Dave Richards AA7EE

October 23, 2011

A Cheap Yet Useful Capacitance Meter

I remember John AE5X blogging a while ago now about a cheap capacitance meter that read the capacitance values out in Morse code.  Some time later, on searching around online, I found a cool-looking and cheap meter  on Sparkfun. John blogged about this meter too. More recently, anticipating an upcoming need for such a device, I shopped around to see if I could find the one that SparkFun offers anywhere else. I found it for a little less money, so for $11 plus $5 shipping, a small bag of parts arrived in the mail from Amazon just a few days later.  I won’t show you what a small bag of parts looks like, as I’m sure you can visualize it yourself, but when I stuffed the parts in the board, here’s what it looked like:

I plugged it into a power supply (8 – 16V DC through a 2.1 x 5.5mm jack, which is a popular size) and well, there’s not much to say – it works. I tried a variety of different capacitors from a few pF to several hundred uF, and they all measured within their tolerances. The meter is auto-ranging, so all you do is plug the capacitor into the socket at the bottom-right of the board (the one marked J5) and read the value from the display. It will measure from 1pF to 500uF – a range that will encompass pretty much anything the home-brewer is likely to come across.

My motivation in getting this is my eventual desire to build a K2. The manual for the K2 recommends the use of a meter to check the cap values, and with a kit like that which has so many parts, I want to be armed in case any doubt exists as to the value of any particular capacitor.

In other news, Jason NT7S is putting in a lot of work solving issues with the first beta of the CC-series of kit transceivers and it looks like he has one of the major issues solved.  I’m very much looking forward to building another CC-series transceiver and then seeing as it becomes available to the public in kit form.  He’s aiming to put it on the market in January 2012.

Had a very enjoyable, yet all-too short QSO with KI6NTB Shin recently. Shin lives in Huntington Beach, CA because he’s a surfer and well, Huntington Beach is a very good place to live if you love to surf. Shin – it looks like you have a great life there – and living in a smaller community like Huntington Beach is definitely a great way to live in SoCal without living in the general sprawl that much of SoCal is.  Not that I dislike the general sprawl – I lived in LA for over 20 years and loved it. Shin reads  this blog – so hello Shin and thanks very much for the QSO.

October 18, 2011

A Trilogy With T32C – Thanks To The CC-20

Filed under: Amateur Radio,Ham Radio,QRP,Uncategorized — AA7EE @ 4:42 pm
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In the last post I reported that I had made contact with the T32C team on 40M with 4W from my Norcal 2N2/40, and also with 4W on 80M from my Tut80.  The goal was to make a contact with them on every band I have capability for here, which meant just one more band – 20M with the first beta version of Jason NT7s’ CC-20.  Last night I achieved that goal, and was surprised at how easy the mechanics of it was with this monoband QRP rig. What made it easy was Jason’s recent addition of XIT to the firmware. If you push and hold the tuning encoder in for half a second, on releasing it, you hear a morse code “R” in the headphones and the front panel LED lights, indicating that you are in RIT mode.  Holding it in for another half second gives you an “X” in the headphones, and the LED flashes, indicating that you are in XIT mode, giving you independent control over your transmit frequency.

Here’s where it gets neat. While in RIT or XIT mode, if you briefly depress and release the tuning button, you can listen on either your transmit or receive frequency, which is very useful for finding out where stations are calling during a split-frequency operation in XIT mode. Press the tuning knob once, and you hear an “R”, meaning that you’re listening on the receive frequency. Push it again and you hear a T, which means that you are now listening on the transmit frequency.  Also, while in RIT or XIT mode, pushing the FREQ/OK button (one of two front-panel pushbuttons) will trigger a readout of the frequency difference between your receive and transmit frequency in morse code. When operating normally, this button triggers a direct readout of the operating frequency. If you look at this new picture of my first beta version, you’ll see one addition; the front panel LED to indicate RIT/XIT mode. You’ll also notice that I forgot to install the screws on the side of the case for the photo. The screws have been off recently, as there have been several firmware updates while Jason fine-tunes the firmware:

It has been fun watching the CC-20 slowly take shape and for a compact and trail-friendly radio, I do believe this is about as full-featured as they come. This is not a final spec – that will have to come from Jason, but here’s a rough list:

*Rx current consumption ~ 40mA

*Tx output power 2W

*Full band coverage (14 – 14.35MHz) from a rock-solid DDS VFO with fast (100Hz) and slow (20Hz) tuning steps

*Readout of operating frequency in Morse code, also readout of difference between receive and transmit frequencies in RIT and XIT modes

*Readout of battery voltage in Morse code

*Built-in keyer with two programmable memories (I think this will be increased to 4 memories for the final production version)

*This kit will make extensive use of SMT devices.  Models available for 40, 30, 20 and 15.  Not sure if Jason’s planning an 80m version

* The board will come with the micro-controller installed and pre-loaded with the firmware, though the source code will be freely available for those who want to write and share their own code.

