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As someone who likes a walk in the great outdoors I enjoy reading accounts of people who take their radios out into the countryside for a bit of QRP fun. Today I thought I would try to emulate them. However although I did make a few contacts the attempt was a bit of a disappointment on several counts. Even the photos I took with my camera self-timer were disappointing as the operator completely obscured the radio and a picture of myself sitting on the ground at the foot of a tree apparently talking to my hand is not something I feel should be preserved for posterity on the internet.

As the CQ WW WPX SSB contest was on I thought this would be a good opportunity to make some QRP SSB contacts. The batteries in the FT-817ND seemed to be less than fully charged, and the battery endurance of that radio is poor enough already thanks to its power-hungry receiver. I decided to take my K2 instead, which would give me the benefit of 10W output and really punchy audio. So the local dog walkers witnessed the odd sight of someone setting off up the forestry track into the woods near Watch Hill wearing boots and rucksack and carrying a small Pelican case.

Fifteen minutes later they would have witnessed the even odder sight of the same person trying to throw a stick with a bit of wire attached over a tree branch. Now I know why the MP-1 was invented! After about ten minutes of persevering I managed to get the wire over a branch about 12ft high. The stick hung down the other side tantalizingly out of reach and I spent the next five minutes trying to hook it with the end of my walking stick so that I could pull the wire taut and secure the end of it.

I had previously prepared two lengths of wire for my portable antenna. One is about 22ft long, and has a few feet of nylon cord attached to the end for tying to sticks or rocks to hurl over branches and then secure in position as the radiating element. The other is about 16ft long and is laid out along the ground as a counterpoise. They are fixed to the red and black terminals respectively of a BNC to binding post adapter which is plugged in to one of the antenna sockets of the K2. The reason for the selection of these particular lengths is that I seem to recall them being suggested by Elecraft as good lengths to use with the T1 portable auto-tuner.

There are no picnic benches or tables in the forest so I just sat down on the ground and used the Pelican case as a table. The K2 sat on that, and the antenna ran off directly behind it at about a 45 degree angle, over the tree branch and down a few feet at the other side. The counterpoise ran off at right angles.

I switched on the K2 which was still on 15m from my last mobile outing and immediately heard many strong signals. However signals didn’t seem as loud or as plentiful as I would have expected during a major contest. I pressed the Tune button and the K2 ATU whirred away and finally delivered its verdict: 9.9:1! It couldn’t match it!

I didn’t hear anything on 10m so that wasn’t worth trying. I got a usable SWR on 17m but there was hardly any activity on that band. On 20m the best SWR was between 2:1 and 2.5:1, and on 40m I managed to get 1.5:1. Unfortunately the K2 is a bit SWR-sensitive – something I never noticed during the years I used it as my main home station when I could always get a 1.2:1 or better – and it flashed up Hi Cur (high current) when I tried to use 10W on 40m. So I had to back my power down to use that band, which didn’t help matters.

I made nine contacts in less than an hour’s operating, which included a break to eat my sandwiches:

1130   7.113  ON5SY   59  609  59  001
1131   7.123  PI4Q    59  801  59  002
1133   7.167  PA6Z    59 1022  59  003
1138   7.123  SP4TKR  59 1130  59  004
1143  14.286  YL6W    59 2416  59  005
1212  14.292  HG1S    59 1821  59  006
1215  14.315  OG6N    59 1450  59  007
1217  14.321  SN2B    59 2772  59  008
1218  14.335  SP9LJD  59 1876  59  009

But these were not nice easy contacts like I made using the same radio and the same power from the car using the MP-1 antenna. My thanks, as well as my apologies to the stations that wasted valuable minutes trying to pull my call and serial number out of the ether.

It was getting a bit cold and I felt a few spots of drizzle so I decided to call it a day. I think I’ll stick to taking VHF on hikes in future.

These last two Polar Bear adventure radio sprints in January and February was quite an experience operating QRP (5 watts or less) outside in the snow. I never thought I would never do anything like this in freezing weather. There I was knee deep in snow; with a wind chill around 15 degrees, under an open air shelter at Cobus Creek Park, located in the northwest corner of Elkhart County in January. I was invited by Bob, KB9IVA, who said it would be fun. So I got my portable gear and winter parka and headed out to the site. When I arrived Bob wasn’t there. I got out of the warm car and looked over the snow covered picnic table. The bright sun reflected off the stone on the side of the building helped warm things up a bit.

First one gets the warmest spot!

Then the sun disappeared and it became colder.  The heated outhouse was open so I warmed up for a few minutes.

