First RF

CC1-40 Prototype

CC1-40 Prototype

Two days ago, I received my pack of 10 CC1 prototype PCBs from Seeed Studio. The excitement was too much, so I immediately started building the first CC1 prototype as soon as my wife got home from work. Not surprisingly, I didn't go to bed until I completed the build, sometime around 3 AM. I knew it was futile to even try to sleep, as I'd just lie in bed wondering if I had messed something up with the circuit. The radio seemed to pass all of the basic checks early that morning, but had a few oddities that needed to be worked out.

Yesterday, I was able to tweak some component values and got almost everything in line with my Manhattan-built prototype. I could hear a good rush of band noise as the antenna was connected, signals were coming in, and there was a stable 3 W CW output from the transmitter. Everything was looking great, but by the time the radio was ready to go QRV, 40 meters was closed and I was dead tired anyway.

NT7S CC1 Beta Test QSL

NT7S CC1 Beta Test QSL

Tonight, I tried to make a first QSO with AA7EE, but 40 meters had already gone long by the time I was able to make it to the radio at 6 PM, and Oakland was well out of the skip zone. There were a lot of signals from Rockies and east on the band, so I cruised a bit looking for a CQ. No luck finding anybody CQing, so I found a clear spot just above the QRP watering hole and called CQ with the CC1 keyer memory. Right off the bat, I got a call from WA0JLY! We gave each other 559 reports, but he actually came up to 579 by the end of the QSO. It was a very short QSO, as just as we exchanged reports, I was called away to help with our 10 month old son Eli. So I apologize Denny for the cutting the QSO short and for my shaky fist! Earlier today, I made some special QSL cards to commemorate the occasion and WA0JLY will get the first one. I do plan on getting more on-air time with the CC1 over the next few months, something that I've set aside far too much while I've been doing design.

So the initial verdict for this CC1 beta test is looking good. I will be getting in touch with the original beta testers soon and soon after that will contact those who requested to be in on the next beta (if you are one of those people and you don't hear from me soon, feel free to contact me). As I've been saying recently, I'm cautiously optimistic about this board spin. I hope that I will be able to deliver a good product to my beta testers that has all of the original bugs eliminated.

Edit

I've had a lot of people ask for details about the CC1 and I forgot that it has been a while since I've last reviewed the details about the rig on the blog. So here's a quick list of specs. Please keep in mind that this is strictly preliminary and subject to change for the release version.

  • Monoband CW QRP transceiver kit
  • DDS VFO (AD9834), full band coverage
  • Mostly SMT construction (0805 resistor/capacitors)
  • Initial available bands: 40, 30, 20, 15 (probably will add 80 and 17 if there is demand)
  • ATmega328P microcontroller with built-in keyer and straight key mode, audio frequency annunciation, RIT/XIT, voltage supply readout, breakout headers to UART, I2C, ADC, GPS port for WSPR transmission (and hopefully APRS over PSK63)
  • TX output power: 3 W
  • RX current: ~40 mA
  • TX current (13.7 VDC, 3 W): ~370 mA
  • MDS: -125 dBm
  • IF rejection: 86 dB
  • Image rejection: 95 dB
  • Two-tone, 3rd order IMD dynamic range: 75 dB
  • PCB dimensions: 70 x 99 mm
  • Custom matching aluminum enclosure measuring 70 x 100 x 25 mm will be included

HNY

Yes, a belated Happy New Year greetings! It's hard to believe that 2013 is already well under way. I figured it was about time to give you a quick update on what's going on in the shack right now.

First up is the discrete component grabber receiver for 14.141 MHz that I prototyped to be paired with the OpenBeaconMini project. The receiver itself consists of a roughly 2 kHz wide crystal filter on the front end, feeding into a single-balanced diode ring mixer, which drives an AF amp using 2N4401 and 2N4403 transistors. Because I'm not able to put up a proper outdoor antenna for the grabber right now, I decided to put the VE7BPO cascode active antenna on it instead. It seems to work well, but I don't know for sure because there are basically no signals on this part of the band. I intended to use my Raspberry Pi with the receiver as a grabber, but I had no luck getting either LOPORA or QRSSVD to work properly and reliably. It may just be asking too much of the poor beast. So I'm going to try to appropriate another PC in order to get the grabber receiver QRV so that on-air testing of OpenBeaconMini can begin in earnest.

