This past winter, my old high school buddy, who we shall call “Laurence” handed off to me his Zenith Model G724 radio, a nice 1950 Bakelite case table top AM/FM superhet. According to Larry, the radio played well but had a broken dial string.
Dial strings can easily be replaced using common twine, and while I had the radio apart, it made good sense to replace the old wax and electrolytic capacitors and to test the tubes – simple basic maintenance to keep this radio working.
This radio has a selenium rectifier to convert AC to DC [Figure F, below]. While I was aware that selenium rectifiers are prone to failure as they age, I have never experienced a failure – most of the radios I have serviced feature tube rectifiers.
Laurence had shared my Facebook post about the service I had done to his radio on a vintage radio forum where an astute member spotted the selenium rectifier and asked if I planned to swap it out for a diode.
I decided I needed to broaden my knowledge of selenium rectifiers and what happens when they do fail. I came across two useful YouTube videos from two content providers I already subscribed to – Shango066 and All American Five Radio – that helped me fill my knowledge gap.
What I learned from both videos was that selenium rectifiers put out reduced voltage as they age, not delivering enough B+ voltage for the tubes. I also learned that if the selenium rectifier shorted out and overheated it would smell pretty awful and could cause more damage to the radio.
A modern general purpose rectifier diode, the 1N4007 can be used as a direct replacement for the selenium rectifier, however the selenium rectifier has a higher internal resistance than the 1N4007 which means a dropping resistor needs to be added in series with the diode to prevent tube filaments from burning out due to too much voltage.
In order to determine the value of the dropping resistor, I consulted the Sam’s Photofact and studied the schematic and voltage notes to find a reference voltage. According to my documentation, the grid voltage on pin 5 should be 125 VDC+.
Using jumper cables I placed the 1N4007 in circuit with my Heathkit Resistance Subsitution Box in series and my Voltmeter connected to pin 5 of the 35B5.
With the resistance set to 33 ohms, the voltage on pin 5 was 124.9 volts. [Figure A., below]
Because the resistance substitution box was old, I wanted to check the resistance with my ohm meter – I discovered that the 33 ohm setting actually read at 39.1 ohms. [Figure B., below]
I chose a 36 ohm 1 watt resistor from my parts box for substitution and when I tested it with the ohm meter and it read 38.0 ohms. [Figure C., below]
I soldered the 36 ohm resistor in series with the 1N4007 diode and soldered it into circuit. [Figure D., above]
I then tested the voltage on pin 5 of 35B5 and found the substitution worked fine as the voltage reading was now 128.8 VDC+. [Figure E., above]
In the end, Laurence gets a tuned up Zenith and the next time I see him, I shall collect my friends and family fee – 2 snorts of Jack Daniels Whisky! 🙂
Please leave your comments on this site, or drop me a line at James@ab1dq.com!
I earned my first amateur radio license, the gateway Technician ticket, in March of 2002 at the age of 37. It had been a lifelong goal to become a ham radio operator every since the radio bug first bit back in the 1970s when I spent countless hours in my grandfather’s radio/TV workshop melting solder and into the early 1980s when C.B. radio was the craze and I first discovered the wonders of shortwave radio listening.
Had I pursued my dream in earnest back then, the entry level license I would have studied for would have been the Novice license, requiring me to pass both a written exam and a 5 word per minute Morse Code exam. However, that era ended in 2000 when the FCC stopped issuing the Novice license.
In 2002 when I was first licensed [as KB1IAR], although I did not need to pass a Morse code exam for the Technician license, I did need to pass the 5 WPM Morse code exam along with a written exam in order to upgrade to General class ticket which brought with it coveted HF privileges.
I passed the 5 WPM Element 1 Morse code exam along with my Element 3 written exam to upgrade to General a few months after earning my Tech, and a little over a year later I passed Element 4 to earn my Amateur Extra class license.
In earlier times, a ham radio operator needed to pass a challenging 20 WPM Morse code exam to upgrade to Extra class. Many older hams who worked so hard to clear this hurdle back in their day continue to sneer at us 21st century Extra class licensees, referring to us as “Extra Lites” while bitching and moaning about how licensing exams have been dumbed-down.
In 2003 the International Telecommunications Union ended the international Morse code requirement for an amateur operator to qualify for transmitting privileges on frequencies below 30 MHz and in December 2006, the FCC retired the Element 1 exam, eliminated all Morse code testing for US amateur radio licensees.
In the nearly 15 years since the Morse code exam has been gone, you might expect to find the CW bands dead, but I’m happy to report that Morse code remains a very popular operating mode today as amateurs like me are still drawn to and enjoy using Morse. It turns out that sending and copying code is a fun and worthwhile pursuit and ham radio operators are continuing to learn and use the code, not because they have to, but because they want to!
So given that there is a hunger for hams who have no code expertise to learn code, I hear the same question in a variety of amateur radio communities – either local clubs or online – “What is the best way to learn Morse code?”
When I was studying the code years ago for my General upgrade, I listening to Morse Code instruction lessons on cassette on my Walkman. The ARRL recorded code lessons, which are still available on CD, did an adequate job of teaching me to memorize the 26 letters, 10 digits, and various pro-signs at the dreadfully slow 5 WPM – sufficient enough for me to pass my Element 1 exam.
While it helped me earn my license upgrade, those recorded lessons did little to prepare me for operating CW on air. For the next several years I looked for other tools to improve my Morse skills and up my speed. These included online tools and smart phone apps.
Then I discovered CW Academy, a three tier interactive Morse code instructional class offered by the CWops organization. The classes are offered in 3 levels – Basic, Intermediate and Advanced and are held online via conferencing software such as Zoom. You meet twice a week with your adviser and several of your peers peers who are more or less at the same level of ability.
