|ROX2-T that has a more conventional way of direction finding using signal strenght.
But i was very happy with my housing design for the ROX2-X so i designed a SMD version of the ROX2-T at exact the same size as the ROX2-X and is switched them out, so now my housing contains a ROX2-T.
|QCX CW transceiver from QRPlabs for a ridiculously low price. Excellent extremely well built and documented kit from Hans Summers
In an effort to make it evenmore excellent then it already is i did a few mods.
As i already have a KX3 with paddle, i 3d printed a bracket to mount the KXPD3 paddle to the QCX, for this had to move the headphones jack (yes i am lefthanded)
I joint 4 Li-ion cells to a 4S battery with nominal voltage of 14.8 Volt (cell type 103040, 30x40x10mm, 1200mAh, 3.7V) it fits inside the housing underneath the PCB. i put a thin sheet of insulating foam between battery and PCB keeping the batterypack firmly in place.
At the GPS connector location a made a 6Pin connector with one pin blocked so i can't put the charging connecter in wrong, now i can balance charge the individual li-ion cells.
I replaced the power connector with a 3.5mm stereo audiojack for the headphones.
I mounted a P-channel FET witch switches the power supply on/off by plugging in/out the headphones.
The transceiver is now standalone and with 1 meter coax and a end-fed antenna using a FT82-43 transformer with 10 meter wire i now have a 5Watt 20mtr portable CW station weighing under 600 grams. As for battery life, it seems oke, but needs further testing.
It is based of the well proven End-Fed principle using a FT140-43 toroid with a 1:7 turns ratio (2 turns primair and 14 turns secundair) creating a 1:49 impedance transformation.
For the 30 and 17 meter band Anderson powerpole connectors are used to make the antenna resonant a these frequencies. The antenna is wel capable of handling powers of up to 100Watt.
|SP7IDX. Good price and excellent build quality, but had to wait 4 months before it arrived.
There is however one thing i don't like about Hexbeams, they are always mounted on top of the mast, but since i also like VHF i wanted to keep my 6/4/2 meter antenna's above the HF antenne.
After some thinking i came up with the idea to mount the Hex beam halfway up in front of the mast using a (homemade) bracket. The bracket is made of aluminum 270mm long 80x80 mm square 5mm thick. 8 holes of 10mm where drilled in the sides for the bolds, a 60mm and 35mm hole was drilled in top for the mast and Hexbeam. Then the bar was cut in two. With this bracket the antenne is mounted rock sollid to the mast. As an extra i also used a smaller bracket to give the top of the Hex beam some extra support.
I did no priore SWR test, but the SWR is fine on all bands. Click on the title of this post and you'll get the picture
|partial kit as sold by DL8UWE. The kit consisting of the PCB (witch UWE kindly offered to solder on and program the processor), the housing in the form of pre cut PCB board, the brass loop already bend in circle and some "hard to get" parts. Uwe also has a link to a reichelt shopping list with all parts necessary to complete the receiver. Excellent service from Uwe. The receiver is good and very sensitive. And it can be operated with one hand. If i now don't win ARDF contests i can't blame the receivers.|
|ROX2-x 2Meter ARDF receiver as designed by Dave G3ZOI. It uses a different approach then I am used to, it has no “real” AM detector but uses the S-meter output of an FM receiver chip. This signal still has traces of the AM modulated fox transmitter so one can still hear the Morse code send by the fox. But the signal is also used to control a PLL tone generator which varies in pitch. The higher the tone the stronger the signal. It's a no nonsense design with only 2 controls, frequency and attenuation (tone hight). I tried to keep the receiver as light as possible and managed to keep it at about 370 Grams.|
