In 1957 I had two important subjects firmly on my mind: Girls and Only 2 more years before I could escape my boring town in Western Pennsylvania -- about 30 Miles from Butler, PA which of course is in the news today.
That is my excuse for not spotting this jewel when it was first published in 1957.
Wow! A 200 milli-watt CW transmitter, all solid-state using RCA Transistors. With some attention to biasing you likely could pop in the circuit, transistors like the 2N3906, 2N2907, 2N4403 or a 2N2905. The Oscillator is a Common Base, and the Amp is a Common Emitter.
[Check Google as to why the Common Base for the Oscillator like Voltage Gain, Input Impedance, Stability, Biasing etc.]
Speaking of Biasing note the use of multiple batteries versus resistance biasing. The Oscillator is keyed, and the Oscillator/Amp is switched on during transmit using SW1. By switching on SW2 a lesser collector voltage is applied likely a spotting signal.
There are three meters in the rig and the output circuit and antenna tuner should provide for good harmonic suppression. Note also JIC (just in case), the output has a wavemeter coupled to the output to assure you are transmitting with "max smoke" on the right band. BTW 200 milliwatts of RF at 7MHz was a big deal in 1957!
I will bet the signal quality, in large, depended on the crystals being used. The plated type might yield a whoop, whoop sound as you keyed the rig. A good place for the FT-243 type.
You can find the complete article by searching for N4TRB + RCA Ham Tips ~ July 1957. This schematic has great potential for a 2024 makeover with less parts, less cost and more power output.
Again, the fun of looking at something from 67 years ago and remaking it with modern components. There is also another incentive to not directly replicate this design -- the cost. The eBay auction site currently has an RCA 2N140 transistor for about $20 shipped.
Afterall, the IARU says the purpose of ham radio is simply contests and operating -- so you must engage in either or both of those activities as an operator or participant.
Sixty-fiveyears ago, if you answered that question in the affirmative, then this might be the type of rig you used. From the February 1959 RCA Ham Tips comes this jewel. [N4TRB host the RCA Ham Tips back issues.]
6AQ5 Regen Receiver.
VFO Driven CW Transmitter
Not shown is the AC power supply deck which already makes it a negative choice for POTA or SOTA ops for field use. Cute but awkward are two appropriate words.
I am smiling when I think of the W7ZOI Ugly Weekender project and can't help to think that Wes' project might have had roots in this rig.
That is the point of this posting and that is to take the 65-year-old design and update it with something comparable or better using modern components and importantly field friendly and fully usable. Or you could take the plunge and simply replicate this jewel -- probably not a good idea.
The receiver is a regenerative type and not a good choice today. Since the W2QEX (a well-known CQ author) design is modular the receiver is the first for the $0.10 makeover. A Direct Conversion Receiver would drop right in for that module and there you have it poppet (Thank You Mrs. Doubtfire).
Simple to build. spare on the use of parts and superb performance the DCR is hard to beat. You could even cap it off with a Glue Stick PTO for added stability (low drift). I would uptown it with an Arduino and Si5351 which using a bit of code magic provides a 3rd output for the Transmitter module.
For the transmitter you could build the module with three or four transistors ending up with an IRF510 and the 3rd Si5351 clock providing an offset frequency. Or if just a small delta on the Transmitter tuning range is not a crisis maximus, then a multi-crystal Super VXO would keep things simple. A spent SPAM can would be a great housing. Then you would have a good kind of SPAM.
We can often get seed ideas from the rigs of old that with more current technology, shrink the size, reduce the build cost and have increased capabilities. BTW I would make the operating frequency 20M not 40M.
If you are fortunate enough to have been a ham for some time, then likely you have owned a Drake radio. Maybe it is a Drake 2B Receiver paired with a DX-100 adorning one of your operating positions or perhaps a TR-7. Somehow AI steered my phone to this video. If all you know is an ICOM IC-7300 then you are missing a true ham radio experience.
Some things I never knew about the R L Drake company: During WW II they built the three tube BC-125 radio (likely a regen) and the number of AC-4 power supplies produced is around 84,000. Foreign competition killed R L Drake. Sounds like Collins, Heathkit, Ten Tec, Hallicrafters, National and Hammarlund.
Of note is the R4C receiver that externally looks like the earlier R4, R4A, R4B siblings but under the hood is a different animal. Rob Sherwood NC0B is well known for documenting receiver performance of all the current ham gear.
He started with improving the R4C with the addition of what is essentially a "roofing filter" (A wider filter in the receive chain to limit the bandwidth of signals passing ahead of the main IF Filter.) Now all the high end non-SDR radios tout a roofing filter.
[Slightly ahead of the curve, the N6QW, KWM-4 SSB/CW transceiver has a roofing filter in the design!]
The R4C has passband tuning with triple conversion to a 50kHz 3rd IF. The R4C works with the T4Xc to provide separate, split or transceiver operations.
