Author Archive
I’ve Got the Power
January 23rd, 2016 | 
Author: Elecraft W1 Power Meter
The Elecraft W1 is another fine mini-module kit from Elecraft. It is an auto-ranging power meter measuring as little as 150mw up to 140w. The 150 milliwatt to 1.4 watt range is an especially nice feature for QRP'ers.
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| Elecraft W1 Power Meter |
Building
I am new to building kits. My first kit was from 4-State QRP (Regen Receiver). This is my 4th Elecraft kit. The instructions are very detailed and easy to follow and I especially like that they give you the resistor color and capacitor identification right there in the instructions without having to refer to a data sheet somewhere else in the documentation.
All the parts come in a single bag so there is a bit of sorting that you need to do when you receive it. I use a big egg carton to sort and inventory the parts so that I can find them more easily.
This kit was a bit more involved than the other kits I've built from Elecraft. It has a binocular toroid which is fiddly to wind, 3 ICs and a couple of resistor packs. Lots of soldering. The most tedious parts to solder are the tiny transistors. Those solder pads are really close together for someone new to soldering like me, but I took my time and everything turned out ok. I worked on this kit a little at a time over 3 nights. If you can follow instructions and have a steady hand you should be fine.
The kit has some ESD sensitive parts so you'll want to be able to properly ground yourself and your equipment. Make sure your soldering iron is ESD safe and that you are grounded.
Lastly, final calibration is performed using just a multi-meter.
Build options
The meter can be built in a number of different configurations depending on how you plan to use it. The battery holder and BNC connectors can be installed on the top or bottom of the board and the BNC connectors can even be oriented vertically on the back side of the board. If you plan to use it in an enclosure give some thought to the location of the battery holder and BNC connectors before you get to that part of the build.
I plan to use some stand-offs to mount it to the front of an acrylic photo frame that I already had.
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| An acrylic-angled photo frame can make a homebrew stand |
Operation
The meter can operate from a 9V battery or from an external power supply via the barrel connector on the side. There is a small power switch at the bottom left of the board.
The top row of LEDs indicate power for a given range. The 3 LEDs mid way down the board to the left indicate the current power range. The range can be automatic or set via a command through the serial interface.
The ranges are:
- 150 milliwatts to 1.4 watts -- Green LED
- 1.5 watts to 14 watts -- Yellow LED
- 15 watts to 140 watts -- Red LED
Computer interface
There is a 1/8" stereo jack below the power connector that provides a serial interface to a computer. There is a command set for interacting with the meter as well as a sample application available on Elecraft's site that allows a number of settings to be modified such as peak hold and saved to the meter.Elecraft sells a $15 serial interface cable kit. What they don't tell you is that it has a DB-9 connector rather than a USB connector. I don't even have a computer with a DB-9 serial port so buyer beware. You may want to skip their kit and build your own. I happened to already have a DB-9 to USB converter but I'd preferred their kit to provide a USB connector.
Demonstration
Photos
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| 3 ICs to solder and toroid winding... lots of fun |
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| LEDs indicate power in each range and SWR |
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| LEDs indicate the power range being displayed |
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| Elecraft W1 Power Meter |
That's all for now
So lower your power and raise your expectations
73/72
Richard, N4PBQ
Get a taste of the RF coming and going
Elecraft CP1 - A tasty RF treat
I had some time this afternoon to assemble another Elecraft mini-module kit. This time it was the Elecraft CP1 directional coupler.
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| Elecraft CP1 Kit |
Couple what?
Ah, so if your new to this like me you might be asking what does a coupler do? Well it sorta listens in on the signal going out (forward) and reflected (back) and is able to send an attenuated sample of the signal to other devices. It attenuates the sample by either 20db or 30db depending on how you build the kit.The 20db version is good for signals 25 watts and less so that's the way I built it. It was easy to build but my glue under the second toroid wasn't strong enough and you can see it popped up a bit. Also the Elecraft instructions had one confusing instruction concerning mounting the toroids. The instructions say "... When wound and mounted correctly, the enamel wire will emerge from the top of each core and connect to the top hole at each inductor location". Well when you wind a toroid only one of the wires can "emerge from the top of the core" while the other comes from underneath. This confused me for a minute until I finally just went on with the install. Anyway, if you're a stickler for following instructions that one may cause a moment of pause...
The switches for the two outputs forward, reflected (J3, J4) are in the up position when they are not in use. When the switch(es) are in the up position the 50 ohm 3 watt resistor(s) take the place of the switched off output. Don't disconnect an output and leave the switch in the bottom position. I'm not sure what will happen... maybe nothing, probably a bit of a mismatch on the SWR, or maybe it could be like "Crossing the streams" in Ghostbusters. Your mileage may vary.