Discrete component monitor RX for 14.141 MHz

Discrete component monitor RX for 14.141 MHz

Next, I wanted to give you a very brief overview of my most recent purchase for the lab: a Rigol DS1022U arbitrary waveform generator. As far as I can tell, this appears to be pretty much the same as the DS1022A model that is sold in the US. But being a typical ham, I wanted to save a few dollars, so I purchased it off of eBay from seller who says he is an authorized Rigol dealer.

Rigol DG1022U Arbitrary Waveform Generator

Rigol DG1022U Arbitrary Waveform Generator

The DG1022[U|A] has two channels that can output a sine wave up to 25 MHz in 1 mHz (as in millihertz) steps. It can also provide square, ramp, pulse, noise, and arbitrary waveforms at lesser frequencies. It can modulate the waveform in a variety of ways, including AM, FM, PM, PWM, and FSK. It can, of course, also do sweeps of various parameters. The output amplitude into 50 Ω ranges from 10 Vpp on Channel 1 or 3 Vpp on Channel 2 down to 2 mVpp on both channels (or -50 dBm). The shielding on this AWG seems to be excellent. Using my HP 355C/355D attenuator combo, I can get a signal down to about -140 dBm (disclaimer: not a scientific measurement, made using my ear as a detector and listening on my IC-718). The dual outputs makes it very useful for a variety of two-tone receiver measurements, one of the big reasons driving my purchase. The Channel 2 output also doubles as a 200 MHz frequency counter input. Paired with the USB connectivity of the device (it seems to enumerate as a usbtmc device), that will be extremely handy for measuring oscillator drift. The DG1022 can also link the two channels together and give them a specific phase difference, as you can see below. This will make it very handy as a I/Q LO when I want to experiment with phasing and SDR rigs.

I/Q Output from DG1022U

So far, I've been very pleased with my purchase. I don't feel like I've had it or used it long enough to give you a full review, but I thought that this preview would at least be a bit helpful for those thinking about using it. One of my goals for the new year is to do a much better job of characterizing everything that I build. Since I intend to start selling transceivers in the near future, it's doubly-important that I can make accurate measurements of my products so that I can properly state their specifications. To this end, I've decided to sell off a bunch of my unused or replaceable test equipment (please take a look at the for sale posting) in order to finance the new, calibrated test gear. Next up on my purchase list is a Rigol DSA815TG spectrum analyzer (just reviewed favorably in the February 2013 QST), but that's going to require the sale of everything on that page!

Finally, I've got the CC1 prototype PCBs on their way from Seeed Studio right now. It looks like they just cleared customs in the US, so hopefully they will be in my hands in the next few days. With any luck, I'll have the first one built by the weekend and will be well on the way to a new beta test. I'll put up a quick post to show off the PCBs, and when the first prototype unit is completed. Stay tuned!

Homebrewing Hangout

As I mentioned in the previous post, I wanted to try the Google+ Hangouts feature to attempt to do a video chat version of the old EchoLink chat that some of us used to have a few years ago on Saturdays. Today we took it for a spin, and I think I really like how it shaped up. We ended up having a total of 12 participants, with about half of the people actively participating, including AK6L, OK4BX, W0EA, LA3PNA, and WG0AT (Steve the Goathiker).

I've never used the G+ Hangouts before, so I didn't really know what to expect, other than a video chat. It turns out that it's quite a bit more useful than that. For example, you can do screensharing with your PC desktop or a particular window. Tomas OK4BX came prepared with an excellent slideshow presentation of the DDS-driven MEPT that he and his father recently put on the air. W0EA was able to show us the schematic and PCB layout of the amplifier T/R switch that he just sent out for manufacturing. You are also able to switch between multiple cams while in the Hangout, which AK6L used to give us some nice closeups of his projects. I've got a USB microscope which is basically a webcam with a high-power lens, so it would work great for showing off close-ups of things as necessary. We also got a neat treat to a live view of WG0AT's goats Rooster and Peanut, courtesy of his iPhone connection to the Hangout.

The only potential downside that I could see when compared to EchoLink is the free-for-all format versus the way that EchoLink facilitates traditional roundtables. It wasn't really a problem for our group, but I was at a bit of a loss on how to handle moderation. In the future, I think we'll start off with a sign-up queue to speak, then end with a free-form chat. There's also no native list of callsigns to call upon, but using a Hangout plugin (Lower Third), you can add a caption to your video stream with your name and callsign just like a TV chyron.

