Ripples in the Ether

I’ve noted with quite a bit of interest the recent surge of comments on QRP-L favoring a QRP exodus up from 7030/7040 kHz to [part of] the old Novice watering hole of 7100 to 7125 kHz. The esteemed Arnie Coro, CO2KK seems to have ignited the fire with this post to the reflector:

Dear amigos :
The 40 meters band changed last year … when the worldwide assignment for ITU Regions I, II and III was finally made totally compatible for the first 200 kiloHertz. According to what we have learned here, this was a difficult to work out agreement, but at the end
thanks to the presence of radio amateurs sitting as members of many of
the nation’s delegations attending the ITU WARC… it became a reality…
So, now we have the 7100 to 7200 segment for radio amateurs exclusive use. My understanding is that the US FCC decided to expand the 40 meter phone band down to 7125 kiloHertz…
That leaves the segment from 7100 to 7125 kiloHertz quite useable for CW…
My suggestion is to start using 7105 or 7110 kiloHertz as the QRP
meeting frequency, replacing 7030 and 7040 kiloHertz that are under so much QRM, especially from digital modes. I agree that many stations have already equipment with crystals for either 7030 or
7040 kHz… but for those of us with VFO capability, enjoying the much
more clear channels between 7105 and 7110 kHz opens up the possibility of many more QRM free QSO’s…
My observations carried on during the past several days confirm that
that segment of 40 meters right next to 7100 is clear much of the time  !
Let’s give it a try !!!

73 and DX
Arnie Coro
CO2KK

The positive response to Arnie’s call to action was immensely gratifying to me. In addition to all of the reflector replies, there have also been some ham bloggers taking up the topic. I’ve long been a fan of this little slice of bandwidth, but at times it has been hard to scare up contacts there. In the last couple of years, SKCC has probably been making the most extensive use of the sub-band, which has increased the traffic there a fair amount and has brought more attention to the frequencies as a place to have a nice, relaxed CW QSO.

Not to long ago, I dreamed about ways to help increase the use of these frequencies, and even started chatting with a few other hams about ways to spark some interest. However, like a whole lot of my ideas, they never get off the launchpad since I just don’t have the time to invest in all of them. After having a few unpleasant encounters with RTTY contesters running me off 40 meter frequencies last weekend, I’m even more determined to help promote 7100-7125 as a QRP (and general CW) safe spot.

I’ve become inspired enough that I’ve decided to take a new design for a minimalistic superhet rig that I’m working on and adapt it to operate on these frequencies. If there’s any interest in it, I might even take a crack at offering it as a kit for purchase. Long live 40 meter QRP!

This weekend, I’ve been participating in the SKCC Weekend Sprint when I get the opportunity in between other obligations. At about 0900 local, I heard F6HKA on 20 meters coming in pretty well with a very fluttery signal. As you can see on the azimuth map for my QTH, the path to France goes right over Greenland, so it’s not a huge stretch to assume that the unique signal quality is due to auroral effects from the increasingly active Sun.

After about an hour of trying, I finally managed to snag a QSO with Bert using 5 watts! A great day for QRP!

F6HKA-1811-14-Feb-2010-14046.mp3

Take a listen to this QSO which was recorded a bit before I made my contact with F6HKA. You can definitely hear the watery, fluttery sound of his signal.

I’m very pleased to report the first (to my knowledge) completed Willamette transceiver which was born in Europe. Vincenzo, IZ5GVP sent along to me a couple of photos of his very nicely constructed Willamette. He reports that it works well and that he’s considering modifying it to operate on the 30 meter band. Three cheers for Vincenzo!

Thanks to some prompting from a Willamette builder who inquired about some performance issues with his rig, I was able to identify an error in the bill of materials which causes a significant degradation in receiver sensitivity.

Fortunately the fix for this problem is very simple. Audio preamplifier collector resistor R49 was incorrectly called out as 10 k, when it should have been listed as 4.7 k. If you have a 4.7 k resistor in your junkbox, just swap it in at the R49 position. A 5.6 k resistor will also work fine here. Alternately, you could just parallel another 10 k resistor across the existing one. I will be happy to supply the correct resistor to any builders who purchased a kit from me and need one.

