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When I attended Maplecon I recorded at conversation I had with Yimin and Fred, VE3FAL, of Youkits.  I have turned that recording into the first VA3STL podcast.  I am making it only available here for the time being.  If I make any more audio podcasts I will think about putting them on iTunes. Please click on the link that follows.

VA3STL Podcast#1 Conversation with Youkits

As the podcast is something new to me and an experiment, I would appreciate any feedback via a comment, or direct e-mail.

I attended the first Maplecon last weekend, which was a gathering of Canadian QRPers. The venue was Emily Provincial Park campground. Gerry, VA3GLT, and myself headed down on Saturday morning, despite the convention’s start on the Friday, as both of us had commitments in the afternoon and evening of Friday 20th Aug. We had an early start and drove down the 401 highway to Port Hope then turned off and travelled North to the park. By noon we arrived and had put up the tent and an antenna.

The antenna for this event was a freshly homebrewed doublet made from some TV twin-feed I bought a few years ago and now decided to use.  It was split 16′ 7″ down to form two arms of the doublet, and the remaining 23′ or so of twin feed was the feedline.  At the end of the twin feed we installed a homebrew 4:1 current balun, which I had built a few years ago.  The antenna was raised between two trees high enough that the feedline dropped vertically down and just reached into the tent.  A short run of coax was used from the balun to my Elecraft K2.  It tuned on 40m, 20m, 17m, 15m and surprisingly 80m (given the length of the antenna is would be a pretty inefficient).  I could not get a tune on 10m. Possibly if I took out the 4:1 balun I may have made it.

There was a just short of thirty attendees at the convention and we chatted with quite a few.  There were three tables set out as stalls, one with QRP rigs, one with QRP-ARCI information and one with Youkits radios.  I would have like to have spent more time looking at the QRP equipment table, but things felt a little rushed as we had arrived late.  We had a lovely barbecue lunch prepared by Jeff, VE3JFF, and his family after which I had a chat with Yimin and Fred, VE3FAL from Youkits about their new line of QRP radios. That will be covered in a future post as I made a recording of that conversation.

There was an antenna competition on so I spent a little time in the tent in the afternoon trying to make contacts on PSK31.  Beside the antenna and the K2 I was using a little Asus notebook, a homebrew interface for digimodes and a large battery pack.  It is so large that Martin, VA3SIE accused me of being a secret QRO operator!  (That hurt Martin).

I had little success with contacting stations on 20m PSK until finally just before dinner when we made a contact with a weak station that was calling CQ.  I replied and was acknowledged by Mirek, SP9ONC in Kozy, Poland.  He was running QRP from a TS-2000 and and we exchanged details. I was really pleased that my first contact was DX and a QRP-QRP contact too. Soon after came my second contact Fred, KD8AQ in Mt Pleasant, TX and we had a nice chat.  As the call for the chilli dinner had gone up earlier I had to break off that conversation.

Dinner was provided by the Ottawa Valley QRP Club and that was the second good meal.  The chilli was tasty and Martin, VA3SIE,  had brought some British delicacies for dessert, including Battenberg cake, which I had not eaten in many years as  it does not often appear on shelves in Canadian stores.

After dinner there was the antenna competition, door prizes and a raffle for a ‘shack in a box’.  For the antenna competition Michael, VE3WMB, won the prize for the best technical design with a folded over vertical antenna, and I won for the best performing antenna with the DX contact with SP9ONC.  I was extremely pleased to find my prize was a Norcal BLT tuner which will very likely become the tuner for that doublet in future.

There were plenty of door prizes including several transceivers.  Gerry, VA3GLT, was lucky to get the first of two HB1A transceivers that had been generously donated by Youkits.  There were so many door prizes that I think all attendees went away with something.  I won a set of pliers and a year’s subscription to QRP Quarterly, the QRP ARCI’s excellent magazine.  So when my current subscription is up I can use that.

After all the prizes had been given out there was chatting into the evening and then Gerry, Martin and myself went back to the tent and made two more contacts on 20m. These were Tom, KJ4QDZ , in Lillian, AL and Virgil, WA5TLP, in Willston, ND. Not too many contacts but enough to make me happy with the performance of the antenna.

