AmateurRadio.com

International Ham Radio News & Opinion

Archive for the ‘qrp’ Category

Foxx 3 TRX build

December 2nd, 2013 |

So it was my birthday recently and to celebrate the turning of another year and that I had indeed taken a day off – I decided to build a FOXX 3 QRP CW transceiver. These little kits are available from Kanga-products.co.uk and are designed to fit in a Altoids tin.

The kit comes pre bagged up in separate bags, and its just a case of soldering the correct component to the correct area on the circuit board. The kit itself is a 1 Watt QRP transceiver that can be bought on various bands. Mine was for the 20m band.

The board has a clear and easy to read Silkscreen and the pads are suitably wide enough to allow anyone with different levels of skill to create the kit. Each step allows you to test each part of the board, so you learn how each part of the kit relates to the transceiver as a whole.

I had a great time building it, it’s a simple, easy and great fun little kit. I hope to take it out and about – so hopefully you can hear my tiny signal on 20m soon.

Roger, G3XBM – get well soon

November 14th, 2013 |

Author: Juilian G4ILO

I was enormously pleased to see a new post from my fellow blogger Roger, G3XBM Roger is recovering from a severe stroke and facing difficulties I can only imagine. I’m sure I’m not the only one missing his posts about QRP projects nd accounts of his low power activities. Get well soon, Roger.

QRP Fun; 2 Out of 3 Isn’t Bad

November 4th, 2013 |

Author: Mike AD5A

Sunspots are up and the DX-peditioner's are out. This is a great formula for getting some nice QRP DXCC counters. I had a free evening after a very busy run over the last few weeks so I sat down in front of the KX3 to work a little DX or at least try to work some new QRP DXCC countries. On the menu were K9W from Wake Island (KH9), XR0YY from Easter Island and 5J0R from San Andreas. Not a bad selection of nice DX on Monday night.

My first target was K9W. Wake Island isn't on very often, so if you have a chance to work them you should, you never know when the island will be on again. At my QTH, northeast of San Antonio, TX, all three stations were coming in nicely, but with good propagation they are heard by many and the pile-ups were significant. I started chasing K9W on 12m, working up, however the operator wasn't paying much attention to NA, so I moved up to 10m where they were working NA/SA. After 10 minutes of chasing him up and down the band, I got them in the log at 00:59z. One down, two to go.

Next up 5J0R on 30m. I called for 15 minutes, no luck and the pile-up was huge. There was then a spot for XR0YY on 10m SSB working simplex. A quick QSY netted a QSO on the first call at 01:18z. Cool. Two new QRP DXCC counters in 20 minutes. Only one more for the trifecta, so back to 5J0R on 30m. Another 20 minutes of calling and no QSO. I stepped away from the radio for a while and came back to their 20m SSB station. I had him in the clear a couple of times, but couldn't manage the QSO, so I called it quits for the night.

Overall a successful night of QRP DXing, my QRP DXCC count is now up to 159. Upward and onward.

QRP/DX IS

Radio on a Monday

October 28th, 2013 |

Author: Mike VE9KK

The temp antenna and op position

Well the weekend is done and I had Monday off so what a better time to turn on the KX3 and see what is happening out in radio land. I have been reading on Twitter how well 10m is doing so this was my first stop. The antenna is the Alexloop now positioned in my second floor radio room and not on the main floor. With my 5 watts of power I was able to make contact with CO8LY and CO2OQ both in Cuba! CO8LY was at 28019 calling CQ and had a mini pileup going I I waited and was able to make contact with a 599 report. He then moved onto the next station. I then came across CO2OQ at 28032 he was just ending a QSO and I gave him a call. Osmany came back to me but needed several repeats to get my call correct. His report to me was 229 but he was still able to pick me out to have a short QSO with me. He was in and out but steady around 559. It would seem that 10m is still open and ready for biz. This was all the time I had as it was time to head out and see my Chiropractor and then off to the grocery store. If time permits I will be back on the air this evening after dinner but there are other things that have to be done now.

This weekend it was DX with the Alexloop!

October 20th, 2013 |

Author: Mike VE9KK

SWR 1.1:1, power 5 watts and memory CQ message

With getting most if not all of my "to do list" done it was time once again to swing the Alexloop into action and have a nice late afternoon of ham radio and relaxation. Setting up the loop has become faster for me I'm getting the hang of the in's and outs of the loop. I also am able to tune the loop in less than 20 seconds and be up and running on different band segments. The SWR is anywhere from flat to 1.7:1 and the band width is very good and retuning is not needed unless 20 khz changes are needed. This weekend the Worked all Germany CW contest was going on so I wanted to be a point giver for the contest. With 5 watts, my KX3 and the Alexloop in the living room I was able to contact the following all on 20m:

DK1NO
DK9PY
DR4A
LX/DF1LON

I did try dropping the power lower than 5 watts but is was just not doing the trick. I then was on 30m and WA3SCM Dave was calling CQ. I came back to him using 5

Time to recharge the battery

watts. I was at times in and out with Dave but he was in P.A and that's off the backside of my loop antenna. Dave was running a long wire with 100 watts and all was going well until my KX3's batteries decided to die! The KX3 just shut down and my lesson was learned in that I should be monitoring the voltage on the KX3 (via it's display) and I would had known it was due time to change over to my external battery supply. I did go upstairs and get the extra battery but it was too late as Dave was gone. I did email him and explained what happened and on Sunday he emailed me back. He was wondering where I had gotten to and did tell me that he was very interested in the Alexloop as he has worked with lots of different types of loop antennas.
I was able to spend some time on the radio today (Sunday) and I again tried 10m to see what was happening.....it turned out that 10m was good to me today. I was only able to make 2 contacts but they were sweet ones!

