wrong relay! If everything checks out, you’re ready to mount the PC board in its case, along with the input/output connectors and on/off switch. If not, you need to go back over your component placement and soldering. If the red acknowledge LED lights when you press a transmitter button that suggests the power supply is fine but if you don’t hear the relay Above is the area of the top side of the board normally hidden by the UHF receiver module. This also shows the row of header pin sockets into which the UHF receiver module plugs. Note the regulator (top of pic) is in this case a 7805 – a 78L05 could also be used. A close-up of the underside of the same section of board, showing the mounting of the four STU 432S Mosfets. It’s a good idea to glue some heavy plastic insulation over the mains terminals of the PC board . . . just in case. It’s not just leathal, it’s lethal! siliconchip.com.au May 2009  83 MAINS OUTLET 1 CASE 12VDC + + + – C ANTENNA WIRE – ENSURE FREE END IS SECURED UNDER CABLE TIE AND NO COPPER IS VISIBLE (USE HEATSHRINK SLEEVE IF IN DOUBT) + D A (UHF RX MODULE) + E RE G NAD LA HTAEL E GATL OV A B + N + + IEC MAINS INPUT PLUG K231A c oatleyelectronics HEATSHRINK SLEEVING ON ALL SPADE CONNECTORS CABLE TIES RLY1 LED1 CONNECTIONS S1 UNDER POWER ON/OFF CUT OFF EXISTING BRAIDED WIRE ON RELAY CONNECTIONS AND USE AS NEW WIRE SOLDERING POINTS RLY2 HEATSHRINK SLEEVING ON ALL RELAY CONNECTIONS MAINS OUTLET 2 Fig.4: follow this wiring diagram exactly – it’s important for your safety. If you don’t want to use a power switch, run one of the brown wires from the IEC Active terminal directly to the D terminal on the PC board – and also leave out the 12V wiring to the LED. thunk, the problem is either in the time delay R/C network, the Mosfets or the relay. If the red acknowledge LED doesn’t light at all, the problem is in either the 5V regulator section or in the UHF receiver module itself. Mounting in the case We used a 95 x 157 x 53mm (UB1) ABS case which is available from a number of suppliers. Ensure you get the all-plastic variety (including lid), ie, don’t use one of these cases with an aluminium lid. It’s a pretty tight fit in this box but it does all go in, as our pictures show. The PC board mounts in the bottom of the case with the input and output connectors above it. Four holes need to be made in the case. On one end, only a few millimetres down from the case top edge, are the IEC mains input connector and the on/off switch with its integral LED. On each side of the case, at the opposite end to the input, are the 3-pin mains outlet sockets. These mount as close as practical to the end of the case to give as much room as possible 84  Silicon Chip inside for wiring. Use photocopies of the cutout diagrams (Fig.5) as templates for drilling the holes. That’s exactly how we cut the appropriate sized and shaped holes – we glued photocopies of the diagrams to the case, then drilled a number of fine (say 2-3mm) holes on the inside of the lines. We then pushed the middles out and smoothed the holes with small files. The 20mm hole for the on/off switch is round, so this was drilled as large as possible then enlarged with a tapered reamer (although the above method would work just as well). You’ll also need to drill two 3.5mm holes alongside the IEC connector for its mounting screws (use the IEC connector itself to ascertain their position) and four more in the bottom of the case for the PC board mounting screws. The actual PC board position is quite critical because it must allow room for the other components inside the case. It actually mounts under the sockets, sitting on four nuts to raise it up enough for the Mosfets soldered underneath. It also sits hard up on the edge of the case so that the relay terminals will fit in (bent back 45°, as mentioned earlier). We used the PC board itself to carefully mark the mounting hole positions but as a guide, if you put the first hole 20mm from the left (inside) edge and 5mm down from the case wall, with the remaining four holes on a 73 x 36mm rectangle, you should be pretty-well spot on! In all cases, the PC board and the IEC mounting screws are Nylon to maintain insulation between inside and outside of the case. The nuts inside may be either Nylon, steel or brass. But don’t put the board in the case just yet – you need to connect wires to the relay terminals first. Connecting it up Start by wiring