My uses for a coupler
My old Ten-Tec Century 21 has an analog VFO dial that gives me a good guess at where I'm at but I use an external frequency counter to give me more information. I had it sorta rigged my frequency counter to sample the signal from RF leaked on the shield but I didn't really know how much power I was sending to the counter so this coupler allows it, as well as other devices, to be safely connected to the transmitted signal.I also plan to use the coupler for IMD tests using a oscilloscope and other projects. It's handy device to have in your collection.
My confusion
I will admit I am still such an idiot when it comes to understanding how this stuff works. After I built it I was testing continuity and saw that input/output (J1, J2) both showed a short from ground to center pin on both BNC connectors. I thought I'd mis-soldered something and spent the next two hours unsoldering components and trying to trace the fault...
There was no fault. The way this thing works is a bit of mystery to me but as best I can tell it simply reverses the phase of the signal coming in one side (J1) and leaving the other (J2) and as far as continuity tests go, EVERYTHING has almost zero impedance. I'm still bewildered but it's AC not DC so my continuity tests don't mean much.
But in the end - It works
I finally just resoldered it, scratched my head and thought I'd give it a try. I connected the coupler between my radio and a dummy load and transmitted a watt and noted that the SWR on the radio was fine. Then I hooked up my frequency counter and it worked like a charm sending an attenuated signal to J3 for the frequency counter.
My MFJ watt meter doesn't seem to be all that accurate but I did a power test with it both in-line and absent. My MFJ watt meter measures 300w / 30w so it isn't very accurate at QRP levels. But I noted a slight difference in power reported when the coupler was in-line. If I had to guess by "Mark-One-Eyeball" I'd say the coupler was stealing about 1/2 watt. Maybe a bit more so that's something to consider. I'll know better once I build my Elecraft watt meter since it's accurate down to a tenth of a watt.
That's all for now
So lower your power and raise your expectations
72/73
Richard, N4PBQ
Elecraft BL2
Two Baluns in One
Elecraft mini-module kits offer interesting and useful, little devices and I am learning a bit more about Ham Radio and electronics as I build them. I previously built the Elecraft AF1 audio filter and tonight I assembled the BL2 switchable balun.
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| Elecraft BL2 kit |
I wanted a small, low loss, balun for use with ladder line and end-fed antennas that I could switch between 1:1 and 4:1. MFJ makes a commercial pre-assembled switchable balun but I suspect that the quality of its cores do not match Elecraft's.
The kit is obviously an easy build. The most time consuming aspect is getting the four stripped wire ends from the core all equally inserted in their tiny holes.
I tried it out with my attic doublet and the ability to switch between 1:1 and 4:1 made a difference on difficult to tune bands.
According to an email correspondence with Gary (AB7MY) at Elecraft...
According to an email correspondence with Gary (AB7MY) at Elecraft...
- The ground lug is there to be used to bleed off static voltage on an antenna that is not DC or earth grounded.
- We don't recommend using the balun with an end fed wire. It will have too much loss. The balun is for use with a balanced antenna and a low impedance of 200-300 ohms or less.
Too Fragile?
The only drawback is the lack of an enclosure resulting in a relatively fragile mechanical connection to the antenna and coax. I had hoped the board would be thicker than average epoxy board with some mechanical reinforcement of the connectors but it's standard thickness and the connections are only held on by their solder points. 450 ohm ladder line is pretty stiff stuff and I saw the connectors flex on the board as I attached the antenna.
I will need to get it in an enclosure before much field use.
Summary
I enjoyed the simple build and winding the cores and tracing out the continuity. I've been studying for my Extra ticket and learning more about inductance. Building even something as simple as a balun is interesting to me.
Update 2-8-2016
N4HAY recently performed a thorough test on the BL2 to measure its loss and current balance capabilities in blog (http://zs6rsh.blogspot.com/) in this blog post.
So lower your power and raise your expectations
72/73
Richard, N4PBQ
Just stand up
The "Nifty Accessories" KX3 stand
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| Nifty Accessories KX3 stand |
The Elecraft KX3 is naturally at home in the wild
My Elecraft KX3 is an incredible radio in many ways. It's small size makes it a marvel for portable operations.
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| The upward facing display of the KX3's short legs is ideal for remote, portable operations |
But on the desktop it's short stuff
But for desktop operation the short rear legs make for a laid back angle that makes the display difficult to see and the buttons awkward to operate. I home brewed a stand that I've used for the past few months. It angled the radio more vertically but it was still low to the desk.
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| The KX3 on my homebrew stand |
The KX3 "Iron Throne"
I finally felt it was time to give the KX3 some love and give it a proper throne chair for its little princely demeanor. The KX3 now has some height and sits more vertically. Access to the face of the radio is much improved.