I’ve determined that this wasn’t a design flaw, but a transcription error. My original hand-written notes have the correct value and my prototype does work correctly (I’m sure NA5N would have caught this problem in the prototype he evaluated). Somewhere in the process of creating the schematics in my schematic capture program, I entered the wrong value. I did build a beta rig with all of the same schematics/BOM that everyone else did, but I didn’t catch the error at the time. I will update the schematics and BOM posted on my website in short order to prevent any further problems.

Please accept a most humble apology from me for not realizing this significant error for a very long time. I do believe that you’ll be pleased with the difference in sensitivity once you install the correct resistor. The receiver should sound like you would expect a proper direct conversion receiver to sound. After the modification, you should be able to run the AF gain at ~75% or less during most operating conditions.

I’d like to thank W0EP, N1RX, WB8ICN, and WB9VTB for their assistance in resolving this matter!

A little while ago, I got a hankering to work on a SSB transceiver. It’s something that I’ve never homebrewed before, and it seemed it like it might be fun to tackle. The BITX20 seemed like an obvious choice, and W7ZOI recently published an improved bidirectional amp which would be nice to try in the rig. But I’m one who likes to try stuff that’s a bit off the beaten path, so I decided to try my hand at something a bit different.

VU2PEP has a lesser-known SSB design on his website, that’s a dual-band transceiver. Besides having 20 and 40 meter capability, it also has a different topology than the BITX series. Instead of reversing the flow of the signal to generate a SSB signal, this design sends the RX and TX signal in the same direction through the IF. Take a look at the schematics to get an idea of what I’m talking about.

I decided to make a “remix” of this design. The basic topology is the same, but most of the circuits are revised. The IF was moved to 4.9152 MHz, and the VFO is heterodyne-style to provide a ~19.12 MHz LO signal. My version is only for 20 meters. The front end has a preamp added and uses a cascode JFET mixer instead of a single JFET. So far, the RX strip and VFO is complete (although I might change the VFO because of some birdie problems), but the transmit amplifiers haven’t been built yet. I got a good chance to work out the RX during Sweepstakes. Check out my YouTube video below to hear me describe the circuit so far and listen to the receiver on SS.

New England Code Talker by AA1TJ

Although there are many days when I can barely stand the level of rudeness on QRP-L (and increasingly on qrp-l.org), I am sometimes reminded why I maintain my membership. Some recent events there have helped to boost up the numerator in the signal/noise ratio, and correspondingly, my interest.

In case you haven’t followed much of what has happened on the list in the last few years or haven’t listened to SolderSmoke, there’s a fellow by the name of Michael Rainey AA1TJ, who could be considered the mad genius of the QRP world. He has created what has to be considered some of the most unique and inventive minimalist QRP circuits that our hobby has ever seen. Take a look at his website to get an idea of what I’m talking about. I’ve also attached a YouTube video below showing you how AA1TJ has to operate this very unique transmitter.

AA1TJ trying for transatlantic QSO

His latest flight of fancy is his New England Code Talker voice powered CW transmitter. Yes, you heard correctly; the transmitter is powered 100% by voice sound pressure energy (about 15 mW RF output). AA1TJ has already made numerous successful QSOs with the transmitter, proving that the concept actually works. Recently he, AA1MY and W1PID met at the beach front cottage of W1REX to attempt the world’s first voice powered transatlantic QSO, as well as what was claimed to be the world’s first transatlantic QRP QSO on 160 meters (I think I misunderstood that. It’s supposed to be AA1MY’s first 160 meter transatlantic QRP QSO), both very amazing feats. I won’t spoil the story, so get yourself over to W1PID’s website to read the details of how this expedition turned out. I must salute all of you gentlemen for pushing the boundaries of our wonderful hobby and trying something never done before. Well done!

Update: Here’s the “Rexpedition2009” report about the event from W1REX (PDF format).

Update 2: A great video from W1REX showing the transatlantic 160 meter QRP QSO:

OK, time to fess up. Someone has been searching Google for “beaverton qrp” and has been landing on my blog. I’d love to know if there are other QRPers here in the Portland-area besides me and all of the big QRP luminaries like W7ZOI and KK7B. Please leave a comment below if that’s you!