|DutchRFShop, also their lowpass filter is used. The advertised power of 300 Watt is produced easily and 3 Watt of drive is enough. i added a small input attenuation circuit, so i can go up to 15W input for the full 300W output, which means i can now vary output power since my 2-meter set only goes as low as 5Watt. A cheap relay is used as input relay. The highpower output coax-relay is located close to the antenna at the attic. Also a Preamp by HA8ET is mounted as close as possible to the antenna. (Without mounting it outside). 2 coax cables and a control cable run to the attic.|
|ARDF80v6 receiver designed by Harald Gosch, OE6GC. This is a single super-heterodyne receiver based on a TCA440 using 455KHz as IF. Since the TOKO IF filters are only 3KHz wide (-3dB) it works wel even on LSB. However the correct BFO frequency must be found empirical by varying C44 (270p in my case). The sense antenne is hidden within the main antenna, and made as semi circle of copperfoil. Because i wanted it to be light i decided to make a tightfitting housing from doublesided PCB board. It is also made as a gun design since i always hunt in the direction of the minimum, it can also be operated with one hand. The handle is a camera grip i got from e-Bay for a few euro. For its ruggedness i use a 5-pin DIN connector to connect headphones and it also acts as a on/off switch by a wire bridge between 2 pins (i removed the original powerswitch FET). Tuning range was somewhat limited so i solderd a 1N4001 parallel on top of D1 and D6, this gave me 100KHz range (3500KHz to 3600KHz). Sensitivity is good. however the LM386 produces a lot of white noise, a 4.7uF capacitor over the headphones reduces this considerably.|
|DF1FO, a more sophisticated version then my previous one. It is a double super with 10.7Mhz and 455KHz IF and it is processor controlled including AGC, timers, distance estimation and much more. The software I use is the PA2TIM version who made some additions to the original software. I kept the design of the receiver itself pretty close to what DF1FO suggests. Again my 3D printer was a great help as it lets me design al brackets, standoffs , holders and other stuff exact the right shape and size.|
|K1EL. However i never got arround making a neat case for it. Since i now have a 3D printer i was looking for thing that could be done better. I don't like the texture of housing that are completly printed in 3D so i did not opt for that. I ordered a goodlooking aluminum case from eBay. And used the 3D printer for a bracket so that te switches don't need a hole in the front plate. And also a support bracket for the pushbutton array. I think it has turned out well. The device has two outputs for connecting 2 transveivers and also two PTT outputs for controling prehipial devices.|
|Geeetech Reprap Prusa I3 Pro X 3D witch comes as a kit and was relatively cheap at only 275 euro. The decision was made and i ordered one. The kit came very complete with tools and all. On YouTube there are detailed videos on howto assemble the printer, this was already great fun. i plan to use the printer for printing parts in my other hobby projects.|
For safety and recommended by Fritz PA0FRI as a minimum modification for the TL-922. I installed a 1 Amp fuse in the high voltage circuit (microwave oven type, obtained for a few euro on eBay) and also added a 10 Ohm 10W glitch resistor in the high voltage circuit, this will protect the amplifier in a case of a short-circuit, random-oscillation or other mischief.
When i bought the amplifier the antenna relay made some bad contact on receive sometimes. So i had to look for a solution. The good news is that the slow and noisy relay can be replaced by two relatively cheap but silent and fast vacuum-relays. Because of this i decided to make a few more mods to the amplifier. Again using the excellent site of Fritz PA0FRI as a guide, the BIAS circuit is converted to solid-state. And the STBY/ON AIR lights are now controlled by a reed-relay. This means that the other slow and noisy (bias) relay was also obsolete. RX/TX switching is now hyper fast and ultra silent.
And finaly a solid-state relay was added to the mains circuit with a 10 Ohm 10W resistor to limit the initial inrush current. After about 100mSec the relay switches to bypass the 10 Ohm resistor.
