From DX with Love – RDXC 2017

In a further example of the benefits of DX contests for those looking to rack up new countries, this weekend’s Russia DX Contest served up another bounty of new DXCC entities on CW.

All in all, I landed 11 new DXCC entities. Since part of the fun of contesting is imagining the operator at the other end of the ionosphere – doing the same thing you’re doing, furiously decoding CW in front of a radio, thousands of miles away – I’ve included the names of the ops below where I could find them:

  • Switzerland (HB9ON – Radiogroup in Piancamara 7, a profilic DXpedition team)
  • England (M2G – not a special event station, just a contest call of John in the UK)
  • Croatia (9A7V – Eugen)
  • Poland (SN8B – Bobowsi)
  • Germany (DA0AA – A radio club in Germany. “Emergency Radio Station Frank Cut Switzerland”, says Google Translate…. so that’s something)
  • European Russia (RU1A, a contest station out of St. Petersburg)
  • Northern Ireland (MI5I – Colin)
  • Serbia (YT3X – Miki)
  • Sweden (SH1DX – could not find)
  • Argentina (L6HKA – could not find)
  • Slovenia (S51J – Janez)
VmB+vAB5.png
A bevy of new European countries worked during RDXC 2017. Argentina can come too.

I also connected with a second Alaska station, my first AK contact on 20m, which should help to cement that state for my WAS goal this year. (To be sure, KL7/VE7ACN has been tearing up the bands this week, since I heard him a week ago. But more contacts in the log never hurt.) As icing on the cake, I heard, but couldn’t contact, Arthur 4X2M in Israel . Still searching for that first elusive contact in Asia.

Unlike the ARRL DX contest, where contacts within the same country don’t count for anything, the Russia DX contest does award a (small) number of points for contacts in the same country. So I picked up a few stateside contacts on 40m later in the evening, just to add to the contact count and continue drilling my CW.

There’s a joke in radio circles about “contest propagation”, which is the notion that even when “the bands are dead,” they somehow “magically open up” when there’s a contest going on. Certainly, during major contests, when everyone who has one brings out their big amplifiers and aims their beams most precisely, contacts are more frequent.

But this weekend, I suspect that the ol’ ionosphere was actually on our side for a change – in the late afternoon, after I’d worked what there was to work on 20m CW and before 40m opened up, I dipped over onto 20M JT65. . After noodling around for about 20 minutes, I had landed both PD7RF (Frits in the Netherlands) and MC0CSO in Wales.

Two more DXCC in the log. That brings me up to 49 DXCC entities reached, with 30 confirmed.

And as a final sign of Sol’s grace upon the upper atmosphere, the following afternoon I heard (but could not reach) both Asiatic Russia (RA0CGY) and Japan (JM7OLW, JH1HRJ, JA1PSS, and 7K4GUR) on JT65.All are over 6000 miles away. They were way below the noise floor at -20 to -24 dB, about the limits of what JTDX will decode. But things look promising as the summer months move closer.

stationsheard_20m_JT65_2
Stations heard on 20m JT65, afternoon of 3/19/17. What a spread!
Image by PSKreporter.com

Hear you on the air, all over the world!

73

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An Embarrassment of DX – ARRL DX CW 2017

After several months of being on the air, I’ve finally made contact with continental Europe! And contrary to my previous post of JT65 DXing, this one was with good old fashioned CW. At around 0204 on Sunday 2/18, I heard a CQ TEST call from EF7X on 20m , and after several back-and-forths and some resending, I had him in the log. Huzzah!

A few minutes later, I found the US Virgin Islands on the air with NP2P. Then the Madeira Islands off the coast of Morocco from CR3W. Then the Slovak Republic, of all places, via OM7M. Then, then, then….

All in all, I made a total of 55 QSO’s with 29 unique DXCC entities over the course of a few hours of operating on Friday, Saturday, and Sunday. Of those, 17 were All Time New One’s for me, bringing my total number of entities contacted (though not necessarily confirmed) to 34. I doubled my DXCC progress in one weekend!