QRP in the parking lot!

It was too cold for me to set up outside so I operated in my mobile on 40 meters.  Bob arrived in a snowmobile outfit with a bag full of tools, and his ICOM-703 and MP-1 portable all band vertical antenna.

The antenna would not tune properly so I ran 25 feet of RG-59U coax from my mobile antenna to the picnic table.  Then the portable battery pack ran out of juice.  So I took my emergency car starter battery and hay wired a connection to the ICOM-703 and we were back on the air.  When it’s cold radios and batteries don’t work properly.  Wires become stiff, batteries quickly discharge, and the straight key was difficult to use.  Not to mention your exposed fingers feel frostbitten.  I had forgotten my gloves but you couldn’t send CW with them on anyway.

Our vertical in the park!

Cold stiff hands on a very cold key! YIKES!

I was more prepared for the February sprint but didn’t count on blowing snow.  Participating in this sprint was, Bob, WA9S Keith, and Steve KB9ZVJ and I Ni9Y.  Keith arrived late and operated inside his Jeep.  I Made a half-dozen contacts from Utah to Colorado to the East coast with my HB1-A 4 watt transceiver using a 50’ end-fed wire only 27 inches high.  Then the wires snapped off my battery pack.  So we quickly repaired the pack with a new connector and we were back in business again.

2 Cold QRP Guys operate in the Feb 2010 PBMME

Bob had his IC-703.  His headphone band cracked in two in the cold.  Bob’s straight key was almost brittle and hard to use with gloves on.  Steve operated SSB with his Yaesu rig, powered by a riding mower battery, feeding a sloping 20 meter dipole about 5 feet high.

A snow proof antenna for 20m

Last man sending!

It was getting too cold for me so I packed up and left as the snow began to really come down. Steve saw me packing so he packed up and so did Bob.  Keith stayed behind moving to the picnic table and made more contacts in a small blizzard.  Then Park Ranger paid a surprise visit to find out what in the world was going on.  The ranger was satisfied that we weren’t suspicious characters after Keith explained the situation.  The ranger failed to notice Keith had wrapped his antenna rope around the door handle on women’s entrance to the outhouse. There was no way anyone could open that door.   The ranger probably thought we were a bunch of nuts playing radio in the snow.  It was fun and we probably will do it again next season.  Only next time I will be more prepared for polar bear weather.  Oh yes I forgot to say this was the POLAR BEAR MOONLIGHT MADNESS event.  You can read all about on their website http://www.n3epa.org/Pages/PolarBear.htm.  Polar Bears all over the country and in Europe participated in the madness.  The final polar bear event was held March 20th but I took a pass on that one because all the snow is gone so it wouldn’t be as much fun operating in warm spring weather!!!

The MEN OF ADVENTURE will soon take off again.  Barry, WD4MSM says “QRP To The Field” has just been announced for 2010.   He recalled that we took part in the 2009 version that had as its theme “The Great Depression.”  We operated from the WPA site of Monkey Island in Mishawaka (the bridge to Monkey Island was built by the WPA).

This looks as if it might be an ideal outing for us.  Saturday, April 24, 2010
Spicer Lake Nature Preserve http://www.sjcparks.org/spicer.html
Small picnic shelter available; Trees for antenna support if needed;
Restrooms (heated and immaculate) just steps away; Ample parking for hundreds!
Just minutes from South Bend; Plenty to do for family members and visitors (trails, grills, visitor center, two lakes, etc.); Handicap accessible trails and parking immediately next to the suggested operating position.

You to can join the MEN OF ADVENTURE even if you don’t have a QRP rig.  Just show up to learn about portable operation and how to put up antennas where they don’t belong.  Who knows maybe you to will be just as nuts as the other members of the group are?  Present company accepted.

That’s it for this edition.

73’s Dan, email DAN

p.s. Consider operating the special event KØS Strange Antenna Challenge Special Event — May 29-31, 2010.
Start Date & Time: Saturday, May 29, 2010, 1000Z
End Date & Time: Monday, May 31, 2010 at midnight (local time zones)
This is not a serious event.   We are all out here for fun!  K0S will employ out-of-the-ordinary antennas to promote Amateur Radio and making do with what might be available during an emergency.  Individuals and clubs may participate as “satellite stations” by using anything but wire or pipe for a radiating element and adding “/K0S” to their call signs. Details are on the KØS, Strange Antenna Challenge Web site. Strange antennas used in past events, dating back to 2002, have included folding chairs, paint easels, ladders, tape measures, dog kennels, fences, cots and chicken fencing with a trampoline as a ground plane. “More people share in the fun each year,” says Erik Weaver, N0EW, a Strange Antenna Challenge founder. “I hope you give me a call this year with your very own strange antenna. Now let’s play radio!”