Over Saturday night and Sunday morning there was a lot of rain.  So after breakfast next morning there were a lot of people leaving.  Gerry and I thought it was prudent to take the tent down during a brief lull in the rain so there was no making contacts, just collapsing and packing a wet tent.  We thanked Jeff, VE3JFF, for all his hard work that had resulted in a successful first Maplecon 2010, said goodbye to those that remained and we headed home before noon on Sunday.

Will there be another Maplecon next year?  Well after the prize giving it was discussed by all and it was unanimous to have another.  So here is looking forward to Maplecon 2011.

Despite Summer not being the best time of year for 80m QSOs I have made a couple of contacts over the last two nights with the recently completed Warbler.

The first was a PSK31 contact with AE1Q who was about 285 miles away in Belgrade Lakes, Maine.  The next was an Olivia 8/500 contact with VE3FMC in St Thomas, Ontario, about 325 miles away. Both QSOs proved to be tougher copy for the other stations as the Warbler puts out only about 2 Watts.  However, they were successful QSOs and as can be seen by the picture above the Warbler receives well.

AE1Q gave me an IMD report which was -24 dB which is reasonable given the simplicity of the rig, but I would like it to be below -30dB.

I was fortunate and pleased that the second contact was using Olivia.  This is a nice mode for QRP. For those wanting to try Olivia I recommend you read the information on the Olivia website by Gary, WB8ROL, including his QST article. Gary writes great articles (including one in the recent amateur radio edition of Linux Journal) and I have enjoyed a few Olivia QSOs with him.

Finally, if you do want to try Olivia or any multifrequency keying mode with the Warbler, you must remember that you are operating on LSB with the Warbler.  Most digimode operators will be using USB so the frequencies will be reversed.  The digimode software, Fldigi, offers a simple solution to this, you must select the “Rv” or ‘reverse’ button (see the lower right of the Fldigi window above, which is selected and green). You do not need to worry about this button if you just use PSK31 as it is symmetrical about a centre frequency.

Radio Amateurs of Canada is the national amateur radio organization here in Canada. It has just had its annual general meeting and coming out from this is a call for transformation. Peter of the RAC blog has sent me a link to the important news and I thought I would pass it on, as I know I have a few Canadian readers of my blog.

I am not going to comment here on what I have read, but will think about it and probably send my thoughts and ideas to RAC. Take a look at the proposal and if you want, send your thoughts to either RAC or post them here, it would be good to have an open discussion.  If you are not a Canadian please still take a look at the details, as other national organizations may be heading in a similar direction, or have faced similar issues.

If you have thoughts and opinions on what you want from a national amateur radio organization please make a comment.

This is the second article describing the two antennas that were used by the Carleton University Amateur Radio Club (CUARC) at Field Day 2010.  The first post described an off-centre fed dipole with a 200 ohm feedpoint impedance.  This post describes the second antenna a loop antenna that worked on two bands, 15m and 10m.

I like loop antennas. I have built large loops for amateur bands, as well as small loops for receiving (which are quite different to their bigger cousins) and have found both types perform well.  They are less sensitive to local noise, so often giving good signal to noise ratios. As CUARC was to operate on 10m and 15m at the Field Day site I was considering a loop for one of these bands, however, which one?  10m could be fun if there was an opening, plus the antenna would be smaller than 15m. However, 15m would be more likely to be open.  In searching the internet I came across a potential solution as KT4QW’s website who describes a 17m and 10m hanging loop antenna.  The idea was simple and elegant, two vertical and rectangular loops fed from the same point, similar as to how multi-band dipoles can be fed from the same feedpoint (sometimes called a fan dipole).

I went about calculating the basic design.  A full-wave loop’s total perimeter length is calculated by:

Length (in feet) = 1005 / f,

where f is the intended frequency of operation in MHz.

So for 21.3 MHz that would be a total loop length of 47.2ft and for 28.5MHz it would be 35.3ft.

To attain a 50Ω feedpoint the loop needs to be rectangular, with the longer length vertical.  Studying J. Carr’s Loop Antenna Handbook and KT4QW’s dimensions the sides were close to being 1/3 of the total loop length for a vertical side and 1/6 for the horizontal side.  So this then gave a design as shown below.