The full list of new entities reached includes: Barbados, Spain, the US Virgin Islands, the Madeira Islands, the Slovak Republic, Jamaica, Portugal, Scotland, Italy, Ireland, the Balearic Islands (had to look that one up), the Bahamas, France, Hawaii (!!!), Belize, Cuba, and Cape Verde. The full map looks like this:

arrl_dx_2017

It’s no accident that this string of contacts came along during the ARRL DX CW contest, when all of the international contest stations have their beams and their amplifiers trained on the United States, and are looking for any stateside contacts. Even a relatively-dinky 100W into a random-wire and tuner is a valuable contact for DX stations in this contest. And I’m tremendously grateful to the stations that took the time to dig my signal out of the noise. One of the peculiarities of the ARRL DX contest is that non-US stations have their output power as part of their exchange. Almost everyone I worked was “K” or “KW” (1000+ watts), with a handful of 500 or 100 watt stations thrown in. Makes my 100 watts look like a pebble in a quarry.

My final claimed score is 55 QSOs & 45 mults, for 7425 points. Not too shabby! Here’s the breakdown by band and multiplier:

The ARRL DX SSB competition comes along in a couple weeks – I’ll surely have to be on the air then. Hear you there!

73

Catching Up: CQ World Wide CW, 2016

Having started a new job in October that’s keeping me quite busy, I’ve resolved to care less about the timeliness and length of posts, and to prioritize getting them down.

To that end, here’s a brief recollection on the CQWW CW Competition that I participated in back in November. One of the largest international contests of the year, this was certainly a hopping time on the air. I participated using my repaired ATS-4, at around 3W, and there were a good many stations I could hear but not contact. Nevertheless, I ended up with 17 contacts over 11 countries and 7 CQ Zones. My best DX was ED8X in the Canary Islands – a little over 4000 miles away, for better than 1300 miles/Watt. What a day

I wracked up a host of ATNO’s (All Time New Ones, or new countries in the log), including: Curacao, Dominica, Bermuda, the Canary Islands, the Cayman Islands, Bonaire, French Guiana, Turks and Caicos, and Peru.

cqwwcw-map

I’ll be back on the air for CQWW 2017. Hear you on the air!

73

California QSO Party 2016 and First 15m and 20m Contacts

Having put up a basic wire antenna last week, I thought I might as well give it a spin over the weekend to see how well it might receive on the various bands I have access to. This being the weekend of the California QSO party, I figured there would be lots of big signals on the air to try to hear.

Much like when I first put the QST-49er on the air, I had much higher expectations for  reception that for anybody else hearing me, but I was to be proved wrong. Using the ATS-4, my power output is about 3W on 80m, 40m, 30m, and 20m, and about 2W on 15m. I figured I would find the strongest calling stations that I could and use them as a gauge of where I was receive in signals from.

Much to my delight, the CW portions of both the 20m and 15m bands seemed to be filled with California stations calling “CQ CQP” (California QSO Party). Some of them S7, a couple over S9 even with my simple antenna. With no AGC, some signals were strong enough as to require me taking the earbuds partially out of my ears. With propagation and the antenna seeming to cooperate, I quickly looked up with CQP exchange (serial number and state) and responded to some of the CQs.

And do you know what? Not one, not two, but twenty-four different stations came back to my little QRP signal. Twenty Four! In the span of a Saturday afternoon (and one more Sunday morning) I increased my lifetime QSO count by almost %500, including my first 15m contact (K6LRN), my first 20m contact, and my first CA contact (both N6CK in Poway, CA). Here’s a map of as many contacts as I could grab Lat/Long data for, all up and down California:

caqsoparty2016map

One of Eric Guth’s guests on the QSO Today podcast (and I can’t for the life of me find who) expressed that the joy of radio sport for him was that he got a little spark of joy every time he made a new contact, and that contesting gave him that feeling hundreds of times in a row. While I didn’t hit hundreds of times, I certainly felt the rush of making contest contacts, fighting to be heard with other stations, the victorious feeling of finally being heard, the reward of persistence…. I could get into this radio sport thing.