Here's a closer view...
If you have a KX3 and use it on a desk in the shack the Nifty Accessories stand is a solid addition to improve the ergonomics of your little jewel. It can be ordered with enough space to clear an attached paddle or lower to the desk if you prefer but I wanted the additional height to get it above some of my taller keys.
One Suggestion... replace the paper clips
The stand comes with big paper clips to hold the KX3 to the stand. They are a a bit difficult to properly attach with all the cables exiting the KX3 on the left hand side and they look ugly.
I replaced the two paper clips with a small bungee cord which I attach as a loop across the top of the stand. The bungee cord connects to itself underneath the stand...
The feet of the KX3 then slip under the bungee cord. It seems to hold it sufficiently and is easier to attach and remove the radio. It looks nicer as well...
So lower your power and raise your expectations
72/73
Richard, N4PBQ
Finer than a frog’s hair split twice
Elecraft AF-1 Audio Filter Kit
I've been working a lot of SKCC CW stations during the holidays and adjacent stations really interfere with my ability to use the vintage Ten-Tec Century/21. Its built-in audio filter is relatively effective if the band isn't too crowded but if I'm working a station and others pop up within a 1kHz on either side I have a real hard time keeping track of which QSO to listen to. I wanted some relief from the relatively porous audio filtering provided by the old girl.
A kit from Elecraft seemed to be the ticket to better signal isolation for my old radio.
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| Elecraft AF-1 Audio Filter Kit |
Building the kit
This kit is about $60 and is pretty easy to build There are a couple of ICs to solder so it will be easier if you have a temperature controlled, fine tipped soldering iron. Santa brought me a nice soldering iron for Christmas so this was my first chance to make some use of it. Everything about the kit is very straightforward and Elecraft has wonderful build instructions along with a well laid out board. Their instructions list components in the order that you will be installing them on the board, left to right and even include the color coding or numbering for resistors and capacitors right there in the instructions so you don't have to keep going back to look up the coding. I've only built one other kit previously and the Elecraft instructions are better.
My only gripe is that this kit has been out for quite some time, but for some reason they shipped me a Version "A" board that required a trace to be cut and a couple of jumpers installed to correct a board error. I would hope that they would ship new versions of the board but apparently you can get an old version. Next time I order a kit from them I may specify that I want the latest revision of the kit.
Performance
The board powered up and worked right as the last of the solder smoke was wafting away. I connected it to the Ten-Tec and tried to find some adjacent station operations to test against but the bands were not terribly busy tonight. I did manage to get a decent audio test on a calling station and created a video to demonstrate the board's capabilities.
Summary
This is the first kit I've built from Elecraft. It was a simple one. The instructions were excellent, the silkscreen layout on the board was straightforward and all the parts were in the bag. The kit does not come with an enclosure so it looks a bit unfinished and the knobs are a bit wobbly on their tall, plastic shafts. That is my only negative concern regarding the finished kit. Putting it in an enclosure would also require the battery holder to be moved to the bottom of the board to clear the shafts exiting the top of an enclosure. Certainly not a big deal but I would be willing to pay an extra $10 for a ready made enclosure because when I've tried to make them they look like junk.
But the bottom line is that if you have an older radio that lacks good filtering or you've built a homebrew radio that you want to be more usable on the air, the Elecraft AF-1 is an excellent addition. I think it is going to serve me well with my vintage radio. Now to find a project box to fit it.
That's all for now
So lower your power and raise your expectations
73/72
Richard, N4PBQ
Which antenna is better?
Real world antenna comparisons
I don't have many choices for my antenna at my residential QTH. I have an 80m OCF Dipole (aka Windom) hung from the peak of my roof at about 25ft and a ladder line fed 40m Doublet folded around in my attic at about the same height.
Generally I've been using my 80m Windom for most contacts because it is resonant on 7 bands and I don't have to tune it. I've had a number of on-air ragchews where I switch antennas and ask for signal reports but it is often a hassle and I don't like to interrupt a ragchew to ask for that sort of comparison.
So how do I know which antenna is better for certain bands and directions?
The RBN
The Reverse Beacon Network offers an objective and patient antenna tester. I just recently learned about this resource and it's a fabulous tool. When my CQ isn't being answered I'll often bring up the RBN and check my signal reports and then switch antennas to see how they compare.
It has been very interesting to learn that the Doublet in the attic often outperforms my Windom usually by 12db and sometimes by as much as 20db especially on the higher bands. I'm guessing that part of it is the greater efficiency in the ladder line but that doesn't tell the whole story because the Windom offers a low SWR on most bands and shouldn't be eating up much power in the coax through SWR losses. Antennas are magic.
