Saturday, September 21, 2013

Emtech - ZM-2 ATU Build

As you have probably figured out for yourself, I have finally gotten a chance to post my build pictures for the last couple of projects.  This topic of tonight's post is the Emtech ZM-2 QRP antenna tuner.

This is a "Z" match tuner,  basically meaning that it has two variable capacitors with no tapped inductor coil.  It does however have a neat built-in 1W dummy load and SWR sensing circuit.

From their website:

"ZM-2 ATU (Antenna Tuning Unit) - Order The ZM-2 is a state of the art Antenna Tuning Unit. It is not just another standard tuner circuit repackaged. The ZM-2 has no inductance switching to mess with, just two variable capacitors to tune. And most times that is 1 to 1 SWR where other tuners only get close.

Just What Will It Tune?

The ZM-2 tunes wire antennas: Random, Long, Short, "that's all I had"... It tunes BALANCED fed antennas such as Loops, Deltas, Dipoles, Verticals, V's! From field reports it has tuned: House Gutters, Window Frames, Swing Sets, Bedsprings, etc. It tunes out mismatch in COAX fed antennas to make the radio happy.

Is It An AutoTuner?

No, the ZM-2 is not an autotuner. But it still tunes fast! Approximate tune time on a strange new antenna is less than a minute!

What Bands Will It Tune?

The ZM-2 will tune all bands from 80 to 10 meters.

Is It Hard To Build?

An evening project for many, maybe two evenings for others. Easy pictorial assembly instructions. 

There is one large toroid to wind, and one small one to wind, but they are probably some of the easiest ones you'll ever do.

What Is Included In The Kit?

Everything but the elbow grease, solder, and tools! All parts are furnished including a front panel label as shown and either BNC or UHF (SO239) connectors. We include large knobs to help tuning because the ZM-2 tunes so sharp.

How Much Power Will It Handle?

Maximum Power is 15 Watts.

What About Weight And Size?

The ZM-2 is a compact 5-1/16" x 2-5/8" x 1-5/8" and weighs only 8 oz. Great for backpacking."

So, on to the build:

The kit comes with a Radio Shack style project box with a pre-punched aluminum plate, which through me off at first, but it turns out pretty nice.  The components are bagged for easy identification.

The part that will give some people heartburn is that you have to wind some toroids, and one has a lot of taps which makes it a bit tricky.  However, I was able to do it have never wound one before in my life.  And if I can do it, believe me, so can you!

There are two toroids with this kit, the one pictured below, and another smaller one that I didn't get a build picture of.  It was far simpler than this one even if a bit smaller.  The included instructions walk you through it step by step, although I think that it would have been much easier had it been a color picture.

Here is a picture of the second toroid already in place in the kit.  Not much to it as you can see.

There are no PCBs in this kit to worry about, it is all "point-to-point style".  Which means that you connect the lead of one part to the lead of the next one directly.  It can get cluttered, but it works.


More pictures of the assembly.

Different angle of the BNC side of the kit.

And a different angle of the balanced line side.

The front of the tuner is covered with a paper label.  I was fairly disappointed with it to be frank.  It is a typical Avery mailing type label.  Normal paper, not laminated.  The instructions suggest a layer of clear lacquer, but how many folks have that laying about?  I ended up using two layers of clear packing tape and it turned out fairly well.  In any case, you need to be REALLY careful when tightening up the components that you don't twist the paper.

But it looks pretty good when you get it completed.

And, just for a size comparison, here is a picture of it next to my Pixie and RockMite-40 radios.  Consider the pictures of my wife and Grandmother in the background a familial bonus and just ignore the clutter on the rest of the desk.  ;-)

The kit is fairly easy to construct, even for the novice.  It is a bit different due to the whole "point-to-point" style technique used, but it turns out alright if you keep a close eye on what goes where and making sure that there are no shorted out leads.

I connected it to my G5RV and was able to get a match on 7.040MHz with the RockMite-40 in just a few minutes.  Just like any tuner, tune for max noise first, being sure to check each of the three added capacitance settings (there are only three options with this one, +0pF, +250pF, +500pF).  After you have max noise, switch into tune mode and key up with low power and tune the two capacitors until the LED gets dim or goes out.  Be careful as the tuning is sharp and the LED might only blink briefly if you twist the knobs too fast.  Once you have the dip, switch back to operate and have at it!

