W4TDJ - Thomas D. Jay's Amateur Radio Blog

Sunday, February 18, 2024

Antennas Have Become More Sophisticated, So Have Antenna Tuners

If you’re an active ham or contest operator you’re frequently scanning the bands for best ionospheric propagation and a signal rich environment. Whether rag chewing or contesting this means spanning the HF radio spectrum from 1.8 to 54 MHz. Add VHF, UHF frequencies and antenna farms can become a real challenge. Antennas are usually specified over a frequency range with SWR plotted on a chart. Usually with the antenna trimmed for a specific frequency the SWR is flat (1:1) and remains tolerable to the transmitter (below 2:1) over the CW or phone band. This operable window becomes narrower at lower frequencies. Today's automatic antenna tuners are gaining popularity, providing a wider spectral performance window for antennas.

There are two primary means of minimizing SWR reflected power. One is to precisely adjust the antenna to its resonant length. The second is to utilize in-line inductance and capacitance to achieve an acceptable impedance match to the antenna (usually 50-75 ohms). The first option is preferable as a resonant length antenna will provide best performance. Where physical space or access limitations are a concern an antenna tuner can enable effective operation without the need for physical adjustment of antenna length.

Always resonant antenna designs are optimal for RF propagation prompting the popularity of antennas such as the Step-IR (for fixed stations) and the Tar Heel or Diamond series (for mobile operation). These antennas provide active remote tuning of the physical antenna. That is to say the length of the resonating elements can be physically adjusted by remotely activated servo motors. Best resonance and SWR can be achieved at all times. Some of these systems auto adjust by tracking the VFOs frequency or a memory plot.

Many years ago I acquired a large variable inductor and capacitor to construct a home brew antenna tuner. It worked but it was difficult to adjust with changes in frequency. More recently I acquired an MFJ-998 auto tuner rated at 1.5 kw. It tunes antennas by rapidly relay switching networked inductors and capacitors to null reactance and optimize SWR. On a 43 foot long wire I can run my linear amplifier at full legal power on most bands. Connected to my Icom transceiver it auto tunes as it tracks the VFO. Living in a condo with limited space an automatic antenna tuner is most convenient. In my mobile I have an LDG auto tuner coupled to a Tar Heel HF antenna. I resonate the Tar Heel mid band and use the LDG to trim the SWR on the fly. This is great for contesting while minimizing operator distraction.

Recently in LinkedIn’s RF and Microwave and Circuit Theory and Analog Electronics groups, Frédéric Broydé, F5OYE and Evelyne Clavelier, F1PHQ posted their paper “A Typology of Antenna Tuner Control Schemes, for One or More Antennas” © 2020 by Excem. The paper is free to download. [1]

After reading the article I had great appreciation for the theory and implementation of antenna tuners. Spanning 24 pages I was surprised at the breadth and depth of their paper. As RF communication techniques proliferate, MIMO and multi-antenna configurations are of great interest in the commercial and amateur radio space. As amateur radio operators we might extract some valuable knowledge from their experience. It’s interesting that Frédéric uses a manual tuner on his amateur antenna (a dipole). Congratulations to Evelyne and Frédéric on their great work.

From an amateur radio perspective there are many antenna tuners available for amateur use. In case you missed the Hamcation hamfest in Orlando you can peruse a recent

Google search on antenna tuners here:

[2] https://www.google.com/search?q=antenna+tuners&oq=antenna+tuners&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTU4MDZqMGoxNagCALACAA&sourceid=chrome&ie=UTF-8

Although I was tempted, I confess I didn’t purchase anything at Hamcation. Hopefully you brought home a few new toys. Wishing you good tuning for DX. Until next time be safe everyone.

Best regards,

Thomas D. Jay, W4TDJ

Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property. Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. Thomas D. Jay is not a registered financial advisor. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated. Thomas D. Jay opts out of requests to share personal information or unidentifiable user data. Thomas D. Jay does not agree to indemnify or hold harmless vendors, clients or third parties to related contractual agreements and reserves the right to applicable legal remedies in lieu of arbitration. Thomas D. Jay retains all copyright and moral rights to his published material, content and brand marketing, and shall in no case be represented, depicted or characterized by parties/entities other than his published "About Thomas D. Jay" descriptor. Contractual agreements are to be written and interpreted in the English language and are subject to the laws of the United States. These terms and conditions shall supersede any conflicting agreement. Clients, vendors and concerned parties should check my blog site at www.thomasdalejay.blogspot.com for periodic updates or changes to theses terms.

