Tag: QRP

Bayou Jumper in a Cigar Box

I was thrilled to see that the good folks at the Four State QRP Group released the 4th revision of their popular Bayou Jumper 40M CW Transceiver designed by Jim Giammanco N51B and David Cripe NM0S last year.

The Bayou Jumper, first released in 2017, is a 40M QRP transceiver that is an homage to the classic Paraset, the legendary transmitter/receiver supplied to the resistance groups in France, Belgium and the Netherlands during World War II.

Whaddon Mk VII – Paraset Clandestine Transceiver c. 1942

The Bayou Jumper, an updated solid state CW only radio kit is intended to be fitted into a hinged wooden suitcase style box available from Hobby Lobby or any other similarly sized box.

Given my recent obsession with building QRP radios and accessories into empty cigar boxes, I felt the Bayou Jumper would make an excellent candidate for cigar box treatment. I found a gorgeous Perdomo 20th Anniversary cigar box in my stash that was approximately the right size, featured gorgeous red and gold artwork on a black background and was constructed of heavier wood than many of the other cigar boxes in my collection.

The Bayou Jumper front panel was a perfect flush fit left to right in the Perdomo box, and only fell 1/2″ short front to back. I modified the box by gluing a 1/2″ square dowel along the top hinged edge to fill the empty space.

Other mods I made to the cigar box included:

  • Adding weights to the bottom of the box to prevent the radio from tipping over backward when the lid was up and to provide a little more heft,
    • Adding a pair of latches to be able to secure the lid closed, and,
      • Reinforcing the original pressed in hinges with three supplemental screw-in hinges.

Building the Kit

I chose the Bayou Jumper to be my 2022 Christmas project. Professionally I have worked in an administrative role in higher ed for the past two decades and one of the biggest perks of working at most leading universities is they completely shut down for an extended winter recess. Building an electronic kit during my winter recess takes me back to my teenage years when I’d spend my holiday break from school constructing the electronic kits I received as Christmas gifts.

Like every NM05 designed 4SQRP kit I have previously built (the Murania One Transistors Boy’s Radio, the 4S-QRP Antenna Tuner, and the Ozark Patrol Regen Shortwave Receiver), assembly was a relaxing no-stress experience. Once again, I was very pleased with the high quality of the double sided etched-through printed circuit board, the quality of the electronic components and hardware, and the in-depth and easy-to-understand instructions and documentation.

I encountered only two minor issues in building the Bayou Jumper Revision D that were hardly a problem, barely an inconvenience.

The first was a missing resistor, R15, a 1/4 watt 100K ohm resistor. I have never experienced a missing part when building a 4SQRP kit and it’s probably just as likely I dropped or lost the resistor than it was wasn’t shipped in the kit. Regardless, I had the correct value resistor on hand in my home stock supply.

The second matter involved the jumper wires provided to supply current to the multi-color LED on the front panel from the main PCB. The instructions stated the kit included a 12″ jumper wire with header pins included in the kit that needed to be cut in half to make two jumpers. However, the jumper wire included in my kit was only 5.5″ long and once cut it in half as the instructions directed, one of the resulting leads was too short to mate to the header pin on the PCB.

As with the missing resistor, I had plenty of jumper wires that I use for breadboard prototyping on hand and was able to create the necessary jumper wires with sufficient slack to reach the contact points.

All in all, the kit went together in just 3 days’ time as I prefer to work slowly and methodically whenever I build a kit. (Whenever I rush through a project I typically find that any time I saved working quickly would be lost in extensive time consuming trouble-shooting that would be needed!)

The topside of my populated PCB. Assembling the kit was straightforward and fun.

Winding the Transformer

The Bayou Jumper features three inductors etched into the PCB but still requires the winding of a single transformer on a T 6-7 toroid core. I have never found winding coils to be difficult or stressful, and in fact, I generally enjoy it especially when the kitter provides excellent directions and illustrations, which 4SQRP did.

