Wednesday, February 13, 2019

160M 1:2.25 Impedance Transformer

In order to try out 160M, I put up an inverted "L" and adjusted the length to resonance using an antenna analyzer (FA-VA4).  My frequency of choice was 1810 KHz - to match my QRP interests.

At this writing, I have 12 radials at the base, with various lengths of 15 to 40 feet over very rocky soil (granite, gneiss).

I did no modeling - just threw up some wire that fit my physical situation.  Impedance at resonance was around 24 Ohms.

I wound a test transformer on an old toroid of unknown characteristics just to see if I could get close to a 50 Ohms match.  That was successful and I even made several contacts at QRP levels.

I decided to wind a better (and I hope, more efficient) version.  I used a FT-150A-K core from  Amidon along with 10 feet of AWG#14 HAPT wire and some glass cloth tape.  The transformer I chose was the W2FMI-2.25:1-HU50 from the Amidon Transmission Line Transformers Handbook on the Amidon website.  this is a Jerry Sevick design.  I am, of course, using it 'backwards'...

To the right is the toroid as wound.  Sevick notes that the #14 takes some effort to wind and suggests leaving long leads on each end for leverage.  Good advice.

The image below shows (unclearly - sorry) the connections before soldering.

And here is the wired version with the "proof of concept " un-un to the left.  The box is an outdoor junction box (with water-sealed lid, not shown) that I picked up at a local big-box store.  Pretty handy.

And here it is as installed.  The BNC feed to the shack is at the bottom, the inverted "L" connects to the right and the ground and radials to the left.

So far, I am very pleased to get something cheap and easy working for 160M.  This might not be the best antenna, but for my circumstance it is up and working.   At 1810KHz, the antenna presents a SWR of about 1:1.1, rising quickly away from that QRP frequency.

I do appreciate Mr. Sevick's work. 

Now for more radials!

cln - Nick
Lake Buchanan

Sunday, November 25, 2018

A Grand Day Out - QRP Portable

With apologies to Wallace and Gromit.

I was able to operate portable four times this year.  Briefly, here are some photos and comments.

Texas State Parks on the Air (TSPOTA)

I operated only on Saturday - April 7th.  As it was cool (~39F), damp and threatening rain, I elected to operate while sitting in the car at Longhorn Cavern State Park (EM00tq).  I only made 15 QSOs  No other Texas state parks were heard.  As of this writing, no scores have been posted.  Used the K1 @ 5W with a 20M dipole.  This is a pleasant and scenic location, and my closest state park.

QRP to the Field (QRPTTF)

Two weeks after the TSPOTA event, I was out again - this time at Black Rock Park in Llano County (EM00ss).  More on Black Rock Park later.  Rig was again the K1 and this time I hung a 40M EFHW in addition to the 20M dipole.  25 QSOs was good enough to get me into the top five..  Got to meet a dog named Gussie.  She was interested in my stash of Ritz crackers.

The Flight of the Bumblebees (FotBBs)

This was on the 29th of July and again at Black Rock Park.  I made 29 QSOs and had another good time.  It was very warm and lots of folks were enjoying the park.  Same rig as above.

The Skeeter Hunt

This was on the 29th of August and once more at Black Rock Park.  Again 29 QSOs with the K1 @ 5W, the 20M dipole and the 40M EFHW.

More on Black Rock Park

This park, on the west side of Lake Buchanan, is operated by the Lower Colorado River Authority (LCRA).  This is not a state park, but is operated in a similar manner.  In my experience, these parks are very popular with families, especially in the summertime.  I would strongly suggest reservations or getting there early and being flexible.  Here are some links:


Black Rock Park

I had a very good experience at this park.  The staff was both friendly and very helpful.  I did a scouting run through the park early in 2018 and made note of the sites with 20 and 40M spaced trees.  :-)   No one seemed to have any problem with me hanging antennas - and on my last visit, I was greeted with, "Oh, you're that radio guy."

cln - Nick

Monday, October 22, 2018

QCX - 30M Transceiver - Mods

Two more mods for my 30M QCX.