References and acknowledgements:

[1] Frédéric Broydé, F5OYE and Evelyne Clavelier, F1PHQ “A Typology of Antenna Tuner Control Schemes, for One or More Antennas”

[2] Google Search

https://www.google.com/search?q=antenna+tuners&oq=antenna+tuners&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTU4MDZqMGoxNagCALACAA&sourceid=chrome&ie=UTF-8

Thursday, March 16, 2023

Amateur Radio Mobile and Electric Vehicles

Operating amateur radio equipment while mobile in a motor vehicle can be challenging. Traditionally twelve volt DC systems have predominated among automotive manufacturers of gasoline and diesel powered vehicles. We’ve become proficient at modifying automotive electrical systems to provide required power for transceivers, auto-tuners and linear amplifiers. Recent interest in next generation electric vehicles (EVs) might require we more carefully consider equipment selection and their electrical load requirements.

Mobile power for equipment has always been straight forward. Selecting battery capacity, alternator and wire size accommodates most higher current twelve volt requirements. Gas or diesel power was always there to power and charge the system. Next generation EVs change the power equation as battery charging is no longer sustained during vehicle operation but only occurs when plugged into a fixed charging station. This means accessory electrical systems (stereo, air conditioning/heating etc.) operate on battery power during vehicle operation and can effectively limit vehicle range between charges. Amateur radio equipment can potentially limit an electric vehicle’s range by additionally taxing the power system (my Icom IC-7300 can draw twenty five to thirty amps while transmitting). It’s interesting to note that amateur radio equipment manufacturers are introducing fully featured systems operating at QRP power levels (the Icom IC-705 is one example). The popularity of QRP operation aside, the IC-705 seems well suited for mobile hams sporting electric vehicles. See the link:

[1]http://www.icomamerica.com/en/products/amateur/dstar/705/default.aspx

We might consider conservation a sign of the times but consider your neighbor who might have a killer stereo system in his car or a ham friend with a vehicle powered up for field day. Americans need mobile power!

With the advent of EVs automotive electrical systems have evolved. Tesla (and most) electric vehicles utilize a high capacity lithium ion battery to power the car’s drive train but also feature a twelve volt auxiliary battery system to power conventional mobile electronics and accessories. A DC to DC converter ports power from the lithium ion drive train battery to charge the smaller twelve volt battery. In its original design Tesla used a conventional twelve volt lead acid cell for the auxiliary battery. Later models now feature a twelve volt lithium ion battery providing more current capacity but at a higher price of $450-500. Hams might utilize the twelve volt power system for equipment but must be careful not to exceed fused power and wiring harness capacity. Before installing anything it’s a good idea to consult your auto dealer on power routing and RF interference/interaction concerns (if any).

Balancing electrical loads on EVs can be challenging as power consumption for traditional accessories (and ham gear) can reduce vehicle range. Estimating your ham gear power load (watt/hours) you can approximate any reduction in vehicle range by using the power loading table below as a guide. See the link:[2] https://avt.inl.gov/sites/default/files/pdf/fsev/auxiliary.pdf

Some Chinese EV manufacturers are offering battery changing stations (as opposed to charging stations). When your vehicle battery is near depletion and needs charging you stop at a station and swap your battery for a charged one. The advantage is no waiting, no charging and no worries of battery replacement cost. This poses a different economic alternative for EV owners. You never need to replace your battery but pay a monthly fee to access battery exchange stations. Nio vehicles boast a five minute battery swap and eliminate lengthy charging times. See the link:
[3] https://www.caranddriver.com/news/a33670482/nio-swappable-batteries-lease/

My mobile solution was to purchase a hybrid vehicle. My Ford Fusion Hybrid has a similar lithium ion battery and lead acid twelve volt auxiliary system but its gasoline engine sustains electrical operation while charging the batteries. I recently replaced the twelve volt battery upgrading it from 390 cranking amps to 1,200. During HF QSOs with 100 watts the battery voltage remains constant.