As a result of Sherwood's modifications, the R4C at that time soon became the #1 radio in terms of receiver performance. Today it is a Yaesu FTdx101 at the pole position. If you are an ardent CW operator, then this was "the radio". In addition to SSB the R4C has three optional CW filters accessible from the front panel. This is in addition to having 15 crystal positions for adding bands of operation outside of the stock five bands between 80-10M.
Behind that panel are a mere 6 tubes (2X6BA6, 3X6EJ7 and 1X6BE6). The rest is all solid state. This is a far cry from the first 13 tube R4 Receiver. Of note the tubes used are really cheap to replace like about $5 each from Antique Electronic Supply --- so not a large maintenance cost.
Notable that the Drake Engineers chose the 6BA6 as the primary RF Amplifier stage and another 6BA6 in the IF. You would think they might choose some really exotic tube for those tasks. I guess if it works well then why change it?
The Drake Gear commands some hefty pricing on eBay. Most unmolested R4C's begin at around $400 and that is without any extra crystals or the highly prized noise blanker. So, getting one is not cheap and even though unmolested may require some additional $$$ to get it back to factory specifications.
Be wary of any R4C's that say the PTO needs repair. THAT type of repair usually means replacement! There are two concentric dials on the PTO shaft, and they move in unison. One dial face is marked in 100kHz increments and the other in 1kHz. They can be reset manually with a process much akin to what it would take to get a date with Taylor Swift! Not for the faint of heart.
So, while many podcasts and blogs focus entirely on the new stuff, some of the boat anchor stuff is top drawer. If you have a Drake R4C, which is operating properly, you simply enjoy what you hear!
It comes with Unbuntu preloaded. Scrap that Crap and load Linux Mint 20. Nice Machine. This may be a bridge too far for some as you have to load over the Unbuntu OS using a USB Stick. But I have QUISK, and the Arduino IDE on this machine. It can be powered from either 5VDC or 12VDC and has a built-in healthy Audio Amp. You will need a powered USB hub to add USB ports as it comes with only two but that is not a showstopper! Add the RTL SDR Dongle and now you have a piece of test equipment on the bench.
Not cheap ($16) but have had these for two years and are my "go to" tool. 1st Rate!
TORX Screwdrivers. I think who ever invented the TORX bolt head had one mission -- to frustrate hams! I bought this set and even found with careful application can sub as splined hex wrenches for the Collins (and others) set screws in tuning knobs.
Transistor Tester Yes, there are those who will say I use my Digital VOM and I get values. But I like this one ($16) as it has a LCD display and those amazing deal Banggood special transistors show up as a resistor. If you are looking for matched pairs this will tell you about the ones with a close Hfe.
For those who lack knack skills you are SOL as you have to assemble the pieces -- yes, it is a kit (mostly mechanical assembly of the case).
Finally knobs . When a homebrewer fabricates a rig, he needs knobs! Here are some look alike Drake knobs to dress up your rig. Don't get too excited as these are smaller than the Drake knobs but work well.
Less than $10 gets you 10 knobs for 1/4-inch shafts.
I just added close to $150 to your Credit Card balance but just like the YL's who always have to have more shoes -- you absolutely need this stuff for your shack.
Subthreshold Conduction! What is it? In MOSFET devices there typically is a minimum threshold voltage necessary to have the device turn on. But there can be some "turn on" below that critical voltage. (Subthreshold Conduction)
Even in standard transistors a small portion of current leaks (collector to emitter) even when they are technically switched off. When that leakage becomes significant things can happen!
[Simple Analogy: Mary Jo is "warmed up" without 1st having the Bob's Big Boy Hamburger]
Simple relay circuit activated from an Arduino. Depending on the actual relay used the 2N3904 may be underrated which could cause it to fail or have excessive leakage current. Use a TIP31C. If the worry may be stray RF activating the switching transistor slip several ferrite beads on the base lead.
Above is a back of an envelope sketch of a relay activated circuit triggered from an Arduino signal. A signal voltage from the Arduino pin turns on the 2N3904 and current flows enabling the relay to close and control various circuits.
A ham friend wrote me about some mysterious happenings where inexplicably the relay on a similar circuit was being engaged without the Arduino signal signaling such an action. The circuit had been working properly and then the issue and it is intermittently occurring.
There are many causal possibilities for this condition, but certainly an overly leaky transistor has to be in the mix. Could this also be heat related -- my shack is 97F at noon so certainly that could make this an event in summer operations.
In a curious convergence of actions, I am seeing a similar mysterious "turn on" in one of my transceivers which uses solid state switching but no relays. We often assume that just because something is solid-state and low voltage that there never is component fatigue and wear and tear on the devices. Wrong!
So, one more item (leaky transistors) to cause hair greying and thinning!
Just a short boring posting today. One critical aspect of the CW code development is the timing. A dash is three time the length of a dot. Then there is the time spacing between the elements like dah di dah dit (letter C) and time spacing between the next letter like dah dah di dah, (letter Q). Finally time spacing between words like CQ CQ.
We pick the dot length as the magic decoder ring and call that "x" and therefore a dash = 3*x. By doing this we are able to define all times by x with multipliers. If we want to change the loop speed, we need only modify the code with a single changed x value.
