Could there be "toob projects" on the horizon? Who in the world builds vacuum "toob" SSB transceivers in this modern age of digital / solid state electronics? Let me know if you do.
[In another life --N6QW was W6JFR! This CW Transmitter used plug in broadband band pass coupling between the 6AG7 and the 6L6 and therefore you only needed to dip and tune the final amplifier. Believe it or not some of our newly minted Amateur Extra Class US hams have no idea about or how to dip and tune the final.]
Our friend the "Fan Dancer" has dropped one of her fans and we get a sneak peak of the underlying "hardware". http://www.hfsignals.com
In a few short weeks we will be in a new year and thus I am taking a break from posting any information about radio/electronic projects. The past year has been chock full of SSB Transceiver projects and I am happy to report that the pile of projects that were successful and work reliably has grown significantly this year. I would like to take credit and say it is all about my skillfulness and homebrew "knack". But that is not the truth! It is technology that has been the real winner.
There is so much new technology that is now available to us that it is very hard to keep up. The other side of the coin --is that the technology is really "cheap". That is not a derisive "cheap" but a low cost (a high quality) cheap. Just bought two 160X128 Color TFT Displays -- $10 and 10 days to my door . You have seen these units before (below). So OK in the second photo it is a bit of in your face with the last line. But that is also a message --you don't have to be a Genius to use this technology.
To that end I did have to read up and study how it is done and I must acknowledge the many hams that really know how to do this stuff that are willing to help. That is what is so great about this hobby.
But to that end I did get an email recently where I was asked to redesign the Simpleceiver Plus SSB to fit what this ham had in his junk box and that I should provide him a schematic with the changes and artwork so he could have boards made in China. Well guys that is something I won't do and didn't do. You do have to invest some time in learning about the technology and there are tools to assist you --like LT Spice.
The very best of the Holiday Season to you and your families. I will be spending time with my family over the holidays --hard as it will be to resist sneaking out to the shop and heating up the iron. There are five transceiver projects on the bench awaiting my attention.
Today I did some initial transmitters tests of the Dual Filter SSB Transceiver. This is in hopes of completing another possibly two more SSB Transceivers prior to year end. You have to have one of these! Those German Filters are excellent!
I am hopeful of breaking some world record for the number of homebrew transceivers built in a single year.
It is hoped we never forget what happened that day 76 years ago.
Bill, N2CQR my friend and Cruise Director of the SolderSmoke Podcast frequently invokes TRGHS, which of course in plain speak "The Radio Gods Have Spoken." To that end just this morning I received an email from Joh in Freiburg, Germany who has been building the Simpleceiver Plus SSB Transceiver.
When I received his email I immediately thought about the current posting. Firstly you should be reminded that Joh, is not licensed as yet but is aggressively pursuing that goal. He has some new found friends as a result of this project and they are assisting him in getting prepared to take his test.
This is exactly the thrust of my posting! Joh is learning about the circuits and how they really work and how to troubleshoot problems. It is the learning that is what is the heart of the journey. Joh told me that he is now attacking a NorCal40 build in line with Chuck Adams 2018 goal to get the Norcal40/40A operating world wide. It is with every confidence based on his efforts with the Simpleceiver that Joh will have a working NorCal40.
Look closely at his photos --you even see "quick connects" on his switches. The two numbers on the color TFT are the LO Frequency (19 MHz) and the BFO Frequency (11.9 MHz). Note the cool backgrounds behind the numbers --one of those even is a close match to Juliano Blue
BTW Joh, tells me that once he got his rig mated with a proper antenna that the performance was amazing --even some of his new found friends were impressed. I am smiling --but I already knew that.
BTW 2 -- get plugged into VU2ESE as he will be commercially producing the uBitx multiband transceiver. Schematics were just released. It is an impressive design and that too is at the heart of this posting about the inexpensive technology that can produce an amazing radio that will not set you back kilo-bucks! !
Ask your self a serious question "Why did I become a ham"? There will undoubtedly be an array of answers and many of those answers will reflect not only your age, your past experience but also where you are today.