Classes typically meet online for an hour two times a week over an eight week semester. The course requires students to commit themselves to the program and there is nightly homework assigned so that you learn by immersing yourself into CW.
Several tools are used for homework assignments including MorseRunner and RuffzXP – two excellent interactive apps that simulate CW contesting. Nightly homework assignments also included listening to recorded sample QSOs and short stories intended to aid in developing good head copy skills.
Tonight I completed the CWAI (Intermediate) level course, and in all honesty, this is the second time I have taken the second level CW Academy course. I believe the key to becoming a good CW operator is to constantly use your skills – on air ideally, but by listening to code whenever you can. The Intermediate level course focuses on head copy, something I have always struggled with, but am becoming better at.
Our instructor this semester was John, AJ1DM, a CWops member and a great teacher. John challenged us, his students, to come up with weekly GOTA (Get On The Air Goals) to challenge ourselves to do more on air with Morse code each week. The GOTA challenge was useful for me as I no longer feel intimidated by operating CW. I feel comfortable with my ability to copy and send at about 18 WPM, enough so that I don’t hesitate to answer any CQs I hear, and I’m also no longer shy about calling CQ myself.
John was assisted this semester by two assisting advisers, Tony VE2KM and Bruce N9WKE. Tony and Bruce presided over break out sessions and came up with copying and sending games, quizzes and challenges for us.
My fellow classmates this semester were Doug K4LSK, Pat AA0O, Steve KC1EJO, and John, AC2SG.
I would highly recommend CW Academy for anyone who is serious about learning Morse Code and is willing to put the time in to do the work over a two month period. The classes are fun, the work is challenging, and the program absolutely works. And, did I mention? It’s FREE! CW Academy is a labor of love of the members of CWops who want to encourage and promote CW and to help us up-and-coming Morse cuckoos to develop good operating skills.
My interest in becoming a good CW operator is so I will be able to get the most out of operating the QRP radios I have built over the years. When operating low power, good copying and sending skills are much more critical. I think I’m getting there.
This past weekend I was leafing through my logbook and realized that everyone of my 2020 QSOs to date have been CW – I haven’t keyed the mic since last year!
After seeing my OCF Dipole and G5RV wire antennas repeatedly come down over the past 3 years I decided to try something different this fall.
My wire antennas, up around 60′, performed very well, when they stayed up, and I am forever grateful to Bill, W1KKF, who was willing to come out each year with his bow and arrow to shoot the lead lines into my trees.
Knowing that the tops of the trees tended to sway in the wind, I had incorporated strain relief into my subsequent installations by attaching either an inline spring or bungee cord between the antenna end insulator and the rope. Yet, despite these efforts, the antennas continued to come down. Two years ago was particularly brutal when a series of bad storms (including a tornado touching down just south of us) sent large limbs and entire trees crashing down along with my antennas.
So I spent a good bit of time this summer considering and researching alternatives. As all hams know, there is no one perfect antenna and every antennas is a compromise antenna. As a married ham, having an XYL adds an extra level of compromise – her sense of aesthetics. A vertical attached to the eaves like my friend Ed, W1YSM has, or a mighty tower and beam =like my friend John K1LYP has, were both non starters.
I eventually considered trying a ground mounted vertical antenna, complete with ground radials. Our property in Cheshire, CT, includes about 5 acres of wetland beyond our backyard which can’t be built upon. I figured that placing the antenna just beyond the edge of the yard among the trees would be help obscure it, thus making the XYL happy, and the damp ground would also contribute to making a good ground plane.
I first considered a non-resonant 43 foot vertical which seems to have been all the rage over the past decade or so among hams. However as the 43 foot vertical is non resonant on any band, it would require the use of a tuner. Most of the articles I read agreed that the optimum location of the tuner is at the base of the antenna. Such a tuner would add significant cost to the project and its something I was not familiar with.
I next considered the trapped multi-band vertical. I discussed the pros and cons with another trusted ham friend, Steve, K1SKL. Steve told me that his first antenna was a trapped vertical and he assured me it should work well if properly installed.
So after a little more reading and research, I decided to give it a try and ordered the Hustler 6BTV antenna which would get me on 10, 15, 20, 30, 40, and a narrow portion of 80 meters. At the present time (Fall 2019) the antenna alone costs $241, and once you start adding the ‘recommended’ accessories – the price adds up quickly.
In addition to the antenna itself, I purchased the following components, accessories and special tools:
Ground Radial Plate $75
Tilt Base Fold Over Kit $62
Tilt Base Wing Nuts $10
Direct Coax Feed Add On Kit: $30
JetLube Pure Copper Anti-Seize $18
1000′ 14 AWG Copper Wire for ground radials $50
Radial Plate Wire Attachment Kits (2) $18
200 Lawn Staples $32
Guying Kit $34
4′ 4×4 pressurized wood post $13
50 lb sacks of Quickcrete (2) $12
Post hole digger $37
Bow saw for cutting down interfering nearby tree limbs $10
100′ LMR400 feedline $120
When you add in the miscellaneous small parts I needed (replacing hardware I damaged such as over-tightened hose clamps, I was in about $800 – wow, that equates to approximately at least a dozen over-priced pre-fabricated G5RV antennas!
My work on the vertical antenna installation started back in late September. I easily identified a good location about 20′ back into the wooded area behind the edge of the backyard where there was a small clearing bordered by some downed trees and rocks.
Digging the hole for the post wasn’t difficult. Using the post hole digger I bought from the Home Depot made for fairly easy work. I encountered some tricky roots along the way, but none too thick that I couldn’t hack through them. My hole ended up being about 28″ deep.