I had fun making x = a really small-time increment. What resulted was "the spy stuff" -- a code burst. The serial monitor showed it was sending the code but there was only but a brief flash of LED 13. How cool is that? I wonder if the Reverse Beacon Network can decode that?
I mention the Reverse Beacon Network as that is a great tool for testing a rig. You call CQ (in CW) where there are CW skimmers worldwide that listen for the CQ calls and if recognized will display your call on an internet webpage. This will convince you that 100 milli-watts travels a long way. The CW Sender will do a lot of the heavy lifting using the RBN.
It is not a matter of absent mindedness but rather of having too much junk. Just yesterday while looking for something in the junk boxes, there I spotted a small box that had dust on it -- hmm this has not been opened in a long time.
Surprise -- not the kind like when you open a baby's diaper but a good kind!
Inside that box was an Arduino Mega 2560. For the unwashed -- the Mega is like an Uno R3 on Steroids with a greatly expanded IO capability both Analog and Digital and about 10X the programming space. This prompted the installation of a small program to see if it still worked.
Mega Next to a Mouse
Following yesterday's post on the one transistor transmitter I thought of a program, I wrote long ago to send the "CQ" string. I set up the program so that the on-board LED would blink the generated CW (pin 13 on the Mega). Thus, I could visually tell if indeed it was sending Morse Code, and I also included the Serial Monitor to see if the right letters are being sent.
Whew! We passed those two tests and so we can now build some interface electronics to take the output from Pin 13 and actually key the transmitter. We have many options for keying the transmitter including a Reed Relay to a PFET.
Then came a stream of conscious thinking that this code string could be customized for POTA or SOTA. Imagine just adding a string of letters/numbers for the POTA / SOTA location and we are there. You could even speed adjust the generated code, so the CQ POTA or SOTA is at a fast pace, but the location info is sent at a more readable speed. Yes, that is a cool idea all automatic and less fatigue for the operator.
But then the Insane Idea suddenly popped into my head. We have the POTA and SOTA which now are like passe'. Thus, time for something new to stir up interest on the ham bands.
We proudly introduce new location ideas, please welcome COTA and WOTA. Yes, COTA is from the parking lots of Costco, (Costco on the Air) and WOTA is Walmart on the Air.
Just think of all our ham contemporaries who would do the double dip -- Shop and Get on the Air all in one trip. We could distinguish the locale by using a Zip Code follow on like COTA 93036 (Costco, Oxnard CA)
This could be huge and would open up a whole new array of signals to flood our bands and cause QRM. This absolutely follows the tenet of the IARU -- contests and operating.
TYGNYB. If you want a copy of the code email me at my QRZ.com address.
That is such a powerful question and one not often asked? Unfortunately, too many times the answer comes before the question. Like Start by charging $1500 on the plastic and buying a radio only to find out you need another $600 to get the stuff that will make the $1500 stuff work, like a power supply and simple antenna.
Good friend N2CQR and I often respond to that question with the same answer -- Start Small and Start Simple 0r 4S. If you are new to a soldering iron this is sage advice, and the benefit learning factors are immense.
A simple One Transistor Transmitter!
Do Not Put This Simple Design on the Air unless followed by a W3NQN Low Pass Filter!
With but a few simple components this transmitter puts out RF and is capable of making contacts heard several hundred miles away. If you get 100 milli-watts out of this jewel buy 10 lottery tickets.
I would change the 2N2222A to a 2N2219A and up the supply to 15 Volts. This will more than double your output. A further keying refinement would be to add PNP transistor keying using a 2N2905 in the supply lead. Later you could add a IRF510 amp stage, and this will get you to watts output.
You likely have spent less than $40 and you have a transmitter. Now for a Receiver, start with a Direct Conversion Receiver and I recommend one I designed and was the subject of an article in G-QRP Club SPRAT. The build is detailed on my website https://www.n6qw.com
The parts for this part of the project likely will set you back about $150 and provides an excellent performing receiver. At this stage I would swap crystals from a 7030 to a 14060 crystal and move the DCR up to 20M. Two watts CW on 20M will net a page of DX contacts. You will need to adjust the Tank Circuit to work on 20M.
Another friend placed a general call via email for anyone who has some spare 80M color burst crystals to which I sent him a couple. Get this -- he is designing a M^3 using vacuum tubes and is planning a vacuum tube DCR. Watts to the antenna is watts to the antenna!
Some 12 years ago, I was presented with an interesting problem when I was designing the KWM-4 (my answer to a solid-state Collins KWM-2). My KWM-4 was a multi-band radio and thus the problem was how to switch the circuitry for the various bands.
The last on the list of candidates was a multi-deck, multi-position switch. I should mention that for the LO I used a Si-570 kit from K5BCQ. As a bonus of that design for the "channels" you picked, each one could generate a unique 3-digit Binary code (this is like saying jumbo shrimp).
Essentially the K5BCQ kit had 999 channels and once you called up a channel you would tune frequencies using the encoder within that channel range. One panel button lets you move a menu through the ranges (bands) and for each range (band) you can set the binary code.