Many answers might be that a father or some relative was a ham, while others might be that at the time they entered the hobby it was a form of arm chair travel. Still others might answer it was a natural part of the Dilbert syndrome that you plain had the KNACK and being a ham was just a natural part of the affliction. Many new hams take up the hobby to fill the retirement vacuum. At the risk of forgetting myself, a friend long ago told me that it was his Mom that encouraged him to be a ham. Seems like in WW II she was an intercept code operator for the CIA. Wow bet she knew a thing or two.
By and large all of the roads lead to a common theme --the desire to communicate with others who have similar interests. Today it is the Internet and Social Media that has taken that common theme; but without the need for a soldering iron, nor a desk for holding your rig or wires strung all over the back and front yard.
Today the equivalent of a "ham shack' is hidden in the thin small case disguised as a mobile phone. That "mobile ham shack" does not need a 6 over 6 beam array at 100 feet ,nor an Alpha 9500 Amp or a Flex 6700 for world wide communications where you signal reports are always 20/S9 and the "band" is open 24/7. True some of the fancier Smart Phones cost a kilo-buck but that is a far cry from the $35K you just spent for the 6 over 6, the linear amp and the radio. Lest I forget within that phone we do have various modes such as phone (voice) and CW (texting) so that part is still within
But in the Good Old Days, the need to communicate could only be satisfied by "rolling your own" [an analogy to hand rolled cigarettes when people smoked a lot]. Thus to get on the air you had to build your own station.
Here another element is added to the array and that was the development of the technical skills necessary to construct, tune, align and operate the rig. Standard tools for bashing metal (these rigs used tubes and you had to mount the tube sockets) included a drill, and various metal files. If you had $$$ you might actually have some Greenlee Chassis Punches which produced a far better looking hole than that ugly one done with a rat tail file.
True the rigs were pretty Spartan consisting of a one or two tube "regens" for a pair of "ears" and the transmitter was often just a simple one tube oscillator. Undoubtedly the receiver was "cranky" and the transmitter if you were lucky might produce 5 to 10 watts of "pure chirp". Initially your station might be CW only but then some clever guys figured out how to add screen grid modulation (low cost) and if you were uptown then it would be plate modulation (higher cost). Your Smart Phone comes with that as standard.
In the building process you learned to be a scrounger and the cost of your rig was in direct proportion to how really good you were at scrounging. A defunct commercial broadcast receiver was a treasure trove of parts needed to build your rig. There was also a lot of hand building many of the parts you needed. I keep thinking of the ham who needed a variable capacitor who experienced a twofer --he took two beer cans and built a cylindrical variable capacitor. He enjoyed the beer first and the variable cap second. If our builder was really lucky and flush with cash he might actually have two crystals so he could operate in various parts of the band. After getting some air time under his belt the next progression might be to build a drifty analog vfo --so now he could work the whole band.
The TR switch often was pretty exotic consisting of a Double Pole Double Throw Knife Switch that was located at some place at the operating position where the operator could throw the switch and hit the key within a fraction of a second.
But what glory it was to make contacts with a receiver and transmitter you built. True the ham that spent $50K gets some glory when he rotates the two 100 foot towers that have phased 6 over 6 beams and opens and closes the band. But just think your homebrew rig might have cost $25. Did you both make contacts --of course. Did you both enjoy the communication process -- yes. But on a cost basis who spent less?
Just heard that the ICOM 7610 is out for distribution and $4K gets you the basic rig. So if you add power supplies and special microphones and auxiliary filters and crystal oven TCO's then add $2K. If you want to add the new Elecraft SS Amp add $6K. So $12K is better than $20K but where I come from in this hobby I would never spend that kind of $$$ just to say I have the latest and greatest. True my homebrew rigs don't have all of the bells and whistles like an ICOM 7610 but I do have a rebuilt Heathkit SB-200 and that will get me to 600 Watts + and so my playing field is maybe $1200 and I do make lots of contacts.
