Some receiving tests with HF magnetic loops on 28 MHz. Is height might? Are two loops better than one? Find out by watching! (info on VK3RMH http://www.qsl.net/vk3rmh/ )
Views: 29924 vk3ye
Describing and demonstrating an end-fed multiband antenna for portable use. It's a full-sized half wave on 20 metres and a loaded half wave on 40 metres. The antenna also works on 10 metres. It's not recommended for use on other bands. A broadband transformer replaces the antenna coupler. While it's likely less efficient than an L-match antenna coupler this arrangement allows instant band changing. Its only disadvantage is that its bandwidth on 40 metres is somewhat narrow (150kHz approx) when used with the loaded half wave wire described. Similar to the Par Endfedz design this transformer will work on other bands with a half wave wire. With 10m of wire I could get low SWR (as indicated by the FT-817's indicator) on 20 and 10m. 20m of wire gave those two bands plus 40 and 15m. Some variation of the trimmer will however be necessary so it's worth carrying a small screwdriver, preferably attached to the transformer unit to prevent loss. There's a bit of cut and try in construction. Those wanting a premade unit should investigate either the Dutch HyEndFed or the American Par Endfedz 40/20/10m end-fed models. Both have received good reviews on eham.net . Check these links for further info: * http://pages.suddenlink.net/wa5bdu/efhw.htm * http://pa-11019.blogspot.com.au/2012/04/149-transformer-for-endfed-antennas-35.html * http://www.hamradio.me/antennas/lnr-precision-ef-102040mkii-examination.html * http://www.eham.net/ehamforum/smf/index.php?topic=56161.0 * http://pa3hho.wordpress.com/antennes/multiany-band-end-fed-english/ * http://www.hyendfedantenna.nl/joomla/blog/17-multi-band-hyendfed.html * http://www.parelectronics.com/end-fedz.php * http://www.eham.net/reviews/detail/5105 * http://www.mwrs.org.au/wp-content/uploads/2014/08/Three-band-End-fed-Half-wave-Antenna.pdf The USA contacts included were on 20 metres, made in the morning. Good contacts have also been made within VK on 40 metres.
Views: 79233 vk3ye
Is mixing with kilowatts on 14 MHz SSB during the ARRL International DX Contest a futile exercise when running 5 watts to simple wire antennas? Or have we stumbled across one of the great low-cost antennas for over water portable QRP DXing? Find out when we put a $20 wire delta loop through its paces at a beach near Melbourne, Australia. We'll tackle what others say is impossible and discuss the merits of horizontal versus vertical polarisation. Feeding and impedance matching is also covered. Watch this video if at all interested in portable QRP operating, DXing or simple wire antennas.
Views: 23040 vk3ye
A description and demonstration of an ultra-simple but 100 watt capability 7 MHz magnetic transmitting loop for units and apartments. There are no hard to get parts or complex workshop skills required to build. Instead of the expensive vacuum variable capacitor, the loop is brought to resonance with a length of RG213 coax (approx 1.85 metres for a 3m circumference loop for 7 MHz). The sliding capacitor's dimensions are not critical but are approximately 6 x 8 cm. As demonstrated performance is excellent and would be significantly better than lighter and more portable loops. It would thus make an excellent project for apartment or unit dwellers who have limited room for other HF antennas. CAUTION: Hazardous high voltages can develop across the capacitor on transmit with this (or any other) magnetic loop. Hence the loop should be operated in an out of reach location. For the same reason the loop should not be adjusted with RF applied even if only QRP. A full article on this loop appears in November 2014 Amateur Radio magazine. Also some notes at http://home.alphalink.com.au/~parkerp/projects/projloop.htm
Views: 153525 vk3ye
This video demonstrates a crystal radio similar to that used in the early days of broadcasting. Crystal sets are powered from the signal being received - no batteries or amplifiers are used. The incoming station comes via a wire antenna (not shown) and is selected by a tuned circuit. A tuned circuit comprises a coil of wire and a variable capacitor. Moving the variable capacitor knob changes the station. A diode detector converts the radio frequency signal from the tuned circuit (which we can't hear) to a sound signal that we can hear through headphones. As crystal sets are self-powered, signals on them are often weak and they might not receive all signals that a more sensitive radio would. Several stations were heard on the set demonstrated but only a couple were loud enough for this demonstration without an amplifier. The stations with the time pips were the ABC about 40 kilometres away. The later stronger station with the news bulletin was 3MP, about 20 kilmetres distant. Other stations were heard in the headphones but background noise was too high for them to be picked up by the camera. The antenna was about 20 metres of wire. If you want to build one, crystal set circuits are readily available on the web. A search will reveal both simple and fairly complex designs, with performance varying accordingly. Part 2 follows with the improved signals obtainable with a better antenna and altered coupling into the receiver.