The VRX-1 receiver kit uses a TDA7052 audio amplifier IC, which is a bit different from your run-of-the-mill LM386. Because of its push-pull output, if you use a phones jack, you must isolate it from ground. This isn’t something you have to worry about if you use a non-conductive enclosure or if you have an isolated phones jack. However, more often than not, you won’t have an isolated jack, and many of the enclosures that we use are metal.

This little hint will allow you to modify a “standard” grounded ring phones jack with a conductive enclosure (such as the 4SQRP Clear Top Tin, like the one I used).

Bill of Materials

• 3.5 mm phones jack
• Small length of 3/8″ OD (1/4″ ID) Polyethylene Tubing
• 1/4″ nylon washer
• CA glue (optional)

Instructions

Cut off a piece of the 3/8″ OD polyethylene tubing approximately 1/16″ long (about 1 mm).

Cutting a small piece of the 3/8" OD tubing

Place the small piece of tubing over the phones jack, so that it rests against the body. You may want to glue the tubing to the body of the phones jack.

3/8" OD tubing over jack

Drill a 3/8″ hole in your enclosure to accommodate the tubing, then place your phones jack in the hole so that the 3/8″ tubing is centered in the hole. Place the 1/4″ nylon washer over the jack from the outside of the enclosure, then use the knurled nut to secure the jack to the enclosure. It’s as simple as that!

Isolated jack installed in enclosure

VRX-1 in 4SQRP Clear Top Tin

While I was away on my honeymoon, I noticed that the upcoming kit that I’ve been hinting about for months has finally been released. The Four State QRP Group announced availability of the VRX-1 direct conversion receiver. The VRX-1 is a simple 40 meter VXO-tuned receiver (crystal on 7.030 MHz), but it’s not your typical NE602/LM386 combo. The product detector consists of only a 2N7000 MOSFET, a capacitor, and an inductor. The audio amplifier is a TDA7052 from NXP. This little 8-pin DIP can output 1 watt of clean audio into low impedance headphones or a small speaker. Current consumption is only about 40 mA, which makes the VRX-1 easy on your batteries if you take it out for portable use. The construction of the receiver is done Manhattan-style, but don’t let that put you off if you’ve never built this way before. I provide a precise, detailed layout diagram to show you exactly where each part is placed and how it is oriented. There’s also some very detailed build documentation to walk you through the build, which you can preview at the VRX-1 web page. Even the novice builder can construct this radio!

The VRX-1 was designed to be a companion to the NS-40, or other similar rock-bound 40 meter QRP transmitters. I also include instructions on how to use some of your own parts to modify the VRX-1 for operation on any HF band, so don’t feel like you are stuck on 40 meters if you would like to try to experiment a little. In a future blog post, I’ll walk you through the process of integrating the VRX-1 with a standalone QRP transmitter to make a complete station.

Proceeds from the kit sales go to fund OzarkCon 2010; I don’t make a dime off of it (just the glory, LOL!). So please support the QRP community and try your hand at a new kind of kit. It’s only $25 postage paid in the States, $28 for DX.

Disclaimer: For those who don’t know, I’m an employee of Buddipole, and I do speak quite a bit of my positive experiences with some Buddipole products in this post.

Yes hams, it’s that time of the year again. Field Day, the Super Bowl of the ham radio world. I haven’t had the best track record of participating in Field Day over the years, due to a few different factors. The largest stumbling block is the nasty allergies that I get during late spring, which usually end up peaking in intensity right around the end of June. The other problem is that I’ve never been a big fan of the big-time organized local clubs. I won’t go in to the reasons for that (you can dig back in the blog if you are really interested), other than to say that in my experience they are not the kind of places that I find interesting.

Now that I own a house with a proper backyard, I feel like I now have the option to participate in Field Day by setting up out back, so that I can duck inside if my allergies get too out of control. It also helped that I recently started taking some new meds, which have helped to control the allergies quite a bit better than anything else so far. So I was more than happy to give FD a go this year, even though it wasn’t going to be more than a backyard adventure.