So despite the IARU saying that hams exist for two reasons: contests and operating, there are some of us who build our own rigs. I take pride in using what I have built and I also insure that at all times I try to put out the best signal possible. In building your own rig this requires an investment in knowledge and time to build the rig. I might spend a month building a rig and when I finish I have a sense of pride in "rolling my own"! There is another factor and that is the availability of advanced technology low cost parts. You can build a high stability digital VFO with color TFT display and have that for a $20 bill.
I am amazed at all of the information that is available on the Internet coupled with the low cost of parts. (If you can do surface mount --resistors and capacitors in bulk will cost a penny a piece). In the final analysis --building your own gear takes time, effort and dedication. In our instant gratification, couch potato world --it is easier to flash the plastic and just flip a switch and regale that for only $12K you are having all this fun! In the Good Old Days the fun was a total process from "noodling" the elements of a rig, building same and getting on the air. You can't imagine my joy when asked about my station and I proudly say "The rig on this end is homebrew!"
If you have not spent time in the Good Old Days, then just make sure you don't exceed your credit limit when you charge the ICOM 7610.
It is very easy to sit back and criticize others work or speak badly how others conduct themselves on the air. No skill or special expertise is needed to bad mouth another operator. But there are times when that operator is deserving of the derisive term "LID". In the early days of our hobby when one wanted to describe a poor operator (often a CW operator) the term used was that he or she was a LID.
Now I have been an extra class ham since 1977 which says I have been at it for 40 years --now you could argue is that 40 years of experience or one year of experience 40 times over. You have seen my published articles, my website and this blog --so you can make your own decision.
What is driving this posting is something I heard on 40 Meters yesterday afternoon. It was a phone (SSB) QSO between two extra class hams. Ham A was in southern California and ham B was in Colorado. Operator A was mobile at a location about 15 miles from me. He was making QSO's and getting reports of bad audio at times seeming to be FM'ing and at times like RF Feedback. Ham B was trying to assist him in resolving the matter.
Operator A stated he was mobile at rest, running a Kenwood TS-440S with the engine off. Ham B specifically inquired about the working conditions and that is what was reported. Based on that info Ham B who also had a TS440S mobile at one time, suggested that one of the issues may be low battery voltage as he had experienced that very same problem with low battery voltage and the engine turned off. [That indeed is a good item to check since there are large current swings like maybe 20 Amps on voice peaks.] Ham A then said he turned on the ignition but not had started the car and inquired was there any improvement? The response from Ham B was no change.
Now what would make you think turning the ignition to on without starting the car would improve the battery voltage. Ham B then said start the engine -- Ham A said that caused noise on receive. Ham B then said the Noise Blanker in the TS-440S usually could resolve the noise problem. Boom when he did turn on the engine --his signal was stronger and briefly the signal sounded quite clear. A clue here. That was reported back to Ham A who now reverted back to having the engine off. The next trick attempted by A was to shut off the speech processor --no change. He then thought moving the vehicle might help the signal --it didn't. He next was mobile in motion using PTT -- a new law in 2017 for CA requires VOX operation.
Ham B did inquire about the grounding situation like that might be a problem with RF Feedback
The QSO ended but I heard him later in other QSO's getting the same signal reports with the engine OFF and the processor ON.
Ok here is my rub and why I think Ham A should go back to being a Novice Operator. First and foremost no matter what class of license you hold, it is your responsibility to put out a clean signal. Secondly this LID has no clue about the basics of operating mobile.
I would question his physical installation as a starting place. What size cable did he use to connect to the battery --he did connect directly to the battery through a Circuit Breaker. He did look at the ignition systems and install the special spark gap cable and did he install the ferrite core type 30 RF chokes on the spark gap cables and most certainly did he insure that the tail pipe was grounded to the body. Oh by the way he did he install his mobile antenna mount so that it was properly grounded to the frame.
I have serious doubts that any of this was done since his answer was to turn off the engine and at most turn the ignition to on. I even wonder if he had an SWR bridge in line and if his antenna was resonant on the 40 Meter Band. But he is an extra class ham????