Setting the post with Quickcrete was a snap too. I started by adding about 2″ of crushed stone to the bottom of the hole for drainage and poured the Quickrete directly into the hole around the post, checking often to make sure it stayed level. Per the Quickcrete instructions I poured about a gallon and a half of water directly into the hole and again double-checked that the post remained level. The concrete set and the post was rock steady by the next morning.
The next step was to attach the DXEngineering radial plate about 2 inches above ground using a pair of lag bolts.
The radial plate has 60 pre-drilled holes to attach ground radials and it was my intent to put in all 60. My first weekend attaching radials, I installed the first 20 radials by crimping the loop connector to the end of the copper wire on site, bolting the loop to the ground plate, and then crawling away from the post, rolling the wire spool outwards, and tacking down the radial with lawn staples as I went. This turned out to be an exhausting way to work, but it did allow me to maximize the length of each of the first 20 radials to fit the space I was installing it, stopping when I encountered a rock, a tree, or downed tree trunk.
I had read that when installing a ground based vertical antenna, the length of the radials isn’t as important as the quantity of radials. For elevated installations it is more important to have radials cut to resonance for specific bands. My first 20 radials measured anywhere from 15′ to 30′ long.
The following weekend brought sub-freezing temperatures and a nasty head cold. So I spent my antenna time working indoors preparing the next 40 radials. These I cut to 15′ in length each, crimped the loop connector, and then coiled the radial carefully so they wouldn’t become tangled. The following weekend I as able to quickly install these radials much more quickly than the first 20.
A few of my crimping jobs failed, so I ended up settling for 50 radials and I subsequently ended up pulling another 3 or 4 from the loop connector when standing on the radials near the post. Next spring I plan to revisit the radials, adding the remaining 10 and repairing any that are damaged to get back up to 60. I will then add crushed stone around the base and covering the radials in order to provide some protection.
Once I was satisfied with the radials, the next step was to attach the tilt over mount to the 4×4 using another pair of lag bolts and the pivot point bolts and lock nuts that came with the antenna. I encountered some difficulty with the one of the nylon lock nuts and ended up having to take a trip to the local hardware store for a replacement.
Assembling the antenna
The following weekend I began assembling the antenna mast in the garage. Assembly was easy enough, however I managed to over-tighten two of the hose clamps that came with the antenna, so this meant another trip to my local hardware store.
Once assembled, I carried the mast out to the base for mating. The 23′ length made it awkward to move, but it wasn’t heavy and actually felt pretty balanced in terms of weight distribution. I used a plastic lawn chair to support the top end of the mast while mating it to the base and then again when folding the antenna over for tuning.
Despite my best estimate of the space needed for the antenna to fold over, I didn’t properly account for 3 gnarly tree limbs that managed to snag the 80M whip when folding the mast over. I picked up a $10 bow saw at the Home Depot and was able to easily remedy this problem this past weekend.
Tuning the traps
The final task was to tune the antenna for each band which is done by loosening the hose clamp at the bottom of each of the traps and sliding the trap downward a bit to adjust for a lower SWR. After each adjustment, I needed to raise the antenna again, take another reading, and then repeat the process until the antenna was in tune for that band.
I used my Rig Expert AA30 antenna analyzer and per the DXEngineering instructions, I started with the 10M band and proceeded to adjust each band in order – 10M, 15M, 20M, 30M, 40M, 80M.
I was able to obtain SWR readings of under 2.0 across most of the bands, which was ‘good enough’ for me given the fact it was below freezing out this past Saturday with a forecast of snow coming. I wanted to be sure I could get on the air before winter fully set in and I planned to revisit the tuning come the warmer weather in springtime.
How does it work?
When I first tried the antenna on the air last Saturday, I was surprised to hear very few stations on 20 M and 40 M. My SWR readings taken at the radio in the shack were also much higher on all bands than observed at the antenna site. Most vexing of all was that I was getting an infinite SWR reading on 20 M! How was this possible???
I decided to not obsess and let the problem go for the night. I returned to the antenna early the next morning to recheck the tuning only to find that nearly all bands were still in tune. (30 M was a bit high in the lower portion of the band than I thought it was the previous day.)
Working logically and through a process of elimination, the next likely culprit would be the feedline. I had purchased a new 100′ run of LMR400 from Quicksilver Radio at the Nutmeg hamfest this fall I had planned to use with the new antenna, but that came up short. I connected it to my existing feedline which ran from the house, underground around the driveway and up to the berm where my previous wire antennas were located. Knowing the new LMR400 should be perfect, I decided to connect it to another 100′ run of coax to connect the antenna directly to the feed point on the house.
That seemed to do the trick.
On Air Success!
After changing out the feed line, I immediately noticed a huge difference on the air. First, there was a lot of activity on 20 M and 40 M, and the measured SWR at the rig was back down under 1.5 for both bands.
I worked KC5SCK in Georgia on 20 M who gave me a 59. My second contact on 20 M was with Belgian Special Event Station OR18TLS (HRH Princess Elisabeth’s 18th Birthday) who also gave me a 59. My next contact was with F5RAG in France who gave me a 55 signal report and my last contact that morning was on 40 M with K0BAK/VE2, a Parks On The Air activation of VE4920 in Quebec. This time my signal report was only 36.
I was relieved that the antenna was resonating and I was able to make contacts and I look forward to getting better acquainted with it in the winter months ahead.
The future and conclusion
When the weather warms next spring, I plan to revisit the installation for some touch up work. My to-do list includes replacing a few of the radials I damaged and installing the rest to get to the full planned set of 60. I also managed to bend one of the hinge bolts on the fold over base (something the instructions cautions you to be careful about) which will need to be replaced. Lastly, I will want to revisit the tuning of all bands.