from the relay terminals back to the input and output sockets, as these are the hardest to do. Use 10A, mains-rated (250VAC) wire as you are switching the Active power lines. You’ll need one length around 100mm long and one around 200mm long. Incidentally, the easiest way to get such wire is to strip it from a dissiliconchip.com.au The completed project, ready for the lid to be screwed on. Note the generous use of heatshrink insulation and cable clamps; also the routing of the antenna wire as much as practical away from the mains wiring. carded mains lead! Bare about 35mm or so of insulation from one end of each wire and wrap each around the right-hand terminals of each relay. The shorter wire goes to the closest socket. The wires should be mechanically secure on the terminals (ie, they won’t fall off!) before soldering. Fortunately, the relay terminals are quite easy to solder to but you will require a reasonable amount of heat to adequately solder the wires on. The other two terminals (bent 45°) are wired in parallel with another length of brown mains wire, prepared and soldered in a similar way. Ideally, the terminals and wiring should be insulated – we used a length of large diameter heatshrink, slit down the middle, which we wrapped around the two relays (and their terminals) be- fore shrinking. It’s not perfect but its better than nothing. While you have the brown mainsrated wire at hand, cut off a short length (~25mm) and bare 5mm at each end. Assuming you’re wiring for 230V, one end is secured in terminal B of the six-way terminal block and the other in terminal C. Make sure no bare strands poke out of the terminal block. Put the PC board aside for a moment while you wire the IEC input and the mains switch (if fitted) plus the mains outlets. The IEC connector and mains switch need to be fitted to the case before you connect to them but the two outlets can be done outside the case – in fact, they have to be to gain access to the grub screws. Follow the wiring diagram exactly, including the heatshrink insulation over the various spade connectors. Start with the IEC connector earth terINPUT PLUG IEC MAINS CUTOUT FOR IEC MAINS INPUT CONNECTOR 14 A 5 6 5 9.5 A 5 18 6 A HOLES: 3mm B 14 33.5 CUTOUT FOR 3-PIN MAINS OUTLET The end-on shot of the case shows the mounting of the IEC mains input connector and the on-off switch with its internal LED. Be sure to use Nylon screws for the IEC connector (as well as for the PC board mounting) to ensure insulation integrity is maintained. For the same reason, an all-plastic switch is used. siliconchip.com.au 10.9 16.75 B HOLES: 4.5mm Fig.5: same-size cutout details for the IEC connector (as seen at left) and the 3-pin mains sockets (as seen in above photo). May 2009  85 14 Parts List – UHF Remote Power Switch 1 double-sided PC board, code K231a, 79 x 73mm* 1 UB1 (157 x 95 x 53mm) ABS utility case with ABS lid. 1 TX01 UHF receiver/decoder module* 1 TX9 4-button UHF keyring rollingcode transmitter 2 JMX-94F-A-Z SPST 80A latching relays* 1 PC-mounting mini mains transformer, 9V secondary* 3 2-way pc-mounting screw terminal blocks (forms 1 x 6-way)* 1 9-way male header pin strip* 1 9-way female header pin socket strip* 1 IEC mains input socket, screwmounting type 1 mains lead with IEC plug 2 surface-mount 3-pin mains outlets 1 250V 1A switch with integral LED and resistor (optional) 1 500mm length 10A brown mainsrated hookup wire 1 500mm length 10A blue mains-rated hookup wire 1 500mm length 10A green/yellow mains-rated hookup wire 1 175mm length hookup wire (for antenna) 1 50mm length red/black mini figure-8 (or individual red and black – for LED 6 10mm M3 nylon screws 6 M3 nuts 3 6.4mm crimp-type spade connectors 2 6.4mm piggy-back spade connectors 2 4.8mm spade connectors 5 mini cable ties 1 piece of rigid plastic, 20 x 30mm, for PC board insulation lengths of heatshrink tubing Semiconductors* 1 7805 or 78L05 Regulator (REG1) 2 IN4001 power diodes (D1,2) 4 STU432S power Mosfets (Q1-Q4) Capacitors* 1 2200μF 16V electrolytic 1 1000μF 16V electrolytic 5 10μF 10V electrolytic Resistors* 4 22kΩ 1/4W 4 47Ω 1W * These components form K321B Kit 86  Silicon Chip minal – it has two green/yellow earth wires crimped inside one spade connector. These other end of these two wires screw into the earth terminals on the mains outlets. You will note that we used a couple of “piggy back” 6.4mm spade connectors on the Active