Views: 71810 vk3ye
Experimenting with a ground plane antenna from which all but one or two radials have been removed. Is the antenna directional with just one?
Views: 8590 vk3ye
Long radials are a hassle with vertical antennas. Can short tuned counterpoises work? Find out as I try a dual band 17/20 metre antenna at the beach.
Views: 25599 vk3ye
A demonstration of how a seperate receiving antenna can help HF radio reception, particularly in urbanised areas where noise is a problem. A large outdoor antenna is best for transmitting but for receiving a small loop can often pick up less noise and allow clearer reception. This is a demonstration of the difference an indoor loop antenna can make when listening to a ZL station in a contest on 160 metres.
Views: 11459 vk3ye
Adding a flashing LED to a UHF data transmitter to form a frequency shift keying pulsing beacon.
Views: 4226 vk3ye
No antenna support available? Here's an attempt to make SSB contact on 40m with a half wavelength of wire laying on the grass. VK2MG, about 700km away, was worked with a weak signal report received. As you will hear much better results will be possible if the wire is raised.
Views: 2854 vk3ye
You'll remember the 'Tiny Toy' pocket sized 7 MHz CW transceiver previously featured. This is its bigger brother, named the 'Bigger Toy', as described in September 2012 Lo-Ley. It's more powerful and has a better receiver but still uses just 8 transistors. This video demonstrates it on air, participating in the 7025 kHz Sunday morning CW net. This long-running weekly net encourages CW contacts by pairing stations off on different frequencies. A variety of signals are heard, including VK7LF who was running QRP.
Views: 5540 vk3ye
Sometimes you don't want to carry all the things needed to support an antenna and just want to plug in to what's there. In this video I walk along a local beach and try to load up various poles and signs on HF.
Views: 5630 vk3ye
For many years I've derided QRP crystal controlled transceivers (eg the Pixie) as toys. There'd be kits, people would build them, make a contact or two, and then they'd gather dust on a high shelf. Which is not a bad thing given the price of the nine volt batteries some of them use. But you'd have to say that there's a novelty factor about a cigarette-pack sized rig. And their low power consumption is in start contrast to a hungry beast like an FT-817. Here is my own novelty rig for 40m CW. Its clunky t/r switching (flip a switch and turn a dial) and a wide direct conversion receiver does not make it a DX machine. But in other respects it is a little less toyish. There's a wide-swing VXO (nearly 20 kHz) and a usable receiver (stable, unmicrophonic and free of broadcast station breakthrough). Plus the 4 x AA batteries provide longer life and cheaper running. Power output is around 100mW (or a bit more). Under good conditions this is capable of contacts up to around 800km during the day. This video provides some footage of contacts made on its first day, a description and, at the end, a circuit. Note the drawing errors in the Colpitts VXO circuit; 1. add a 1k resistor from emitter to earth, and 2. move the lower 1n capacitor's top lead from the 33k resistor to the emitter/1k resistor/220pf capacitor's junction. UPDATE: Two 7030 kHz crystals were substituted in place of the 7040 kHz initially used. VXO coverage is now 7005 - 7028 kHz. The unit is described in detail in Lo-Key March 2012 and Sprat Summer 2012.
Views: 35648 vk3ye
Building an RF current indicator for end-fed wire antennas. Uses just three parts.
Views: 13958 vk3ye
Few antennas offer better than dipole performance at an acceptable weight for the HF portable QRPer. The Moxon Rectangle is an exception. This video demonstrates a vertically polarised Moxon Rectangle on 20 metres CW from locations near Melbourne.
Views: 8250 vk3ye
The Pixie QRP transceiver kit is super-cheap but comes with some performance compromises. This video discusses crystal and ceramic resonator VXO circuits to add frequency agility and make contacts easier. Coverage of the SSB portion of the band also makes it an attractive receiver costing under $20 for the kit plus extra parts needed. Source for 7.16 MHz ceramic resonator: http://www.minikits.com.au/
Views: 37505 vk3ye
Range tests on a 28.571 MHz crystal oscillator module putting out a few milliwatts of power. The module was keyed with its output fed to a 1/4 wavelength antenna plus radial. The module is fed with 5v via a 7805 voltage regulator. A microcontroller keys it. For anything other than a quick test the use of a low pass filter (100pF x 2 & 0.2uH) is recommended to attenuate harmonics. This test was with Morse. Modules can be made to transmit AM if their supply voltage is modulated but their transmitting range will be less. DSB should also be possible if their output is fed to a balanced modulator. Similar unit built by others http://www.ae5x.com/docs/Fire-Ball_QRP_Rig.pdf
Views: 10189 vk3ye
Hand-carried QRP antennas: Simple antennas and accessories to operate from almost anywhere. Info at: http://home.alphalink.com.au/~parkerp/handqrp.htm Whether through choice or circumstance, more radio amateurs than ever before are enjoying portable operating. Suitable equipment is widely available but what about antennas? Manufactured antennas exist but only some suit lightweight portable activity. And, it's easy to overpay for something that's too heavy and too lossy for successful QRP. Hand-carried QRP antennas takes the mystery out of portable antennas. After inviting you to assess your needs, it discusses the pros and cons of popular types. Its style is brisk and practical with almost no maths. Many ideas for cheap but good materials suitable for portable antennas are given. Beginners and those returning to radio after a break should especially find this section handy. Finally there's construction details on a variety of simple but practical antennas and accessories suitable for portable operating. All have been built and tested by the author over almost 30 years of successful QRP activity. Hand-carried QRP antennas is an ebook readable on most devices. It's the author's second book, following on from the top-selling Minimum QRP, released in 2015. VK3YE Radio Books on Facebook: https://www.facebook.com/vk3yeradiobooks/
Views: 2882 vk3ye
Using the 12 metre Spiderbeam mast at home. Video covers the timber support cable and mount for a wire dipole with tuned feeders.