S0 now how to take that binary code, decode it and switch banks of relays on the BPF and LPF. This is how it was done and now installed in the KWM-4. This is nothing more than a binary to digital decoder. For every Binary code created one pin on the IC is hot and fires the transistor (or P Channel FET) controlling relay sets. With 3 binary inputs that gives you a potential of 8 bands. Four inputs yield 10 bands.
The 1st Approach ~ Way too much Hardware!
Final Design P Channel FET!
Today I would use a Mega 2560 to do the Si5351 and the band switching. (The 2560 has more IO and a much larger program space.) This also screams a 4X4 keypad -- just like the Big Boys.
K5BCQ's used an approach similar to mine but used the CD4028 which had the decoding and switching all in one device.
Thus, this little slick circuit can enable you to do all sorts of things. How about a small handheld transmitter that generates a binary code which is decoded on the other end for a set of determined actions.
How about watching from the bushes when that nasty neighbor's dog takes a dump on your grass-- you set off the sprinklers or maybe start up a magneto pumping volts into the grass. Don't you just love technology? Today many things are possible.
I kept hearing fireworks up until about 11PM last night. Some sounded darn right loud and also thought about Cheech and Chong -- a lot of chemicals ending Up in Smoke.
If you happen to be in the less than 1% of hams who actually build stuff, then this is a good time to think about a project for next fall. Will it be an antenna, maybe a 0.1KW linear amp or perhaps some new accessory for the shack or gulp something SSB/CW for POTA/SOTA activities?
This could even extend to learning how something you built actually works. How does a diode ring mixer work or the arcane Gilbert Cell?
Some may argue I only need to know how to make it work well not how it works internally. It is a matter of practicality versus curiosity. But the other side of the argument is that the two are joined at the hip -- making it work well and how does it work!
Or maybe you have been thinking about building a replica DAVCO DR-30 (photo above). So, what is/was a DAVCO DR-30 Receiver?
One of those mysteries of ham radio -- A very advanced Solid-State radio only 600 of the DAVCO DR-30 were built during 1965-66 and then the company went bust. Was it the timing being too ahead of its time? Or maybe the price point was a bridge too far. I actually have no information on the why, but it sure looks and has the right stuff to make it a really good receiver?
You can see with today's technology a replica like project could be designed, built and perhaps improved -- but that skill set is not a part of most of the US ham population. After all contests and operating are not a strong CV attribute for taking on a state-of-the-art SSB/CW receiver.
Is there a Davco DR-30 hiding out in your storage locker?
73's
Pete N6QW
The Davco DR-30 is a remarkable piece of radio history! 📻 Manufactured from 1965-66, this miniature receiver is prized by collectors for its rarity, breakthrough engineering, and mil-spec construction. Here are some key features:
Transistorized Design: The DR-30 was the first transistorized ham receiver, bridging the gap between vacuum tube rigs and modern solid-state equipment.
Smooth Tuning: Its spring-loaded dial ensures deliciously smooth tuning with zero backlash and no VFO drift.
Impressive Specs: With a Collins mechanical filter, noise blanker, high-Q preselector, and sensitive front end, the DR-30 was ahead of its time.
Low Voltage Operation: It draws less than 100 milliamps at 12 volts, making it ideal for field day use.
Mil-Spec Build: The DR-30’s robust construction ensures durability.
Another 4th of July is upon us. Hey Sam, put the Flag right side up!
I am happy to report that the Drake PTO (yesterday's post) is cranking out RF and so that soon may be tried with one of my homebrew rigs. I did replace both transistors and now a bit of lubrication on the gears will make everything as slick as a baby's butt.
Just a bit of reflection on the importance of this day AKA Independence Day. It is not just a day where there is a good excuse to drink beer at noon or to demonstrate your skill at pitching horseshoes, but certainly a lot more than those typical activities.
It marks the birth of our nation and the high cost to maintain this democracy. Do not take this day for granted. Think of our US Service personnel who around the world are protecting our freedom. Amen brother!
Last night about 8PM local I worked 3D2USU on 20M FT-8 using my homebrew SDR running off of a Raspberry Pi4. I had to look it up as the 3D2 prefix is the Fiji Islands. Of note this station has an eye popping 1,179,504 lookups in QRZ.com.
Speaking of the Raspberry Pi 4, it was more difficult to get working with QUISK (SDR Software) than the Pi3B. A bit of a "kludge" on how I did it but I did find a way. I also have the HB SDR working on an ASUS Tinker Board and an Atomic Pi running Linux Mint 20.
Homebrew SDR
Final word -- today is also a good day to turn off the radios and just spend some quality time with the family.
Often the opener, I never thought was followed by "that the car could go that fast as you get a ticket", or "that the gun was loaded" or "that she would end up pregnant". Well, that phrase also covers today's bit of blabber.
The set up ~ Both Collins and Drake used PTOs in their radios which were hallmarked by a linear readout and excellent stability after a warmup. Collins in the rigs prior to the KWM-380 were all vacuum tube and Drake started with tubes and then went to Solid State.