The overall impression was that the hangout went better than expected. We had some really interesting information presented and the turnout was excellent for a first time. I think this definitely is superior to the EchoLink chat. Now that I have an idea of what's going on, it should run even smoother next time. If you are not already a member, go to our Google+ Community page (Ham Radio Homebrewing) and join. The next time there is a Hangout, you'll get an invitation. We've scheduled the next one for two weeks from today due to it being close to Christmas next weekend. I'm not sure if this will continue on a weekly or every other week schedule in the future, but we will continue these Hangouts on a regular schedule.

Community

OpenBeaconMini

I recently did quite a bit of pontificating about the diminished state of our online communities. It's easy enough to complain, but the real measure of devotion is actually taking positive actions to help move things along. In that spirit, I was inspired by the recent announcement of Google+ Communities (a development that's been sorely needed for a long time) to create a new group there called "Ham Radio Homebrewing".

The nice thing about G+ Communities is that is supports a better range of communication possibilities than a traditional listserv or forum can provide. Photos, videos, and links to interesting projects can be very easily shared, in an instantly accessible graphical format. G+ also has the "Hangouts" feature, which allows you to video conference with other members of the group. I envision this could be like a souped-up version of the EchoLink QRP chats, where we could show off projects to each other, in live video chat.

I'm also planning on using the Ham Radio Homebrewing group to organize a small group build of a simple Manhattan construction project based on the OpenBeacon MEPT kit. This little project will be called OpenBeaconMini, and will be a very simple QRSS/DFCW QRPp transmitter kit for the frequency of 14.140 MHz (and if the project goes well, a second run of the project for 3.852 MHz). Keep an eye on the Ham Radio Homebrewing group and this blog for further details as this progresses.

Inflection Point

Hello there. Yes, there is still life at this blog, although whether it is intelligent is still indeterminate. I feel awfully guilty about the lack of content for the blog in the last year, but I've been in a horrible time crunch since getting Etherkit off the ground. When it comes to making the choice between moving your small business forward so you can feed your family or writing a vanity blog post, I'm sure you know which will win pretty much every time. I have no intention for the blog to fade away, so I hope that you all will keep me in the feed reader so that when the time crunch eases up a bit, I can get back to blogging more often and can share some interesting stuff with you.

Anyway, on to the main point. For a fair bit of time now, I've had a vague impression that something was going a bit sour in the online QRP/homebrewer community. It never really surfaced consciously all that often, but I distinctly recall there being a general aura of discontent around my feelings about the state of the community. It has dawned on me that even though we have more communication channels available to us than ever before, we are becoming increasingly insular and fragmented, even within our own little sub-hobby. I don't think it's a coincidence that this has happened while our choices of online communication channels has exploded.

I'm going to attempt to put some substance to this impression, with the hope that if I'm right about it, that maybe I've planted a seed for a way forward in one of my readers. This is probably going to come across as a bit of an Airing of Grievances, but that is not the point of this post at all. I will give you supporting data for my point of view, but I also intend to take a critical look at myself as well, as I'm sure that I've also made plenty of my own mistakes.

I believe that I got my first wake-up call a few months ago, when I learned that one of the most esteemed members of our group, Wes W7ZOI was hanging it up on his online amateur radio technical activities. Not only that, but whatever his motivation for withdrawing, it was also strong enough to make him pull all of his previous content off the web. This hit me like a punch in the gut. Wes has always been a most gracious virtual Elmer to many of us out here. He always seemed eager to pass on his enormous breadth of knowedge to those who asked for help. I have no knowledge of what transpired to change his mind about our community. The only public clue seems to be this quotation left behind on what's left of his technical web page:

I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.

Whatever the catalyst was, Wes seems to be leaving us based on some negative experience. I can't begin to tell you how much this troubles me. People like Wes are an extremely rare treasure in any community, not to mention one as small as ours. I can't draw any firm conclusions based on the very limited information that we have, but it is not a good statement on the health of our community when such a luminary finds it worthwhile to withdraw, instead of continuing to engage.