At the heart of my beef with this CA Extra Class Ham is that he wasn't listening to what he was told by the other station AND he had no trouble shooting process to isolate and resolve the problem. But hey he is an Extra so why does he need any process.
Were it my mobile installation and my rig, the first thing I would do is separate the rig from the install as the problem area. Step 1 would be to put the rig on an home power supply like 13.8 VDC at 25 amps and a resonant antenna and make contacts with local strong stations from home. If the problem persists you know you have a rig problem.
Given the vintage of the rig -- I would take the covers off and look at all of the screw type grounding connections that mount the individual circuit boards to the main chassis. Backing out the screws and giving a small dab of de-oxit and re-tightening the screws is a good practice. Oxidation can cause poor grounding and result in some of the symptoms being observed at the other end. But this Extra Class Ham probably has never opened up his rig nor even have the service manual. The term plug and play to the LID operator means every time you plug it in it should play. Boy is that a bad assumption.
While this easier than ever to get an Extra Class license and that ease is intended to boost the number of hams so that the off shore manufacturers can sell more radios -- box top radio licenses is no substitute for knowing what you are doing or how to do it. Shame on this ham for actively being a LID.
Now suppose the TS 440S passes the home operation tests that now gives data points for three areas in the mobile installation: 1) condition of the battery and connections to same, 2) resolving the noise issues --the blanker will do its part if you address some of the other required factors and 3) the antenna system install and the resonance on 40 Meters. Operating the rig mobile (unless maybe a 2 watt QRP Rig) with the engine running is necessary to have sufficient voltage AND current to put out 100 watts!
But hey none of this was taught when you studied the 20 questions on the Internet and then took and passed the same 20 questions on the test. [I have been corrected you have to memorize 50 questions and can miss 13 for a score of 74% and still get an Extra. I guess the 13 that he might have missed involved questions about FM'ing and RF Feedback or how to successfully run mobile. Sorry guys but Extra Class licenses were just that in the good old days: extra privileges based on demonstrating the ability to use those privileges.]
So no matter what or how you operate --it is your responsibility to know what you are doing -- turning off the speech processor is a great first step but does not resolve FM'ing or RF feedback. Know what you are doing--LID.
This transceiver will leap tall buildings in a single bound, will go faster than a speeding bullet and is stronger than cobalt steel. Save your Christmas money for this project.
The basic circuit uses the Plessey PNP NPN bilateral amplifier as found in EMRFD ahead and following the Crystal filters which are diode steered. I have found you can use 8 VDC versus the recommended 6 VDC and you see a significant gain improvement. Ahead and following the IF amp block are ADE-1's where on the front end it is used as the Rx Tx mixer stage. On the back end the ADE-1 is used as the Product Detector on receive and as the Balanced Modulator on transmit.
While this test setup used a signal 2N3904 as the Rx RF Amplifier the final configuration will have two J310's configured as a Dual Gate MOSFET. There will be two small communications relays that will switch signals so that on Rx it is the receiver RF amp and on Tx it will be the transmit Pre-Driver. I have used this approach on the Simpleceiver Plus SSB transceiver and the Teensy 3.5 SDR transceiver. It works well!!!!
The audio amplifier stage use an NE5534 driving an LM380. For the microphone amp the 2N3904 is pressed into service. The Driver is the 2N2222 followed by a BD139. The Final is an IRF510. The current plan is to have this as a two band transceiver ~ very likely 40 and 20 Meters.
Tomorrow will be December 1st and that brings me back to many fond memories of growing up in Western Pennsylvania just a hair north of the city of Pittsburgh. With Thanksgiving over, December 1st signaled it was the time when the local radios stations (KDKA, WCAE and KQV) pumped out non-stop Christmas music. For those youngsters reading this, the time frame was the late 1940's early 1950's. There were but two TV stations in Pittsburgh and the saturation of TV Set ownership was maybe 10 to 12%. Thus the old broadcast band radio was our entertainment. We even had a radio station in my hometown of New Kensington, where Michael Felak droned out the news and Bob Livorio was our local dis jockey hero.