I have already completed several mods, as detailed in QCX - 30M Transceiver .  The final one I did last year was intended to increase the power output, but was only marginally successful.

Recently, I purchased a 20M QCX, but after finishing construction, I found that the ATmega328P microprocessor was not working.  Hans, at QRPLabs, had seen this problem before and was happy to send a replacement - and I ordered an additional latest firmware chip for this 30M rig.  While waiting on the replacements to arrive, I elected to replace the capacitors in the low-pass output filter.

I replaced C25 and C26 with 560pF silver micas and replaced C27 and C28 with 270pF silver micas.

These capacitors were huge compared to the originals - so I had to get creative in placing them.


Note that C27 and C28 had to move to the bottom of the PCB - and were tilted slightly to provide clearance for the enclosure.

I am fortunate to have a low-priced but effective solder-sucker that I bought some years ago.  This would have much, much more difficult without it.

Here are the parts I removed.  The largest is about the size of the head of a kitchen match.  I used silver micas as I had the correct values for the 30M QCX on hand.

Just as I was completing this modification, the replacement microcontrollers from QRPLabs arrived - with firmware version 1.00f.

The only volatile information that I wanted to keep was the correction for the 27MHz frequency reference (Entry 8.5:  27.004.550), so I made a note of that and replaced the 1.00b firmware with 1.00f.  As expected, no re-alignment was really needed, but I touched it up anyway.

After all these changes, I now have 3.4W out measured with the same equipment as earlier.  This is just about what the designer predicts, given my 12.4V motorcycle battery power supply and the polarity protection diode.

I am pleased and will call this good for now.

My thanks to W5IQS for suggesting mounting the capacitors on the bottom of the PCB.   And to Hans, of course.  The more I use this little rig, the more I like it.

Here is an image of the 30M QCX in its new enclosure.

cln - Nick

Saturday, September 22, 2018

Automated XLog backup - Revised version

Back in the days when I worked for a living, one of the computer guys at the plant corrected me while I was talking about disc drives in our computers - I was saying "if it fails..."  He corrected me with "Not if it fails.  When..."

Though no longer required, lots of old-school Radio Amateurs keep a log.  Some use pencil and paper, but most do it digitally (and some, like me, do both).  Belt and suspenders.

With that in mind, I have written a Linux script that will help me avoid manual re-creation of my digital Amateur Radio log from the pencil and paper copy - which dates back to 1970 - when the computer finally fails.  I use XLog, but this should work for other Linux logging programs.

You will need some basic familiarity with Linux scripting and permissions, have crontab up and running and Dropbox installed.

The general scheme is to copy the XLog log file to a safe place at least once a day.  When my computer dies (and they all will), I could re-install XLog on a replacement and retrieve the latest of my daily log file copies kept remotely by Dropbox.

The scheme has three parts:
     (1)  Linux 'crontab'
     (2)  Dropbox
     (3)  The 'xlog_backup.cmd' script


Linux has a very handy program that allows users to schedule events at intervals.  I will not do a tutorial on cron or crontab, but will just show you the appropriate crontab file entry, below:

#       min     hour    day     month   day of  command
#                                       week            
30 * * * *                        /home/MYHOME/bin/xlog_backup.cmd

Crontab reads this file and is directed to run the command xlog_backup.cmd (in the directory given) on the half-hour of every hour of every day of every month on every day of the week.  For you old timers, that's every time Mickey's long arm points down.


Dropbox is a commercial file sharing and storage program.  There is a fee if you want to store lots of data, but since XLog files are relatively tiny, we can just use the free ('Basic') version.  Check out:

You will have to create an account.  The script below could possibly work with another file-sharing program that works in a similar fashion.  Your decision.  I have no commercial interest in Dropbox, but it is quite handy for things other than saving Amateur Radio log files.