Station Setup

Field Day 2009 - Backyard

Given the recent development of my employment with Buddipole, and the demise of my main station random wire antenna in a recent spring storm, it only made sense to deploy the Buddipole. I could have dragged out the IC-718 sitting idle in the shack and paired it with my very heavy 35 Ah gel cell, but I was feeling up for a bit of a challenge. I settled on using the FT-817, and considered pairing it with my recently constructed 20 watt linear amp, but I realized that running 20 watts would give me the same power multiplier as running 100 watts would. So I figured, why not take the dive and go QRP for the entire event? Not only that, but why not make SSB the main mode of operation? This was appealing to me not only because I am a QRPer at heart, but also because it would push my limits, and give me something new to try.

I’ve run into my share of hams who think that QRP is the devil’s handiwork, and that anyone running less than 100 watts is inflicting undue hardship on the poor receiving station. While I know that a QRP signal does have a more difficult time being heard (especially SSB), I also know that there have been plenty of times when the receiving station would have had no idea that I was running QRP unless I told them (and many times, I won’t tell them). The fact is, if you can hear me well enough, you’ll answer me. If not, you won’t. Yes, I get less contacts running QRP. But if the conditions are too painful for the other station, they will just not answer me or will politely cut it short. I especially feel absolved of any guilt running QRP SSB on Field Day because of the whole nature of the event. The concept is to test how well we do under less-than-ideal conditions. Quoth the rules (emphasis mine):

2. Object: To work as many stations as possible on any and all amateur bands (excluding the 60, 30, 17, and 12-meter bands) and in doing so to learn to operate in abnormal situations in less than optimal conditions. A premium is placed on developing skills to meet the challenges of emergency preparedness as well as to acquaint the general public with the capabilities of Amateur Radio.

Field Day 2009 - Buddipole

The great thing about using the Buddipole was the ability for me to use it in conjunction with the frequency agility of the FT-817 to hop around the bands. Yes, it does take a bit of time to change bands, which is not quite as fast as using a multiband doublet with a tuner. However, with just a bit of practice, you get to know what setting sare needed to resonate your antenna on any band and can reconfigure and tune it in a matter of a few minutes. Given that I decided to run QRP SSB, I needed every bit of power I could get, so I was glad to not have a lossy tuner in the way.

Given the somewhat last minute nature of my decision to play in Field Day, I didn’t have a way to power a notebook PC with a battery, so I settled on the old standby of paper logging. Since I decided to stay strictly search & pounce, it wasn’t a big deal to paper log. The biggest pain is in dealing with dupe avoidance, but I figured that I wouldn’t have to worry about that too much since I would be racking up huge QSO counts.

Field Day 2009 - A123 Battery Pack

The only thing left to nail down at this point was power. I knew that I wanted to try out our brand new A123 lithium nanophospate battery technology that we are ramping up at Buddipole. If you don’t know about this battery technology yet, prepare to be blown away when we officially roll these out. This technology has been used in the R/C hobby for a few years, and is just now making it’s way into amateur radio use. It also happens to be the same technology used in the upcoming(?) Chevy Volt plug-in hybrid vehicle. It would take too long to list all of the advantages of this technology here, but the amazing flat discharge curve, long life, very quick charge time, and incredible safety are all reasons why I’m confident that this will be the dominant battery technology in the portable/pedestrian mobile ham circles within the next few years. The particular pack that I was using is a 3S1P configuration, which means 3 cells in series, one parallel set (we also have 4S1P and 4S2P packs). Each cell is 3.3 V nominal, so this pack is rated at 9.9 volts, which is perfect for use with the FT-817. A **1P pack has a capacity of 2.3 Ah, which I figured would give me at least a few hours of operating time.

Field Day 2009 - Solar Power

Being at a bit of a disadvantage in the “contest”, I wanted to pick up some extra bonus points, so I remembered the 5 watt Harbor Freight solar panel that I had gathering dust in the closet. Using that in conjunction with my half-depleted 7 Ah gel-cell, my power strategy was fully formed in my mind. During the sunny part of the day (my backyard is on the north side of the house and is fairly narrow, so it doesn’t get a ton of sunlight) I would use the solar panel/gel cell combo, then switch to the A123 pack when there wasn’t anymore sunlight to be had at the station.

Given the set up that I described, it looked like I would fall into the 1E class for the event. Given a very strict reading of the rules, it seemed like I might have been able to claim 1B Battery, but in the spirit of the event, 1E was the appropriate choice.