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| Two highlighted records show the difference when I switched antennas and moved the transmit frequency slightly to cause a new report to be sent |
Process
Ok so here's what I do... The RBN stations will report only when they see a new frequency or it's been 15 minutes since the last report for a given station, so when I switch antennas I will move frequency slightly to trigger the new report. Now admittedly QSB or other conditions may change between the reports so you'll need to do this a bunch of times over the course of days and compile some records to get a clear idea of how each antenna is performing in certain directions. This isn't hard science but it's more real-world than a smith chart or the occasional signal report from a station or two.
If you make use of the RBN I encourage you to donate on their site.
That's all for now...
So lower your power and raise your expectations
72/73
Richard N4PBQ
Can anybody hear me
Calling QRP CQ - Inconceivable
My 80m OCF Dipole has been a surprisingly good antenna and I've made contacts with it on all bands except 6m and 160m. Based on my past experience trying to tune up short antennas on 160m I really hadn't considered trying to use this Windom for 160m. But through some email exchanges with another ham in Illinois who had recently put up a 160m antenna we decided to try a scheduled QSO on the top band. So it was time to give the Windom a shot on 160m.
Amazingly my 80m Windom / OCF Dipole has 4.5:1 SWR native around 1.8 mHz and it matches easily with a tuner across the entire 160m band. That was a surprise.
Amazingly my 80m Windom / OCF Dipole has 4.5:1 SWR native around 1.8 mHz and it matches easily with a tuner across the entire 160m band. That was a surprise.
I tossed my mighty 5 watts call out at 1810 kHz not expecting much...
Within a minute of calling CQ I had a faint QRP station from Maine tried to work me. After about 4 tries I finally copied his call correctly but then lost him. Immediately another station called me and we exchanged the niceties of signal reports, location, rigs and weather. I received a nice 579 report for my 5w and I gave him a 599+ report for his thundering kilowatt station. He needed to work my County so I was glad to be able to provide him with the contact. Following that call the former QRP station from Maine was back in there and finally we worked each other. We had a nice QRP to QRP QSO on the top band. He gave me a 549 report but he was using a 400 ft beverage receive antenna. I was struggling a bit more to copy him through local QRM on my side and a less qualified receive antenna and reported his signal as 339.
Those were my first two contacts on 160m using CW. Who'd have thought my cloud burner antenna and QRP power would get me such quick results on the top band. I just figured no one would hear me.
So how do you know if and where your signal is getting out ?
The Reverse Beacon Network
I had to quit right after those two QSOs but when I later checked my email the original station with whom I'd planned the scheduled QSO reported that although he had not heard me he said I was getting out and sent me a link to something called the reverse beacon net showing a couple of stations that were hearing me on 1810 kHz.
You mean I can find out in near realtime if and where my signal is being heard by an automated system? No way! That is cooler than a Ronco Pocket Fisherman. Recall that I'm relatively new at this stuff and this may be old hat for a lot of you. But the ability to toss out your call and in real-time check where your signal is getting to just warms the push-pull final transistor in my heart.
The Reverse Beacon Network can give you the last 100 reports of your station. So I took a look and saw some of my weekend activity where I was shooting some fish in a barrel (I mean working contest stations) and there were beacon reports of my call from such places as far South as the Antilles and as far West as Utah.
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| Map of the last 100 reports from Reverse Beacon stations of my call sign Color coded by band |
So the reverse beacon network report tells you what station heard you, the frequency, the signal to noise ratio (higher is better) and your word per minute (wpm) speed.
It even includes a speedometer
Being a new CW dude my word per minute speed is of interest to me. Most of my QSOs in the past week have been at 15-16 wpm. I'm using a Vibroplex Bug I received last weekend and have slowed it down with a home-made weight attached to a drywall anchor pressed on the end of the pendulum. I found it interesting that some beacon stations reported me at 19-23 wpm. I looked at the time and the frequency and realized that the higher speed was from my first on-air QSO using the Vibroplex Bug with N4HAY before I slowed it down with my junk box bug tamer.
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| My brief speed key session with N4HAY |
So if you are using a manual key and don't know what speed you are sending just check out a beacon to see what speed they are reporting.
Summary
This reverse beacon stuff has been around a while. So unless you're a newbie like me you probably already knew about it. But if you haven't used before it's very cool, especially with regard to knowing how your QRP station is being heard. Are you making it 1000 mile per watt? Is your antenna propagating East, West, North or South. How and where is the skip? This answers many questions that I had been wondering about as I'm operating. A shiny new toy, just in time for Christmas
So that's all for now.
So lower your power and raise your expectations
73/72
Richard N4PBQ