It also worked great on a EFHW on 40m with my FT-817ND, which is a feat as these types of antennas can be a challenge to some tuners.  I was also able to load that wire up on 15m (of course) and 20m as well.  
In summation, it is a fun kit to put together and a nice break from more traditional kits.  Don't be afraid of winding toroids, they are not that bad.  For $65 you can't beat it for price and it works a treat.


Richard, KK4JDO


Special thanks for Steve, WB6TNL, for giving me a better understanding of how this circuit works and correcting my errors on build terminology!  Here is a copy of his extraordinarily helpful email:

"Hello Richard,

I checked out your blog and the photographs of your ZM-2.  Nice work on the tuner and the photography.  I'm certain there are plenty of QRPers out there who have wanted to see just what's inside the ZM-2 and your well illuminated and close-up photographs certainly do that.

There are a couple of nits I'd like to pick, however:

You said that a Z-Match tuner basically means that it has two variable capacitors with no inductor coil.  It does have an inductor; that is what the larger of the 2 toroidal coils is for.  More accurately, the primary, resonant winding of the Z-match inductor does not have multiple, switched taps hence it requires no switching to select bands.  The central theory it is based upon is that of the old "multi-band tuner" circuit (which was not an antenna tuner) made popular back in the 1950s and 60s.  Back then, multi-band tuners were very often used in mobile tube-type transmitters for interstage tuning and final amplifier plate matching networks.  The reason that no band-switching is required is that the ganged, 2-section tuning capacitor and the main coil winding are selected so that the resonant point of the circuit only hits one ham band for a particular setting of the tuning dial.  The larger winding resonates on the lower frequencies and the smaller winding the higher.  Impedance matching is performed by the switched input variable and fixed capacitors.

You described the construction as "dead bug".  Actually, that method of wiring is called "point-to-point".  "Dead bug" commonly refers to construction using integrated circuits (and sometimes transistors) where the components are glued to a substrate with the leads (legs) pointing up, like a dead bug.

Actually, tuners and QRP mix very well since it is extremely important for us to get maximum power into the ether and matching the transmitter to the antenna system is paramount.  Sure, some tuners are not as efficient as others but the Z-Match is not one of them, provided that the impedance of the antenna system falls within its transformation ("matching") range (typically 30 to 500 Ohms depending upon the load reactance).

Anyway, thanks for sharing the great blog page and best of luck with your tuner.

73.......Steve Smith WB6TNL
           "Snort Rosin"

Friday, September 20, 2013

Small Wonders Labs - Rockmite-40 Build

Since I posted about my Radi0Kit-140 build-out yesterday, I figured that I would post pictures of my Rockmite-40 build today.   For those not familiar with the RM-40, it is another QRPp CW only radio.  It is crystal controller (in this case, the crystal is for 7.030MHz) hence the name RockMite.  Again, being a QRPp radio means that it puts out less than one watt.  In the case of this radio, about 750mW.

Unlike the Pixie, this transceiver has a sidetone so that you can hear your code as you send it, as well as an adjustable transmit offset.  I decided to go ahead and get the connectors/controls option, PicoKeyer upgrade by Ham Gadgets, and a MityBox by American Morse Equipment at the same time that I ordered the kit.

About the transceiver kit from SWL's website:

"The Rock-Mite is a crystal-controlled direct-conversion transceiver available for 80M, 40M, 30M or 20M.   It features an on-board 8-pin PIC microcontroller which controls a T-R offset on key-down. A brief tap of a pushbutton control switch reverses the offset to yield a second operating frequency. Pushing and holding on the pushbutton activates the speed adjustment routine for the built-in Iambic keyer. If you'd rather use an external keyer or straight key, there's a 'drop-through' mode which allows use of an external keying source.

You'll note in the image above that the Rock-Mite uses two crystals. The first is used in the local oscillator for transmitter and receiver. The second is used as a receiver front-end filter. This crystal significantly reduces the SWBC energy present at the receiver mixer; as a result, unwanted SWBC reception is dramatically reduced.