 

If I had a multi-band HF rig, I’d be gunning for a clean sweep with T32C on all HF bands on CW. The one band on which I’d really like to make contact with them on though is 160M. It would be a real challenge from this QTH.

As well as our current beta-testers Mikey WB8ICN, Paul K3PG, and Brian N1FIY, we will be welcoming John AE5X and two more beta testers for the second round of testing before the CC-series becomes available as a kit. Fun times!

September 24, 2011

The CC-20 First Beta Version

Phew.  I’ve finally finished the first CC-20 beta and fitted it into a case.  I can now sit back, look at it and listen to it! In this post a few weeks ago, I showed the unpopulated board with the connectors lying on a sheet of the red PCB material I was planning to use to fabricate an enclosure. By the way, the 6 pin connector you can see at the bottom of the board in the center in the photo in that post is one thing that makes this rig different from many others. It is marked ICSP, which stands for “In-Circuit Serial Programming”.  Etherkit bills itself as an open-source amateur radio company and the hope is that code-minded amateurs will write their own code for this rig if they feel they can add features, or improve on the code that the micro-controller in the kit will come programmed with. If you don’t write code, by the time the kit is available to the general public, the stock code will be solid, so no need to worry if, like me, you’re the type of person who needs others to write your programs for you. I did build a USBtinyISP so that I could flash the firmware on my beta though – the beta kit was shipped to the testers with a version of firmware that is not the final version.

Before we go any further, just in case you’re wondering what the CC-20 is, it’s the first transceiver in what will be known as the CC-series, designed by Jason NT7S.  These are a series of monoband trail-friendly QRP CW transceivers with a DDS VFO, superhet receiver with 3 pole crystal filter, and TX that puts out about 2W.  The kit makes copious use of SMT devices. If you’re good at soldering, have reasonable eyesight and a steady hand, you should be able to assemble this kit, but I wouldn’t recommend attempting it if you have never soldered SMT parts before – it would be best to get your practice on a smaller and easier kit (I built 2 KD1JV Digital Dials, which also uses SMT devices, but is a much simpler project, taking less time to complete).

In that previous post, you saw what the board looked like. Here’s what it looks like when fully populated with connectors and controls wired in. Bear in mind that the final board will be a little (though probably not much) different. This board has some blue wire jumpers that will not be present on the final board:

Of course, the first thing to do after completing the board was hook it up to a paddle, earbuds and antenna, and see if it would work.  The first QSO was with W7VXS in the Salmon Run.  I then rattled off 8 more Salmon Run QSO’s – looks like this little rig works! I also had a regular QSO with K1CTR in Denver, CO.

At some point afterwards (I think it was during an extended key-down period while tuning the TX) the finals overheated and fried. The production version will have a redesigned driver and finals and will most likely have an automatic dotting mode programmed into the firmware to prevent overheating of the BS170 final transistors.  For this version of the rig however, to help guard against this happening again, I epoxied a small chunk of aluminum to the new finals to act as a heat-sink.

Here’s the enclosure I fabricated from PCB material. The great thing about making enclosures this way is that you can make it to whatever size you need.  Finding ready-made enclosures to specific sizes can be a lengthy task that doesn’t always end in success but this way,  I got a case for the CC-20 sized exactly how I wanted it – a nice low-profile enclosure just a little over 1″ high:

The next image is of the CC-20 in it’s enclosure. You can’t see them, but I fitted 4 rubber feet to the bottom of the case. You can see where I accidentally drilled a hole in the side of the chassis, redrilled it in the correct place, and filled in the mistake hole with JB Weld. I did make a number of mistakes on this case from which I will learn if I make any more. I say “if” because making these PCB enclosures is quite time consuming and I’m feeling the strong urge to use ready-made enclosures for future projects:

On the front panel, from left to right, is the headphone jack,  the AF gain control, the CMD button, the FREQ/OK button, and the tuning encoder.  The tuning control tunes in either 100Hz or 20Hz steps, switchable by pressing the tuning knob. The CMD and FREQ/OK buttons are used to access much of the functionality of the rig,  functions which include:

– changing keyer speed

-selecting straight key or paddle

-recording to and playing back the keyer memories

-reading out supply voltage (in Morse code)

-reading out SWR (to be implemented later)

-reading out operating frequency to the nearest 100Hz

-reading out keyer speed

A lot of functionality is controlled from quite a minimal front panel:

What a cracking little radio:

Oh yes. One thing I almost forgot to mention is that after fitting the new finals, I called CQ on 14061 and was replied to by Steve the Goathiker WG0AT. Now that’s a good omen!