and Neutral IEC connector terminals. The Neutral has three blue wires, one screwing into each of the mains outlets “N” positions and one terminal “A” on the terminal block on the PC board. Brown wires connect the IEC Active terminal to the on/off switch and to the paralleled relay terminals. Another brown wire connects from the other terminal of the switch to terminal “D” on the terminal block on the PC board, while the + and – LED terminals on the switch connect to the + and -12V terminal block positions. There is a series resistor inside the switch so the LED can be connected directly to 12V. Again, follow the wiring diagram exactly and you shouldn’t go wrong. Incidentally, the reason we are specific about which terminal is wired with which wire is that connecting the blue wire (Neutral) to terminal “A” keeps the brown wire (Active) as far away from the 12V supply as possible. Because mains wiring is involved, all of the spade connectors really need to be crimped with a ratchet crimper – the “plier” type of crimper really doesn’t apply enough pressure to adequately crimp the cables. If you don’t have a ratchet crimper, it’s a good idea to solder the wires to any spade connectors (as well as crimp them). Before you get too far down the track, you will need to insert the PC board into the case, along with the two mains outlet sockets, to complete the wiring. Dressing the cables Where mains wiring is involved, we must assume the worst-case scenario where, somehow, a wire lets go (eg, it unsolders due to heat, or is not screwed in properly, etc). This being the case, we must assure the wire cannot flail around and contact something it shouldn’t. Therefore, all of the wiring within the case needs to be routed along the edges and fastened together with small cable ties. Small cable ties are very cheap ($2 a bag at bargain stores!) so don’t scrimp on them There are a couple of handy mounting holes on the mains outlets (which we don’t use here as the outlets “sandwich” around the case) which make handy cable tie anchors – see the photos. The UHF receiver requires a short length (173mm) of hookup wire for its antenna. Ideally, this wire should also be mains-rated. One thing that would concern us about this wire is if there were any strands of copper poking out the end. Just to be on the safe side, we covered the end of the wire in a short length of heatshrink and made doubly sure it was secured properly. You will note in the photographs that this antenna wire is also kept away, as much as possible, from the mains wiring. This is not just for safety reasons; keeping the antenna wire separate will also give the receiver its maximum sensitivity and therefore greatest range. When you are satisfied that the project is wired as shown in our diagrams, place the lid on the box and screw it in place. Now connect the power and turn it on. The LED inside the switch should glow, indicating you have 12V – and when you press “A” or “C” on the transmitter you should again hear that “thunk”. Press “B” or “D” to turn it off, then connect a mains device such as a lamp or other easy-to-recognise device to either of the power outlets and check that you can turn it on and off via the transmitter. Finally, remember that turning off the power switch will not turn off any device which is being switched – it stays in its current state until you switch it with the key transmitter. The power switch only disconnects power to the UHF Switch. Where from, how much? This project was developed by Oatley Electronics, who retain copyright on the design & PC board. The K231B Kit, which includes the UHF receiver and all on-board components sells for $49.00 inc GST The TX9 transmitter, including keyring case, sells for $16.00 inc GST Freight is $7.00 per order web: www.oatleyelectronics.com.au or (02) 9584 3563 siliconchip.com.au What is a latching relay? These shots are of the type of latching relay used in this project, with the one on the right removed from its case so you can see what makes it click! The two braided leads welded to the terminals should be cut off as they are not used. This explanation comes from our December 2006 issue but we thought it would be opportune to repeat it, as a latching relay is not something that you come across every day. In fact, even those “in the trade” may not understand the operation nor purpose of a latching relay. First, a conventional relay