Overall, this was a really fun project that consumed the better part of two months and in the end my antenna is performing as anticipated. I would recommend the Hustler trapped vertical for any ham who has the time, space and money to undertake the project. It is not a quick installation, nor is it inexpensive. But the project was manageable and even fun and the satisfaction of making contacts with an antenna I assembled can’t be beat.
Have you installed a Hustler trapped vertical? What was your experience like? Feel free to drop me a line at email@example.com.
Have you discovered the wonder of shopping at Banggood or AliExpress? They are both something of a Chinese version of Amazon.com (in fact the Banggood logo is not at all unlike Amazon’s) – online superstores where you can buy a wide variety of products from electronics to clothes to sporting goods to cellphones to jewelry to automotive parts and so on.
The smiling Banggood and amazon logos also feature similar color schemes
One can make several arguments – political, risk, quality – for not purchasing from Chinese online vendors, but I can think of two solid arguments why I enjoy shopping there – the wide selection and the low prices.
Both Banggood.com and AliExpress.com sell several DIY (do-it-yourself) electronic kits – such as radio receivers, MP3 players, test bench equipment, digital clocks, ham radio QRP kits and accessories, etc. The variety is fairly large, especially in comparison to what is available these days from US vendors.
When I was a young scrub, Radio Shack sold a popular line of P-Box (perf-box) kits and I pretty much built all of them including the one-tube AM receiver, the indoor/outdoor thermometer, the shortwave receiver, and the “GoofyLight.”
For the last couple of decades before they folded, Radio Shack did not offer electronic kits that required soldering and several other companies that produced DIY electronic kits, such as Heathkit and Ramsey Electronics have now too either gone out of business or no longer sell DIY kits.
While there are still some excellent smaller scale firms producing mostly ham radio oriented kits today (Four State QRP Group,QRPme, Elecraft), the easy availability to basic electronic kits, like the ones I enjoyed building as a child, doesn’t exist today.
Enter our Chinese Friends
In recent years I have purchased a few DIY electronic kits from Banggood and AliExpress. My experience has been mostly a good one – the kits are crazy cheap, but sometimes the quality of the parts has been marginal at best.
Another problem I have had building kits from China is reading the instructions. English instructions aren’t always included, and when they are the translations are horribly fractured.
The ability to read a schematic can be beneficial, but may not be enough. I have attempted to construct Chinese radio kits where the schematic did not match the PC board and/or the parts provided. I have also been been frustrated at times to find key identifiers for parts like transformers are identified only with Chinese characters on the schematic.
One interesting hack for dealing with a problem with color coded parts such as RF transformers, that I picked up from a shango066 YouTube video, is to reference the resistor color code chart that might be included the instructions. This makes it possible to identify the parts by the Chinese character for the color in order to correctly place transformers on the circuit board.
The Banggood Calculator
Speaking of resistor color codes, what initially attracted me to building this specific calculator kit is that I noticed on the Banggood website that the buttons on this calculator had the corresponding colors of the resistor color code.
The calculator has a mode that will calculate 4 band or 5 band resistor values by entering the color of the rings. (Yes I know that you can easily calculate resistance with the simple table, but this is sort of a cool novelty.)
The calculator has 3 other function modes – basic decimal arithmetic, voltage calculations for LEDs, and decimal-hexadecimal conversion.
One of the great things about this specific kit is that the printed instructions were very good overall and they also included a QR code and the URL for a very well done fully illustrated online step by step assembly guide.
The entire kit took less than 90 minutes to build and I encountered no problems along the way. I did use an ohm meter to confirm the values of the resistors before soldering them in place. The acrylic case went together fairly easily, although aligning the last three screws that hold the LCD in place required a little back pressure with my free hand.
Overall this was an excellent project for a Sunday morning at the workbench and now I have a one of a kind calculator that I can take pride in having built myself.
The only criticism I have about the calculator is that in order to change the two CR2032 batteries, you have to disassemble pretty much the entire acrylic case as there is no battery door. As mentioned above, mounting the LCD screen was a bit fiddly so I hope the batteries exhibit a long enough life.
Overall I would recommend this basic kit for anyone who enjoys building such things.
Have you built any DIY electronic kits from a Chinese online retailer? If so, which ones and what have your experiences been? Please drop me a line at firstname.lastname@example.org.
Every year on the fourth full weekend of June, the ARRL (American Radio Relay League) and the RAC (Radio Amateurs of Canada) sponsor Amateur Radio Field Day, when amateur radio operators all across North America practice emergency communications, operating either from outdoors stations they set up for the event using non-commercial power, or from Emergency Operations Centers (EOCs).
In addition to providing ham radio operators with the opportunity to practice operating in challenging conditions, Field Day is also an opportunity to give amateur radio greater exposure in the public eye as our sites are open to general public and many include a GOTA, or Get On The Air station where unlicensed persons can experience communicating on the ham bands with the help of a licensed operator.
This is the second time that I have participated in Field Day with the MARC/WARG folks, and once again I had a great experience. My ongoing amateur radio resolution for this year has been to work on improving my CW (Morse Code) skills and Field Day provided a great opportunity to practice my ‘fist’ as I signed up to take the graveyard CW shift from 2:00 – 6:00 am along with my friend K1STM, Anne.
Anne has been a licensed ham radio operator longer than I have been alive, and her CW skills are amazing. Not only can she copy Morse Code sent at a much faster speed than I can, she can also pick out the faintest Morse Code signals burried under the background noise that I completely miss!