Mikey WB8ICN, Paul K3PG and Brian N1FIY are getting close to finishing their CC-20 betas, and I’m looking forward to comparing results. Mikey has already finished the receiver part of his, and our results are similar.  There are a few issues with the first beta that Jason will be working on to fine-tune. This, of course, is the whole purpose of beta-testing.  I was also thrilled to hear that John AE5X will be joining us for the second round of beta testing. I think we will also have one or two more beta testers joining us for the second round, but I’m not sure who they are.

In the meantime, I now have 20M capability and this little radio is fun to operate. Thanks Jason!

February 18, 2010

Baby Steps at AA7EE

No major moves forward at the AA7EE shack recently, just a few little ones.

I’ve been eyeing a fairly tall tree (50-60 feet) that is right at the edge of the apartment building next door.  It’s just a few feet over the property line, and overhangs the small back yard of my apartment building.  With the aid of a slingshot, I attempted to get a line over it some months ago, but this is a built-up urban area and I didn’t try too long or too hard with the slingshot.  It was my first time using one (whatever DID I spend my childhood doing?) and I didn’t want to accidentally put a 1oz lead sinker through a neighbor’s window, or worse, hit a passerby. My initial attempts failed, I stashed the slingshot away and continued to use the Buddistick vertical from my first floor balcony.

The thing about tall trees though is that if you’re a radio amateur, unless you own a tower, they’re near impossible to ignore. Yesterday afternoon I gave in.  I grabbed the slingshot, walked out onto my balcony, took aim, and the next thing I knew the lead sinker had arced over a branch and was hanging just a few feet above the ground on the other side of the tree. Bingo!  It wasn’t as high up as I wanted, but if I had aimed it higher it wouldn’t have made it through the dense foliage to the ground, and a heavier sinker wouldn’t have made it as high in the first place.  It’s a regular catch 22.

Long story short – with the aid of a reel of 26 gauge magnet wire, I now have an approximately 65-70 foot longwire antenna about 35 feet off the ground. The magnet wire will keep my antenna relatively stealthy (I hope). It’s still a pretty crummy location for an antenna, but at least I now have frequency agility with the aid of an LDG Z11 tuner and 4:1 balun.

In other news, I finally fitted a KD1JV Digital Dial to my Norcal 2N2:

This is a really worthy upgrade. The only other thing that this rig could use now is a small electronic keyer. Here’s another view in which you can see the 100 ohm resistor and 100uF electrolytic mounted at the power connector that serve to filter out the low level interference from the display multiplexer:

The 2N2 is an absolute pleasure to listen to.  The only commercial rig I have is an FT-817, and when I use that for the other HF bands, I cringe at the high level of noise generated by the receiver. The receiver noise in the 2N2 is much lower.  There is a clarity to signals heard on the 2N2; in comparison the FT-817 sounds noisy and mushy (it is a great jack of all trades radio though and has served me well).

I also started putting the Fort Tuthill 80 into a case.  A KD1JV Digital Dial should be arriving soon and will be fitted, along with decals (probably yellow, to contrast with the black, as inkjet printers won’t print white).  Here’s a view of the Tut80 without it’s top cover.  Imagine this with a digital frequency readout and yellow decals.  I think it’s going to look pretty sweet:

I’ll save the top view until I’ve tidied up the wiring inside a bit so stay tuned.  John AE5X is waiting on a Ten-Tec TPB-41 case to put his in, and I’m keen to see how he does with it in the ARRL International DX Contest this weekend (if the case arrives in time that is – if it doesn’t, how about a bit of bare board operating eh John?) While we’re talking about cases for the Tut80, Steve KB3SII has designed and is manufacturing a custom drilled and painted aluminum case for it.  Target price is under $35. Check the Tut80 Yahoo Group for more details.

I’ve been trying to get a QSO with the Tut80, but the electrical interference in the evening at this location is so bad on 80 that I can’t hear much without a noise blanker. Oh for a nice quiet radio QTH…….