To support the wire I bought two 10ft lengths of PVC piping.  The inner support for the upper part of the 10m antenna was some thin wood.  Both the wood and PVC were drilled with holes prior to Field Day.  The wire was cut from a single 100ft roll and the whole antenna was built by CUARC members at the Field Day site on the day. At the feed point a 1:1 balun was used,  an Elecraft BL2.  The intention was to suspend the antenna from a single central point so the loop(s) could be rotated, using a line tied to one lower corner.  However, we could not get enough height and clearance from tree branches, so we mounted it between two trees and it keep it static with the signal projecting in South-West and North-East directions.

After construction the SWR was measured and found to be nicely below 2:1 for both bands (at least the lower part of 10m which is quite a wide band). As mentioned in the earlier post Maria, VA3MMI, brought a portable analyzer to the site on Sunday morning and the trace of the SWR profile is shown below.  You can see the antenna has two nice dips in the SWR within the two bands. In an effort to see the usable bandwidth (below 2:1 SWR) the max SWR on the Y axis has be limited to 2.0:1.

To further examine the bandwidth of the two dips in SWR Maria, VA3MMI, set markers at the 2:1 points of the SWR curves.  These are shown in the next two traces (one for each band).  Both show good usable portions of the bands for phone, see the tables on the right of the trace. (Thanks to VA3MMI for the measurements and traces).

So, with the off-centre fed dipole and this dual loop antenna, CUARC constructed two antennas for Field Day that worked on 15m and 10m without the need of an antenna tuner unit.  Performance was good on both antennas and I heard at least one comment that that we had a strong signal (we used 100W).  During Field Day we made over 100 contacts on 15m and 16 contacts on 10m.  Not bad, as for many of the CUARC members this was their first chance at operating on HF.  It was enjoyable for the newly licensed CUARC members to build and then use the two antennas and to find both worked successfully.  For me that was perhaps the highlight of 2010 Field Day.

I finally finished my Small Wonder Labs Warbler kit last night.  This was started probably two years ago and then was shelved for no particular reason other than I was working on other projects.  Last week I decided it was time to get it finished and so have been working on it in the evenings.  It is a nice kit with a clever design based around colour burst crystals and the receiver is direct conversion.  It was straight forward to build but note there are two SOIC components, the SA612 mixers (look for U1 and U2 in the photo above).

When it came to the smoke test it worked first time. I adjusted the one tuning capacitor (the only adjustment), for frequency alignment and checked power out.  Alignment was done as recommended with W1AW which was coming in well (see the screenshot below). On transmit, I get 2W out on my Radio Shack power meter.  It is expected that you can get 3 to 4W out of the Warbler.  Given the accuracy of the meter I happy with what I measured.

I have an aluminium enclosure, which is a tight fit for the board, so there is some careful drilling and filing to come.  You can see in the photograph I have already cut out the corners to accommodate for the enclosure screw mounts.

Given the simplicity of the transceiver I am very pleased at how well it works. No contacts yet, so will have to see what the IMD is later.  Anyone within 100 miles or so of Ottawa want to try a QSO?

Jeff, KE9V, has recently released a podcast called Cornbread Road.  It is quite a different type of amateur radio podcast.  It is not a commentary or discussion of amateur radio, it is a story with amateur radio involved in it.  The production quality is high and I have found the story captivating.  Jeff tells me the next episode, number 6, is out tomorrow (Sunday 1st Aug.). If you have not already sampled Cornbread Road give it a try, I recommend it.