If that’s going to be an area of interest, I’ll need to practice a little more on my reception speed, especially when it comes to numbers. For this contest, I would often listen to the California station go through two or three other contacts to try to pick out the serial number he was on and his county before I’d make a call myself. My receive speed just isn’t high enough to go into a contact from scratch. But I’m grateful to all the ops who were willing to slow down and repeat themselves when asked. It made me feel very welcome as a new op.

In any case, my claimed score for this one was 1224 points, distributed like so:

ca-qso-party-2016-score

I suspect my actual score will be much less than that. I know I botched a couple numbers early on, and even gave out the wrong number once (oh the shame). But even if I only get one point in the log, that’s good enough for a first time out.

Hear you in the air, and in the contest!

73

A New Random-Wire Antenna and First 80m Contact

Sometimes the simplest of radio work pay the biggest dividends. Last week, after a few weeks of hemming and hawing about it, I finally committed to putting up a longer wire antenna that allowed the possibility of using multiple bands. The 40m dipole I put up at the end of August has proved to be fine as a receiving antenna, but it suffers two key limitations. First, it’s obviously a single-band antenna (though I may try it on 15m as well). And second, situated as it is between two apartment buildings, I think I’m wasting most of my energy heating up the bricks rather than propogating energy out into the world. It’s also only ~10′ off the ground.

The new antenna helps with all of these issues. It’s simply a ~58′ piece of 22-gauge speaker wire strung from the office window out to a tree that sits in the apartment’s back yard.at its highest, the wire is maybe 20 feet up. While it’s a little visible in the alley if you’re looking for it, it blends in with the surrounding tan brick enough that I don’t think it’ll be noticed. I dropped a ~16′ piece of the same wire out the window to act as a counterpoise.


No, I swear, there’s an antenna running right through the center of this picture.

Like any random-wire, this one needs a tuner to be useful. I first tried using the ZM-2 tuner I got last Christmas. I sadly think I have a short in one of the variable caps in that tuner, which makes it non-functional for now. The MFJ-949e tuner did the trick though – I attached the long wire directly to the “WIRE” banana jack on the back, and the counterpoise to the grounding lug. The antenna tunes up better than 1.2:1 on 80m, 40m, 30m, 20m, and 15m. Which doesn’t necessarily mean it’s an efficient antenna, just that it won’t unduly stress my transmitters.

When I tuned the antenna the first time, I made myself a cheat sheet of the capacitor and inductor settings that gave me the lowest SWR on each band. I then taped this cheat sheet to the top of the tuner. This gives me a place to start when I need to retune for a particular band.


The same evening that I put the antenna up, I did a tune-through of the CW portions of 15m, 20m, 30m, and 80m. It’s really the first time I’ve been able to hear anything on a band beside 40m, so I figured a little exploration was due. I came across an S7 signal at 3.545 MHz calling CQ, and just for grins, I gave him a call. And he came back to me! Arthur, N8ART in Columbus Ohio, running an older rig into a dipole, if my copy was right. 

Columbus is a little under 300m from my QTH in Chicago, so this was probably a single-hop contact, or really NVIS. But it represents my first contact outside of 40m, which is terribly exiting! The new antenna is already proving its worth.

This was also my first contact with a new transceiver, an ATS-4 which I snagged as a “tech-special” (i.e. broken) from qth.com and repaired. That process deserves its own write-up. I’m also using a second-hand Ham Key I picked up at Radio Expo 2016 in Belvidiere, an event that also deserves its own post. But really, I’m just too excited about the contact on a new band to try to keep these posts strictly sequential.


Hear you on the air, maybe on 80m!

73

 

K3NG Arduino-Based CW Keyer and Homebrew Paddles

Last weekend, I built a little morse-code keyer and a small set of iambic paddles. As I try to continue trying to improve my more code sending and reception, I’ve been running into the limits of what I can accomplish with a traditional straight key. The paddle not only allows for faster sending with perfect spacing, but the back-and-forth motion of he paddles is much easier on the wrist than the up-and-down pressing of the straight key.