It was a special time for me, as my birthday was but a few weeks away and as luck would have it exactly one week before Christmas. My Mom's birthday was December 5th and there were several others aunts/cousins whose birthday were interspersed between the 5th and 18th. So every weekend in December was a party. Thus we had the music and we had celebrations.
The very best celebration was December 1945, where my Dad and four uncles all were released from the US Army in time to be home for Christmas. This was a special celebration for one of my Uncle's who spent two years in a German POW camp. Uncle Frank shared with us that on two prior years on Christmas that the packages that were sent via the Red Cross were smashed to bits right before their eyes. My Uncle Carmine told stories about all the native girls he met while he was island hopping across the Pacific. I thought about Uncle Carmine a lot while I spent some time in the Pacific --never did see all those gorgeous women he spoke of in such glowing terms.
January 1 was often a sad day in that the music was over and we had celebrated so much that I gained about 10 pounds. But it was a good time.
Given what is happening here in the USA today I long for those good old days. Let us be honest our government is in chaos and is adrift. A big thank you to those who wanted the swamp drained! The old adage --be careful for what you wish for has such a truth to it.
I am personally appalled at all of those who have been identified with sexual assault, sexual harassment and having egos so big that they honestly believe they can get away with it. Shame on them!
What happened to the Christmas music non-stop on KQV hosted by Ray Noble, and where are all of the celebrations?
Stay tuned --a whole new raft of projects are lined up on the bench.
Today I wanted to spend a bit of time comparing the new SDR homebrew transceiver to "filter" type rigs I have built. First though I do want to share that I worked my very 1st DX station with the SDR rig and that was XF1IM who is in lower Baja California. The distance was 1600 miles running 100 watts. So I am beaming from ear to ear.
Firstly I do want to acknowledge once again the pioneering work of Charlie, ZL2CTM and his several you tube videos that got me kick started into rolling my own SDR rig. Notwithstanding I do have several SDR kit radios including several Softrocks and the Omnia based on the Peaberry --and even one that uses a Softrock with a Raspberry Pi. So I am not brand new to SDR, but I am new to rolling my own.
Above all there seems to be a clarity to the signals and perhaps that is because the bandwidth may be a bit wider. It was even suggested to me (by an appliance operator no less) that I should open up the bandwidth to 3.5 kHz. Well friend that may be problematic. But the sound is fuller. It does have presence and brightness with no "yellowy sounds" in the mid-range.
I also note that signals seem to pop out of nowhere. Boom no signal and very quiet then suddenly a rock crushing signal. There was an occasional you are 20 hertz low and I disregarded that since I rechecked --and that station was 20 Hertz high.
All in all there is very little hardware as such and in going over the cost --about $100 with half of that in the Teensy 3.5 and Codec board. So it does cost almost 2X the Bitx and you do have to build it yourself; but there are opportunities beyond the basic radio from India. Those are mainly in adding software functionality like variable filtering (you can decide how many filters and bandwidths you would like). Charlie has developed some software so you can watch the FFT display of Frequency Spectrum -- that would be hard to do with the Bitx. So think about it -- a far greater capability for about $41 more. There is a wave coming and we are the beneficiaries of the low cost technological wonders.
11/26/2017 ~ More Refinements & More Contacts.
That is the pure beauty of our hobby -- you make contacts and you get feedback on your signal. I did get some feedback about signal quality that appeared to be related to signal distortion on large voice peaks. It was not RF feedback; but more in line of things running "too hot". [Not hot in the sense of heat but rather too much gain".] It also appears there was somewhat of a restricted voice in that the signal sounded a bit narrow.
To address these issues I went back to Charlie's original low pass filter (as I would have to design a new Band Pass filter that was a bit wider) and a clue from one of the QSO's was what happened when I reduced the gain on the J310's in the combo Rx Tx amp stage. The report back was that the distortion on peaks had almost disappeared. Big Clue. But that also reduced the Rx RF gain significantly. So I had to strike some sort of balance on the gain settings between receive and transmit.