My "I never thought is followed by that they did that this way" involves a Drake PTO. While rummaging around one of my junk stashes, I found a box marked Drake PTO. I seem to recall having to repair a Drake PTO and that was by installing a replacement PTO as the rig I bought had an inoperative unit.
Given my current mode of operation of trying to fix things, it was time for this PTO. There was no info in the box about what was wrong with the PTO and likely what I did was replace the unit without trying to fix the original one.
In all honesty, likely I said to myself, self you would be treading in very deep water trying to fix this PTO and took the easiest path.
Above and below are some shots of the Drake (R4A) PTO. Somewhat aghast that Drake used cheap circuit board material and that the board was not more rigidly affixed to the assembly. Well, I guess it worked.
BUT what really jumped out was the staggered pitched winding of the inductor. Before commenting more on this, the PTO (permeability tuned oscillator) consists of a fixed inductor whose inductance value is changed by inserting a gear driven powdered iron core through the windings -- id est, no variable capacitor. Back to the physical winding, the stepped pitch makes the inductor act in a linear fashion. Were it a constant winding the change in inductance would not be linear.
All roads lead to Rome and all analysis starts with a schematic. The first problem -- there are so many schematics for the Drake R4 radios. The R4 series includes ones with 13 tubes, 11 tubes and 10 tubes. The latter rigs were a hybrid mix as more solid-state circuits were included like the PTO and Audio stages. There were even two different solid-state PTOs with one a bipolar device (2N706) followed by one a JFET (2N5990).
This specific PTO had the 2N706.
Q2 (2N706) is the Oscillator and Q3 (2N3563) is the Buffer. Notice anything of interest with Q2 having a Cap (10nF) to Ground. So, if I want to test this PTO where do I connect 12VDC?
We now have the old what I see in the schematic is not what is in the hardware. R85 is a 4.75K Ohm resistor at 5 watts and that connects to an OB2 Voltage regulator which is a gas fired 108VDC regulator tube --- if R85 fails you sure smoked a 2N706. With the R85 dropping resistor you get a regulated 12 or so volts into the PTO.
But wait in this PTO the lead going to R85 appears to be encased in shrink tubing and tucked away. What does follow is that a wire is installed at the junction of R85, R104 and R54 and the diode and connects to something in a radio.
This PTO likely came from later production models whereadditional solid-state devices were present and other provisions made for supplying low DC voltage. Thus, what you see in a schematic is not always in the hardware.
Hooking 12VDC to the wire produced no output. Next steps, pull the 2N706.
So why am I doing this? Well, the first part is playing detective, and the second is I might succumb to using an analog PTO in a radio. Despite its flimsy looks the Drake gear mechanism is pretty solid.
Thanks for traveling along -- tomorrow is the 4th of July and don't forget what that stands for -- fly your flag and remember the flag etiquette. Never upside-down Sam, the proper flying hours and it must never touch the ground!
Mention Atlas Radio and immediately you think of Herb Johnson who also was the creative genius behind Swan Engineering later Swan Radio.
Atlas 180
I often wondered if the name Atlas was chosen because of the comic books ads that featured Charles Atlas. Charlie who decried that he was a puny kid used his exercise regimen to become a body builder. He is quoted as saying give me a place to stand and I can lift the world. The Atlas Radio logo appears to have a world globe cleverly hidden in the graphic.
I was an early purchaser of the Atlas 180 and installed it in my Chevy Vega. My one-way trip to work using the California freeways was about 30 minutes so enough time for a few QSO's.
One of my best ever QSO's was with a friend and fellow employee of Douglas Aircraft. My friend Dan was a pilot and for about a 2-year period was a FAA designee qualifying Japanese Pilots (JAL) to fly the DC-10. He would crank up the Collins 618T on board the DC-10 during a check flight over Japan and would look for me on my way to work. Now this was like Applebee's: Some really good eating in the neighborhood.
While its specs touted SSB and CW -- the CW was ok for a rare QSO, but the manual switch over would render it useless in a contest. The Atlas 180 tuned 160 through 20M. All-important a linear dial scale and a reasonably stable analog VFO. For operation on various bands the VFO was shifted in Frequency with no crystal mixing. The IF was at 5 MHz.
The Atlas 180 circuitry was unique having some roots back to a military radio the RT505. Les Earnshaw ex ZL1AAX had a hand in the design of both the RT505 and the Atlas 180. I say unique as there is no RF amplifier stage to be subjected to overload.
Like many in our hobby I got an itch to upgrade to the Atlas 210X (5 Bands) and away went the Atlas 180. That was a mistake! A couple of years ago I found this unit on eBay for $100.
It was a compact radio and I think all versions 180, 215, 210 and 210X had a run of over 14000 units. Icom and Yaesu essentially put Atlas out of business with radios costing the same or less but with 10X the features.
At one time I had a very nice two-hour conversation with Herb Johnson, and he shared that the Japanese Manufacturers were selling (dumping more like it) radios on the market a cost less than just the parts of an Atlas Radio. That will put you out of business real quick.