While I was tempted to roll my own Arduino keyer code from scratch, the sheer number of features available in the K3NG Keyer Code made that a much simpler starting point. Frankly, I can’t think of any keyer-related function that the K3NG code doesn’t do, and I’m only actually using a small portion of its capabilities. I’m using it as a generic ultimatic-style keyer with sidetone and a potentiometer for speed control. Among the features left by the wayside (for now, at least) are:

  • USB and PS/2 Keyboard support
  • An LBCD display
  • Recordable memories
  • Beacon/Hellschreiber/QRSS Sending
  • Sending practice
  • Callsign receive practice
  • CW Decoder
  • So much more….

Simplifying the K3NG circuit considerably left me with the following schematic:

k3ng-keyer-schematic

The unit and its batteries are contained entirely within a 1-gang plastic junction box, an idea shameless stolen from an old W6KWF project. The power source from the project is just 4 AA batteries in series. The power switch for the unit is built into the potentiometer – pulling it out turns the unit on, pushing it in turns it off. The little 1.5″ speaker came from one of the old AM radios I pulled apart, I think. The remainder of the electronics are just point-to-point wired on a piece of perfboard, which rests on top of the battery pack.

img_1319

I considered adding an power indicator LED, until I noticed that the power LED on the Arduino Pro Mini itself is clearly visibly through the plastic of the box. Looks nice!

IMG_1342.JPG

The speaker-enable pushbutton was a last-minute add, when I realized that I wouldn’t want to hear both sidetone from a rig and from the keyer. It’s just a SPST latching button. The K3NG software has an option for turning off the sidetone in software, but I opted for just a hard cut-out switch.

I’ve yet to make a contact with the new keyer, but it’s proved useful as a code-practice machine if nothing else. And it should be interoperable with any future radios that accept a straight key, so I think it’ll be a part of my shack to stay. I do wish there was a way to adjust the programming without pulling the box apart, but at only two screws, I think that bit of difficulty is a good trade for a cleaner presentation.


Of course, for the keyer to be useful, it needs a set of paddles to go with it. Mine took about an hour to make from start to finish. It’s just four pieces of scrap copper-clad glued and soldered together. Two pieces of single-sided copper clad, copper-side-in, form the paddles.  A 1/4″ bolt with two nylon lock-nuts forms the center-contact -rotating the upper lock-nut changes the spacing between the paddles and the contact, which allows for some adjustment in the feel of the paddles. A small raised piece of copper clad keeps the paddles elevated off of the base. The 1/8″ stereo cable is soldered to this last small piece of copper clad.

This actually works pretty well for such a quick project, though it became obvious pretty quickly that it needs some kind of base or strap to hold it steady when operating. That can be the next project.

Hear you on the air!

73

QST Forty-9er with DDS VfO

(Since this was originally posted, this transceiver has also gained a laser-cut faceplate.)

Long story short, I’ve got a new transceiver!

Back in March, QST magazine published an article about modding a cheap Forty-9er kit from eBay to incorporate a digital VFO. The original Forty-9er was a kit from the NorCal QRP club, a 40m transceiver designed to run on a 9V battery, hence the name. It, like many other kits, is based around an NE602 and an LM386. In the last couple years, cheap kits bearing the same name have been appearing on eBay, which bear only a scant resemblance to the original. The biggest difference is that where the original kit had a VXO attached to the NE602 mixer, the eBay kits are designed to be rock-bound to a single frequency. Perhaps this was the motivator for the QST article, to restore some frequency coverage to these fixed-frequency kits.

ebay 40-9er.jpg
The Forty-9er kits from eBay – not a huge number of parts, but not a tiny kit either.

The process of using a digital VFO with an NE602 architecture is simple enough. Specifically, an AD9850 breakout board is used to provide the signal, and a small BJT amplifier increases the power output from the DDS chip. The oscillator power is adjusted to show about 300mV P-P in-situ. After the article was published, one of the authors, K2ZIA produced a limited run of kit boards, which include the amplifier and sockets for both the AD9850 board and an Arduino Nano to control the DDS over i2c.

K2ZIAboard
The K2ZIA kit board, with attached Arduino Nano and AD9850 board. Image credit: K2ZIA

I purchased the breakout board, AD9850, Forty-9er kit, Arduino Nano, and a rotary encoder from a fellow ham, Justin AJ2Q, who had gathered the pieces but was focusing on other pursuits and wanted to pass the project on. Final assembly was pretty straightforward; there are a couple of mods that need to be made to the Forty-9er (specifically, replacing the oscillator crystal with an input for the VFO, and swapping the crystal input bandpass filter for a much-wider two-element bandpass filter), and connection made so that the Arduino can detect when the key is down and shift frequency. AJ2Q had already done most of this, so only some final tweaks and cleaning up some soldering were necessary.