In my opinion hybrid vehicles are the best interim green solution as electric vehicles and the power grid evolves. If you’re a ham considering the purchase of an electric vehicle find the best fit for your requirements.

Mobile safe everyone. Wishing you good DX.

Best regards,

Thomas D. Jay, W4TDJ

Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

References and acknowledgements:

[1] Icom, Web Site

http://www.icomamerica.com/en/products/amateur/dstar/705/default.aspx

[2] Idaho National Laboratory, Web Site

https://avt.inl.gov/sites/default/files/pdf/fsev/auxiliary.pdf

[3] Car and Driver, Web Site

https://www.caranddriver.com/news/a33670482/nio-swappable-batteries-lease/

Tuesday, March 7, 2023

SDR Mobile Installation for Contesting or Emergency Communications

As an active ham I’ve always enjoyed mobile radio operation. Over the past ten years we’ve seen the evolution of amateur mobile HF/VHF/UHF, all mode one hundred watt radios into a single form factor. The Icom 7000 was a favorite. Several years ago in my first effort to outfit my Ford Fusion I chose an Icom IC-7100 which features HF/VHF/UHF and all mode capabilities. In addition I installed a Yaesu FTM-400XDR/DE featuring C4FM/FM and many attractive options. The IC-7100 is a great radio but has become dated. Given current product offerings the 7100 lacks a color display and SDR capabilities. The Icom rep at Orlando Hamcation 2023 was quick to suggest the newer IC-705 all mode SDR portable. I acknowledged it was an attractive, innovative package but its transmitter power maxes out at ten watts. The 705 seems targeted at the QRP market. Serious HF enthusiasts are accustomed to one hundred watts of transmit power for contesting and DX pursuits. Most linear amplifiers operate comfortably with a one hundred watt drive level. In this regard the IC-705 seems anemic (at least for my requirements). While there are linear amps that will work with the IC-705 the additional cost can be significant. What’s a ham to do?

Unwilling to make a major investment in QRP hardware I eyed my IC-7300 for possible mounting options. Too big for under dash mounting I began observing emergency EMS and police vehicles which typically accommodate a lot of gear. How did they mount large equipment? I didn’t see any over sized radio equipment but the common component was a pedestal mounted lap top computer stand. Most emergency vehicles place a laptop stand over the front passenger seat for easy access by the driver. While providing laptop access to the driver the occupied space negates any normal usage of the passenger seat. Having divorced many years ago the laptop stand solution became a viable option and for a few hundred dollars I procured a sturdy floor mounted unit. Installation was a simple task. A base flange mounts sandwiched under the front passenger seat and floor (removing and reinserting the front two seat mounting bolts). A vertical tubular steel pedestal welded to the flange accommodates an adjustable swing arm and equipment platform. After drilling a few holes an Icom mobile mounting bracket was quickly attached to the assembly. After routing coax and power cables I was on the air, mobile with my IC-7300. Cool.

Having the IC-7300 mobile brings all the convenience of home shack operation. Band spanning activity can be observed at a glance and signals of interest can be tuned by touching the screen. After a few weeks of mobile HF operation on the IC-7300 I swapped it with my IC-9700 (they use the same mounting bracket). It was equally cool to have the 9700 mobile. With one hundred watts on VHF, direct QSOs on 146.520 become possible with fewer drop outs. Eye level SDR display makes mobile radio operation a breeze.

What next? After another few weeks of mobile operation with the IC-9700 I wondered if the mobile mount would support both radios (the 7300 and 9700). I had to try. I found some steel mounting brackets at a local hardware store which enabled me to stack the two radios on the pedestal mount. Success. Stacking the two radios took only a few minutes (see the photo). What was really cool became super cool having both SDR rigs in the car. While snapping the photos I laughed out loud to myself thinking it was all a bit too much (but still really cool). Having achieved an almost ultimate mobile installation (no legal limit HF linear yet) I began to consider more practical alternatives. The stacked radios and mounting platform weighed almost thirty pounds. On a bumpy road the top heavy assembly rattled and rolled to the point where I would support the pedestal with my right hand, not good while driving. The stacked installation was great for field day or stationary mobile operation but unstable for off road activity without additional reinforcement.