The Rock-mite uses one surface-mount part with fairly large spacing. There are no toroids to wind, so assembly should be a snap! The Rock-Mite uses subminiature epoxy-encapsulated RF chokes instead of toroids."

About the PicoKeyer from their website:

"Here are the main features of the PicoKeyer-RM:
  • Low current operation - typical sleep current well under .1µA, only 1-2mA when keying.
  • Direct replacement for your Rock-Mite's or Hi-Mite's original keyer chip, no modification to your Rock/HiMite is needed.
  • Simple one-button "menu" interface
  • Setup and message entry using your paddle
  • Speed adjustable from 5 to 45WPM from the paddle - or add an optional speed control pot!
  • Variable pitch audio sidetone
  • Adjustable weight
  • Selectable Iambic Mode A, Mode B, Ultimatic, semi-automatic "bug" or straight key operation
  • Automatic straight key detection. Both message memories are available for playback even with a straight key! (You will need a paddle to record messages, though.)
  • Beacon mode! No switch or jumper required for beacon mode, just insert a special prosign character into your message. Great for calling CQ!
  • Message pause with auto-resume - You can insert a pause to manually send RST or other information in the middle of a saved message.
  • Auto-incrementing, resettable QSO/serial number can be inserted into your messages for contests. Send them with or without cut numbers (0 and 9 only) and leading zeros!
  • Greatly improved tuneup mode for hands-free steady carrier or 50% duty cycle pulsing.
  • Two message memories hold up to 100 characters each. Message memories can be chained to make one 199-character memory.
  • Paddle switching - effortlessly select left or right handed operation without switching wires or turning the key upside down.
  • All settings and message memory is maintained in non-volatile memory, even with power off.
  • "Factory Reset" option to restore all default settings to your PicoKeyer-RM.

The PicoKeyer-RM uses FLASH and EEPROM memory to store all settings and message memory, meaning NO backup batteries and NO lost settings."

And finally, about the Mity Box, from their website:

"Custom CAD/CAM engineered CNC hogout enclosure for the Small Wonder Labs Rock Mite transceivers
  • CNC machined from Aircraft Aluminum billet
  • Designed specifically around the Rock Mite boards
  • Absolute minumum size & weight - 2.2x3.3x.875 inch, under 2 ounces
  • Beautiful Blue Anodized finish - very durable
  • Uses standard miniature off-board components
  • Pre-drilled for all components - board & cover hardware included"

And now, for the build-out:

This first thing that I added was the one surface mount IC.  I keep reading about how easy it was, but it was a serious pain in the butt for me.  To the extent that I had to touch it up after completion of the kit due to a bad solder joint.  But I finally got it!

Adding the IC and some capacitors

Adding the resistors

Adding the sockets for the non-surface mount ICs.

Adding the diodes

Adding more diodes since I forgot some...

Adding the RF chokes

Adding the transistors and some more capacitors

Adding even more capacitors

Adding the crystals

And finally, after adding the ground connections for the crystals, Finished!

Unlike the last post I was so excited that I didn't get any video of the initial smoke testing and subsequent irritation as I tracked down the bad solder joint on the surface mount IC.  I have only minimal test equipment, by which I mean I have one off-brand multi-meter and an off-brand capacitor tester.  But the build documentation is absolutely stellar with this kit, TO INCLUDE a really great troubleshooting section.  It walked me through the testing and verification step-by-step until I had a working radio!

Another great resource is the builder community for the RockMites and Minimilist QRP Radios in Yahoo Groups.  I can't say enough good things about the guys and gals on that email reflector.  Great bunch of folks that are always willing to lend a hand with building tips and troubleshooting ideas.

All-in-all this is an amazing radio, especially for the price!  With the connectors/controls, upgraded keyer chip, and enclosure, I am in for about $77 not including shipping.  For that price you get a radio with tons of upgrade potential, a top notch case, and more fun than you can shake a stick at!  Build-out can be completed in an evening (although it took me about three).  The soldering is a little more challenging than the Pixie, but very doable with a little patience.