As I mentioned in the earlier Field Day 2010 report, the CUARC group built two antennas for the event.  In this post I will describe the first one of these, an off-centre fed dipole. The common place for the feed point of the off-centre fed dipole is at a 1/3 : 2/3 split in the arms. This has the advantage of providing low SWR (with a 4:1 balun) at even harmonic frequencies, such as 20m and 10m for an antenna cut for the fundamental frequency of 40m (around 66ft). Whereas a centre-fed dipole will only have the odd harmonics which for a 40m (7MHz) dipole is 15m (21MHz). Rather than use the traditional off-centre length split of 1/3 : 2/3 for our Field Day antenna, it was decided to follow the design proposed by Richard Formato, K1POO, in two technical correspondences published in QST ^1,2 and followed up with further article with by Dale Gaudier, ³. In this design the feed point is moved closer to the 1/6 point on the short arm, the advantage being stated in the articles that you should get a 200Ω feedpoint there and so a low SWR on 40m, 20m, 15m and 10m bands when using a 4:1 balun, with no need for an antenna tuner unit.  The emphasis on the 15m band is intentional as a low SWR on that band is not usually possible with an off-centre fed dipole with the feed at 1/3 : 2/3 and a 4:1 balun.  Four bands on one 69 foot wire antenna with no tuner looked very attractive for Field Day. The antenna was cut carefully prior to Field Day and the end insulators were added.  When cutting the antenna the length measurement included the ‘pig-tail’ connections that I have on the 4:1 balun. The diagram below shows the arrangement of the antenna. On the day the antenna was installed between two trees at about 35ft off the ground. While the second antenna was being constructed (to be featured in a later post) its SWR was measured with my Autek RF-1 antenna analyzer.  The results were taken by Maria, VA3MMI and Gil, VE3JRY and are tabulated below. _______________________________________________ Band (m)    2:1 VSWR Range (MHz)          Minimum VSWR 40                                                                      3.1 : 1 (at 7.38 MHz) 20                       13.29 – 14.65                            1.4 : 1 15                       21.20 – 22.31                            1.5 : 1 10                      27.78 – 29.25                            1.7 : 1 _______________________________________________ The overall results were very pleasing, although the 40m band was a little disappointing. This higher than expected SWR on 40m was also encountered by Dale, M0AOP/K4DG, and was reported ³ by him to be due to the severe imbalance in the antenna, so requiring a choke balun to remove the stray RF on the coax.  We did not try a choke balun, since we were unlikely to operate on 40m, that was another station’s band of operation.  However we had an antenna tuner unit if we needed to try and tame the SWR. It was very good to see the SWR profile observed in reference 3  was repeatable. On Sunday morning Maria, VA3MMI, returned with a portable analyzer borrowed from work and did a sweep analysis.  The response is below and markers have been inserted to show the minimum SWR associated with the bands. Thanks goes to Maria for the measurement and the plot. It would be interesting to remeasure the SWR response again with a choke balun in place.  I expect the SWR will drop below 2:1 within the 40m band as found by the author of reference 3.  If this does happen then four bands and no tuner needed makes this antenna one for serious consideration on HF. Even without a low SWR on 40m the antenna offers three bands and it performed well on 15m and 10m for us on Field Day. As a final note, I should reiterate the warning by Dean Straw, N6BV, at the end of reference 1 where he warns about using the antenna on 30m, 17m or 24m, as a very high SWR could damage the balun at the feedpoint. References 1. “Improved Feed for the Off-Centre-Fed Dipole” R. A. Formato, K1POO, Technical Correspondance, QST, May 1996 p76. 2. “Off-Centre-Fed Dipole Comments, Part 2″, R. A. Formato, K1POO, Technical Correspondance, QST, October 1996 pp72-73. 3. “Choke the OCFD” D Gaudier, M0AOP/K4DG, Technical Correspondance, QST, September 1997, pp82-83. Note: all three of the above papers are collected together in “More Wire Antenna Classics Volume 2″ ARRL, (1999). The Field Day photographs above are from the Ottawa Valley Mobile Radio Club’s photo gallery.

The station has a great QSL card (above) which was drawn by Ed Piskor of Wizzywig Comics.  Ed shows on his blog how he created the QSL card. I will have to try and catch N2H on the air to get one of those cards.

Great to see amateur radio involved in the hacker scene.

For above image note: Ed Piskor / CC BY-NC-ND 3.0

Well it has been a week since Field Day (FD) and so it is time I gave a report on how it went.