Next considerations. How else might one achieve simplified, cost effective enhanced mobile SDR operation? I considered using a laptop computer with an SDRplay dongle. For my purpose a mobile, broad spectrum SDR receiver used in conjunction with my IC-7100 was a viable choice. By spotting signals of interest on an SDR receiver it’s a simple task to bring the 7100 on frequency. However such an arrangement requires a laptop or tablet computer requiring boot up and load time before each mobile excursion, not really practical or convenient.

I considered other SDR radios, Xiegu, Apache Labs, the Yaesu FT-991A etc. Each represented additional expense, some with QRP power only. What I really needed was an inexpensive SDR receiver. While surfing Amazon I came across the Malahit SDR receiver (also marketed as Malachite). A few hams have reviewed it on YouTube as Malachite (take a look). The Malahit is a small, self contained SDR receiver utilizing a Chinese RF ASIC (Application Specific Integrated Circuit) and Russian software. There is no dongle, a built in 3.5 inch LCD color touch screen, runs on battery or 5V USB, and covers 50 Khz to 400 MHz, 2 GHz AM/FM/SSB/CW and features an SMA antenna connection. Quoted prices approximate $230, shop for the best price and software release.

I ordered a Malahit receiver a few weeks ago and installed it in place of the Icom stack. Not sure of its sensitivity I also borrowed from my shack a TimeWave ANC 4+ with a Hustler 40 meter resonator plugged into the noise antenna input. The noise input amplifier provides active antenna functionality while enabling 40 meter SDR reception (separate from the IC-7100 connected to a Tarheel LT-Il screw driver). Amazingly, in this configuration the Malahit provides good SDR visibility of 40 meters (and over the ham bands) with surprisingly accurate frequency calibration. I recently acquired an MFJ-1708B SDR antenna coupler which enables the simultaneous use of the Tarheel antenna on both radios.

The Malahit receiver is very small and can be seen mounted with the TimeWave on the pedestal platform. Mounting was achieved with double sided tape.

Not to worry, I'm keeping all my Icom equipment. The Malahit is not a replacement but an SDR complement to my IC-7100.

The Malahit demonstrates good performance and value for hams seeking a supplemental SDR receiver at reduced cost. It's not a replacement for your existing tranceiver, but its SDR display makes it viable for use a signal spotter. Its small size and functionality demonstrates the ease with which major manufacturers might incorporate enhanced designs and performance in future products.

Be safe everyone. Wishing you good DX. Have fun out there.

Best regards,

Thomas D. Jay, W4TDJ

Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

Wednesday, April 27, 2022

EME - Earth Moon Earth Communications

Living near Kennedy Space Center I get a daily reminder of the ever increasing activity in our space program.

While watching this morning’s launch of a Space-X Falcon 9 taking Mission 4 astronauts to the ISS (International Space Station) I was also perusing the May 2022 cover of QST Magazine [1] (the official publication of the American Radio Relay League). The cover features an EME (Earth Moon Earth) parabolic communications antenna while the accompanying article features the contest scores of participants in the 2021 ARRL International EME competition.

The EME contest is unique. While most ham radio contests concern reflected earthbound ionospheric propagation, EME contestants contact one another by bouncing signals off the moon. At a lunar distance of 240,000 miles a round trip at the speed of light (186,282 miles per second in a vacuum) the transmission delay time approximates 2.5 seconds.