In the meantime I’m searching for a new living situation. There are two main criteria – affordable rent, and the ability to string a longwire antenna to nearby tall trees. It’s time for me to experience the amateur bands with something more than a marginal antenna. I know that I could probably move away from the San Francisco Bay Area and buy (or rent) a little place on a big piece of land but, for the time being at least, I want to stay in this area. So if you know anyone with a cheap room or studio to rent in the Bay Area that would be amenable to a friendly and quiet QRP operator, send ’em my way!

January 11, 2010

Software Defined or Hardware Defined – Which Way to Go?

The main project going on in the AA7EE  “shack” (for which read “main room of my studio apartment”) has been, and will continue to be, the monumental task of committing my sizable collection of cassettes, CDs, DAT tapes and broadcast carts to backed up hard drives.  This is an ongoing project which I expect to take several years. Over the course of a 22 year career as a DJ, I amassed a lot of stuff that is becoming wieldy and expensive to lug around, so it’s time to start consolidating.

So whenever I’m listening to the radio or soldering something, I’m often also ripping a CD, scanning the artwork, or calling up my friend Antoinette and trying to give her as many of the CD’s that I just ripped as possible. I spent 22 years accumulating stuff (opens in a new browser window) and I now want a good portion of it gone (thanks Antoinette!)

All that aside, the amateur radio goings-on here have included building a neat little direct conversion receiver for 40M – the VRX-1 designed by NT7S and sold by the 4SQRP club. It’s a cool little DC receiver.  I’ve been having a bit of a problem with the input bandpass filter, so it’s on the back burner for a while, but it’s been a fun Manhattan building experience:

NT7S’ fun DC receiver got me all charged up.  The first successful TX/RX I ever built was an 80M DSB TX/RX designed by G4JST and G3WPO and published in the UK magazine “Ham Radio Today” in March 1983. It utilized a direct conversion receiver, to which I added an audio filter built from a 741 op-amp.  It was my first experience with DC receivers, and I remember being surprised that such a simple receiver could sound so good. Jason’s VRX-1 re-introduced me to the pleasures of DC receivers, as well as the technique of Manhattan construction (my first time), so by the time I’d finished construction, I was all primed up and ready to swoon at any direct conversion receiver that might flit it’s tail feathers at me.

John AE5X’s post couldn’t have come at a better time. Allow me to repost this picture of the 80M direct conversion TX/RX that the Arizona ScQRPions will be providing a kit for very soon:

The details are here. I was beyond excited when I found about this (thanks John).

I have a mental list of several different QRP rigs that I want to build, among them the Weber Dual Bander, and either the Elecraft K1 or K2. However……SDR has been on my mind too recently.  I built the SoftRock Lite II for 40M a few months ago and was impressed with the performance for such a simple piece of hardware, and low price too.  Of course, the simplicity of the hardware and the low price is a bit misleading because the signal processing is all done in software.  This is the beauty of SDR though – if a better demodulator or filter is available, you just download it.

I’ve been using the SoftRock to monitor the CW portion of 40M, and then once I see a signal, I can work him on the main rig, which is currently a Norcal 2N2/40.  Yesterday, I built a combined switch and dummy load into an Altoids-type tin so I can easily accomplish switching the antenna between the SoftRock and the 2N2/40.  The 2N2/40 is a cracking little rig – a sensitive low-noise receiver with a stable VFO (after the intial warm-up period).  It has a nice narrow crystal filter too which is great for working people, but not as convenient when you’re trying to find stations to work.

So….what I do is use the SoftRock to look at a wide portion of the band.  With my soundcard, I can look at a 96KHz-wide slice of the band on my screen, and the minute I see a station, flip over to the 2N2/40 and work him. It works well but it got me to thinking – why switch over to a traditional radio to work a station that I find with SDR? Why not just get an SDR transceiver and avoid having to switch over to a hardware defined radio?

Hardly original thinking.  I’m sure it’s the same thought process that has led many an amateur to adopt an SDR rig as their main station radio. FlexRadio are about to introduce their Flex-1500, which is a 5 watt all HF band SDR transceiver.

Mighty tempting and with my limited amateur radio budget, I’m now wondering whether to continue building all the QRP transceiver kits I’ve had my eye on, whether to build the SoftRock v6.3 HF TX/RX, or whether to go for broke and get the Flex-1500 when it comes out.

In the meantime, I have a KD1JV Digital dial on order, which will turn the Norcal 2N2/40 into an even more usable little radio.

Oh, and I have 1,000’s of CD’s to rip and perform hi-res artwork scans.  It’s not as if I’ll be sitting here twiddling my thumbs.

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