Yesterday while doing my shift at the Board and Care I thought about that subject. If you are new to the hobby likely the answer is a radio currently being sold through one of the popular suppliers (DX Engineering, Gigaparts, Amazon).
If you been at this hobby for some time, the answer is often something you no longer own. It is with lament that you hear: "I really loved that FT-101B" and I regret ever selling it. Or perhaps your shack had one of these.
A Hygain 3750.
Atlas 350XL
Hallicrafters FPM 200
Astro 102BX
Likely the above radios are not well known to the average 1/2 the total US Ham population (those who can work HF). The offerings were aimed at a niche market but at the time touted as having the latest technology, but often priced like a King's ransom. Frequently the production runs were small in numbers. The Collins KWM-1 line only produced 1250 units.
What was so good about these specific radios? Yes, they did have sizzle with the displays or that if you owned one you would be considered in today's terms -- an influencer. In reality it was all in the marketing. They also had some quirks that were dismissed as "nothing".
I am no different than most hams although I do practice TYGNYB. I own too many radios and I too lament that I should have not parted ways with a specific radio or rig.
During recent months I have cycled through some of those radios and have come to a stark realization that each new generation of radio or rig perhaps solves an old problem while likely adding new issues.
I have no patience for drifting radios and therefore do not build analog VFO's. Yet some of my homebrew SDR rigs are good enough to detect when my neighbor flushes his toilet. Still working on that problem...
It is also a matter of never being satisfied with what we have and are always chasing the bright new shiny penny. This is where you should never be the 1st to buy a new radio offering.
I sold some radios to buy a Ten Tec Pegasus (computer-controlled radio). It went back to TT two times in the first six months, and it was Clunky to operate but I was one of the first to own one. I traded it back to TT for an Omni VI Option 3. Still own that jewel.
Perhaps some or one of the best radios often are simple in design and easy to operate with one hand. They may lack in all of the frills such as the RIT offset control in an SBE-34 that actually caused you to never be in sync with transmit and receive but its predecessor the SBE-33 had no RIT but always was in sync.
Just because a radio could spew out 200 plus watts (Swan 500) does not necessarily mean the sideband suppression was that good. Foiled again by touted power output and not signal quality.
Some radios are impressive in the sheer numbers sold and still in use. The Yaesu FT-101 may have topped 250K units sold and lest we forget the ICOM IC7300 has surpassed 100K sold. The KWM-1 with 1250 units seems like a fly speck.
So what was your favorite radio or rig? Drop me an email and let me know.
As a follow on to yesterdays post, this is hamfest and flea market season. Don't pass up a good deal on one of those old boat anchors for with a bit of "N6QW Magic" you can have a really neat new rig for just pennies.
The colorful pictorial shows how to construct a VFO/PTO to replace the LO scheme in those old boat anchors. This bit of magic selects the proper range and frequency for injection into the boat anchor mixer stages (Buttons 1-5). But the slick stuff, in addition to the encoder knob, Buttons 8 and 0 let you up down tune the radio from the keypad and Buttons * and # let you transmit 10kHz up or 10 kHz down for those DX split operations. You can also select two large step tuning ranges for a fast QSY.
Detailed documentation is available at https://www.n6qw.com. While this was built for a Ten Tec Triton II -- it would easily work with the Hallicrafters SR-160, The SWAN 240, National NCX-3 and the KW Atlanta 2000.
I bought a rather pristine NCX-3 for $70 and it is a candidate for a makeover. You get full band coverage and think about FT-8 on 20M with a very stable NCX-3.
No new exciting rigs on the air that I created and my New Year's resolution regarding weight loss has gone south. Circumstances have just sort of happened. So how to recoup what is left in the 2nd half of 2024?
The physical building of a rig, in my view, is the lesser part of the process as that is something that can be and is taught to individuals who are not rig designers, but simply skilled craftsman. The hard part of the process is actually designing a rig for excellent performance. The key is research and information gathering. That is something that can be done without a soldering iron or Nano VNA being turned on.
The other aspect is the integration of new technology and new hardware into the designs. Older technology is just that. We can now operate radios thousands of miles away using an internet connection. It is a much more difficult task to remotely tune that LC VFO from afar.
While some may pooh and double pooh an SDR radio, the fact remains that the new technology is SDR. You need only listen to an SDR radio as compared to a conventional design using say TIA amplifiers and you will get the message -- loud and clear. There is a whole new world out there and the orb is not a Bitx40.
Of note I find that I am using my Hermes Lite 2.0 more and more as a test instrument than a station rig. It is indeed a real time spectrum display and in effect a frequency counter. This can all be done using a Raspberry Pi3B as the computer resource.
I spotted a less than $25 single board computer that to me looks like it could be a foundational piece in an SDR Radio. It is made by Orange Pi. (A quad core 64Bit, 1.5GHz machine.) It is from Lauren Sanchez's boyfriend (Bezos).
You will need a powered hub for more I/O and a power supply but that is peanuts. For field use, Mean Well makes a 12VDC to 5VDC, DC to DC convertor. Park this near a Wi Fi hotspot and FT-8 is at your command.