During global DX (Distant contact with other stations) it's common to hear a phasing effect when a signal is simultaneously received from two directions; the shortest direct path and the long path around the earth. The signals are received milliseconds apart in time, rising and falling in strength and changing in phase as the physics of constructive and destructive interference act on the signal. The EME moon bounce recording found in the Wikipedia article (see link in next paragraph) illustrates another DX phenomenon. At the end of the recording we hear a farewell and what seems a response from a voice lower in pitch and weaker in strength. In actuality station PI9CAM is hearing the tail of his own signal (approximately 2.5 seconds delayed) as reflected from the moon and doppler shifted lower in pitch. Listen carefully as he says "73, bye bye". It must be pretty cool to hear your own echo from the moon. It seems to me that EME propagation is the ultimate in current DX pursuit.

In preparing for this blog entry I searched EME on Wikipedia and to my surprise found an excellent well referenced article on the subject. Rather than restating the article’s content I recommend you follow this link to Wikipedia and view the EME article directly. [2] Kudos to the editors for excellent content and illustrations. I’ve always been interested in EME experimentation. After reading some background on the subject you might share my enthusiasm for another perspective of amateur radio.

Cooincidently, in a recent YouTube search I ran acrossed a science fiction short film titled “The Man in the Moon”. [3] It’s a “twilight zone like” short story about young experimenters who mysteriously work at night on projects unknown. While it would be a stretch to equate their efforts with EME there might be a common thread of experience for some. Watch, enjoy the film and you decide (about 10 minutes run time).

Many thanks for visiting my blog site.

Wishing you good DX. Be safe everyone.

Have a great weekend!

Best regards,

Thomas D. Jay
W4TDJ Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

[2] view the EME article directly

Wikipedia

[3] The Man in the Moon

YouTube

Saturday, May 9, 2020

Are You a Code Warrier?

As of February 2007 the Federal Communications Commission removed all requirements for Morse code proficiency on amateur radio license exams. Many were sad to see the end of the Morse code requirement as hams have sustained this specialized communications language for many years. Known to hams as CW or Continuous Wave transmission, it is the most fundamental of radio transmission technologies in which a carrier wave is turned on and off to form dots and dashes with a telegrapher’s key. Given the technology advancements at the time everyone had to admit that the CW mode of operation had given way to modern text messaging, email and voice data. Ham radio evolved to include RTTY (Radio Teletype) and automated PSK31 and FT8 digital data/text modes effectively rendering Morse code obsolete. These facts aside, CW remains a highly reliable mode of communications when others might fail and is still popular with hams the world over.

I obtained my novice license in 1967 when the Morse code requirement was five words per minute with thirteen words per minute for the General and Advanced class exams. A Novice license term was one year and without an overlapping General Class upgrade you were off the air. No way. Several months into my Novice term I obtained my General ticket and shortly afterward my Advanced Class license. The Extra Class exam required twenty word per minute proficiency and having obtained an Advanced Class license (my current license) I decided to defer an Extra Class license upgrade till my retirement years. My retirement years have arrived, the Morse code requirement is gone and I’m planning an Extra Class upgrade soon.

That said, I’ll recount some valuable Novice experience as insight to newer hams pondering the craft of CW. When other voice and data modes might fail, a skilled and persistent CW operator will succeed. Upon passing my Novice license exam I immediately ordered three quartz crystals from Texas Crystals (a forerunner of today’s Texas Instruments).

FCC rules required Novice operation with crystal control, no VFOs (Variable Frequency Oscillators) allowed. Note that in the 1960s frequencies were designated in Kilocycles and Megacycles until the NBS (National Bureau of Standards) became the NIST (National Institute of Standards and Technology) and Hertz (cycles per second) replaced the Kilo-Megacycle convention.