The transformer required 3 windings, one of 19 turns, one of 4, and the last of 2. The completed transformer can be soldered to either the top or bottom side of the PCB, based on the builder’s preference and tje screen printing on the circuit board makes installing the completed transformer essentially foolproof. I chose to mount the transformer to the bottom side of the board to make it easily accessible for adjusting the spacing of the winding to adjust the receiver’s tuning range.

The completed transformer mounted to the bottom side of the PCB.

Faux Crystals?

The Bayou Jumper’s crystal socket accepts the classic FT-243 crystal form, a popular Cold War era crystal size that today is no longer manufactured and increasingly rare.

The Bayou Jumper comes supplied with a pair of HC-49 crystals for 7.030 and 7.122 MHz, and two crystal adapter boards to fit the HC-49 crystals into the FT-243 sockets.

Vintage FT-243 cases are large enough to accommodate modern small HC-49 crystals and with its 3 screws, the FT-243 can be easily opened and re-sealed, making it possible to re-stuff FT-243 cases for modern QRP use.

Using several of the FT-243 crystals for non-amateur frequencies that I picked up at ham-fests, I have modified 9 crystals for use on the 40 meter CW sub band, all ready to go in my Bayou Jumper.

Receiver Alignment and Final Assembly

Again, the excellent directions made aligning the receiver a snap. Instructions are provided for a variety of alignment methods using an oscilloscope, a frequency generator or a calibrated receiver capable of CW reception. Having all three available to me, I tried all three methods and was pleased when all three were in sync.

I started taking a frequency reading with the tuning dial set to the low end of the scale with my O-scope and read 6.897 MHz.

Next I tried sweeping the dial of my frequency counter to spot the point where oscillation could be heard in the earphones. My frequency counter has an analogue scale and was able to read the resonant frequency at about 6.9 MHz.

Finally I set my portable C. Crane Skywave SSB travel radio for LSB and tuned to the 6.900 and tuning up and down was able to hear the receiver’s oscillator at about 6.895 MHz.

Following the directions to adjust the tuning range by spacing the L1 windings on the transformer closer together or further apart and then adjusting the C30 trimmer, I was able to achieve a final tuning range of 7.000 – 7.167 MHz which should be more than adequate for the CW sub-band I would use.

Finally, I followed the directions to verify regeneration and was happy to find that my receiver needed no further adjustment. Satisfied with my work, I mounted the radio in the cigar box and am looking forward to putting my Bayou Jumper on the air.


Stay tuned for Part II where I will report on my experience operating the Bayou Jumper on the air and any future adjustments or modifications.

QRPGuys End-Fed Multiband Antenna

“Unique ham radio kits for the budget minded.” That’s what the masthead proclaims on the QRPGuys website and that is exactly what you’ll find there – a collection of project kits for the builder/QRPer that aren’t found on other kit sites and all offered at a more than fair price.

Current transceiver kits include their AFP-FSK Digital Transceiver, now in its third edition and they also offer a wide variety of other QRP essentials including several antennas and tuners, test gear including power meters, attenuators and filters and other accessories,

The QRP Guys are an affiliation of a “who’s who” of QRP building and will give you an idea of the innovative and high-quality products they develop. Ken LoCasale (WA4MNT) provides kit mechanical design, board layout and documentation, and NorCal cofounder Doug Hendricks (KI6DS) is credited with logistic support and beta testing.

Circuit design is by Steve Weber (KD1JV) of Pacific Antenna, Dan Tayloe, creator of the N7VE SWR Bridge, and Cliff Donley (K8TND). Both Steve and “Kazu” Terasaki (AG5NS) author firmware, technical assistance is given by beta builder Yin Shih (N9YS) and John Stevens (K5JS) is credited with assisting Ken with website maintenance.

Building the QRPGuys 40-30-20 M End Fed Antenna

The QRPGuys multiband end fed antenna meets my definition of an easy build with only 16 solder-in components on the main tuner circuit board and the two traps. I started as I do with all of my kit builds by inventorying and arranging all of the parts. I have been using cigar boxes with clasps on their lids to prevent me from losing small parts before they are needed. Cigar boxes are also ideal for storing works in progress kits when a project will extend beyond a single building session.

This easy to build kit has a minimal number of parts.