In preparation for the start of my 2 am shift this morning, I went to bed early last night (before the sun set!) and set an alarm for 1 am. Before turning in, I had the coffee maker programmed to brew a pot of coffee which I brought along in my trusty Stanley vacuum bottle.
Arriving at the Wallingford EOC around 1:30 am, I met up with KC1SA, Steve, who was wrapping up the prior shift. He walked me through some of the basics of operating the club’s Yaseu FT991A transceiver which is linked to the N1MM logging software and controlled by the shack PC.
Operating CW in a contest from a PC keyboard is pretty easy. The software allows for the easy transmission of several pre-recorded messages such as our club call sign, the basic Field Day exchange, etc.
I operated the first ninety minutes of our of shift and made 13 contacts on the 40 meter band between 2:00 and 3:30 am. The band was not crowded and most ops were sending at a speed I was comfortable copying at, right around 20 words per minute. I was able to work several stations on the west coast in Arizona, California, some in Florida and even one station in Hawaii.
Anne took over around 3:30 and she also made 13 contacts on 40 meters before our shift ended at 6:00 am. Anne is blind so she relied on me to log the contacts she made in the N1MM logging software. Instead of using the computer keyboard to transmit, Anne operated using the Bencher paddles.
By the time our shift was over, I was exhausted, but felt good about the work we did. We were rewarded with a feast of a breakfast that included omelets, pancakes and Chorizo. In addition to making contacts on the air, we hams really love to eat too. Last night at the EOC, John Bee, served his famous “road kill stew” – a MARC/WARG Field Day staple for years.
After breakfast, I drove Anne home and then decided I would make a few additional contacts from my home station. I worked another dozen stations, mostly in the midwest, running 100 watts on 40 meters using my Kenwood TS2000 radio to my G5RV antenna.
So, Field Day 2019 is done and I had a great time once again. Did you operate Field Day? Let me know how it went!
The National Institute of Standards and Technology Radio Station WWV will be celebrating its 100-year anniversary in October 2019. The oldest continuously operating radio station in the world deserves a
The National Institute of Standards and Technology (NIST) and the Northern Colorado Amateur Radio Club (NCARC) have reached an agreement and are working together to organize the event.
NIST will focus on the plans for Tuesday, October 1, when they will host a recognition ceremony and an open house at the radio station north of Fort Collins.
NCARC will operate a special event amateur radio station, call sign WW0WWV, on the WWV property starting September 28, and going 24-hours a day through October 2. The goal is to make as many U.S. and world-wide contacts during the 120-hour period as possible, using multiple bands and multiple modes on at least 4 simultaneous transmitters. The effort will require hundreds…
As I have previously blogged about in this space, my ham radio resolution for 2019 has been to get on the air and make contacts with the low-power or “QRP” kits – transmitters, receivers, transceivers, and accessories, that I have built.
Today I write to report that I have achieved my goal, having made my first two QRP contacts today with W1NVT in Vermont and N1QLL in Maine on 40 meters.
my G5RV antenna running N-S about 70′ up in the trees parallel to my driveway in Cheshire, CT.
QRP: What and why?
Operating QRP (ham radio slang for ‘low power’) is a distinct niche within the hobby. The generally accepted definition of what qualifies as QRP, is using a transmitter putting out 5 watts of radiated RF power, or less. By comparison, most commercial high frequency amateur radio transmitters today are capable of transmitting 100 watts. Many hams will use amplifiers to increase the 100 watts up to 1.5 kilo-watts. Operating high-power is known as QRO, as opposed to QRP.
QRP operations attracts tens of thousands of hams, including yours truly, but why? After all, conventional wisdom holds that more power = more contacts as a stronger single may be received further away and be easier to copy.
Speaking for myself, there are several factors that have attracted me to QRP. Here are the top five:
1.) Building and operating my own gear
Any regular reader of the AB1DQ.com blog will know that I love to melt solder, to build kits and home-brew projects, and to troubleshoot and repair vintage electronics.
It all began when as a child I would while away the hours in my grandfather’s workshop. As a younger man, Grampy had enrolled in the DeVry Institutes home radio & television repair course (originally known as the DeForest Course) and his workshop contained not only all of his text books and tools, but also a cornucopia of old radio an TV carcasses for me to ‘work’ on. (I let out more than my fair share of magic smoke in those days, and blew the house circuit breakers more than once!)
Today when I am in my workshop, I feel a connection to my late grandfather, especially when I am using his vintage test equipment that I have restored and kept in service.
And, as magical as it is to have someone on the other side of the planet respond to a signal I transmitted using a commercial radio, it’s just that much more special when I hear my call sign coming back to me on a radio I built from scratch.
Amateur radio is the only citizen radio service sanctioned by the FCC that not only allows, but encourages, its licensees to build, modify and experiment with their own transmitters and QRP allows me to do just that.
2.) The challenge & satisfaction of using minimal power
Quoting the FCC rules §97.313 Transmitter power standards… (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications.
Because the communications I desire is anycommunication with another station using a transmitter I built myself, 5 watts is more than enough power to get the job done – and its going to provide me with plenty of fun
One S-unit, the minimal change in signal strength that is noticeable, is equal to 6 db. For one S-unit increase in gain you would need to quadruple your power output. To gain one S-unit from 5 watts output, you would have to go to 20 watts to increase your signal strength by 6 db.
K3WWP, a co-founder of the North American QRP CW club NAQCC has provided this handy table on his excellent website addressing the matter:
This suggests that all other factors being equal, an operator could expect his signal report to go from a very good 579 report to a perfectly copy-able 559 when running 5 watts vs. 100 watts barefoot.
What I know from first hand experience is that I have on occasion logged successful contacts on SSB from Connecticut all across the US to the west coast running 5 watts on my Kenwood TS2000. If I can make transcontinental contacts running QRP phone, it should be that much easier to do so with the narrower bandwidth needed for CW.