Anticipating operation on the Novice 40 Meter band; 7.150 to 7.200 MHz, I ordered crystals for 7.153, 7.155 and 7.158 MHz. The crystals arrived in the mail and that evening I went on the air as WN4JVJ, a CW Novice. DX propagation was excellent as the sun was at solar maximum. The 40 Meter band was packed and a very large AM broadcast signal occupied 7.150 MHz. It was Radio Moscow [1] whose typical power output peaked at one Megawatt. Radio Moscow’s AM bandwidth spilled well above and below 7.150 and appeared to render my selection of 7.153 a poor choice. During the 1960s many Short Wave broadcast stations took residence in the ham bands and my other crystal frequencies provided no clear channel advantage. Recalling the old adage “Work with what you’ve got”, I went on the air. With my brass pounder’s key I tapped out a CQ on 7.153. Because Novice’s operated on fixed crystal frequencies you would rarely hear a response on your own transmitter frequency. Operating technique required calling CQ on your crystal frequency and then listening for a response, searching adjacent frequencies and acrossed the band for someone keying your call sign. After calling CQ several times I thought I heard a response near my own frequency. I chuckled to myself thinking another ham had made a poor choice of crystal frequency, but within the envelope of Radio Moscow’s one Megawatt upper sideband I could hear the faint heterodyne of a CW station calling me. It was another Novice station in Virginia, closer than Radio Moscow but almost overwhelmed in the QRM (interference). Novices were limited to 75 watts of transmitter power output but physics intervened to make the signal readable. When two radio carrier waves are close enough in frequency and overlap they heterodyne to form a tone known as a “beat” frequency. Early ham radio receivers were designed to receive AM (Amplitude Modulated) voice signals but were also equipped with a BFO or Beat Frequency Oscillator. The BFO could be switched on to inject a receiver generated carrier signal which would beat against selected CW reception. An audible interference tone resulted from the opposing carriers providing the familiar CW tone/note we hear in our headphones or speaker. A good CW operator can copy signals through seemingly insurmountable interference.

The human brain is a remarkable signal processor. A good CW operator can focus the mind to sift through static noise and interference to copy CW messaging with great accuracy. During the last months of my Novice term I logged for a veteran CW operator on Field Day. During the contest Arnie worked CW exclusively averaging 25 words per minute (my estimate). I improved my CW speed significantly by copying and logging the contacts he made and gained valuable operating experience along the way. After a few hours Arnie seemed to sense this and began to point to the left or right above the Drake Twins (radios T4X and R4B). Not sure what he meant I removed my headphones and asked. "What are the hand signals for?" He laughed and explained he was spotting signals for me to pre-log. As he was working one CW station he would simultaneously copy another he could hear within the receiver’s bandpass. If I could log them in advance we would save time and work more contacts in the contest time allowed. If he pointed left it meant the station he wanted pre-logged was below the tuner curser. If he pointed right the target station was above the tuner curser. Laughing out loud I asked, “How do you know if they’re above or below?” He laughed in return explaining the pitch of the heterodyne note made by his intended target was either higher or lower in tone indicating its position above or below our dial frequency. I laughed again in amazement and began following hand signals while listening high and low. While Arnie would listen to the tone of a CW signal to determine its location within the bandpass, today's SDR displays enable us to see the RF spectrum above and below our operating frequency.

Note the vertical curser mark above the spectral display shown below. You can visually spot the Single Sideband traffic +/- 20 KHz on either side.

I'll pause here for a side note: A frequent curiosity is how Morse code speed might equate to a bps data rate. As explained by N2EY, [2] (scroll down the linked page) "Paris" is used as a five letter test word to compute per minute code speed; Paris sent fifty times in one minute equals fifty words per minute. By totaling the dit times, (that is the dahs (three dit lengths) dits and spaces between words), this fifty word per minute CW speed represents 2500 dit times or 41.66 bps. By extrapolation we can surmise a ham who copies CW at 25 words/min copies an approximate data rate of 20.83 bps. Machine code for the mind?

After several hours our CW shift concluded and another Field Day operator/logger team relieved us. I shook hands with Arnie and thanked him for a great lesson in CW operating skills. We departed with another great laugh as we exited the mobile van housing our Field Day station. It was three or four AM as I began walking toward my car when I stopped in my tracks to copy CW traffic. Had I left my headphones on? No. I listened again intently and realized I was trying to copy the crickets in the woods. Another great laugh (at myself). My mind had become so conditioned to copy CW that everything, every noise I heard was being processed as Morse code. Enough ham radio for one weekend. Time to go home. My girl friend awaited.

We might think CW a lost art but a few weeks ago I tuned around to hear new General and Extra Class operators QSO on CW at five to ten words per minute. Using straight keys they brought back memories of the not so old days. CW has regained popularity as hand held decoders can now scroll received data. Computer based software is available for contest logging and the automated send/receive of CW. If you've been to a recent Hamfest you might have seen the new product lines of straight keys, semi-automatic and Iambic electronic keyers.

