Tag Archives: CC1

Wideband Transmission #1

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This is the first in a series of blog posts covering a wide variety of topics. In the past, I have used Twitter for my microblogging needs. For a variety of reasons, I'm on a Twitter hiatus right now, so I'll be using this series to convey some of the disconnected (and possibly connected) random thoughts that I feel I need to get out there. I don't think I'll be abandoning Twitter completely, but I will be reworking the ways in which I use it once I come back.

I'm also in the process of disconnecting completely from Google, so I wanted to give fair warning to those who correspond with me via my Gmail account that I will be abandoning that service very soon. I've already deleted my Google+ profile, and will be deactivating the rest shortly. I'll probably describe my rationale for this later, but keep in mind that I've been a Google customer data mine for nearly a decade, so this is not something that I undertake lightly. I'll try to get alternate contact information to those of you who regularly correspond with me.

It is an age of new beginnings.

Clackamas 2 Prototype

With the introduction out of the way, let's get down to the good stuff. Above, you can see the latest project on the Etherkit bench. It's a re-work of the receiver from the Clackamas transceiver (the rig that I submitted to the 2010 FDIM 72-part challenge). I've decided to make this receiver into a cheap & cheerful little kit to get people warmed up for building the CC1. It's currently for 40 meters only, is a superhet, and is VXO tuned (covers 7.030 MHz plus a bit more). It is 100% discrete component (you can see a TDA7052 IC above, but I've abandoned it for a different AF amp) and will be SMT construction. The receiver itself is pretty simple, but you can see there's a fair bit of other circuitry on there. That stuff is mute and sidetone circuits. It's easy enough to design a standalone receiver, but most of them will probably just gather dust after being built unless they can interface to a transmitter easily. With this extra circuitry, you can just split off your transmitter's key line and connect it to this receiver to have built-in muting and sidetone. My goal is to make this project cheap and fun to build. I'll be fast-tracking this one so I can get back to the CC1 soon.

Oddly enough, another project from the FDIM Class of 2010 is also coming out soon. As spotted on The QRPer, the Cyclone 40 transceiver is based on the rig that Dave Cripe, NM0S submitted as his 2010 FDIM 72-part challenge entry. I recall that the rig had a very unique design and that the specs were impressive. Dave's a great designer, so be sure to buy one to get a rig unlike anything else you've seen before and to support 4SQRP.

Choking off the Internet firehose that I had previously directed at me has allowed me to devote a bit more time to enjoyable activities that I've neglected, one of those being reading. I'm currently enjoying a book I've had on my shelf for a while now called Seeing in the Dark by Timothy Ferris. It's billed about being about amateur astronomers, but it does get into the professional side quite a bit as well. It's a good read and very entertaining, and I can't help but see a lot of parallels between amateur radio and amateur astronomy.

That's a great segue to the final item, which is a bit of fun from our favorite Canuck astronaut, Cmdr Hadfield. He's leaving ISS in a few days and just released a surprisingly touching (although obviously light-hearted) rendition of Space Oddity by David Bowie (one of my guilty favorites). Cmdr Hadfield may not be on the level of Neil Armstrong or Yuri Gagarin, but he's definitely making a play for Coolest Astronaut Ever.

Stuff 'n Things

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As a mild winter turns into an unusually nice spring here in Beaverton (last week we had multiple days with clear skies and highs in the upper 70s °F), a young ham's thoughts turn to portable activations, Field Day, SOTA, and the like. I've been looking forward to this summer for the opportunity to take the CC1 out in the field, but I may not get to be quite as adventurous as I hoped. Last winter, I slipped in a wet patch on the concrete in the garage and hurt my knee. As a typical guy, I didn't go to the doctor to have it checked out, I decided to "walk it off". It did heal, but not completely. So I finally gave in and saw my doctor about it a few weeks ago. She strongly suspects a torn meniscus, and ordered an MRI to confirm it. Unsurprisingly, my insurance company denied coverage on the MRI, instead expecting me to do a bunch of physical therapy based on at best a guess on what the problem is. Coming from a technical background such as mine, this boggles my mind. When you have a problem and you have the tools to make a measurement, you make the measurement to see what's wrong, not just take a course of action based on a guess! I understand that money is the driving factor behind this decision, but it still seems like a waste of resources for both myself and the insurance company. Not to mention that I don't have the faith in the efficacy of physical therapy that consensus medicine does.

So now I have to decide whether to shell out beaucoup bucks on physical therapy that probably won't do anything other than siphon money from our family to their coffers. And if that fails to miraculously heal the non-specific "knee pain" referred to by the insurance company, then I guess I get the privilege of paying for the MRI that I should have had in the first place.

I'm completely fed up with politics, so I have no desire for a political battle in my comments. I'm quite aware of the history of employer-provided health insurance in the US, and the effect of government distortions in the medical marketplace. There's plenty of blame to be handed out all around, so let's just leave it at that.