The receive on this radio is really good, way better than the Pixie in my last post.  It is much less sensitive to BCI overloading, though not immune, due to the crystal acting as a filter on the front-end.  The only downside that I could find was that it is sensitive to microphonics.  If you tap the case you can hear that tapping in your headphones.

The Mity Box case makes for a really nice and sturdy package for the radio, but be forewarned, it is TIGHT in there.  Plan ahead as much as possible when you are ready for final assembly.

To close out this lengthy post, I really do recommend that you get this kit if you are looking for a fun project.


Richard, KK4JDO

Thursday, September 19, 2013

Radi0Kit-140 QRPp Rig Build

I was browsing eBay the other day and discovered a Pixie variant that I had not played with before.  On a whim I sent the seller an email asking if he would send me a sample to review for my blog.  Yiannis from radi0shop was kind enough to send me one of his Radi0Kit-140 kits free of charge!  He shipped it promptly and was very easy to deal with.  I highly recommend his product if you are into small done-in-one kits!

Here is a link to his eBay store:

He is shipping from Greece, so allow some time for his shipment to reach you as international post takes a while.

For those not familiar, the Pixie transceiver and its variants, are CW only QRPp radios.  Being QRPp, they transmit less than one watt (usually 500mW-750mW).

Form their website:

"The kit is based on the famous Pixie transceiver introduced many years ago. The design was improved over the years and still catches the interest of many radio amateurs over the world due to it's simplicity, satisfying performance and ease of construction.
The kit isvery simple to construct even for the novice kit builder.
RadiØKit-1 incorporates additions and improvements. The circuit board is constructed by FR-4 material, the placement of the components is silk screened on the top side. All the copper traces on the bottom side are solder masked to prevent short circuits and accidental bridging between conductors. All component holes are already drilled. There are also four drilled holes for placing the board inside a box using appropriate screws and spacers.
A crystal is used at the oscillator circuit in order to achive the best possible stability.
The components that are used for RadiØKit-1 are of the highest quality. All the resistors are metal film 1% type. The capacitors are of the MLCC type except for the electrolytic ones that are mini sized 85°C types. The inductors used are resistor type and provide high performance and minimum space usage. The famous 2N2222A and 2N2219 transistors are used in order to achieve a little bit more output power.

DC voltage is supplied by a 9 Volt battery or a power supply 9-12V (not included) and the output RF power produced can reach or exceed 300mW depending on the voltage applied. You only need to connect the battery, a Morse key, an earphone or small speaker and an appropriate antenna to have a fully working ham radio transceiver. RadiØKit-1 comes in two flavours. One for the 80M CW radio amateur (RadiØKit-180) band, one for the 40M band (RadiØKit-140) and one for the 20M band (RadiØKit-120).
This is Radi0Kit-140 designed to work on the 40M band. You have to solder the components on the board. All the components supplied are shown in the photo above. Detailed theory of operation, construction details, parts list, schematics and resistor, capacitor and inductors identification instructions are provided inside the printed owners manual accompanying the kit. 

We use "registered signed for" post services for all our items in order to insure the best services to you. Will post same or next working day of payment. We would be happy to combine postage for multiple items in order to reduce P&P cost please email us after you place your order.
In case you decide not to keep the item you may return it within 14 days of receiving it, inside it's original packaging and at it's original condition for a full refund excluding shipping costs.
All items are covered by 2 years warranty. You may return them for repair under warranty to us, you only pay the shipping cost both ways. In case of DOA (you have to report it within 14 days after receiving the item) we will cover all costs for sending you another item and for returning the faulty item to us."

Now, for the build-out....

The packaging consisted of a sturdy padded envelope with the folded instructions and a small jewelry type box inside that contains the kit.  It made the trip from Greece to central Florida in fine fashion.

The board itself is quite nice for a novice builder.  The holes are nicely spaced.  The only complaint that I would have if I had to dig deep is that the holes are only plated on one side.  But it isn't a major concern.

The instructions walk you through the process nicely as well as explaining things like resistor colors code.  As far as component fit goes, the only issue that I encounted was the R4 resistor holes being a little too close together, but again, not a major issue.