Many new technology toys await hams as the spring season draws near. What was old becomes new again. Wishing you good DX. Be safe everyone.

Have a great weekend!

Best regards,

Thomas D. Jay
W4TDJ Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

Saturday, April 18, 2020

How's DX?

Given the social isolation imposed by the Covid-19 virus I’ve resumed interest the pursuit of DX. In ham radio jargon DX means distance. In casual conversation hams might ask one another “How’s DX”? Translated for non-hams this means “How’s propagation? Is distant radio communication optimal? A major interest for many hams is the ability to speak to others in far off exotic locations wirelessly. During the 1970’s the sun spot cycle peaked and optimally effected the ionosphere. Radio signals reflected off the upper atmosphere so efficiently that with 100 watts of power or less it was possible to talk with other hams all over the globe. While living in New York I could routinely contact the ham shack at McMurdo station on Antarctica, call sign KC4USV. [1] Both our signals were typically + 20 db over S9, enormously strong considering we were over 9,000 miles distant. We might not think of the frigid south pole as Shangi-La but it qualified as exotic DX, a distant location inaccessible to most excepting our military, well funded explorers and ham radio operators on the air.

As DX communication is challenging during the current solar minimum, innovative hams are constantly testing the ionosphere in search of band openings. Optimal DX propagation can occur suddenly during unpredictable solar flare activity. To test conditions hams will often broadcast a CQ, an invitation/call to others listening to engage in conversation. Hams calling CQ DX are searching for radio contact with distant stations in other countries. Occasionally hams will organize a DXpedition; a group of hams will travel to an exotic location, set up a radio station and become a highly sought contact pursuit by other operators seeking a “Worked All Countries Award”.

Testing DX conditions can be challenging. It’s difficult to evaluate the ionosphere when no signals are present. In this regard, DX beacons are helpful. There are many automated radio stations covering our globe which transmit beacon signals. As “radio light houses” their signals can be heard distantly when atmospheric conditions are optimal. DX conditions can also be determined by monitoring scheduled networks. Hams maintain daily “nets” over a wide rage of frequencies. Net control operators for these nets are volunteer hams operating in shifts. Two popular HF (High Frequency) nets can be heard on 14.300 MHz. During morning hours the Intercon Net is active. The Intercontinental Amateur Traffic Net [2] acts as a check in center for hams monitoring the frequency. Hams can obtain signal reports, weather condition updates and check in to rendezvous with distant friends. At 12:00 PM the Intercon Net closes and the Maritime Net resumes its net activity on 14.300 MHz. Known formally as the Maritime Mobile Service Network, [3] this volunteer group is a valuable resource to licensed hams on sea bound traffic ranging from pleasure craft to large commercial shipping, cruise ships and sometimes military vessels. Similarly, the Maritime Mobile Service Network broadcasts weather conditions to ships at sea and sometimes relays messaging to land based systems. In addition to VHF/UHF I also have an HF radio in my car. While mobile I listen to the nets on 14.300 for propagation conditions and obtain signal reports. Once you’ve checked in you’re logged into their computer system for future reference. It’s often surprising to be greeted by name upon your call sign check in. Both of these nets are very popular and supported by a huge following of the ham radio community.

When mobile, seaborne or in the air (airplanes), hams frequently exchange grid square information. In addition to simple location plotting, grid map information can assist with aiming directional beam antennas and navigation. The ARRL explains the origins of the Maidenhead Locator System. [4] HA8TKS provides an excellent Maidenhead grid location utility on a zoomable map. [5] Such resources and utilities simplify global communication coordination for mobile operators and systems.

Did I mention that ham radio and DX are great fun?

Have a great weekend!