The next data point I present is a blog post from John AE5X, published earlier this month. It's a succinct entry, so I suggest that you click over and read it for yourself. In the case that you don't, the Cliff's Notes version of the post is a reflection on the changes in the QRP community in the last decade. Some of the relevant ideas that I'd like to point out are:

QRP-L was alive with real content. People were talking about the latest kit they built and what they were doing with it. The QRP contests and events were well attended, providing further topics for discussion on QRP-L. Norcal 40A’s, SST’s, great rigs from Small Wonder Labs and Oak Hills Research could be heard, worked and talked about.

There was diversity among QRPers too – the hang-a-wire-in-a-tree gang and the QRP DXers all rubbed shoulders on QRP-L. As a result, all QRPers were exposed to various aspects of the 5-watt realm.

and

On the negative side, QRP-L is little more than a small circle of the same dozen people making 90% of the posts that occur there with the real meat of QRP technical discussion taking place on a specific rig’s dedicated YahooGroup. Ditto for the operational aspects of QRP: SOTA and IOTA have their own forums, leaving QRP-L relegated to sharing space in the dusty bins with newsgroups.

and

I am more thankful than I can describe at the exposure I received to ideas, techniques and equipment on the old QRP-L. That doesn’t happen anymore with the real brain power having been sucked away to specific forums.

John hits the nail on the head. I started being active in QRP a bit more a decade ago, right at the same time about which John is writing. And my memory is exactly the same as his. There was an excitement, vitality, and cross-pollination that made QRP-L nearly indispensable to both the QRP operator and the QRP homebrewer. QRP-L was pretty much the only game in town, at least on the online frontier. Today, it's a pale shadow of its former self. Nothing new is happening. Hardly any new blood is joining (or if they are, they are not speaking up). At least that was my last impression of it, because I rarely even look at it any more. I'm still subscribed to QRP-L (and a handful of other listservs), but I admit that I hardly even open up the Mailing List folder in my mail application any more. The amount of worthwhile content just doesn't seem worth it any more in exchange for the time spent sifting through the flame wars, pissing contests, and endlessly regurgitated arguments.

I don't mean to pick on QRP-L, but I think it's very illustrative of the issues we face. Almost all of the best and brightest has left, for one reason or another. And yes, people have been bemoaning the death of QRP-L for years. I bring it up because I think it's a leading indicator of the state of our online community. One of the most important statements in John's post is where he identifies the brain drain to all of the tiny little niche forums in our already-small sub-hobby. The QRP-L exodus happened in earnest years ago, but I think we are now starting to see the second order effects of this phenomena. We have scores of Yahoo Groups, forums, and social networks for our specific little area of interest within QRP or homebrewing or for our favorite rigs or vendors, but we don't come together under the larger banner of QRP any longer, in any way. I suspect that this gets us a bit locked in to our little corners of the 'net. I don't know about you, but I'm finding myself having an increasingly harder time managing all of my different communities of interest. Which tends to make me just throw my hands up and ignore large swathes of those communities at times.

This brings us to the new kid on the block: social media. The big dogs on the block are of course Facebook and Twitter, with smaller networks like Google+ also getting some play in the ham communities. I've never used Facebook for a variety of reasons, but I've been on Twitter for a few years now and did dabble in Google+ for a bit, so I can speak from experience on those two. The nice thing about the social media networks is that you do break free from that self-imposed ghetto mentioned above. Once you get a well established network, you tend to have connections to all kinds of different hams.

But that blessing can also be a curse. The reason for this is the different expectations that different hams tend to have with each other on these networks. A fair number of people expect that if you have a Twitter account with ham radio as your primary focus, you should only talk about ham radio. Likewise, I found that a number of hams on Google+ did not like it if you posted anything non-ham related to all of your "circles" ("circles" are your self-defined groupings for the people in your network). It's a fair point of view, but it isn't the one that I have subscribed to. I am person with different interests and I just don't have it in me to manage different social media accounts for each of my interests. Nor do I expect others to curate their output to cater to my desires.

The problem is that as much as I try to be tolerant of the diversity of other people's interests and ideas on the social networks, I'm not always successful. Admittedly, I unfollowed a few dozen Twitter accounts (not all hams, but definitely some) right after the last election due to either incessant gloating or whining. Probably not my finest moment, but I guess election fatigue got to me. On the flip side, while I don't think I have been a flaming partisan most of the time, I didn't leave my feed politics-free either. I have no doubt that I have annoyed my share of followers and drove them away due to my politics (especially since I'm a devotee of a political ideal that is not very popular).