The original Arduino code was designed to make use of a 16×2 LCD display to display the current frequency, as well as licensing information according to the 40m band plan. Since I’ve already been playing with an LCD display on another ongoing project, and since I wanted this to be a simple and durable bit of kit, I wrote a bit of code that instead flashes the current frequency in morse code on a panel-mounted LED. The display is triggered by the press of a button. The number of digits to display is configurable. I’ve found that just displaying the three kilohertz digits is plenty (I don’t need to be reminded I’m on the 7 MHz band every time, and I don’t need precision better than KHz for simple operating). As always, you can see the code on Github.

IMG_1184
The internals of the transceiver. The two green perf-boards are an experimental audio filter to be documented later. The 40-9er board is bottom-left, the K2ZIA board is bottom right, and the small black board on the upper right is the rotary encoder mounted to the front panel.

 

The full schematic of the original Forty-9er as well as the necessary mods can be found on Farruk K2ZIA’s website. The only additional hardware changes I made were to wire an LED and a 1k resistor between Arduino pin 14 and ground for the LED, and an SPST button between Arduino pin 4 and ground to trigger the frequency display. Like the original code, depressing the encoder changes the tuning rate, though I modified the possible step values to be only 1000Hz, 100Hz, and 10Hz, in that order. 1KHz is useful for zooming around the band, 100 Hz is useful for tuning a specific signal, and the 10Hz step is mostly for resolving SSB/DSB/AM signals cleanly.

On the rear of the radio are the BNC antenna jack and the power pole power input. (Useful tidbit – a pair of connected 30A powerpoles fit neatly in the cut-out for a VGA connector!) I’ve yet to fashion a front-panel, so the connections on the Forty-9er board for a key and headphones are directly accessible.

img_0950

I’ve had the rig out to the park a handful of times now, and it sounds good! Like my other direct-conversion NE602-LM386 experiments, the audio quality is great, but broad as barge, so selectivity suffers. The sidetone is clean, at around 700Hz, from the Forty-9er’s little BJT oscillator. I enjoy being able to tune up into the phone portion of the band and listen to SSB QSOs and nets and such, which provide a good sketch of current propagation conditions. Being able to quickly switch between tuning steps is helpful, as I tune around and try to find someone sending CW slow enough for me to keep up.

IMG_1185.JPG
The top of the rig. Not fancy, but functional.

The only major limitation of the rig is that, with only a single-resonator input bandpass filter, out-of-band signals can get into the radio and cause interference. Specifically, World Harvest Radio WHRI, who maintain and 500KW (no that’s not a typo) transmitter in South Carolina, is often audible everywhere on the dial, which is distracting at best. A stiffer bandpass filter will be necessary soon. I’ve also been experimenting with a peaked audio filter to help with reception of CW, but that’s still experimental.

The unit puts out about 3 Watts, which proved to be enough to make my first CW contact and, over the weekend, my second. The gentleman on the other end this time was Gary N4PIR, who was running 5W on his FT-817 into a trapped vertical. I think a little afterburner would be helpful on my end, as we were definitely fighting QSB. But that’s a later project.

Hear you on the air!

73

First Encounters of the HF Kind

Today, for the first time, I reached out into the ether on HF, and had someone reach back! All with three Watts and a wire. I’m still in blog-post-debt for both field day and the new transceiver, but I’m just so excited, I’ll drop this in as quickie post for this evening. It’s not a proper QSO, but it’s as close as I’ve come yet.

(A small caveat – I’ve worked a couple field days, one with WVARA in Silicon Valley and now one with NS9RC in Chicago, but someone making rapid-fire contest contacts on somebody else’s very shiny K3 doesn’t feel like my contact, you know?… I’m still counting this as an emotional first.)

