Hello, listeners! We're putting out our latest episode of Linux in the Ham Shack just before Hamvention. We have great topics tonight including hams suing hams, the fight between Oracle and Google, antenna and kit building, mobile operation and so much more. Don't forget that we WILL be at the Dayton Hamvention this year in the East Hall, booth 625. Also, please note that we could still use your help in defraying some of our Hamvention expenses. If you'd like to donate (and maybe pick up some cool LHS swag in the process), please click on our Generosity Campaign link. See you there!
The Universal 1Watter (also called the 1H2O) is a full featured little superhet radio transceiver that you can build for about $50. It doesn't come with an enclosure, a tuning pot, speed pot or an on/off switch so that will cost extra unless you already have some in the junk bin.
Some of the features include;
1 mighty watt of output
Good selectivity from the 3 crystal filters
A VCXO tuned frequency range for the 40m band from approximately 7,020 kHz through 7,039 kHz
A built-in full functioned keyer with provision for adding a speed pot and messages
Included command button accesses the functions of the electronic keyer
Natural sounding sidetone (nicer than my Ten-Tec Century/21)
The kit is delivered in a box and inside are a couple of brown paper bags stapled together. Inside one of the bags are a couple of plastic bags with the components. The other bag contained the header kit. The ferrite toroid mix types are separated in different unmarked plastic bags so don't mix them up (the instructions tell you which bag has each mix). If anything is missing the kit supplier (Diz, W8DIZ) is very responsive.
The kit includes both SMT caps and through hole caps. I tried to solder one of the SMTs but I didn't have the right kind of tweezers to hold it in position for soldering so I used the through hole caps.
SMT and through hole caps are supplied
This is the 3rd revision of the Universal 1Watter board and I was the first to build the 40m version.
While the schematic was correct, some of the instructions weren't sorted out properly for the 40m kit. I related issues as I found them to the designer and he promptly updated the online documentation.
I soldered the components and wound toroids as I had time over a few evenings and the initial voltage tests went well.
using through hole capacitors rather than the SMTs
some of the bits and bobs
build is progressing
XTAL filters give it good selectivity
Everything except the final transistor
When the build was completed I connected the rig to an antenna and heard nothing.
The keying circuit and transmitter worked fine and I verified those functions but the receiver was deaf as a stump.
Thus began a number of days of investigation. Diz (the creator of the board) guided me through a number of debugging steps.
The first recommendation was to examine and rewind the binocular toroid balun that transformed the impedance from the xtal filters to the input of the U5 oscillator. He believed that I may had wound it incorrectly. I desoldered it and rewound it but that did not resolve the issue.
He then guided me through determining if one of the filter crystals or filter capacitors was bad. I desoldered a few components as a tests but that did not resolve the issue.
There are 3 identical mixer chips on the board. I swapped them around as there was a suggestion that there were some faulty chips in one of Diz's shipments.
I then took the board to my Elmer Paul Stroud AA4XX. He had a signal generator, Oscilloscope and RF detector. He traced the RF and all looked well but we still were unable to obtain any signal through the U5 mixer. Lastly we tried disconnecting the AGC transistor to see if it was clamping it and that didn't resolve it either.
Diz asked me to return the radio to him so he could take a look. After a couple weeks he emailed me saying he thought the BFO xtal might have a problem. But he later discovered that the oscillator in U5 was not starting up. Apparently the circuit design had a low Q and needed more current to get the oscillator working. He modified the design, adding a 16k resistor to the bottom of the board on U5 to get the oscillator going. After that all was well and he shipped the board back to me.
The FIX for all those problems required an extra resistor connected across U5
Learning from problems
Being the first person to build a particular version of a kit brings its own set of challenges, especially when you're as new to kit building debugging RF problems as I am. However I'm actually glad the kit didn't work right at the initial build. The process of debugging the board, was a great learning process. I studied the schematics and learned, as best I could, the function of each circuit so that I could better understand how to test it. During the debugging process Diz instructed me that although RF signal generators and scopes are useful you can tell a lot by touching a RF component with an inductive metal object and listening for a buzz or hum from the BFO. So all-in-all, even though the bug in the board was not due to a error on my part, I'm glad it occurred. I understand more about superhet radio design than I did before and more than if the kit had worked right off the bat.
On the air
After receiving the board back, I hooked up the frequency XCO potentiometer, paddle, command button, audio and output potentiometer and an external speaker. I then connected a 12v battery and heard the 1H2O keyer chip announce itself at power up in Morse "1 W".
Frequency control pot on the left
Volume control, output jack, cmd pot and paddle input
You can change speeds and modify settings via the command button which I have not reviewed yet. I also plan to add the speed pot so that I can easily change keyer speed without entering the command menu. For this first on-air excursion I was using it at the default startup 15wpm keyer speed. You can default the speed higher with a different resistor value. I have a resistor shrink wrapped and connected in-line to the blue-white wire coiling above the radio connecting to the speed pot terminal. In essence fixing the speed at 15wpm until I add the speed pot.