The prospective builder should be forewarned that of those sixteen components, four of them are inductors that must be hand-wound on toroid coil forms. Many builders seem to abhor the winding of coils, and while I find it sometimes fiddly work, I’ve come to not mid the process.

I give props to the writers of the QRPGuys manual, as they provided some of the clearest instruction on how to wind the inductors, including the number of loops and where to place the taps. The manual also includes a nicely done illustration of each inductor and hints on how to assure the builder wound them correctly.

The diagram from the instruction manual clearly depicts how to wind the four inductors.

The inclusion of Thermaleze® brand magnet wire for the inductors was also a nice feature – the enamel coating was quickly dispatched after a few seconds of exposure to my Zippo cigar torch.

The entire build, including the winding of the four toroids, building the traps and measuring the three driven element lengths of wire took me less than 2 hours working at a leisurely pace on a winter’s Sunday morning.

Before
After

About the Antenna

Field testing this antenna will have to wait a few more weeks for more reasonable weather here in Connecticut, but my plan is to use this antenna for QRP POTA activations this year with various homebuilt radios such as the Ramsey QRP20 transmitter I assembled last week. The end-fed design should make for easy deployment as a sloper while operating from the field with easy access to the tuning controls from my operating position.

The tuner circuit design is as straightforward as it gets – your basic tunable L-C circuit with a varicon capacitor. But the kit also employs the N7VE LED absorption bridge that keeps SWR to a minimum of 2:1 when set to the tune position. According to the kit documentation, the LED indicates only reflected power. Full LED brilliance will indicate an SWR at 4:1 or greater. At half brilliance SWR is approximately 2:1, and the LED will completely extinguish at 1:1.

I was impressed with the apparent high quality of the PCBs and components, and I found the instructions and supporting documentation to be exceptionally well written – easy to follow and understand.

If you would like to build the QRPGuys Multi-band End Fed Antenna, you can purchase the kit on their website here. The current price of the kit is $40 USD.

If you have built this kit, or have any questions or comments, please feel free to leave a comment or drop me a line at james@ab1dq.com.

72 de AB1DQ/James

AB1DQ-QRP is on the air.

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 station today consisted of:

AB1DQ QRP station on the air today.: The WA3RNC 40M transmitter is the yellow device on the left. Clockwise, above, is the MFJ 913 tuner, the 4S Antenna Tuner, and the VEC-201 CW keyer. To the right of all and behind the paddles is the speaker for the LM386 antenna. I built all equipment seen here excepting the wattmeter and the Vibroplex paddles.

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!)

`This article from the July 1967 issue of Pop’Tronics, found in my grandfather’s workshop, first introduced me to the concept of QRP decades before I got my ham ticket.

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 any communication 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.

QRP ARCI’s QRP Quarterly is one of the most fascinating and useful ham radio publications available today.

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.

In conclusion…

For many years I have enjoyed building various QRP kits and feel I have learned a lot about radio fundamentals along the way.

Some of the many QRP transmitter and receiver kits I have assembled over the years.

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 james@ab1dq.com to share their experiences.

Stay tuned for future blogs about my experiences and in the meantime,

72 de AB1DQ/QRP

©2019 JMSurprenant

The Murania “One Transistor” Boy’s Radio Kit

INTRODUCTION & CONSTRUCTION

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.

I have a few of their kits over the past few years, most recently including the Bayou Jumper Paraset transceiver last year. I presently have the NM0S 4S-Tuner/Antenna Coupler kit on order.

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.

Unpacking the Murania kit.

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.

My first attempt at
winding the coil.

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.

The 10 transistor equivalent circuit of the TA7642 per the datasheet.


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.

The assembled Murania TRF radio ready for testing.

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.

  • THE FINISHED PROJECT – IT WORKS!

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.

The unmodified Murania Schematic ©NM0S, 4SQRP Group

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…

The revised schematic based on WB2LHB’s mods

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.

My modified Murania – notice the new ferrite coil, the replacement of R2, the removal of C8 on the right, and the jumper going from R1 over the speaker to the VR R3.

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.

©2019 JMSurprenant