I had a 40m inverted-V thrown in a tree by Lake Michigan like I described in my previous post. I’d been listening an tuning around from about 7:45pm local time, throwing out the odd CQ, trying to tail-end some conversations without much luck. I’ve been hanging out mostly around 7.110-7.114 MHz, which are both a slow-code area and the area near the SKCC calling frequency, which seems to attract patient and friendly code operators. Finally, around 9:25pm, I heard a very, very slow “CQ CQ” right on 7.114 MHz. The call was from W4JWC, I suspect from a keyer – it was very slow and regular, and easy to copy. I shot him back a quick “W4JWC de KK9JEF,” and he came back! Still slow, medium-signal but with some serious fading.

Here’s the entire text of my first contact. I’m including it, not because it’s particularly interesting, because I think I’ll enjoy looking back on it later:

CQ CQ CQ CQ de W4JWC W4JWC K

W4JWC DE KK9JEF KN

KK9JEF DE W4JWC UR RST IS 539 RST 539 NAME IS JERRY JERRY QTH WIRTZ VA WIRTZ VA KK9JEF DE W4JWC K

FB FB JERRY NM HR IS JEFF JEFF QTH IS CHICAGO IL CHICAGO IL HW? HW? W4JWC DE KK9JEF KN

KK9JEF DE W4JWC QSB QSB SRRY SRRY DE W4JWC K

W4JWC DE KK9JEF YES QSB QSB UR RST 539 539 W4JWC DE KK9JEF KN

KK9JEF DE W4JWC QSB QSB SORRY QSB DE W4JWC K

The key thing to notice in all this is the Q-signal “QSB,” which denotes fading. In addition to dealing with general noise on the bands, both man-made and natural (including static-crashes from lighting), signals can also fade-in and out, just as if someone was playing with the volume knob. One moment the codeis loud and present, the next it just fades into the sonic underbrush. Frustrating, to say the least.

I’m calling this my first HF “encounter” because I don’t think Jerry will have copied any of my information – typically, it seems, an HF contact or “QSO” involves the exchanging of signal reports (RSTs), names, and locations (QTH). Since Jerry didn’t get mine, I don’t think I’ll be in his logbook, and he isn’t officially in mine. But he’ll be remembered here, as the first key from the airwaves to respond.

Hear you, and hopefully talk to you, on the air!

73

Si5331-Driven Transmitter – Beginnings

In Spring, a young man’s fancy turns to thoughts of transmitters. Having recently completed a receiver, and with the weather starting to warm a bit, I’ve got an itch to actually get on the air and talk back to the stations whose code I can now (slowly, painfully) decode.

Re-purposing some hardware and code from my DDS VFO project, I’ve been working on on a digitally controlled CW transmitter based around an Si5351. This is by no means an original thought, and my designs are largely based on Qrp-Labs’ Ultimate3s Kit. You can check out that original design over on the QRP-Labs site, under the PCB assembly instructions.

Essentially, this transmitter uses an Si5351 DDS clock chip to directly synthesize the desired output frequency, at up to 200 Mhz. This frequency is then amplified by a simple FET amplifier to approximately a 1W output level, then passed through a low-pass filter and out to an antenna. The Si5351 is controlled over i2c by an Arduino Uno, which has an attached LCD, a rotary encoder, and a couple buttons for frequency and band control. The updated code for this project is on Github.

Here’s a block diagram of the transmitter:

Si5351TransBck-3-6(3).png

The nice thing about this design is that the main frequency-dependent component is the low-pass filter; the Si5351 should be stable enough for CW contacts up to at least 50MHz. (Without an ovenized environment for the reference clock or some GPS disciplining or similar, there’s still a little drift and inaccuracy, but I don’t think it will be noticeable.) Above HF, I’d expect to see diminishing returns from the FET amplifier. But switching HF bands should just mean switching LPF filters and pressing a button on the VFO.

Here’s the circuit as constructed, up to where the LPF would go:

CW Transmitter sCHEMATIC
The simple Si5351-based transmitter, with a 3-FET amplifier.
Let’s walk through the circuit starting from the signal generator and working out toward the antenna. The output of CLK0 on the Si5351 is coupled into the amplifier with a 100nF cap. This drives the gates of three J110 FETs, and is biased upward by a voltage divider formed by a 10K pot and a 4.7kOhm resistor between 5V and ground. The power end of this voltage divider is bypassed to ground with a 100nF cap.