I still haven’t made a contact with the little Nano-40 QRPP transceiver I made, but after listening on several occasions I finally heard its signal coming back from the Web SDR at the University of Twente in the Netherlands at 2100 this evening.

I sent a few V’s and clearly heard them come back with a second or so delay from the remote receiver. I then attempted to send CQ, but the distraction of the delayed signal made it difficult. The signal was lost in the noise some of the time, but at other times it was perfectly clear and readable. I calculated the distance between my QTH at locator IO84hp and the Web SDR at JO32kf to be about 750km or about 450 miles. Not bad for 150mW to an MFJ magnetic loop antenna in the attic! Isn’t QRP amazing?

I will treasure the first contact I make with this little radio, so for the time being I am not going to cheat and try to arrange a sked because it would be much more of an achievement to make a contact that happened naturally. But if you should hear me one evening calling CQ close to 7.030 please reply slowly because I can probably hear 4 or 5 different stations at the same time and my CW is not that hot so it will take a lot of concentration for me to read you. A bit more power might help too because the little guy’s receiver isn’t as sensitive as the one you’ll be using.

I didn’t plan to produce a schematic of the Nano-40, the tiny 40m CW transceiver I built based on Roger G3XBM’s 80m XBM80-2 design as modified by Alan VK2ZAY as I don’t claim any originality for the circuit. I provided the original sources and discussed the changes I made to the circuit and thought that other builders would follow the same path.

However I have been asked by a couple of people already if I could provide a schematic so I have patched a copy of the circuit diagram produced by Alan to show what I ended up with. I hope that will keep everyone happy, but please remember that without Roger G3XBM’s genius and Alan VK2ZAY’s improvements the Nano-40 would never have happened.

Today I finally completed the little 40m CW transceiver based on Roger G3XBM’s 80m XBM80-2 design as modified by Alan VK2ZAY and further modified by me to work on 40m. I tried to think of a name for it that would acknowledge both these sources of inspiration, but I couldn’t come up with anything snappy, so in the end I named it the Nano-40 because it is very small and works on 40 metres.

The circuit is essentially the same as the one given by Alan VK2ZAY with a few component changes determined empirically while the rig was on the breadboard to allow for the fact that it is working on 40m instead of 80m. There is only one stage of low pass filtering instead of two, as I described in an earlier post. This seems to be quite adequate. I checked the output waveform using my new oscilloscope and it looks nicely sinusoidal. I also used an MPSA13 Darlington transistor instead of a 2N3904 in the audio stage for a bit more sensitivity and gain.

With the component values I chose the little rig gives 150mW output on a 12V supply or about 75mW using a 9V PP3-style rechargeable battery. There is no sidetone, but it has full QSK. Using my Elecraft XG1 test oscillator I found that a 1uV signal is just about audible. However, bearing in mind that you can receive all activity around 7.030MHz plus and minus the limits of your hearing, a workable signal would need to be a bit stronger to stand out from the crowd!

The circuit was built on to a small piece of Veroboard and the result is shown above. In case anyone wants to try to replicate it, the reverse side of the Veroboard showing the breaks in the copper is shown below.

The rig was built into a small translucent blue project box. The box I ordered for the project turned out to be just a bit too small for comfort. It was not quite high enough for the crystal, so I had to cut away part of the circuit board so the crystal could be mounted with its base below the board itself. The space was also a bit too tight for the connectors. Consequently final assembly took much longer than it would have done using a larger enclosure.

A fair bit of “fine tuning” with a file was needed to adjust clearances which were down to the last millimetre. With the lid on there is not enough room for the spring loaded contacts of the two 3.5mm jack sockets to fully open so the key and earpiece plugs are a tight fit. There was not enough space for a power socket to be fitted internally so after a lot of thought that was eventually resolved by super-glueing a PCB-mounted power socket to the side of the case.

Although I had tested the circuit prior to assembling it into the case there was a heart sinking moment when I applied power and heard no signals at all. Close inspection showed that I had a solder bridge across the antenna socket. This was quickly removed and then the transceiver was found to perform as well as it always did.

I have put out a number of CQs with the little rig but have yet to make a contact with it. Because I don’t live in a densely populated area I don’t have any nearby hams to make a sked with to prove that it really works. You don’t build a rig like this to make a lot of contacts, of course, you do it to prove that it is possible to make a fully functional transceiver this simple and this small. Nevertheless I do hope to make a QSO with my little Nano-40 one day.