Views: 5744 vk3ye
Going portable with just 8 x AA NiMH batteries. How long do they last? In this video I test two packs of Ladda low discharge NiMH batteries from IKEA while portable operating SSB and WSPR.
Views: 4606 vk3ye
Some alternative uses for the Pixie CW Transceiver kit. More detail on the Pixie Hack Challenge page at http://home.alphalink.com.au/~parkerp/projects/pixiehack.htm My review of the Pixie is at http://home.alphalink.com.au/~parkerp/projects/projpixie.htm
Views: 4094 vk3ye
Not as good as a full high pass filter, but still worthwhile for the one component required. The reception and contact were on 80m.
Views: 2049 vk3ye
A review of the WSPRLIte Flexi from SOTABeams. Testing a palm-of-your-hand 200mW WSPR transmitter for 630 - 6 metres and comparing it with the original WSPRLite (reviewed last year - see https://www.youtube.com/watch?v=Oz5a93rupjs ). Product details at https://www.sotabeams.co.uk/wsprlite-flexi
Views: 3241 vk3ye
Should you buy a cheap 9 metre telescoping fishing pole or a heavy duty Spiderbeam mast to support your radio antennas? Get the lowdown from someone with both. Haverford - Australian fishing pole source: http://www.haverford.com.au/ TTS Systems - Australian Spiderbeam agent: http://www.ttssystems.com.au/ Spiderbeam direct: http://www.spiderbeam.com/
Views: 23184 vk3ye
Whenever I go portable the most common question I'm asked over the air is whether passers by ask many questions. This video answers this and gives some examples. Some thoughts on portable station setup and operation in public areas are also provided.
Views: 2605 vk3ye
Testing a lightweight HF magnetic loop antenna made from 7 metres of RG58 coaxial cable. Contacts were made on 40 and 20 metres during the Lighthouse Weekend. It uses just three main parts: the coax itself, an air-spaced variable capacitor (approx 50 - 100pF max) and a T50-43 ferrite toroid. The toroid is threaded over the coaxial cable. RF from the transceiver is fed via a 2 or 3 turn winding over the toroid (experiment with this for lowest SWR). The coax inner is left unconnected; only the braid is used here. The loop is for low power use only - it will take 10 - 20 watts before the variable capacitor arcs over. Performance is, as expected, somewhere between a smaller pedestrian mobile magnetic loop and a full sized wire antenna. It would be improved if the variable capacitor was a low loss type and the coaxial cable was soldered straight to it. While there's enough information above to make your own, it's worth checking out G4FON's website ( http://www.g4fon.net/ ) for similar loops. My loop is closest to his Version 2.
Views: 19365 vk3ye
A look at how an AM broadcast receiver is used to allow an AM-only shortwave receiver pick up SSB signals (this is how I used to listen when starting out). The demo shows reception of 80 metres. The BFO signal is the second harmonic of an AM receiver's local oscillator around 1.8 MHz (approx 1300 kHz on the dial). 40 metre reception is similar but requires a different dial setting on the AM receiver.
Views: 18231 vk3ye
One or two capacitors can improve transmit and receive audio if your transceiver is misaligned or doesn't suit your voice. Find out how by watching this video.
Views: 6641 vk3ye
Running the previously described 1.5 volt battery powered VHF beacon transmitter off a solar cell which also houses it. The circuit is the same as shown except the redundant LDR is shorted.