Operating

I wasn’t able to start operating right at 1800 UTC due to some chores that needed to be completed first before play time. When I did get going, I started on 20 meters with the Buddipole in vertical dipole configuration and quickly started to get QSOs in the log. As I mentioned earlier, my strategy was strictly search & pounce, choosing only the loudest stations to try to work. For the most part, it was a successful strategy. I was able to work just about everyone that I heard at a S5 – S7 signal level or better.

Once the afternoon wore on and 20 meters started heating up, the pileups started to heat up as well. I found that it was getting harder and harder to be heard as I was the little fish in the big pileup. So by mid-afternoon, I started working my way up the bands. By jumping to 15 meters (then 10, and eventually 6) was the band was starting to open, I was able to stay ahead of the really competitive pileups. One of the coolest things about the operating was the feeling of riding the QSB like a wave up and down; waiting for a crest in the propagation to strike fast with my callsign. It could have all been in my mind, but it did seem to help to operate like this.

As the sun started to set behind the neighborhood houses, a good sporadic E opening hit the West Coast and I was able to get some nice 6 meter and 10 meter QSOs out to about 1000 miles or so. I had big plans for staying up late after dark to operate, but by the time that dusk fell on Beaverton, I was totally exhausted. So I laid down on the sofa and set the alarm on my iPhone to wake me in a few hours. Not surprisingly, I must have turned off the alarm in my sleep, because the next thing I remember is that it was 5 AM the next morning.

A bit disappointed, but feeling renewed, I put on a pot of coffee and decided on my strategy for the morning. It seemed obvious to give the lower bands a shot, since the propagation was bound to be best there and I hadn’t worked them the day before. So the Buddipole was reconfigured as a Versatee Vertical with the low band coil, and the power was supplied by the A123 pack. Once I got going again around 7 AM, I was shocked at how well I was doing on 75 meters. The puny 5 watt signal from the FT-817 into the Buddipole had some good mojo, as I got multiple unsolicited “great signal” reports from the stations that I contacted (many of them VE7s). In my QSOs on the previous day, it was obvious that I was a QRP station, often needing multiple calls to bust a small pileup and sometimes needing a repeat or two. But both 75 meters and 40 meters were working remarkably well for me. The call got through on the first try nearly every time, and almost no fills were necessary. It truly felt like I was running 100 watts.

After a morning of fun, I had to go QRT for the day in order to complete some other chores that I had put off for far too long. It was a bit tough to tear myself from the station, but responsibility trumps fun, even if you try to put it off for as long as you can.

Results

Before I started operating, I thought that 50 QSOs would probably be a reasonable goal to shoot for as a QRP SSB station. As it turns out, I got really close; with a final tally of 49 QSOs, all of them SSB. Twelve of those QSOs were on solar power, so I qualified for the 100 point alternate power bonus. Since I was on emergency power the entire time, I also got 100 points for that. Given my 5 watt power limit and 100% emergency power status, I qualified for a power multiplier of 5. I also managed to copy the special W1AW bulletin for 100 points, and plan to submit my log via the web for another 50 points. If I did the arithmetic correctly, that should give me a final score of 595 points.

I also want to make note of the performance of the A123 battery pack. I started the event by charging the pack to a full charge with my Cellpro Multi4 charger. Although I did the majority of my operation timewise on the solar panel, by far I had the most QSOs with the A123 pack. According to my rough log calculations, I used the A123 pack for over 3 hours of operating time and logged 37 QSOs with it. When I returned the pack to the charger after Field Day, the charger reported 19% of the charge was left (the voltage display of the FT-817 never dipped below 9.6 V the entire time I was operating with the A123 pack). The next charge only took 38 minutes to get me back to 100%, and ready to go again. The 3S1P pack only weighs about 8 oz. and gave me a ton of operation time, much more than I expected. It sure blows away the much heavier and bulkier 5 Ah gel cell that I usually use with the FT-817. Ask the Goathiker, he’ll tell you how great these things are.

I could wax poetic about the event, but I think you get my feelings about the thing by now. I’ll just end by saying that this was my best Field Day by far, and that I had more fun with QRP SSB than I thought possible. I have a great appreciation for the excellent ops that put up with my peanut whistle, and learned a lot more about how capable a QRP SSB station can be.