One you have Dropbox running and understand how it works, make a subdirectory, perhaps named "XLog", to match the script location below.


Here is the backup script.  This is a revised version (23 February 2019) that is slightly more logical and creates a new backup if you change your log.  You will have to edit the various lines that are unique to your application - one example is the name of XLog's log file.   XLog typically keeps this file in the hidden directory '.xlog'.  Mine is named wb5bkl.xlog.

Make a copy of the script below and edit it:

#  /home/urhomedir/bin/xlog_backup.cmd
###  Edit each of the following for your situation:
###    urhomedir - your home directory
###    YOURCALL  - your callsign in CAPS
###    yourcall  - your callsign in lowercase
###  Note the asumptions about directory locations
###  including the Dropbox directory structure.
###  All the 'echo' statements can be commented out once
###  you've got it working to your satisfaction.
#  Define paths to xlog data file and Dropbox backup
DROPBOX_XLOG=/home/urhomedir/Dropbox/Xlog/yourcall.xlog.`date +%j`

#  Housekeeping  -  comment this out if you want to keep them all
#  Get rid of all but the 10 most recent log backups
rm -f  $(ls -1t /home/urhomedir/Dropbox/Xlog/yourcall.xlog* | tail -n +11)

  First, check to see if the backup for today exists
#  If not, create it and exit
if [ ! -f $DROPBOX_XLOG ]
    # create it
    echo -e "\n Creating today's backup file:   yourcall.xlog.`date +%j` \n"
    #  place a note in .xlog containing the latest backup time
    date > ~/.xlog/Last_Cloud_Backup
#  Or see if the logfile in Dropbox is newer than your logfile
#  If so, do nothing and quit
    echo -e "\n yourcall.xlog.`date +%j` exists and is newer."
    echo -e " Quitting xlog_backup.cmd...\n"
    #  if the Dropbox version is older than the logfile, overwite it
    #  with the newer version
    echo -e "\n Overwriting today's backup file:   yourcall.xlog.`date +%j` \n"
    #  place a note in .xlog containing the latest backup time
    date > ~/.xlog/Last_Cloud_Backup

Save the edited copy in your 'bin' directory (or wherever - but match your crontab entry) and make it executable.  The script only makes one Dropbox copy per day - but overwrites that copy if your log changes within the last hour.  Safe enough for me - but you can modify the if/then routine above and the crontab entry to suit your needs.

The backup file will have the name yourcall.xlog.Julian_date, for example:  wb5bkl.xlog.147

And the the latest backup time will be noted in your .xlog directory.  Backups from at least the last 10 days will be saved.

I hope this works for you - and keeps your log(s) nice and safe.

cln - Nick
Lake Buchanan

Tuesday, May 29, 2018

Fiberglass center support - 40M extended double Zepp

I do not recommend anything to anyone anymore.

Having said that, I am personally pleased with the fiberglass tubing products from Max-Gain Systems.

I wanted to replace the relatively short fiberglass over galvanized steel center support for my 40M extended double Zepp (edZ).  I had two goals:  make it higher and make it non-conductive - simplifying the routing of the ladder-line feed.  

The telescoping fiberglass mast from Max-Gain is very nicely made.  The clamps are well thought-out and the instructions are clear.  The problems I had were entirely my own.

The clamps are entirely non-conductive and have a clever over-center lever to hold the tubing in place.  My problem was similar to the old British motorcycle joke about fasteners in aluminum castings:

Stages of bolt tightening for the novice mechanic:
                                               Very Tight

I snapped one of the clamping bolts during extension of the third fiberglass tube - it had been tightened to the 5th stage above.  After that, I was much more cautious.

Within a month I discovered I was too cautious.  With the constant flexing in the wind, two of the sections had partially collapsed - you can see one just above the roof level in the image to the right.  The looped ladderline is a dead giveaway.  