Ready to transmit
On the air... I was using my paddle out of the photo to the right of the Bug
First On Air QSO
I tuned around and found a strong station at the end of a QSO near 7030 kHz.
When he sent the final dit-dit I called and WD4AXJ answered my first call. He was in TN near Knoxville, and I received a 559. We chatted for about 10 minutes. Sorry about the blurry video. I thought I'd focused.
After I recorded this video I found an open frequency and sent out my call. Very shortly thereafter KD2FSHanswered my call and reported me as 599!
Whoo - hoo. 599 for my little 1Watter 40m.
I was transmitting using my 40m attic antenna. So deed restricted HAMs take note. You can build a one-watt radio and make contacts using your attic antenna. Haha.
You'll hear in the video there is some weirdness going on with the audio derived AGC. It is clamping down sometimes and is worse when I don't have the volume turned up very loud. When I began calling it clamped after every semi-break-in but didn't do it much after that. I'll have to look into that.
The AGC clamping may be a side effect of the increased gain Diz added to the BFO oscillator. I'll ask the forum.
Other than the AGC issue I'm super pleased with the little board. I touched the heat sync a couple of times after transmitting my side of the qso and it was warm but not really hot. It seems as though as long as you have a reasonable match to the antenna the power transistor should be happy.
My next steps are to get it in an enclosure and get it out to the Excalibur antenna site to hook onto that nice 40m doublet we put up a couple weekends ago. I plan to use my efficient little BLT tuner for that purpose. I will do a further review of the feature set on the keyer and record some more qsos for a later review.
The band was fairly busy and the little 1Watter did a fine job with stations on nearby frequencies. You can hear some getting around the passband but it is not bad at all. I'll do some tests to further define it's selectivity but at first glance it is far better than my old Ten-Tec Century/21.
My calls were answered quickly and I received good signal reports. It didn't sound as though the transmitter was drifting at all during the QSO. That's one advantage of using VCXO in the design. The disadvantage of using a crystal controlled oscillator for the frequency control is limited tuning range. The transmitter only has about a 18 kHz tuning range around 7030 kHz and I don't find many of the SKCC folks around that frequency but it is the QRP watering hole for 40m.
It is possible to shift the frequency with some capacitance changes but I think I'll leave it as is for a time and see how many states I can work.
Just imagine. This little $50 single band kit has good selectivity, a nice built-in keyer with a natural sounding sidetone, and lest we forget... You get a MIGHTY 1 WATT of OUTPUT. What more could a QRP ham need.
That one-watt of output was sufficient for all the QSOs I attempted tonight.
So lower your power and raise your expectations
I am still having the AGC pumping issue and others on the list have reported similar issues but only on receive. It happens to me when I key unless I turn up the volume very high. I did get it installed in a case but I still need to wire up a real power connector rather than using alligator clips.
!Watter installed in a case
After doing quite a bit of reading I learned that the LM386 op-amp used in the 1watter is rather notorious for audio oscillations. There are a number of suggested fixes. I went with a 4.7uf cap connecting Pin 7 on U6 (the LM386) to ground. That hasn't totally resolved the issue but it's much less pronounced now.
cap fix for LM386 oscillations
I have it in the case with all the proper plugs now (see below) so I'm happy. I've been making QSOs every day with it and it continues to amaze me and the stations that work me. It is stable as a rock with regard to frequency and the large knob with the single turn 10k pot seems to work well for tuning. I have enough control to vary the frequency slightly without having to turn it too much. The tuning range is only about 20kHz so just 3 frequency markers are plenty to let me know what frequency I'm near. The selectivity is just fantastic for such a simple little radio. Diz has created an inexpensive winner.
1Watter in enclosure with all the proper connectors for the case
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.
Elecraft W1 Power Meter
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.
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.
An acrylic-angled photo frame can make a homebrew stand
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
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.
Welcome to Episode #160 of Linux in the Ham Shack. In this episode, minus one VE2XPL, your hosts discuss amateur radio scholarships, the demise of a legendary kit maker, several Linux tutorial sites, a new web-based SDR resource, WSPR, a logger for Android and much, much more. Thanks for listening, and Happy New Year!
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.
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.
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.
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.
See http://www.aliexpress.com/store/331885 . This website has some very low cost rigs for sale. An example is a 40m Pixie at around $10 post free. You’d be hard pressed to buy the individual parts for less!
UPDATE 1430z: I have just ordered a 40m Pixie kit from them. Should be here in 2 to 3 weeks time. I hope I can manage to build it with my clumsy soldering currently.
UPDATE 2000z: G1KQH has found the same Pixie at an even better price:
I could of saved you a fiver out of your pension but you had to rush in:
Each individual posting is the property of its respective author and the opinions expressed may not represent those of AmateurRadio.com including its editor, staff, or sponsors. Content may not be reproduced without written permission.
Sign up for our free Amateur Radio Newsletter
Ham radio news and commentary, plus free radio gear giveaways