As previously mentioned I have been involved in establishing an amateur radio club at the university where I work.  For this FD, the first one for the club, the Carleton University Amateur Radio Club (CUARC) teamed up with the Ottawa Valley Mobile Radio Club (OVMRC).  Since February there have been 14 new amateurs licensed through CUARC so here was a chance for these newcomers to gain some operational experience and to mix with some very experienced amateurs in the OVMRC.

The site was the very front of the grounds of the Canada Science and Technology Museum, by the lighthouse.  We ran a 4A operation as VA3RAM and the CUARC contribution was a 100W SSB station on 10m and 15m.  CUARC used two antennas, an off-centre fed dipole and two nested full-wave vertical loops for 15m and 10m.  These were built by the students, the dipole prior to FD and the loops on the day.  The antenna building was a good exercise, translating theory into practice  and the antennas had low SWRs on the required bands of 10m and 15m when checked with my Autek antenna analyzer. There was quite a lot of interest in the antennas from other amateurs and I will describe these in detail in a later post.

On Saturday 10m was open so operations started on that and it was great to see the thrill the CUARC members had when making contacts on the antennas they had built.  As the afternoon wore on there was a move to 15m.  CUARC members mixed with the OVMRC members and were given the opportunity to run the other stations.  A great report on this is given in a post on Bob’s, VA3QV, blog.

Field Day is a good time to get operating experience and some of the CUARC members took this opportunity, others were a little ‘mic shy’.  One notable operator was Campbell, VA3CNS, who did an excellent  job at calling CQ on 15m and logging stations one after another.  He was almost running a pile-up for a while. Another highlight was Maria, VA3MMI, working 80m with Bob, VA3QV, and receiving some NTS for the International Space Station.  This is detailed in Bob’s blog post.  One contact that I made that pleased me was when I was manning Ernie’s, VE3EJJ, 40m station and I logged W1AW.  Nice to work a station I had heard so often on CW.

The weather was a little damp and not too hot.  Overall, not unpleasant weather which helped to make the 24 hours manageable, even on only three hours sleep.

Overall a great FD and very enjoyable.

Special thanks to Ziad El-Khatib,VA3ZEK, for most of the photographs.

Back in March I wrote about my experiments with a minimalist transceiver design that was published in Sprat earlier this year.  Today I received an e-mail from Claude, W5FYI, who enquired about this work.  He wrote:

I, too, am interested in building G0EBP’s FET transceiver. One thing that puzzles me is reference in the Sprat article to the 560pF C5. Tony says it is for the final filter. Is he referring to the FET’s capacitance, or his value for the pi filter’s capacitors.

When you get your schematic ready, please let me know.

I thought I would share my reply as others may be interested:

Thanks for the e-mail.

Yes I wondered about that reference to C5 too.  I presumed it was the 100nF cap connected to the drain and the inductor on one side and the filter on the other.

I have done quite a few mods to this circuit and still tinkering trying to get a 700Hz  freq. offset on transmit, so avoiding issues if someone is zero beat.  My first attempts were poor, using an idea in Solid State Design for the Radio Amateur, which plays with some feedback in the oscillator circuit (Fig 6 p36 if you have that book).  I see a brief freq. shift and then it seems from my freq. counter the oscillator locks back again. Perhaps I need to switch in the capacitance with the crystal which I think will work better.  Been too busy recently with work to finish this experimentation.

Back to my main changes that I did.

1.  I changed the oscillator to a FET based Colpitts with a J310.  Better waveform, but lower output than a 2n2222 and hence only about 1/4W out with 9V.
2.  I have used a different muting process.  On keydown I put +Vsupply to pin 7 of the LM386.  That mutes the audio op-amp. See LA3ZA, Sverre’s notes on this at http://www.qslnet.de/member/la3za/Pixie_mute.htm
3.  Rather than have the key in line with the supply I included another transistor (PNP BJT) so key is connected to ground for transmit.  This helps if you mount an un-isolated socket for the key jack in a metal chassis.

I need to finish off the experimenting with the offset and then write up the changes for SPRAT.

I looked in my notes and see I blocked out the basic circuit but have not added any component values, so I attach it here, to help you.  The offset circuitry is not included.  I think you will be able to work out the component values from the original diagram.  If you need the calculated values for the Colpitt’s oscillator, let me know and I can supply those.