My QTH is in an area with almost constant breezes (a good thing in the Texas hill country).  The mast has one clamping support (at the roof apex) and is guyed only by the 40M edZ itself.

This means the mast is free to move in the wind.  In strong winds (say around 45 mph), I have seen the top of the previous fiberglass mast bent to almost 45 degrees.  We have had wind gusts of over 65 mph during storms with no permanent damage - it waves around like a fishing rod.   But all this movement did allow the telescoping mast to creep downward, especially in the lower sections which bear the weight of the sections above plus the downward component of the tightened edZ wires. 

[I know I am taking a chance here with minimum guying - but I am willing to bear that risk.  The previous fiberglass support was up for well over 12 years with no
apparent damage.]

I did not want to secure the sections with non-conductive pins. Sooner or later I would have to lower the mast and Max-Gain specifically warns against damaging the tubing finish as clearances are tight.  The same argument applies for any sort of clamp that would mar the tubing.

What I devised is shown to the left, just above the clamp mechanism.  It consists simply of three or four layers of electrical tape overlaid with a very tight tie-wrap (I have lots of tie-wraps, so I don't mind snapping one to get to stage 4, above).  Obviously I had noted that the tubing collapse halted when the electrical tape and tie-wrap holding the ladderline hit the clamp.  

Seems to work well.  I will post a follow-up report in a year or so.   

40M extended double Zepp details:

Orientation:                Roughly North-South
Center height:            about 46 feet
South end height:      about 25 feet (Live oak)
North end height:      about 30 feet (Pine)
Feed:                          450 Ohm ladder line

Best wishes to all.

cln - Nick

Sunday, December 3, 2017

QCX - 30M Transceiver

Recently, I built a QRPLabs QCX, the 30M version.  I have stopped recommending anything to anyone, but I hope to build both the 40M and the 20M versions in the near future.  I have collected a few hints, in no particular order:


*  There is a impressive video of a QCX build here by IZ7VHF.  Worth a look if you are considering the QCX.

*   The local big-box office supply store wanted more than the list price of the QCX to print a color manual - even just B/W was more than Hans charges for the kit plus shipping.  I put the manual on an old iPad and propped it up near my work area.  I only printed the inventory pages, the section concerned with winding of T1 and the Cheat Sheet near the end of the manual.  I had the Cheat Sheet laminated.

*   If you use something like an iPad or PC to display the manual, all the illustrations can be handily expanded.

*   I used a pair of binocular magnifying glasses.  Also very handy.

*   I would strongly advise a complete inventory of all parts (also see below).  I had one extra capacitor.

*   I would also strongly advise organizing - at an absolute minimum - the capacitors and resistors by value.  Muffin tins would be nice (and would only take moments to wash and slip back into the kitchen).  If you are fortunate enough to have a workplace that will remain undisturbed, at least draw circles for each value on a piece of cardboard and stick them in that.

*   All of my placement errors were with the resistors.  I strongly advise the hint above, and re-checking the color codes against each other and the inventory listings.  Use a VOM to resolve problems with color resolution.  Slight color (colour?) blindness runs in my family.

*   With my tired, old eyes, I found it hard to count the turns on T1.  I ended up taking a photo with my phone, transferring it to my PC and enlarging it on-screen.  I had one turn too many on the S3 winding.

*   When you cut the small connectors apart, I would strongly advise covering the connector and tool with a cloth.  My first cut ricocheted off the wall, then the bookcase then my chest.  Miraculously, I found it in the work area after an extensive search of the floor.  Of course, use eye protection.

*   Take Hans' suggestion and orient all the parts either the same way or at least in such a fashion that the values can be read later.  Remember that this project will be very crowded at the end.

*   The page breaks in the manual are occasionally unfortunate.  Be extra careful when the instructions and the illustration are on different pages.  As mentioned earlier, the illustrations in the Manual I downloaded to my iPad can be enlarged when clicked.

*   From my experience with SMT projects, I now have a large, cheap aluminum foil cookie sheet with a properly sized piece of white cotton cloth taped inside.  Very handy.  If you ground it, even better.