As you can see, it is a low part count kit that goes together very fast.  The only part that would be challenging for a beginner is soldering the IC socket.  But at least it is a socket and you don't have to worry about burning up a chip.

As you can see below, the spacing is nice and it is really easy to solder, even for a ham handed guy like me (pun fully intended, even if painful).

The radio runs off of a simple 9V battery making it a really nice "get up and go" rig.  The picture below is during final "smoke testing"

Here is a quick video of the testing.  You can clearly hear the CW, and you can just as clearly hear the BCI interference as well.  In this kit's defense, it was 40m in the evening in central Florida, so BCI is a fact of life.

I ended up putting it into an aluminum project box and adding a few options:

  • Ability to have an internal battery and an external power source
  • An on/off switch with volume control (I had intended on adding an LM386 audio amp, but didn't get around to it)
  • An internal/external power switch
  • An on/off LED indicator
  • Jacks for headphones and key in front with external power and SO-239 in the rear

All-in-all this made a really nice and fun little one evening project.  I found it to have a capable receiver, although it is wide as a barn door and really subject to overloading by broadcast stations.  I think that adding a filter crystal to the front-end might help that a bit.  On transmit it puts out about 500mW according to my NCG2050 power meter which admittedly isn't made for such low power verification.

In summation, if you're looking for a fast and easy first-time project, you could do worse than to get this little guy!  I ended up passing it on as a gift to a ham that was trying to get back into the hobby and find things to do with his son after losing all his gear due to some life problems.


Richard, KK4JDO

Tuesday, September 17, 2013

Behold the awesomeness that is to be my 160m dipole...

This is a paraphrase/enhancement of a cross-post that I made to Reddit.  I'm putting up a ladder-line fed 160m dipole in the near future.  I forgot the insulators when taking the picture...

I should be able to get it up to around 60' in the trees that I have available. It won't be perfectly straight so it will favor the southeast a bit (watch out Caribbean, I'm coming for you!), but it should be better than what I have right now. Here is the planned layout as of right now.

After working it out in EZNEC it doesn't look as if the slight jog will throw off the pattern that much. It's still basically an NVIS antenna at the design frequency. Or to say it another way, I don't have any 260' trees to make it act like it would at a half-wave up.

At 1.8MHz it is definitely an NVIS antenna:

At 3.8MHz it is starting to look a little better, but kinda looks like a tumor (this is the favoring of the SE that I mentioned above):

At 7.2MHz it is starting to look more like a traditional dipole over real ground:

Once you get up to 14.2MHz you start seeing some weirdness:

To be honest, the main goal is for this to be a multiband doublet that just happens to be cut for 160m. I'm okay with NVIS on 160 for now. If I really start getting into it I might try an inverted-L or a vertical at some point in the future.  Several Redditors made that suggestion.

Total cost of the antenna is:

$47 for the wire at Home Depot
$50 for the spreaders and center support
$24 for the dacron rope at tractor supply
$06 for the insulators
$127 total

And I have enough wire left for a 40m end fed half wave for my Rockmite-40 with enough rope for hanging that as well. So I guess it was basically $127 for two antennas (plus the xformer parts for the efhw).  Not too shabby as one comment that I got so eloquently put it!  ;-)


Richard, KK4JDO

Sunday, September 15, 2013

More mesh cross-posts

I am a visual person, so I built a quick diagram of how I visualize a mesh deployment. I have most of these parts already, with the notable exception of the two additional routers, three additional cameras, and additional ATAs.

 What does everyone think of this with specific regards to EmComm?

One of the goals of this layout is to allow Incident Commanders, etc, to be able to communicate with disparate agencies via multiple radio systems on multiple frequencies on multiple bands all from any corded or cordless phone.  Additionally the option exists to listen to the police/fire/etc scanner from anywhere as well.

Scalability is an core design goal with this architecture with the only limiting factor in theory being the ability of the mesh to scale to lots of node.  In theory it will scale to >2000 nodes, but in practice I would be happy to see 500 supported (not that there will ever be a full mesh that size).  In the current deployment another limiting factor is the Raspberry Pi that I am using for the voice server.  If this were to grow much beyond the size above a larger voice server would be needed.