Hope the above helps you.

By the way I have started to call this transceiver “The Bay” after Morecambe Bay where G0EBP lives and coincidentally where I was born and grew-up.

The draft circuit diagram is above.  It is unfinished but still gives a good idea of what I have done with Tony’s, G0EBP circuit.

When I get time to return to this circuit I will report findings and updates here on the blog.

Thad, AJ8T, sent me a nice report on my 30m 160mW QRSS signal.  A screenshot of what he received is above and clearly shows the ‘a3stl’ part of my signal.  In his e-mail he reported

It was received about 20:40Z on May 26,2010 using Spectran, a Signalink interface, a Yaesu FT-897d and an 80m horizontal loop up about 10m fed by ladder line. I’m located in Sturgis, Michigan (grid EN71hs) half way between Chicago and Detroit.

My transmitter has been running continuously now for a few weeks and it is good to see how stable it is. For those readers unfamiliar with QRSS those frequency changes that give the CW are about 5 or 6 Hz steps. Which gives an idea of the stability, as well as the challenge to detect these signals (the 30m QRSS ‘band’ is just 100Hz wide).

He also reported that he too will be putting a QRSS transmitter on the air soon.  I look forward to seeing AJ8T’s signal on the grabbers.

Thanks for the report Thad!

Before this blog I had a web site with some amateur radio information.  It is still out there, but I should close it down or update it totally.  Here is one of the projects from those pages which I had great fun with and which is worth adding to this blog.  I was quite impressed with the quality of the audio from this receiver which has just seven components (three capacitors, two transistors, a resistor and a transformer).  Below is an edit of what was originally written a few years ago.

I constructed this simple receiver having seen the circuit at WB4LFH’s web site which he calls the ‘audion’. This circuit is almost identical to the last circuit on that page, except I changed the inductor connection to the variable capacitor from being a tapped connection to being a transformer coupling.

The inductor was a T50-2 toroid with secondary being 28 turns of enameled copper wire and the primary (connected to the antenna) being two turns. (Remember a ‘turn’ on a toroid is the passing of the wire through the hole). The transistors were 2N3904 types, but you can try any general npn transistor. The tuning capacitor was a air plate type taken from an old radio receiver, likely about 300pF. The circuit was constructed ‘ugly style’ on a small piece of unetched circuit board. Use what you have in your junk box and experiment.

The performance is very good considering the simplicity of this receiver. Below are a set of sound recordings from this receiver.  The recordings show how the volume can change (no AGC here!) and that the selectivity is not too good.

• Guitar music
• Station identifier
• Radio Habana Cuba

If you consider building this receiver please note that these recordings were done with the receiver connected to my external antenna at that time, a G5RV. I tried using a long whip antenna, which I had in the junk box, and there was no discernable reception of a signal with it. So you will likely need to use a good length of wire to act as an antenna. Post a comment if you have any success with this circuit.

I recently acquired a DV access point (DVAP) dongle from HRO.  This is a very interesting piece of D-STAR equipment.  It is a 2m transceiver that is connected via a USB 2.0 port to a computer, which has to be connected to the internet. This then allows the dongle to be effectively a simplex repeater passing D-STAR signals on and off the D-STAR network.   So using my IC-91AD HT I can link to either D-STAR gateway repeaters or reflectors and talk to other operators.  The audio quality is very good.  I have heard other operators using theirs and I have had good reports when using mine. Output power is 10mW (but can be lower) and I can link to the dongle from around the house.  So I can make contacts around the World on the D-STAR network from the comfort of an armchair or whilst sitting outside on the deck.

The device is made in the USA and it is very well put together and packaged.  Even the supplied USB cable was a quality molex brand cable. (Please note you must own a 2m D-STAR radio to use a DVAP, it will not convert FM to D-STAR.  If you do not have a D-STAR radio consider the DV Dongle.)

Here are a few videos that talk about the DVAP dongle.

First an overview from the US National Capital Radio D-Star Association.  They talk about the DVAP dongle for about the first 2 minutes then go on to talk about other equipment.

Next a detailed DVAP demonstration by Tim, G4VXE,

Finally HRO has them in stock!