My point in bringing this up is not to whine, but to contrast the social networks with the "old-school" communities such as QRP-L and web forums. It seems that you have two different extremes, neither of which lend themselves very well to the type of online QRP community which would be nice to have (at least in my view): knowledgeable, open, free-flowing, fun, and mostly on-topic but not on lockdown.

One other point I'd like to bring up that applies to all of us, regardless of what communication medium we use, is our etiquette. I'm sorry, I'm not trying to be a nanny, I know we're all grown adults. But I would also bet that the majority of us are on the left side of the bell curve when it comes to emotional intelligence (me included), which means that we are more apt to give and receive offense at times when we should not. For example, in my "career" in the QRP world, I can think of at least three different times when I've deeply offended very prominent people in the QRP world. And I can say that each time that I was notified of this offense, I was completely taken by surprise. Without getting into details, I've done and said some incredibly boneheaded things. Not because I was trying to troll the QRP stars, but just because I didn't think through the consequences of my words or actions, or didn't clearly enough communicate my intentions. Likewise, I've been wounded by the words of others, who meant no harm, but I didn't realize that until later. (We'll leave aside the issue of the intentional jerk, for whom this essay would mean nothing anyway)

All of this butthurt really damages our relations and breaks down the community, perhaps more than anything else. Again, I'm not trying to be your mommy, but I do ask that you sleep on the stridently-worded rebuttal to the post which offends you, or that you forgive the newbie question that might seem stupid or obvious. I don't know for certain, but there's a decent chance that something like this is what caused a number of our best QRPers to leave the online QRP world. Let's not shoot ourselves in the foot any longer, eh?

If, after I depart this vale, you ever remember me and have thought to please my ghost, forgive some sinner and wink your eye at some homely girl.

—H.L. Mencken

Why have I rambled on for so long about all of this? I'd like to see some of that old magic recaptured. When I designed the Willamette DC transceiver and organized the group build on the now-defunct qrp-l.org listserv, I had one of the best experiences of my ham career. I'd love to do something like that again. But I don't know where or how. I'm pretty sure that the current QRP-L would not be the place, and definitely not on a web forum like QRZ.com or eHam.com. I have the capacity to host my own forum (I could even stick it under my Etherkit forums), but it would be too insulated, as mentioned above. I have some ideas for some simpler group project builds that I'm itching to get out there, but I'm honestly at a loss of where to present them. I'd love to reach a wide audience of QRPers. Where would that be?

So if you're still around, you're probably thinking "wrap it up already!" OK, I appreciate that you had the fortitude to stick around to the end of this diatribe, so I'll get to the point. I think I've outlined an issue that needs to be addressed, but I don't have a solution. But I think I may know some elements that will be part of the solution. We need some common meeting ground like that has the same "melting pot" formula of the old QRP-L. With the withdrawal of some of our sharpest minds (and the loss of others as silent keys), we seem to be a bit adrift of leadership. The old guard is departing. Not that we need people trying to take charge and give orders. But we do need new thought leaders and innovators; people to inspire by example and by word.

I am quite fond of QRPARCI and all that they do for our community (especially QQ and FDIM), but I think it could also use a bit of a kick in the pants. A rejuvenation effort brought about via ARCI could be very effective, if done correctly. I'd hate to see it get stagnant and not take advantage of the great resource that it has: it's large number of QRPer members.

Hopefully I've given you some serious ideas to chew on, and with any luck, just might inspire one or two of you to make a positive change to help our community. I'm not one who will be any good in trying to rally others to a QRP renewal, but I hope that I can at least reach out to one who is.

Now on a much lighter note, my next blog post will be back to my normal fare! I'll give you a peek at the little group project idea that I've been working on. Who knows, maybe we can get this going somehow.

Mythbusters at The Tech

This year I made a quick trip to Pacificon (hopefully I'll have a full blog post about the trip later) but I managed to squeeze in a little time on Sunday to visit with my Mom and Stepdad, who drove down from the Sacramento area to spend a bit of time together. They took me to The Tech Museum of Innovation in downtown San Jose before dropping me off for my flight home. The museum was cool, but it reminded me of OMSI and seemed to be geared towards kids and the less tech-savvy. However, they had just opened up a special exhibit called Mythbusters: The Explosive Exhibition a day prior to our visit. It wasn't a huge exhibit, but it was obviously well thought-out and a ton of the actual props from the show were brought in for display, which are instantly recognizable to fans of the program. Most of it was interactive, and they even had a live stage show with audience participation. Given that M5 Industries is also in the Bay Area, it seems like a natural choice for The Tech to host this exhibit.