Power for the amplifier is fed from a nominal 12V (or lower) through an RF choke, in this case 25T on an FT37-43, into the FET drains. A 100nF cap here helps further bypass RF to ground at this point. Output is taken off the drains through a final 100nF cap. The FET sources are grounded.

While an actual RF transistor like a BS170 would likely be ideal, I had a bunch of J110 FETs in my bin after my last trip to California, so that’s what I used. They’re only rated for about 300mW dissipated power, so I’ll need to be careful with my heat sinks and duty cycle until I can replace them with something a little more sturdy.

IMG_0393
Three J110 FETs with their heat sinks on a piece of copper clad. In the back you can see the PA power coming in through the black alligator clip via the small RFC. The bias pot is on the left, signal comes in on the red wire on the bottom, RF out via the BNC connector on the right. The big white box down in the bottom is a 51 Ohm, 5W resistor I was using as a basic dummy load for testing
Preliminary results are encouraging – I hooked the output of the above circuit directly to a dummy load with no low-pass filter and ran the clock generator at 7.050MHz. I assessed power by reading off the peak voltage on an oscilloscope.I started with just 1 J110 and a 5V PA supply instead of 12V. This yielded about 9V peak-to-peak, or 200mW into 50 ohms. Installing the other two J110s bumped the output up to 10V P-P, or 250mW. Finally, after installing heat sinks on the FETs for safety and taking the supply voltage directly from a 12V SLA battery (~13.2V), the output hit 22V P-P, or 1.2W into 50 Ohms.   This last reading was verified with the power meter on an MFJ versa tuner.

IMG_0376
The transmitter spread out on the bench, with the display and Arduino at the top, the amplifier visible on the copper-clad in the middle, and a bulky MFJ tuner at the bottom acting as dummy-load and power-meter.Power provided by the 7Ah, 12V SLA battery at top-right.
I’ll need to put a little elbow grease into low pass filters before putting this on the air, because even on a scope the signal looks a bit gnarly. But first the first time, I’m responsible for 1W of Homebrew RF power. Watch out!

73

 

First Received Code! (W1AW)

Today, for the very first time, I copied CW that was on the air! Though my morse is still very poor and slow, here’s what I pulled out:

CH?S_  … W1A?… ..HQ STATIONS INQR____SES EXCITEMENT… AND ADDING TO THE INTRIGUE IS THE … _OR. END OF 5 WPM TEXT. QST 1_ DEC…. AG….

What luck! I’d caught the end of a W1AW code bulletin! Pretty neat for the first code I’ve picked out on the air. Here’s how it happened:

I was noodling noodling around putting my Direct Conversion Receiver into a new enclosure (more on that later). The receiver is rock-bound to whatever crystal is sitting in a bit of female header next to the NE602 Mixer. I tend to leave the 7.030 Mhz crystal in there when I’m experimenting – it seems like big-signal stations seem to congregate down in the Extra portion of the CW band, and that extra oomph is helpful when I’m testing a new receiver with an improvised antenna.

After doing a preliminary fitting of the receiver in its enclosure, and a quick repair (yes, it helps to restore all the connections), was I ever surprised when I applied power and my earbuds leapt to life with clear, slow code! Most QRS (slow code) stations seem to be up in the 7.050 to 7.055 portion of the band. What the heck was this very slow, loud station doing so low in the band?

I grabbed a nearby post-it note and started copying, and pulled out the code above. I know I butchered a bunch of it, even at 5WPM, but it was very exciting to (a) hear un-anticipated CW come over the airwaves and (b) to be able to actually copy some of it!

For my own reference (and others’), here are the W1AW Slow-Code transmission times, both in UTC and CST:

Day CST UTC
Monday 4pm 000z
Tuesday 2pm, 8pm 2100z, 300z
Wednesday 4pm 000z
Thursday 2pm, 8pm 2100z, 300z
Friday 4pm 000z

Hear you on the air! But only if you transmit very, very slowly.

73