IS0GQX from Sardinia
MD0CCE from Isle of Man

I was shocked at both these contacts two very nice and sometimes rare areas and I did both in one day! If I get the time this evening I will try some more radio time but if I don't get around to it I am very happy with the two contacts I did make today.

The radio bug was bitting…………..

October 19th, 2013 |

Author: Mike VE9KK

Things around the house are slowly getting packed away but the ham radio bug still bites. It's true what they say....."you don't know how much you miss something until it's gone.....or semi packed away" Ham radio is not gone from VE3WDM, the antenna may be sold and gone, coax all rolled up and boxed. The Elecraft K3 sits idle at the desk but all is not lost as the KX3 and Alexloop are calling my name!! On Saturday once our Thanksgiving preparations were going smooth...the turkey was in the oven and the side dishes were slowly cooking it was time to feast on some missed ham radio time. The night before, I charged the batteries in the KX3 having them ready to go if the opportunity came about. It did on Saturday afternoon so I setup the Alexloop in the living room and fired up the KX3. It sure was nice to hear some atmospheric noise and even the woodpecker QRN from some offending appliance was ok as well. (the KX3's NB and NR took care of any offending interference)

I had been reading about some hot openings on 10m's from some of my blog buddies but I found 10m to be dead. I ended up hanging around 20m at the QRP watering hole. My power was reduced from it's normal 5 watts to 3 watts. Julie was on her Mac beside me and since our living room TV had been sold it was a Sony boom box radio entertaining her with tunes. The Sony radio along with it's antenna was only 10 feet from the Alexloop anymore power than 3 watts could be heard over the radio. The way Julie see's it CW is NOT music to the ears and it's much better to be on the radio and have Julie happy thus down went the power.
As for contacts I only made 2 short contacts as I did not have much time and was up and down checking on dinner. I was able to make it into Utah to WA7LNW and N3PDT in Missouri, not much but from the ground floor, indoor antenna and 3 watts I was happy with the contacts. I kept tabs on my signal using the Reverse Beacon Network and it showed only U.S stations were copying my signal. I was on again Monday evening and could hear PV8ADI from Brazil at S8 but I was not able to make contact with him.

The KX3 now is resting on the radio desk and the Alexloop is away in it's carry case until next time. I was please to get this short radio time in and the results were pretty good as well.

The simplest possible AM transmitter

October 13th, 2013 |

Author: Sverre LA3ZA

Here’s a design for a 1 MHz amplitude modulated (AM) transmitter. I’ve been looking a while for something like this, a simple short range AM transmitter for the medium wave band, as I needed something for demonstration of my collection of old radios.

The result is the AM transmitter shown here in an Altoids tin on top of a Radionette Kurér radio. This is a portable tube radio from the 1950’s. Several hundred thousands were produced, and it was exported from Norway to 60 countries. It is still popular among collectors.

The transmitter is as simple as it gets. The heart of it is a 1 MHz crystal oscillator in a can. Its 5 Volt power is modulated via an audio transformer, one taken from the output of a transistor amplifier (primary 147 ohms – secondary 3 ohms). I drive the modulator from my cell phone into the low resistance side of the transformer and get good audio when the phone’s volume is set to maximum.

The design was inspired by one from Instructables, but mine also has a 78L05 5 Volt voltage regulator and a red LED in series with the power supply. It indicates that the battery is plugged in. In total the transmitter draws 4.4 mA at 9 Volts. The input power to the oscillator is less than 5 Volts * 4.4 mA or in the order of 20 mW. The power output is just a fraction of that. I have tested it with a 1.5 m wire hanging down behind the built-in frame antenna in the back of the radio with good results.

This is really just a modulated marker transmitter as I have briefly described on this blog before, and the square wave will have harmonics of 1 MHz over the entire short wave band. Some of these frequencies may propagate really well, so if used with a longer antenna, it should really have an output low pass filter to prevent that.

I’m not totally happy with this design, despite its simplicity, though. If I could, I would rather like to transmit in the long wave band at 216 kHz. This is the old frequency of the Oslo transmitter which ceased operation in 1995. As a member of the Norwegian Radio Historical Society, I am allowed to use that frequency with a transmitter input of 0.5 W for demonstration purposes.

For other frequencies, one simple alternative is a standard canned oscillator at 1.288 MHz. I also believe some of the Silicon Labs oscillators can be used in order to get an adjustable frequency, but I haven’t tried that myself.

But until I find a suitable frequency source at 216 kHz, I’ll stay with the 1 MHz alternative at a mere 20 mW. It is in line with the best principles of KISS (keep it simple stupid) or with Occam’s principle : “It is vain to do with more what can be done with less“, i.e. the QRP philosophy.