This was by far the best part of the day for me. I snapped some photos with my lousy phone camera, which are presented below. If you're a fan of the show and you are in the area, it's well worth your time to visit, and I think you can get admission separate from the main museum if you would like.

A Few Questions

Hello Dear Readers,

Sorry for the thin content on the blog once again. In the insufficient free time I have, I've been swamped with trying to keep OpenBeacon in stock and development of new products going. I've got a couple of questions for you, if you don't mind chiming in.

First, I tried asking a question similar to this on the KnightsQRSS mailing list, but it rapidly devolved into a flamefest and I never really got much good, constructive feedback. So I put it to you. I'm interested in putting an 80 meter version of OpenBeacon on the market. There doesn't appear to be much 80 meter activity in North America, but what there is seems to be located just above 3.500 MHz. The issue that I'm seeing is that choice of frequency excludes all American non-Extra Class hams. With 80 meters being such a large band, I don't see any reason why another frequency could not also be used. I'm proposing to put the 80 meter OpenBeacon on 3.582 MHz. If operation was kept between 3.581800 MHz and 3.582000 MHz, I don't believe it would interfere with any current informal band plans, but I'm not certain about that. I have a very large stock of 3.582 MHz crystals, which obviously also plays a factor (I would be willing to sell them individually to anyone who wanted the for their own homebrew endeavors). So my questions are: does this look like a decent frequency and is this something that would interest you?

The second query is in regard to a potential new product. I'm giving consideration to bringing to market a sort of companion receiver to the OpenBeacon. It could be used for a QRSS grabber or a dedicated monitor receiver for any of the digital modes with automatic propagation reporting such as WSPR, PSK31, or JT65A. I envision it being paired with a small SBC such as Raspberry Pi so that it could make a complete, stand-alone, efficient HF monitoring solution for around $100 total cost (Raspberry Pi currently costs $35). In my opinion, there is a lack of QRSS grabber stations in North America, and using OpenBeacon or other MEPT transmitters will be a lot more fun when there are more stations that can listen for your signal. If you use the receiver for the automatic reporting modes, you can build up a very nice set of data about propagation to your QTH. Here is a list of preliminary specs:

  • DDS or Si570/Si514 LO for wide tuning range and stability
  • Multiband
  • PC tuning and control via USB (similar to OpenBeacon)
  • Single-signal reception (probably filter method, but maybe phasing)
  • Line-level output for PC consumption

So I ask you: is this something you would be interested in? Is there anything feature-wise you would like to see included?

Thanks for letting me pick your brains. I hope you stop by in the comments and leave some feedback!

OpenBeacon Miscellany

WA4KBD OpenBeacon in enclosure

I've got a quick grab bag of OpenBeacon updates for your reading pleasure tonight.

First off is the wonderful find and awesome mechanical construction skills of WA4KBD. He posted a message on the Etherkit forum about an extruded aluminum enclosure that he found on eBay that works perfectly for OpenBeacon. He brought pushbutton S1 and the TX and FSK indicator LEDs out to the same panel as the connectors, leading to the cleanest and best build of an OpenBeacon that I've seen yet. Bill also reported much greater frequency stability once OpenBeacon was housed in the enclosure. FB Bill!

There is also some new OpenBeacon firmware available for testing to those who have the ability to in-system program AVR microcontrollers. This update will correct some minor bugs, including a bug in the msgdelay function in CW mode. Importantly, there is also the addition of CW ID mode in the non-CW modes to give better compliance with FCC Part 97 ID rules. All of the details can be found on the Etherkit blog.

Finally, due to some unexpected and unsolicited blowback that I received on the KnightsQRSS listserv regarding the suitability of crystal oscillators in QRSS applications, I decided to look into methods of increasing frequency stability for OpenBeacon. To that end, a crystal heater seemed like the best bet, but they don't seem to be manufactured anymore (at least to my knowledge). Some investigations let me to discover that one type of heater was simply a thermistor mounted to a metal clip which slipped over a HC-49 crystal. So a bit of research at Mouser led me to a candidate thermistor which gets to about 80°C when connected to 13.7 VDC. I've mounted it using epoxy (JB Weld, to be exact) to a heat sink (rumor is that it might be a coin...but that might be of questionable legality). Then the heat sink/thermistor combo was secured to the side of the crystal with 3/4" diameter heat shrink. I'm in the middle of running tests right now, but initial results look promising. If I have a winner, I'll post instructions on how you can build your own cheap crystal heater, and might even offer a "kitlet" for sale.