First impressions - the receiver is HOT!  I am impressed.  The QCX seems to hear almost everything my K3 does.  

Power output was low - measured externally at about 1.4W.  

I spent some time reading the QRPLabs e-mail reflector and then followed Hans Summers' recommendations for mods to the QCX.


Here is a listing of the modifications I made.

Before and after each change, I made a series of measurements.  First was a 5 second key-down followed by a 15 second rest, then repeated twice more.  Then a 30 second key-down, followed by a 1 minute rest , then repeated twice more.  I am reporting averages of these measurements.  Power was measured independently of the QCX with a 20W Elecraft 50 Ohm dummy load.  I also recorded the supply potential.

I did the mods in two stages, mostly because the changes to L1, L2 and L3 were a little tedious.

Mod #1        -   12.55V supply
    Before:      5s      1.55W
                30s      1.69W
    ** Removed 1 turn from L1, L2, and L3
    After:       5s      1.36W
                30s      1.38W
    ** Re-alignment
    After        5s      1.56W
                30s      1.52W 

Mods #2&3&4   -   12.38V supply
    Before       5s      1.4W
                30s      1.5W
    **Install 1N5819 Schottky diode
    After        5s      1.5W
                30s      1.6W
    **Install 10K resistor from Q5 drain to +12V
    After        5s      1.4W
                30s      1.6W
    **Replace MPS 2907 with MPS751
    After        5s      1.5W
                30s      1.6W

    After        5s      2.0W
                30s      2.0W

The image below shows the diode and resistor addition to the bottom of the PCB.

I think (but do not know) that the removal of one turn from the low-pass filter did not do much.  I think the addition of the 10K Ohm resistor and the change to the MPS751 did a little good.

At this writing, I am satisfied enough that I will await more information from the designer before diving into the circuit board again.  

As it stands, 2W seems to do well on 30M given reasonable propagation.  The Reverse Beacon Network seems to hear me just fine.

More to come, I hope.

cln - Nick


Friday, December 1, 2017

Ham Gadgets Ultra PicoKeyer

I have been using the AA0ZZ EZKeyer II for several years (see my earlier post).  It has worked well with my K1, which I typically use portable.  There are shortcomings, however:  No easy speed control and only 3 memories. 

I tried a keyer with 8 memories, but had so many problems with missing, broken or incorrect parts, odd i/o design and sporadic support that I gave up - sadder but wi$er.

 Then I found the Ham Gadgets Ultra PicoKeyer.

The price was right - and I could even chose a color!  Woo-hoo!  

The construction was pretty easy (and the manual is very good).  It was ready to go in under two hours (I work very slowly).

I hooked it up to the Elecraft K1, switched the K1 to 'straight key' mode and gave it a try...


After several tries and careful inspection - to no conclusion - I decided to give it a try with my K2.  Again semi-gibberish. 

More experiments and some searching of the Elecraft e-mail list archives suggested that the 'ring' connection was live. 

Note:  Elecraft requires a 1/8" three-conductor (stereo) plug for CW input to their K1 and K2 transceivers.  If used in straight key mode, nothing can be connected to the 'ring', just the tip and the shell.  Straight Key mode allows control by an external keyer.

I sacrificed a cable and opened the 'ring' wire.  Everything worked just fine!   How odd.

Then I decided to take a very close look at the PCB for potential shorts.  None found, but there was a PCB connection to the 'collar' pin on the output jack.  It was NOT on the schematic, but it's there:

Since it seemed to be the cause of the problem, I cut that trace.  Success! 

Everything worked normally for both the K1 and the K2. 

I did communicate my findings with Ham Gadgets, but I am not sure they fully understood the issue when the PicoKeyer was used with these Elecraft rigs. 

Hence, this entry.

I filled in the embossing on the front of the keyer.  Looks nice.

This is a neat little keyer.

cln - Nick