I have had great success with some small RF amplifier boards from the same source -- 2 for $9.
These are good for 30dB gain from 1 MHz to 2GHz -- for $4.50 a board. Another building block for an SDR radio.
You need only look at the SBitx from VU2ESE and it is apparent that he has moved to SDR.
It looks like the Chinese are firmly entrenched in the low end SDR radios and if not now will soon be leading the world for this market segment. Where are the US manufacturers? They are at the high end of the market and way beyond what I would spend. FLEX is out of stock for their $21oo SDR but you can get quick delivery on the $6K job.
Tour Amazon and it will blow your mind at what is available. Start your design process today.
Whether you roll your own or flash the plastic for a rig, the process has to start somewhere. Often the starting point is at the wrong end of the process. Let us define what I mean.
As hams we are often overtaken by the cosmetics. That radio is cool looking, or I want to build a cool looking radio. How many of you start out by saying I want a radio or rig that performs well? The ne plus ultra is to have both.
That plain black box with no knobs has no curb appeal -- yet perhaps it is one of the best ever performing radios. The flash is in the software!
The tangle of wires and PC boards mounted on a plank of pine can be and often is a DX machine.
The best place to start is with what often in government contracting is called a "requirements list". Let us use a real-world example: you are more than a closet POTA or SOTA guy --you are an addict! Every weekend is a planned adventure to some park or mountain top.
You scour data bases to see which parks or summits have not been activated -- one that has not been activated or only infrequently is moved to the top of your list.
It follows -- rare DX has the whole world listening for you and the same for POTA and SOTA. You make a schedule of events and if the XYL is not joining you -- you reassure her that you have only radio in focus for the time away. You are ready to go -- really, are you?
So, how did you decide what rig to use? Did your radio selection or homebrew rig consider what was required in the hardware. Things like how much does it weigh with batteries? Is everything in one box like a built-in antenna tuner or now you have to lug two boxes 2 miles straight up? How is the battery consumption?
One ham made a foray up a summit that had many radio repeater sites in close proximity. His SOTA event was cut short as his low budget Chinese box was desensitized from all of the RF floating around -- something he never thought about when he flashed his plastic.
Other concerns should be the mode. Will you do both CW and SSB or for efficiency or saving on battery consumption just CW. How about the antenna? Often simple wire antennas have a small footprint, and that smallness often results in a small number of contacts. Did you look at a pair of phased verticals to give your signal a bit of a boost. The fold down whip antennas is now looking a lot better.
Finally for a guy with FFS -- those small knobs will soon give you an acid stomach. The latest rig from Elecraft (KH1) would get a pass from me with the key and knobs mounted on the bottom -- it looks weird!
The homebrew rig presents many problems as the performance factors are not well documented as they might be with a radio that has to be type certified. Often homebrewers simply replicate already published projects and thus your mileage may vary. However, if your work is an original design then you have more control over performance.
Too much RF gain in the front end also amplifies the noise. Putting a modest amount of front-end gain with a lot of audio gain results in copying more of the weak signals. Forget those pixie style radios. Your requirements list should make clear -- 5 watts and forget 1oo milliwatts for a POTA or SOTA.
What is on your requirements list? BTW did you choke at the price point of the KH1 @$550 which is about where you can buy a XIEGU Model 6100.
Playing with the electrons most decidedly is like a British mystery novel or movie. Not unlike Murder on the Orient Express -- they all did it!
A couple of huge clues were totally missed by me in the resolution of a problem, and this also links back to the need to document everything. But 1st a bit of stage setting.
The Spilsbury Tindal SSB Transceiver
The above cool looking commercial SSB Transceiver was built by a company in Canada by the name of Spilsbury Tindal. It is all solid-state with 4 crystal channels operating in the 2 -10 MHz range.
Inside is a Collins 455kHz Mechanical Filter and a Motorola RF Transistor good for about 15 watts. This was a 1970's built radio. It was single conversion with a 455kHz IF, thus even making it to 10MHz involved a very large pair of cojones! [With such a low IF and single conversion as you go higher in frequencies images ARE a problem.]
The four crystal channels could be simplex (same frequency for Transmit and Receive) or entirely different. Internal to the set were a battery box and even a wire antenna. The primary market was the Canadian logging and mining industries. These often show up on eBay but command a pretty hefty price.
Of course, getting one would limit you to 80, 60 or 40M. But with a bit of Juliano Magic, the crystal approach could be changed over to the Arduino and Si-5351. Were you anchored down to keeping it stock then I would opt for four channels on 60M. Documentation and schematics exist on the Internet. So, the other option is to scratch build one. I did although not pure Spilsbury Tindal -- not even close!
This unit was built about two years ago but had some issues. The 1st notable point is the use of the ILI9341 2.2-inch display. This same code will work with the 4-inch display which would consume the whole front panel. If you are thinking Color TFT - get the ILI9341. A series of voltage dropping resistors takes care of the level shifting to the display.
Now to the mystery -- it just didn't sound proper on receive or transmit. The first test was to switch back and forth between LSB and USB. I added the two-sideband selection in the event I would make this into a 20/40M rig. A switch and a couple of added BPF and LPF filters and some relays would make that happen.