Best regards,

Thomas D. Jay
W4TDJ Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

Saturday, April 11, 2020

Social Isolation at the Speed of Light

I originally posted this article on my technology web site TDJ Technology Group.com. As it relates to amateur radio I've decided to post it on my ham radio blog as well. Please keep in mind I was writing for non-ham technologists. Here goes:

After weeks of news media frenzy on the Covid-19 epidemic we’re all weary of the social isolation imposed on friends and families. Many stay connected via television, and social media but another social network remains unseen to most. Amateur radio operators (known colloquially as ham operators) populate their FCC licensed radio spectrum sandwiched between commercial radio and TV channels. There are over 764,000 federally licensed hams in the US, with several million internationally. In spite of Covid-19, the global ham radio community remains actively social, communicating long distance wirelessly.

By day I’m an investor, writer and technology consultant. After hours the large computer screen on my desk becomes an SDR display for my amateur radio station (SDR is Software Defined Radio). Last night I tuned in to monitor several ham radio contest events. The month of April features many Spring season “QSO parties”. A QSO party is a contest in which hams make radio contact with as many other stations as possible in a predetermined time period (usually a day or two). WA7BNM (Bruce Horn) publishes a comprehensive list of ham radio contest schedules with eight events scheduled this April. [1] Thanks Bruce for a great resource.

As a hobby, amateur radio has evolved to a new level of sophistication. SDR is Software Defined Radio. Recent adaption of FPGAs (Field Programmable Gate Arrays, a specialized ASIC device technology, (Application Specific Integrated Circuits) found in communications electronics now provide a graphic view of the RF spectrum and its radio signal inhabitants. Utilizing “direct RF (Radio Frequency) sampling” techniques, ASIC technology extracts a radio’s received spectral data and displays it on a computer screen much as an integer number line, or in this case a spectral line extending above and below the zero point frequency (with zero referencing the radio’s tuning dial pointer). SDR graphic displays have revealed that as ham radio operators, we also comprise a real life “Matrix”. Hams populating their FCC allocated radio spectrum can be seen as individual signal traces along the spectral line. The signal traces scroll over time on a “water fall” display leaving after image “foot prints” behind. Run the embedded YouTube video I’ve prepared and you can see the spectral display I’ve described (approx 2 minutes run time). [2] The signals you can hear are captured by the tuner centered on the spectral display. Switching display modes can also provide an oscilloscope view of the signal’s audio envelope. In the past, radio receiver display technology was little more than a box with an inscribed tuning dial. SDR technology was first seen in military applications but now enabling ASIC device technology is also utilized in many automotive and consumer products. The display images in my video were taken from my Icom IC-7610 transceiver. Icom’s first SDR radio the IC-7300 features an Altera EP4CE55F23I7N Cyclone IV E running at 200MHz) which facilitates simultaneous audio processing and graphic display of this information. Advanced specifications aside, SDR has helped enhance the “social” aspect of our hobby. At a glance hams can “see” live radio spectrum to quickly identify lone signals or clustered contest/network activity. Tuning the radio is simplified. Point at a signal trace on the graphic display and a mouse click will tune there instantly, minimal dial tweaking necessary.

Ham radio contest enthusiasts empowered by SDR have infused the community with new interest. Many of these social contest events feature highly coveted award certificates. A few examples are: The DX Century Club award, (DX meaning distance) is presented to operators confirming contact with one hundred international stations. Similarly there’s a Worked All Countries award, Worked All States award and Worked All Counties Award (challenging as you must confirm radio contact with hams populating every state county in the US).
In spite of the Covid-19 epidemic amateur radio remains a vibrant, socially active hobby connecting hams globally. In times of emergency, natural disasters, or communications outages, hams provide a volunteer base of highly skilled communications operators with global reach. Although there’s been no call for ham radio communications during the current Covid-19 epidemic, a valuable volunteer resource stands ready. In the interim, social distancing at light speed is great fun. Dropping out of warp now. See you on the web.

For additional background on SDR technology see my March 2017 article “New Trends in The Field Programmable Gate Array Market - Software Defined Radio”.  [3]

For additional information on Amateur Radio see the American Radio Relay League web site. [4]

Stay safe out there.

Regards to all,

Thomas D. Jay
W4TDJ Member ARRL
Thomas.Dale.Jay@gmail.com
TDJ Technology Group.com
Thomas D. Jay YouTube Channel

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