I’m preparing to build my 40m version of Roger G3XBM’s XBM80-2 QRPP transceiver into a little box but before I start I have one thing more to do. I have to design an output filter for the transmitter.

Roger didn’t bother. Comments from him suggest that he was aiming for a low parts count and assuming that any filtering would be provided by an external ATU. However Alan VK2ZAY comments that the output was more like a square wave. The second harmonic of my 7.030MHz signal would be on 14.060MHz, also a QRP frequency and I can’t be sure that my antenna won’t radiate this too. So I think an output filter is a good idea.

Alan used a two-stage pi network, each stage consisting of two 820pF capacitors and a 2.2uF inductor. I built this up on my breadboard, terminated the end with a 50 ohm load (actually 47 ohms, the nearest resistor value I had) and checked it with my SWR analyzer. The picture above shows the result.

Out of interest I also checked the response of a single stage of filtering using the same values, shown in the next picture. You can see that the cut-off frequency is a lot shallower than when two stages of filtering are used, so clearly attenuation of harmonics would not be as effective.

My problem is that I need a filter for 40m not 80m. I tried searching the web to see if I could find some online design tools, and I did here, here and here. However when I fed the design parameters for 80m into the calculators the results they came up with were a lot different from each other and also from the values VK2ZAY used.

In the end I decided to use trial and error. I figured that since the frequency is higher the values I would need to use would be lower. The next lower value inductor I had in my parts box was 1uH, so I don’t have a lot of choice in the matter. I substituted that for the 2.2uH. The result shown by the SWR analyzer was promising, but there was a big hump below the cut-off frequency and the SWR at 7.030MHz was a bit on the high side. So I then tried lower values of capacitors. The lower I went, the shallower the cut-off but the lower the hump as well.

In the end, I settled on 680pF capacitors with the 1uH inductor. There is still quite a steep hump below the cut-off frequency but I’m only concerned with the performance at 7.030MHz where the SWR is 1.2:1, which I don’t think is too bad. The cut-off curve of this one stage filter seems as steep as the two-stage one VK2ZAY used on 80m so I think one stage of filtering will do.

After I’d written the above, the thought occurred to me to try the low pass filter in the circuit while it was on the breadboard. I’m glad I did, because I’d have been disappointed to find after soldering everything into place that the output power had fallen from 100mW to 25mW. After a bit of experimentation, it appears that connecting the low pass filter directly to the collector of the first transistor as VK2ZAY did in his version of the transceiver loads the circuit and reduces both transmit power and receive sensitivity. The solution seems to be to couple the transistor to the filter using a small value capacitor – I found 180pF gave the best results. This removes the need for the DC blocking capacitor on the output. The power is still down quite a lot, but part of this may be due to all the harmonic energy which is now not making it through to the power meter.

My QRP crystals finally arrived. Murphy worked overtime on this eBay purchase: the first batch apparently got lost in the post and the replacements were sent by mistake to another customer with the same surname. But I have at last been able to try out the little QRP CW transceiver built to G3XBM’s design on the QRP working frequency.

The transceiver is still on the breadboard as I was waiting to try it on both 40m and 80m before deciding which band to make it up for. Certain components need to be optimized for the band in use, and even the crystal in use, since to save space I’ve hand picked a fixed capacitor to set the transmit frequency instead of using a trimmer. I need also to decide how much power output I want because that is governed by other components. I have had over 200mW out of it but I’m not sure if a 2N3904 without a heat sink could really handle that, so at the moment it is set up to give 100mW output when powered by a 9V rechargeable PP3 battery.

I’m leaning towards 40m as this would make a nice little fun portable rig and the antenna being half the size of 80m would make things much easier. 40m generally has more activity during the daytime, too. I have never found 80m an easy band to work with limited antennas and low power, so it has always surprised me that the lower band is so popular with QRPers.

Of course, it being the weekend there is a contest on today, so not much chance of being heard with 100mW. Even if someone did hear me and reply, it’s doubtful if I could pick them out using a receiver with no selectivity whatever! This tiny, simple transceiver is amazingly sensitive, as you can hear in this 1 minute audio clip recorded on 40m this afternoon using my MFJ magnetic loop for an antenna. How many different stations can you copy?

This evening I may put the 80m crystal in and see what it sounds like on that band. Unfortunately the little receiver has no tools for fighting the terrible QRN that comes on during the evening when all the neighbourhood plasma TVs are switched on, and sometimes 80m is all but unusable.