SSB In A Box

Unnamed SSB QRP Rig

For the first time in quite a while, I've taken a project from start to a complete finish in an enclosure. I wanted to have my prototype SSB QRP rig ready to take with me to Salmoncon, so I busted a move this weekend to tweak the last bits of the circuitry to my liking, build an enclosure, and get it properly mounted. You can see the results to the left. I have an assortment of Ten Tec enclosures on hand, but none of them were large enough to accommodate the bulky circuit board that I used, so I had to fabricate my own out of copper clad based on the WA4MNT instructions (such as AA7EE did with his wonderful CC-20 beta build). I would say that my mechanical construction skills are average at best, so it's not the nicest looking enclosure, but I guess it's OK for a first try (the perfectionist in me sees lots of flaws). The two-tone blue and grey doesn't look too bad from a distance. Regardless of the aesthetics, the final enclosure is quite sturdy and will work well to keep the radio safe.

SSB Rig Guts

Here to the right, you can see the insides of the radio (sorry for the crummy photo, it was taken with my phone). The mainboard is the one laying horizontally and filling most of the room in the enclosure. To the left of the mainboard is the microcontroller/DDS board, standing vertically. Crammed in right in front of that, is the 4-digit LED frequency display and all of the other controls. Unseen and in the top cover, is a 1 watt, 8 ohm speaker. The LM380 AF amplifier can easily drive it to room-filling audio.

Here are some preliminary specs so you can get some idea of the performance:

  • Tuning range: 14.000 to 14.350 MHz (DDS)
  • IF BW: 2.3 kHz (3 dB), 6 crystal ladder filter
  • Current consumption: ~150 mA RX (not optimized for current yet)
  • TX Power: ~8 watts @ +13.7 VDC
  • MDS, IP3, etc.: not measured yet, see below

I haven't measured any of the important RX specifications yet, but I'll give you some subjective operating impressions. Compared to my IC-718, the sensitivity is very close. Maybe a few dB down but not much. Noise seems pretty good, a bit better than the IC-718. A rough guess of dynamic range and intermod distortion is that it is decent as well. Haven't heard much in the way of distortion products or "crunching" in the pileups that I've tuned through. There's no AGC, so you can listen to some pretty weak DX signals, then have the local guy replying really blast through but sound relatively clean. Since the architecture is based on ADE-1 mixers and low-noise MMIC IF amplifiers, it's what you would expect. There's no preamp, but that doesn't seem to be much of a handicap on 20 meters. In fact, I think it would probably be counterproductive, especially since you probably aren't working any stations that far into the mud that you need a preamp to hear them.

As I previously alluded to, my mechanical skills are a bit suspect at times, so I needed to have a test QSO with the radio once it was all buttoned up to make sure that it was working correctly. So I did a bit of tuning around at about 9 PM local and heard K2L, the South Carolina station for the Original 13 Colonies special event station, thumping my speaker off at well over S9. He was working stations at an easy clip with fairly short exchanges, so it was perfect for a quick test. I snagged him on the first call with an honest 59 report (at least I think it was honest...I heard him giving other stations lower reports so I assume I was really a 59) with approximately 8 watts PEP into my ZS6BKW at 30 feet. Mission accomplished!

It will be fun to take this rig to Salmoncon for some camping portable operation. I've never attended a Salmoncon before, but I think any of the attendees can use the special K7S callsign, so maybe I can do some CQing on 20 meters SSB with the short call and attract some stations. We won't be up there until Friday evening, so I think we'll miss the SOTA runs, but hopefully I can also get the radio out to a SOTA peak near here when I return. It might be too ambitious, but before Salmoncon I would also like to finish a 40 meter CW rig based on my Clackamas design that I entered into the 2010 FDIM contest. We'll see if I can actually pull that off.

Stay tuned for more news on Salmoncon as it gets closer and hopefully I can get a video of the SSB rig on YouTube so that you can see it in action for yourself soon.