operation: this has an electromagnet, formed by a coil wound on a laminated iron core. While current flows through the coil, a magnetic field is created which attracts a spring-loaded steel armature towards the iron core. The armature either pushes or pulls electrical contacts towards or away from each other, making or breaking a circuit (and in most relays, both – breaking one circuit then making another). When the current stops, the magnetic field collapses, so the armature springs back and the contacts revert to their normal state. A latching relay is much the same, except that once the armature has switched over to the opposite position, it will stay there, even when the current through the coil stops. It will only switch back the other way when told to by the controlling circuit. You could even disconnect the latching relay from the circuit completely and it would still stay in the last-set position. A good analogy is a standard switch: you push the lever one way and it stays there until you push it the other way. The difference is that instead of a finger pushing or pulling a lever, you have the magnetic field pushing or pulling the armature. The armature may be held in place by a permanent magnet or it may be mechanically latched, based on a spring and detent system (which, incidentally, is how most switches stay in the selected position). Another analogy is a bistable multivibrator or flipflop – it has two stable states, neither of which has any pre-eminence over the other. Latching relays may have two coils – one switching to one position, the second switching to the other – or it may have a single coil, where the current is reversed through the coil to switch to the opposite state. This is the type of latching relay used in this project. It is a common misconception that latching relays do not consume power when energised. Although current is not required through the coil to hold the armature in position, current will still flow if applied, negating the reason for using a latching relay over a conventional relay. Therefore, a short pulse of current is normally used to actuate it, just as in this project. Where conventional relays have “normally open” (NO) and “normally closed” (NC) positions, latching relays with changeover contacts don’t – because there is no “normal” position. In our case, the relay is a SPST type so, like a switch, the contacts are either open or closed (off or on, if you like). Finally, no relay coil suppression diodes can be used on a single-coil latching relay because of the polarity reversal. Therefore the voltage rating of any switching transistor (or Mosfet in this case) must be high enough to safely handle the sp‑ike which occurs when current ceases and the magnetic field collapses. siliconchip.com.au Want really long range (2km or so!)? Oatley Electronics have available a tiny (27 x 20mm) add-on transmitter module which is claimed to increase the range of the TX09 transmitter from tens of metres to kilometres. It’s the TX-03 module, which also operates under Australian LIPD (licenceexempt) regulations. There are only three connections required – data (which can be taken from the antenna output), power (3V or 5V) and ground. It will operate from 315MHz - 433.92MHz and from -40° to +80°. Oatley’s RRP is $16.00 The manufacturer of the TX-03 states that the transmit power is 15dBm, which equates to 32mW. Presumably this is at the upper end of the specified operating voltage range (3-12V). The maximum legal output power of LIPD devices in the 433MHz band is 25mW, so (again presumably) the transmitter would need to be operated at the lower end of the supply voltage range to remain legal. Indeed, Oatley Electronics warn that operating at 5V may exceeed the legal limit. Therefore, we suggest operating only from 3V. Oatley claim a range of 2km+ at 3V and 4km+ at 5V. Naturally, the TX-03 module will not fit inside the keychain transmitter case so you will have to make other arrangements to mount it and also power it. The telescopic whip antenna can be unsoldered from the TX-01 PC board and a short wire used to connect that point to the “Data” input on the TX-03. While the TX-01 has a 12V battery, using this would result in too much transmitter power, as described above. Unfortunately, despite extensive searching, we have been unable to obtain any further specifications for the Chinese-made TX-03. SC May 2009  87