Anyway, I may not get to do any SOTA summits this year (except for perhaps a super-easy one such as Cooper Mountain right on the outskirts of Beaverton), but hopefully I can at least get out with the CC1 for portable ops to the park or while camping.

Speaking of the CC1, it's at a bit of a lull in its development right now. I'm waiting for all of the beta builders to complete their construction so I can be sure that I have all of the major hardware bugs worked out (which looks tentatively promising right now). I still have quite a bit of firmware coding to work on, then I'll be ready for the next (and hopefully last) PCB spin. With any luck, that should come in about 8-10 weeks.

In the meantime, I want to work on some side projects, and perhaps some opportunities to raise more capital to fund CC1 development. In that regard, I've been looking at a neat part recently. It's a MEMS VCXO from SiTime called the SiT3808. What's cool about this part is that it has linear voltage tuning, so that you don't have the uneven tuning response like you would from a varactor-tuned VCXO. The phase noise on the spec sheet also looks very good. I ordered some samples for 7.030 MHz and 28.060 MHz and breadboarded them to test the frequency stability. It was nothing short of amazing. The 7.030 MHz part had a long term drift of 5 Hz in 1.5 hours. The 28.060 MHz part drifted only about 20 Hz in 2 hours. That's pretty spectacular for CW use.

Since the 28 MHz part was so stable, I created a QRP transmitter for it by adding on a keying circuit and a couple of BD139 amplifiers. It outputs a very clean and stable 2 watt signal and has a tuning range of about 20 kHz. I also was fairly easily able to create a TX offset circuit, so that the transmitter can be paired with a direct conversion receiver (which I plan to do soon). Since tuning is linear, the offset is the same anywhere in the tuning range, unlike a typical varactor-tuned crystal oscillator.

I've been thinking about a way to introduce these parts to the ham community, since I don't believe that I've seen them mentioned by any homebrewers or used in any kits. Last week on the qrp-tech listserv, K7QO proposed a group build of the venerable NE602/LM386 direct conversion receiver (this one from chapter 1 in Experimental Methods in RF Design). Since this design is so well known, it seems like a "remix" of this design using the SiT3808 as the local oscillator might be a fun way to spread the word about the product. I breadboarded a version with the 7.030 MHz SiT3808 sample, which you can see below (the SiT3808 is in the upper-right corner, and it obscured by the tuning pot wiring).

NE602/LM386 Prototype Receiver with SiT3808

NE602/LM386 Prototype Receiver with SiT3808

It works exactly as expected. Wide open band signals directly dumped down to baseband, and a nice, stable LO. This particular SiT3808 part number only tunes about 4 kHz, but I will be able to get parts with a greater tuning range. I'm consulting with SiTime right now about bulk pricing, and hopefully I'll be able to do a kit run of at least 100 of these bad boys in the near future. Let me know in the comments if this is something that may interest you.

So that's my big rant for the day. Stay tuned for further updates on all of these projects in the near future.

PJ2/K8ND

The Thrill of QRP DX

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Last night after the rest of the family was in bed, I was hacking on the CC1 firmware to add the BFO calibration routine so that I could get an accurate readout of my receive frequency. After successfully completing that task at the late hour of 0130, I decided to cruise 40 meters to see what was going on. Normally the best time for 40 meter DX at my QTH seems to be from about 0200 or so until sunrise, so I thought I might catch something.

Scanning below 7.030 MHz, I came across a very loud station. I figured it was somebody in CONUS, but decided to listen for an ID just in case. It actually turned out to be PJ2/K8ND in Curaçao. Not exactly rare DX, but it's still quite a ways from my QTH and it's a new one for me. So I figured I would take a crack at it with the CC1. Long story short, I set the CC1 in XIT mode and after an hour of trying, my 3 watt signal finally managed to crack the JA-wall. I was pretty excited! Not exactly a heroic snag in the annals of DXing, but it was a good one for me. My single HF antenna is a ZS6BKW only up about 30 feet, so busting a 40 meter pileup to a station 6000 km away made my night. My first DX contact on the CC1! Even better, I woke up to find that the FB op uploaded his log to LoTW immediately, and I've got +1 to my DXCC count.

QRP is fun!

CC1 #1

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A brief post to show you the CC1 prototype, now inside of its aluminum enclosure. This is the actual enclosure that will be used for production, but I will have the end caps custom cut and silkscreened, so you won't have to do it yourself. Pardon my questionable metalworking skills, and please note the the production tuning knob will be different (a bit smaller so as to not interfere with the LEDs). At least this will give you some idea of what the final product will look like. The dimensions of the enclosure is 70 x 100 x 29 mm (or 2.75 x 3.93 x 1.14 inches). The first photo shows a size comparison with a standard deck of cards. The weight is 190 grams (6.7 oz).

After the latest circuit tweaks, everything is looking very good with this beta test. I will have more news for the beta testers in the near future. Exciting!

CC1-40 In Enclosure

CC1-40 In Enclosure

CC1-40 Front

CC1-40 Front

CC1-40 Rear

CC1-40 Rear

First RF

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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

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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!