With any properly operating transceiver, switching sidebands should not make a huge (if any) difference in background noise. Such a state means you have the proper Carrier Oscillator frequencies, and these are placed on the filter slope at the right location. A non-symmetrical filter might result in frequencies that are not equally spaced from the filter center frequency i.e. not +/- 1500 Hz.
My replica uses a 9 MHz commercial filter and when you switched sidebands there was a huge difference. Initially, I had the LO at 23MHz and with a 9 MHz IF nets 14 MHz. LSB sounded stronger than USB and USB sounded pinched. I checked the code and the BFO frequencies were correct for that filter. So, my jump to the gun thought was a bad filter.
The next step was to install a new filter -- two wires and two nuts. Same problem. Then I tried a test where the LO was now at 5 MHz and thus what was USB was now LSB and the reverse. A most interesting outcome -- USB was now strong and LSB sounded pinched.
Then a small light in the tunnel led me to another possibility and one often is the last thought or never looked at all. I cruised up to 15.0 MHz to listen to WWV. I was receiving WWV at 14.998.8 MHz. The frequency was off by 1.2 kHz. The Carrier Boards for the Si-5351 have either a 25MHz or 27MHz reference crystal that must be calibrated to get the proper frequencies generated. You dial in 15MHz, and you receive (or transmit) on 15MHz when all is calibrated.
Failure to calibrate the Si5351 with a proper correction factor for the on-board crystal means all three clocks will be generating improper frequencies. The code may say one thing but what results will actually be different without a proper correction factor.
There are many references on the internet as to how to properly calibrate including a software routine. In thinking back some two years ago, I seem to remember I had smoked the Si5351 board which had been calibrated but the replacement was not.
My calibration process is to use my SDR radios where I sample CLK0 and adjust the correction factor in the sketch so what frequency that is being called up matches what I see on the SDR -- that can get me to about 1Hz. Sometimes on purpose I leave it at 20Hz off -- just so the FLEX guys can tell me I am 20Hz low. A few trial runs will get you the right calibration.
So, a calibration of the replaced Si5351 resulted in that switching sidebands has no change in background noise and when you tune 15MHz WWV --the rig reads 15MHz. Mystery solved with a culprit not 1st on the list to check.
TYGNYB!
73's
Pete N6QW
PS. When I searched the Internet for a calibration routine, I found a website that had the process. When I went to copy the link --it was on one of my own websites. Scary is a good word.
Having a wheel of fortune like device in my garage I use that to select topics for the blog. Today it landed on 17Meters.
This band undoubtedly is a Hidden Gem! Typically, devoid of any contest crap like Field Day it can provide many contacts including DX QSO's, all at QRP power levels. I worked my 1st ever station on Saipan using FT-8 at 5 watts on 17M.
The bonus is it usually is devoid of those hams in call areas 5, 7 and 4 who start cocktail hour at 6:00AM -- you know the ones that lurk on 75 M.
Some 17 years ago I built my 1st ever 17M SSB Transceiver. That was my 1st attempt at building a Shirt Pocket SSB transceiver which didn't quite get there but it was small. The IF was at 4.9152MHz and used a crystal switched VXO that covered most of the phone band. The final was an MRF260 which was good for about 3 watts output.
Fast forward to 2023 and I decided that technology would move that radio from VXO to the Digital world and taking the 7X7X2 aluminum chassis enclosure it was modified to incorporate a rather spiffy looking Color TFT display.
N6QW 17M Homebrew SSB Transceiver
17M SSB VXO Version
Of note it has two VFO's with memory and the 2nd VFO boots up on the FT-8 frequency. This affords a quick way of checking band activity. If there are FT-8 signals present, then the band is open.
Couple this jewel with my Digital Adapter along with a Raspberry Pi Zero W and you are cooking on FT-8. An advantage of 17M aside from sidestepping the inebriated hams is that the antennas can be quite small so great for those small postage-stamp sized lots.
Now a twizzle on this project would be to add a second set of Band Pass and Low Pass Filters so that when you switched bands instead of 18.1MHz the rig would boot up on 40M. The SPST band switch below the display would be changed out with a DPDT switch and add the filters and you are there! One or two lines of code changes would round out the conversion.
TYGNYB. The 40M would open things up for the POTA/SOTA guys.
73's
Pete N6QW
PS: Someone will ask so best answer this up front. I used the existing on-board Crystal BFO so the change in 2023 did not include the LSB/USB select. If the two-band version is in the "idea chamber" then it would be best to actually "ON" the BFO in the Si5351. Just the value of the BFO is used in the code for a proper display and the BFO is not actually turned ON in the code. If you choose simply to run the LO at 2 MHz and sideband inversion would automatically give you LSB. NOT a great idea because of BFO harmonics slipping through the 7MHz BPF. This was covered in the link. Thus, placing the LO above 40M would be the better option and using the LSB Carrier Oscillator frequency. You would also need a USB/LSB select switch to the mix.
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