Views: 2913 vk3ye
Reviewing the Bitx40 7 MHz 7 watt transceiver module available from http://www.hfsigs.com Modifications at http://bitxhacks.blogspot.com.au/ N6QW's Bitx page http://www.n6qw.com/Bitx40.html Bitx email list for ideas and questions at https://groups.yahoo.com/neo/groups/BITX20/conversations/messages QSO Today with VU2ESE http://www.qsotoday.com/podcasts/vu2ese My first Bitx https://www.youtube.com/watch?v=pB1IC2qRw6g Please note that if you add an external VFO and use the onboard local oscillator as a buffer the capacitor to remove is C91 - ie the 1000pF between base and emitter of Q9. My ceramic resonator mod for better stability https://www.youtube.com/watch?v=10109ueIEO0
Views: 17774 vk3ye
WSPR can work with inefficient antennas. But what if you use a good antenna - such as a half wavelength vertical? Video shows a test with a kite supported wire antenna from a local park. Exploiting greyline propagation, 200mW on 7 MHz is sufficient to be spotted as far away as North America and the Canary Islands.
Views: 1734 vk3ye
Another look at the modified MH-31 microphone as used with the Yaesu FT-187. Here I reduce the value of the 47nF series capacitor to 22nF and do some crude white noise tests to examine the difference in frequency response compared to an unmodified MH-31 microphone.
Views: 3093 vk3ye
Sometimes you can do everything wrong and still get results. The antenna was half down and the antenna plug only half in. Yet Peter VK6APZ, over 2600km away, still heard me from his quiet country location.
Views: 2993 vk3ye
Description of a 80cm diameter magnetic loop antenna for HF pedestrian mobile operation on all bands between 7 and 28 MHz. This one is heavier than my previous loops (being made of copper tubing) but delivers better performance. JUNE 2012 UPDATE: A video comparing this loop with another is presented at http://www.youtube.com/watch?v=YswnVmAKSP0 I have a new favourite loop!
Views: 21181 vk3ye
It's nice having a good case for the uBitx. But commercially available type may the wrong size and you might wish to try making one yourself. Here's an idea for a no-bend case using commonly available angle aluminium and chopping board.
Views: 2383 vk3ye
Connecting trimmer capacitors in circuits. There is a right way if you want easy adjustment of them.
Views: 9497 vk3ye
An introduction to the amateur ten metre (28 MHz) band. Describes a simple antenna, propagation, common frequencies and activity. Further reading is available at http://home.alphalink.com.au/~parkerp/gateway/nooct98.htm
Views: 2905 vk3ye
During summer when the bands are hopping you don't need much to work DX. Shown here is an small magnetic loop antenna ideal for pedestrian mobile. It does 15 through to 6 metres, giving a great range of frequencies for the summer sporadic-E season. In this video I talk about the antenna and demonstrate its use on six and ten metres. Photos and constructional information is provided at the end. A full constructional article also appears in Amateur Radio magazine for March 2013. In case anyone is wondering, I'm not in the kit or manufacturing business. This is something you MAKE yourself, and it's so quick, cheap and simple there's no excuse not to give it a go. UPDATE: This loop has now been rebuilt into a more efficient version with aluminium strip. Details at: http://www.youtube.com/watch?v=kykqimN7nvI Some handy links are below: http://www.66pacific.com/calculators/small_tx_loop_calc.aspx (I used this to design my loop's dimensions) http://www.g4fon.net/ http://www.g4ilo.com/wonder-loop.html http://aa5tb.com/loop.html http://www.g4tph.com/ http://www.alexloop.com/
Views: 9133 vk3ye
A magnetic loop that fits inside a laptop computer bag. It's inefficient but works for WSPR on at least 7 and 10 MHz. A lower value of variable capacitor would also allow coverage of all bands up to 50 MHz. Video describes construction and demonstrates its use on 7 and 10 MHz for SSB receiving and WSPR transmitting.
Views: 3930 vk3ye
Possibly the simplest possible pulsed beacon transmitter. Video describes where I got the circuit from, modifications to make it light dependent and complications along the way. I then do a range test on a local beach and get a surprising distance for a 1 transistor circuit powered by 1 x AA battery. The beacon operates just below 37 MHz using a commonly available 36.864 MHz crystal. In Australia frequencies around this are allocated to 'low interference potential devices' with a 100mW EIRP power limit. This transmitter would have an output of a few milliwatts only.
Views: 9411 vk3ye
A 7 MHz dipole made to operate on 3.5 MHz by adding end loading coils. It won't be as efficient as a full sized 80m dipole and the bandwidth will be narrow. However it will get you on the air from a small yard. The antenna here was inspired by and is very similar to VK5AH's 4 band dipole (website http://users.picknowl.com.au/~wavetel/antennas.htm#4bandHF ). The only thing that's different with mine is that it has a dipole for 10 metres (not 15 metres) and I didn't use a balun. Coil dimensions: 115 turns of medium sized insulated hook up wire on 40 mm plastic pipe close wound. Length of coil about 250mm - cut your pipe for 270 and preferably 290 mm to allow room for wire thickness variations.
Views: 20769 vk3ye