Richard, KK4JDO

Saturday, September 14, 2013

HSMM-MESH a.k.a. "Broadband-Hamnet"

Sorry that I haven't posted in a while.  Life has been very busy with shake-ups both personally and professionally.  Things are kind of in flux just now but hopefully I can get back to a semi-regular posting schedule.  For now though, here is a compilation of some posts that I've made to our local hsmm-mesh Facebook group.  For those wondering, you can learn more about hsmm-mesh here.

September 7 at 12:59pm
Got one of my additional routers in. A WRT54GL, got it flashed and a mini mesh created. Also got in touch with a rep from TerraWave/Tessco, a company that manufactures outdoor WiFI antennas and got them to commit to sending us some free antennas. Getting four or five omnis from them hopefully coming this week.

September 3 at 6:51pm
Just found these on eBay. Would really come in handy to powering a WRT54G that is co-located with the antenna!

September 10 at 8:27pm
So I still haven't seen the other two routers yet, but I've managed to find some time to work with the two that I have. I've gotten Asterisk running on the R-Pi correctly again (the flash card got corrupted by not shutting down properly) and have two extensions running using Cisco 7961 VoIP phones with a SIP image on them, running one phone per mesh node. I also have a Grandstream HT-286 ATA that I will throw into the mix as soon as another router gets here.

The process is fairly simple as far as the hsmm router configuration is concerned. All that is needed is to edit the /etc/dnsmasq.conf to make DSNMasq hand out the proper DHCP options. Simply add the following to that file:


Replace x.x.x.x with the proper IP addresses of course. Option 150 specifies the TFTP server that the phones will use to download their images and config files. Option 120 points out the SIP server itself, and option 42 points to an NTP server.

If using an R-Pi, keep in mind that it does not have an onboard RTC, so you will need to point to something that can provide the proper time (or use a script as a work-around to set the time on boot, but there are obvious drawbacks to doing that).

One thing that I did notice is that we will want to plan out our subnetting scheme. The method employed by the hsmm image is neat, but not extensible in a large mesh.

Now to find the time to look into how QoS is handled, as well as multicast traffic. Those two things are important on any WiFi network and especially so on a mesh where you lose half of your bandwidth with each RF hop.

I've included a picture showing the two mesh nodes on top of my workbench with the two phones under their respective node. Audio quality was excellent, which I would expect with the two routers less than two feet apart.

Hopefully Terrawave/Tessco will ship those antennas soon. I should have at least one to spare and will throw it and any additional up for grabs when it gets here.

September 11 at 11:10pm
I'm *still* waiting on the two additional routers and five antennas to arrive, but I've been able to get a little done while I'm waiting. It is frustrating only have an hour or so per night to work on this after the kids go to bed.

I've managed to get an additional two phones and a sidecar for the main phone. They are all set up to call each other, as well as some outside agencies. I even added a little personal touch to the phones.

The speed-dials listed as "RF TAC x" will be for extensions that connect to phonepatches via an ATA. This would enable incident commanders to be able to talk via a phone to multiple groups on different radio systems or frequencies. This is a homebrew version of the Cisco IPICS solution that is used by Cisco TACOPS on deployment. Obviously intended to be used only by licensed individuals unless during an actual life-safety emergency.

Currently it is receive only via the internet for the 147.120 stream as I don't have the phone patches built yet, and would need radios for them to connect to as well. But once the proof of concept is done the rest is just "wash-rinse-repeat", right?

I also have an IP camera with environmental sensors running via the mesh as well. This would enable remote observation of triage areas or supply distribution points. It isn't weatherproof, but is fairly sturdy.

My goal is to have deployable go-kits each with a mesh AP, phone, camera, and switch for data connectivity built and ready for the October installfest.

There are other posts, I will have to go back through it and grab some more.  I also have non-hsmm stuff to share.  I got the Rockmite-40 built, as well as a Pixie II (that I recently gave to a ham that lost his gear in a divorce), with build pictures of both.  I also built a go-kit for mt FT-840 that my son and I took to the WMA a while back that I would like to share pictures of.  And I just acquired an FT-817 that will be fodder for some future posts.  Hopefully I'll have time and inclination to get the posts up.


Richard, KK4JDO