3.) QRP is inexpensive
A lot of hams get their General class ticket giving them access to the HF bands but then discover that commercial gear, can be cost-prohibitive.
The popular basic Icom IC-7300 currently retails for $1,099 and the bare-bones IC-718 (the very first HF radio I purchased back in 2002 when I was first licensed) costs $599 new today.
Compare those prices to the cost of my QRP station above…
The WA3RNC transceiver base model without the digital dial, retails for $99, the 4S Tuner retails for $53, the VEC201 CW keyer is $30 and the MFJ-813 QRP wattmeter costs for $40 new. That comes to under $220 for everything (sans paddles, power supply and antenna—all of which you would need to get on the air with either basic Icom radio above).
4.) QRP is portable
The small size of most QRP radios and equipment makes it ideal for portable operations, easily fitting in a backpack or suitcase. Many QRP operators enjoy taking their stations with them when they travel and operating from hilltops, campsites, or hotel rooms is very popular.
Although I have not yet done so, it is my desire and part of my 2019 radio resolution to go portable with my QRP station. This weekend I attended NEARfest in Deerfield NH as I do most years. The weather was a washout for the most part, but I did stop by the Quick Silver Radio table in the commercial building to address my need for portable power.
Proprietor John Bee, N1GNV, a good guy and fellow member of the Meriden Amateur Radio Club here in Connecticut, hooked me up with one of their new Hammo-PWR power boxes, which contains a 12 aH rechargeable battery in a compact water resistant ABS case and some PowerPole connectors.
The only piece I am now missing for my portable QRP operations is a very good portable antenna. In the coming weeks as the weather improves I plan to experiment first with my Buddi-Stick antenna as well as some wire antenna ideas including easily transported dipoles and end-fed wires – stay tuned to this space for updates!
5.) The QRP community is awesome
There are many excellent radio clubs dedicated exclusively to low power building and operating and I am a member of several of them.
The QRP Amateur Radio Club International publishes my hands-down favorite ham radio magazine, the QRP Quarterly. I read every issues cover-to-cover as soon as it arrives as it is chock-full of excellent articles including technical pieces, equipment reviews, hints and kinks, and experiences of fellow QRPers.
The North American QRP CW Club is a dynamic club dedicated to the promotion of QRP operations. Each month the NAQCC operates a fun month-long on-air challenge and a sprint. There is no membership dues and the club also publishes an excellent online newsletter each month.
The QRP Club of New England is another fine local club to which I belong. The club holds a weekly CW net on 80 meters on Thursday nights and always presents well attended informational sessions and a buildathon at the Boxboro New England Hamfest each September. I really enjoy meeting other club members and melting some solder with them each year.
For many years I have enjoyed building various QRP kits and feel I have learned a lot about radio fundamentals along the way.
This year I am finally venturing into going on the air with the radios and equipment I have built and the prospect of making contacts with homemade is very exciting.
I invite other QRP enthusiasts whether old timers, noobs like me, or prospective QRPers to write me at email@example.com to share their experiences.
Stay tuned for future blogs about my experiences and in the meantime,
Following up on last week’s successful build of the Four State QRP Group TRF one transistor radio kit, The Murania, this Sunday I thought I would tackle the build of their 4S Antenna Tuner kit.
As I wrote in last week’s blog, I have been a long time fan of the great kits the 4SQRP Group develops and sells, so I was excited to tackle this project. My overall ham radio goal for the spring is to assemble and put a completely home-built portable QRP station on the air this spring, and the 4-S Tuner should prove to be an essential component of my station.
Like the Murania kit I built last week, the 4S Tuner was designed by NM0S, David Cripe, and both kits share several of the same features including “Pittsburgh construction” where the backside of the PCB doubles as the front panel, and a case that is cleverly assembled by soldering six pieces of PCB together.
The fist step in building the tuner is to construct the inductor which is mounted directly to the back of a rotary switch. For many folks, winding toroids can be a chore. I’ve messed them up myself several times in the past, but as a general rule, I don’t shy away from kits that require toroid windings.
I found that winding the 4S Tuner toroid was actually a pretty straight forward task. For one reason the toroid itself was large enough to manimpuate easily in my hands. Another factor that made the project easier was that the kit comes with BUSS wire instead of enameled wire which is difficult to create taps with as the insulation must completely removed at each tap… a fiddly prospect at best.
But best of all, because the toroid is mounted directly to the back of the rotary switch, “stitched together” if you will by the windings, the overall construction was very straight forward.
The instructions provide two options for the builder, whether to place maximum inductance at the first, “A” position on the rotary switch, or whether to place maximum inductance at the last, “L” lug. I chose the first method.
Once the inductor/switch assembly ws completed it was time to move on to attaching components to the PCB. The kit contains a nominal amount of parts – 6 resistors, 3 ceramic capacitors, 2 LEDs, 2 transistors, and 3 diodes.
“Pittsburgh” construction is sort of a large scale surface mount method where there are no holes and components are soldered directly to pads on the PCB. Pittsburgh native Joe Porter, W0MQY is credited with developing this construction method. and this is my second 4SQRP kit built in as many weeks using the Pittsburgh construction method. I have found it to be especially beneficial when removing components – desoldering is a snap and there is no need for a desolder pump or wick to remove solder from plated holes. In the case of the Murania last week, the ability to unsolder and swap out components made modifying and experimenting with the radio a true joy.
The next steps involved attaching the inductor, tuning caps, a FWD/REV DPDT switch and a pair of BNC connectors. The entire build took less than three hours and was a wonderful way to waste a blustery spring Sunday.