|PA0FRI who has many, many very intresting items on his site, a site well worth visiting. The capacitors are from eBay and rated at 2Kv (2x 100pF, 2x 82pF, 2x 150pF), the coils are made from 6mm2 tinned ground lead wire. SWR and attenuation is very acceptable trough out the passband, while at 100MHz ~50dB attenuation is achieve|
|EA5070-OWA9 from Wimo. Those are not cheap, but they are well made. It uses the "open sleeve" technique, so only the 6 meter dipole is fed. It is a 4 element Yagi on 50MHz and a 5 element on 70MHz. Here some pictures of how I put it together, A electrical box was placed at the center of the driven dipole to waterproof it and to install a current choke balun.|
|DF2FQ. It is all-mode and converts from the 10meter band to 4meter and back using a 41MHz SMD oscillator. Input power range is from 1mW to 8W depending on the input circuit. Output power is made by a Mitsubishi power module delivering about 25W Pep SSB and up to 40W in CW. Building it was very easy and the kit is well designed and very complete, including housing, BNC plugs and cooling. Alignment is pretty straight forward and there are no expensive device's needed. Made some great contacts with it including a QSO with EA8 on the second day i was on the air with it. A lot of fun kit for moderately experienced builder. I made some small modifications, i'am using a P-channel FET as reverse polarity protection. And fitted a DC power jack and RCA connector as PTT input.|
SWR goes up in a steady line, but on 10 meter band still usable with 1:1.5. On 6 meter SWR has risen to 1:2 making it not very usable any more.
I found that a little salt is enough, only half a teaspoon was sufficient to get as close to 50 ohm as possible over the complete range from 1 to 30 MHz.
The antenna is tuned for the CW portion of the band. It is made from army field-telephone wire witch consists of 3 steel wires and 3 copper wires. Thus being strong with somewhat better conductance.
I use a 12.5 meter long fibreglass pole from DX-Wire as a mast. Bandwidth on 80 is small witch is to be expected for such a short 80 meter dipole. However it works fine.
You get 15 meter band as a bonus, but you need an antenna tuner to fine tune it.
|Rainer Flößer - DL5NBZ. The complete project can be downloaden from ardf.darc.de. It is a single super-heterodyne receiver with a 1.6MHz IF. The IF filtering is done by only one RC filter so selectivity is not very good. The receiver only has two controls, one for frequency and one for RF/LF gain. Some parts especially the coil where difficult to find, and i had to made some adjustments to de PCB board to fit a larger IF RC filter. However the receiver is quite sensitive and pretty directional. Until now i found every fox i ever hunted with it.|
Several options can be set by pressing a number while switching on the power of the transceiver.
1 = 4800 Bps, 2 = 9600 Bps, 3 = Audio beeps ON, 4 = Audio beeps OFF, 5 = Thru ON, 6 = Thru OFF
With thru ON the CAT signal is passed thru to make it possible to connect additional CAT software. However this means the processor stays active and since it uses a 4MHz x-tal there might be some interference signals in the shortwave bands. Switching Thru OFF means the processor goes into sleep modus after sending a command. The x-tal oscillator is switched off in sleep modus.
This is done by mixing the wanted signal with a local oscillator, and making the local oscilator level adjustable. Thus creating a dynamic range of more than 100dB, regardless of the poor shielding and limited S-meter range of most hand-helds.
The mixing attenuator can be used for ARDF on any band the hand-held and antenna permit. but most likly in the VHF/UHF range. My design uses a 4MHz X-tal. Thus creating an offset of plus or minus 4 MHz witch one to best listen to depends on interference.
check out his site
At the top a vacuum capacitor of 4 to 100pF made for max 5KV. Motor controlled via a 16F819 PIC processor with LCD for frequency readout.
Total length is about 12 meters and it does not need any radials. Mounted in a 12.5 meter fibre portable antenna pole it is ideal for portable use. It can easily be used on other bands by changing to another length of wire.
Total length is about 9 meters and it does not need any radials. Coax traps are used for 10 meter and 15 meter and a choke/loading coil for 20 and 40 meter bands.
Many thanks goes to Bertrik Sikken, and his excellent site on Bat-sound detection
Print layout PDF
Onderdelen lijst www.reichelt.de
The piezo transducer did not quite do what i wanted, so i now use a electret microphone element. This works much better over a wide frequency range. The electret used is a Panasonic WM61a which has good characteristics in the ultrasonic range. The diagram is somewhat changed. Power supply for the electret is added, a highpass filter is added to prevent LF feedback, and the LM386 is given somewhat more gain.