“The transceiver drives R1, R2, and R3, three 47 ohm resistors, with the antenna forming the fourth leg of the bridge. If the antenna is 47 ohms the bridge is balanced, and the differential RF voltage between the two legs (between R1-R3 and R2-Antenna) is zero.
“The diode-capacitor circuit D1-C4 detects any differential RF voltage present and generates a negative DC voltage across the capacitor proportional to the amount of mismatch.
“The benefit of using a resistor bridge, as opposed to a more conventional transformer-type bridge, is that regardless of the impedance of the antenna, the worst VSWR ever seen by the transmitter while tuning up is 2:1. For QRP rigs without internal VSWR protection, this should prevent damage to the finals.
How does it work?
You will need to stay tuned for my on air review. As I mentioned above, my overarching project for this spring/summer is to put a completely home build QRP station on the air and while several components have been built, I’m not quite there yet.
Future blog posts will describe some of the QRP transmitters, receivers and transceiver projects I have worked on.
The Four State QRP Group (Oklahoma – Kansas – Arkansas – Missouri, in case you were wondering), founded in 2003, is one of the best developers and retailers of high quality and reasonably priced QRP (low power) ham radio and other do it yourself electronics kits.
Tonight I tackled one of their popular new non-ham radio kits, the Murania, a one transistor Tuned Radio Frequency (TRF) AM broadcast band receiver kit. The kit was designed by NM0S, David Cripe, who has engineered several of the 4SQRP kits.
The documentation for the Murania tells of the advent of transistor radios in the 1950s and how radios with 1 or 2 transistors were considered toys and therefore not taxed like radios containing more transistors. These 2 or less transistor “toy” radios became known as “Boy’s Radios” and are highly collectible today.
The designers of Boy’s Radios employed some creative design techniques to maximize the performance of these minimalist circuits, with sometimes amazing results. The Murania kit was inspired the design of those simple high performing transistor radios.
My Murania kit arrived quickly within 2 days of placing my order online….WOW!
The Murania features a unique construction technique called “Pittsburgh Construction” developed by W0MQY , Joe Porter, in which components are soldered to the surface of pads on a silk screened double sided PCB.
Like other 4SQRP kits, the assembly manual needs to be downloaded from their website. Documentation is very good with clearly expressed step by step directions, but lacks pictures which might be helpful in illustrating potentially confusing steps for the newbie builder, such as the correct orientation of a polarized component such as an LED, diode or electrolytic cap.
The 4SQRP website suggest the kit can be built in about 2 hours time, and that was my experience. The radio is built in five stages… (1) wind the coil, (2) build the voltage regulator, (3) build the audio amp, (4) build the RF circuit, (5) final assembly.
1. Winding the Coil
The first task is to wind the coil which consists of 37 turns of No. 22 AWG enamel wire around a ferrite core. The instructions call for covering the core with a layer of masking tape first and using masking tape to hold the first and last winding in place.
I chose to use black electrical tape, and that was definitely a mistake – the electrical tape made it difficult to compress each winding snug against the previous winding and it didn’t do a very good job of holding the first and last winding in place.
I believe this may have also affected performance of my radio (see below). I am planning on modding the set and rewinding the coil with 61 turns (also, see below) and will use the recommended masking tape at that time.
2. Voltage Regulator
The first circuit constructed is the power supply/voltage regulator which consists of installing the volume control pot and attached power switch, one electrolytic capacitor, the battery connector, another capacitor and a resistor and the LED which serves three functions – power on lamp, signal strength indicator, and voltage regulator delivering 1.6 – 1.8 +VDC to power the radio.
I appreciated that the instructions called for testing the voltage regulator circuit before proceeding on to the audio amp stage. My Murania was putting out 1.792 VDC+ within the acceptable range of 1.6 – 1.8 volts.
3. Audio Amplifier
The Murania has a single stage of audio amplification based on the 2N3904 NPN transistor that drives the speaker through a matching transformer.
Other components in the stage included a pair of capacitors, a single resistor and of course, the transformer and speaker.
4. RF Stage
The bulk of the RF work is handled by a single IC, the TA7642, which has its origins in the late 1960s. Equivalent to the ZN914 and MK484, the TA7642 contains ten transistors and performs the task of RF amplification, audio detection, and automatic gain control. The documentation points out that with the TA7642, it is possible to construct a Tuned Radio Frequency receiver with useful sensitivity and selectivity, using only a handful of components and that this device served as the basis of many radio receivers that were the successors to the Boy’s Radios.
Like the voltage regulator and audio amplification stages the RF stage went together without a hitch. All parts in the kit were properly identified and clearly referenced in the assembly manual. The etching on the circuit board made mis-installation pretty much an impossibility if you’re paying attention to what you’re doing.
5. Final Assembly
After testing the radio to make sure it works (it did), the last step was to assemble the rest of the cabinet which is comprised of five additional pieces of yellow PCB material with pads strategically placed to match up for soldering to connect.
The pieces fit together perfectly, although I should have taken time as recommended in the directions to file off burs and rough spots so the pieces fit together more perfectly. Overall this is a pretty ingenious way to build a radio cabinet.
PERFORMANCE AND MODS
I was very pleased that the radio worked right away. I was able to pick up several AM stations with ease. Stations received were clear and the audio, while not as loud as I would have liked, was not distorted.
One problem I did encounter that is worth mentioning is that after I tested the radio on my bench I attached the back to the radio and brought it to my wife to show off my handiwork.
She was impressed, however when she turned the radio on, the LED lit up but there was no sound coming from the speaker – absolute silence – UGH!
I took the back off and quickly diagnosed the problem – the top of the 9V battery was shorting the speaker terminals – a problem easily fixed with a piece of electrical tape across the speaker terminals.
I did expect the radio to be a little more sensitive than it was initially and I realized that the radio’s performance might have been inhibited by my sloppy coil winding.
Online I found a list of three simple mods for the radio published by Jim Marco, WB2LHP in MI, the third of which that involves additional windings on the coil so I thought I’d give them a try.
Here are Jim’s mods…
1. Detector Gain Control…
FLOAT the wiper lug of R3 and place a jumper between the PADS for the R3 wiper and the high side of R3.
Lift the leg of R1 that intersects with R2 and R3 and connect a jumper between the floated leg of R1 and the wiper of R3.
According to Jim, this allows R3 to control the gain of the detector stage in the TA7642 acting similar to a regen control where there is both volume and gain reaction. The audio amp runs wide open and R3 should be adjusted for the best sounding audio.
2. Reduced audio distortion…
Changing R2 from 1K to 2.7K biases the output stage of the TA7642 for linear operation.
3.Frequency coverage and dial mapping…
Increasing L1 from 37 turns to 61 turns and removing C8 centers the frequency coverage and makes the dial tracking spot on…
I am pleased to say that the mods were easy to accomplish and I had no difficulty with any of them. I did not have a 2.7K ohm resistor on hand so I tied a 2.2k and a 470 ohm resistor in series for R2. Using the recommended masking tape instead of rubbery electrical tape on the ferrite rod made a world of difference too – winding the 61 turns was a snap.
And how did it work? Even better than before – the radio seems to be more sensitive and is picking up more stations and the audio is definitely more crisp as promised. If you’re looking for a fun one-evening project that will take you back to your earlier days of melting solder – the Murania TRF receiver is worth building.
My dear wife Ellen returned from spring break in the Dominican Republic with her college girl friends last week with some wonderful gifts for me – a box of 25 Cohiba Siglo IV cigars – and – two Behike 56 cigars. No man ever married better than I, as last year she returned with some Cohiba sticks as well as a box of Romeo Y Julietta cigars.
I know that I should have kept both of the Behikes in my humidor to save for a special occasion, but I simply could not wait to try this, Cohiba’s most legendary ultra-luxury, highly rated and greatly desired cigar brand.
So yesterday afternoon found me at my favorite local cigar bar, The Owl Shop in New Haven, Behike in tow, to meet up with my good friend Carl J. Frano for a Sunday afternoon cigar and a whisky.
As the Behike is a good two notches above my typical smoke, I reckoned it was right to pair it with something a bit more upscale than my go-to double Jack on the rocks. I chose Laphroaig 10 year old single malt, and in retrospect, it was a good choice.
About the Behike
The Cohiba Behike BHK line was launched in early 2010 and is a limited production stick. It comes in three sizes – the BHK 52 is the smallest at 4 3/4 inches by 52 ring gauge, the BHK 54 is the middle child at 5 3/4 inches long by 54 ring and BHK 56 is the big boy Toro at 6 1/2 inches by 56 ring.
What places the Behike above the other Cohiba cigars is the medio tiempo leaf which comes from the two top leaves of the tobacco plant which gathers more sunlight and contributes significantly to the flavor and the limited quantities.
The Behike 56 was beautifully crafted, featuring a very neat triple cap with pigtail, a noticeable spiral seam, some slight leaf veins throughout. The cigar was nicely packed and firm from foot to cap. It felt glorious in my hand.
I cut the cap and savored the delicious cold draw. The predominant note was earthy barnyard grass and cedar with a slight hint of cocoa. The cold draw was milder than I had anticipated, but very pleasant. I did not rush to light the cigar.
I found the draw to be a little tighter than anticipated but not bad by any stretch. Flavor notes were mild earth and cedar and mild spice too. Not overwhelming but not underwhelming either. Many of the other reviews I read fault the 56 as being a little milder than the BHK 54 and 52, due to its size. While I haven’t sampled the 56’s little brothers and am not likely to anytime soon, I would say that the 56 was definitely mild.
The burn was excellent, very straight and the cigar produced a nice firm salt and pepper ash that hung on to about the inch and a half mark.
Towards the end of the first third, I picked up on some mild nuttiness.
The flavor notes of the second third did not change appreciably from the first, and that wasn’t a bad thing at all. Again there was a mild cedar or leather flavor, some mild spice (black pepper) and a hint of sweetness, perhaps cocoa. The flavor, though mild, was very pleasant and very smooth overall. I did pick up on some creaminess developing around the midpoint of the cigar.
The burn continued to be excellent and the draw, which I previously noted as a bit tight initially, was good throughout the middle third.
In my experience, the flavor profile of the Cohiba Behike 56 was nothing if not consistent. I didn’t notice any new notes as I smoked my way through the final third – I would say the cigar was a bit creamier at the start of the last third.
I did note that the overall taste, which was pretty mild, got much more intense in the last half of the last third. It wan’t unpleasant, but the flavor intensity was increased and noticeable.
Burn and draw remained excellent right to the very end. Total smoking time was 2 hours and 15 minutes.
What can I say about this cigar that more experienced reviewers haven’t said before? Clearly this was the finest cigar I’ve ever had the privilege to smoke, and I totally get why it fetches such a premium price.
This cigar was simply delicious all the way through. The one word that would best summarize my overall impression would be ‘smooth.’
If you have the opportunity to smoke a BHK 56, I don’t think you’re going to be disappointed. Perhaps the 54 or 52 might be a better choice as they are purported to have a more intense flavor profile.
I look forward to saving my other Behike 56 in the humidor for a special occasion. Clearly a 10/10 smoke, anyway you slice it.