In the EMRFD stage the input had a 5.5 dB T Type attenuator pad as I found over several earlier builds this tremendously helped the stability of the stage. Thus a plan was formulated to increase the size of the pad from the 5.5 dB to 10db and this enabled me to increase the gain on the Rx RF Amp side by about 5 dB overall. Thus we had best of all worlds. So the balance was struck. Next I went into the software and reduced the microphone gain which was set at 40 down to 30. The full gain setting is 60 --so we are at half gain versus 2/3. As a final adjustment I tweaked the bias level of the IRF 510 to about 4 volts --it was running about 3.6 VDC.
In listening to the signal on an outboard receiver and then looking at the scope pattern I could tell that the signal quality had greatly improved -- and I still was getting 100 watts out with the outboard amp. Three contacts, one in Colorado and two local contacts including one with my friend Ben AI6YR verified that all was good in the hood. I also took the time to "clean up" some of the wiring including running some leads under the base PC Board. That clean can be seen in the photo below.
The next goal is to finalize the switching circuits and get everything into an enclosure. I then want to turn my attention to learning more about the software and some upgrades in functionality like adding the 160X128 Color TFT display, switchable USB/LSB and a TONE for Tune Up whish is pretty much standard in all N6QW Homebrew Rigs. Yet another upgrade in the software is switchable filters for SSB and CW.
The next goal is to get this in a box and finalize the switching and control ciruits
11/22/2017 ~ Adding the RF Power Amplifier Stage
DRUM ROLL ~ 1st Contact with K8NG
As luck would have it I heard K8NG calling CQ on 7.213 MHz at 1510 PST and gave him a shout. Boom he came back to me with a report of 5X3, 5X4. Mac, K8NG is located in Duck Creek Utah and interestingly enough one of the video made with the Simpleceiver Plus SSB was made with Chris, KF6FZY -- also in Duck Creek. There must be a pipeline. Mac reported the signal sounded fine albeit with a bit of restricted audio. That reflects the narrow band pass filter software that I installed. I was running 5 watts with the IRF510 and no amps. the antenna was my usual droopy dipole. A great day. It doesn't get any better.
I went over to the Simpleceiver Plus Prototype and temporarily liberated the Driver, Final and Low Pass Filter stages and connected them to the Teensy SDR. I got about 6 watts out and was pleased to see this work.
I am lacking a relay to make this a fully functional Transceiver so for these test all was hardwired. I am overcome by getting ready for the gang that is coming in for Turkey Day--so I will have to curtail any activity for a few days. You can also visit my cooking website as some of the recipes on the site will be the fare for Thursday. www.pastapete.com
11/21/2017 ~ Relays added to the Front End Board
If you look closely at the J310's RF Amplifier you will see a couple of 12 VDC SPDT Communications relays that I purchased from All Electronics.
Look closely as these are listed as micro-miniature relays. These are made by Fujitsu and are the BRD series. These bought in quantities can be had for 35 cents each. The contacts are good for 2 amps. A little super glue and they are solidly mounted to the PC Board. I tested this configuration and it works FB. The relays can be seen along the upper right hand corner of the board.
Charlie, ZL2CTM shared with me how to change the Microphone Gain and I have been able to do that successfully. Stay tuned --we may be not too far off from some on the air tests.
11/20/2017 ~ First Transmit Test and More Listening Tests
The transmit concept works with my front end board. The Modem Transformers are also now a proven concept on transmit. I need to find a way to adjust the Microphone gain and to look in more detail the output SSB Envelope. But this is getting exciting.
11/19/2017 ~ Block Diagram of the SDR Front End
11/18/2017 ~ We are 98% there ... Listen to the Video
This video is a great leap up from where we started. I think we have some positive trends going here. My next task is to get it t work on Transmit and then we can see if we can make a Transceiver from these two boards.
11/17/2017 ~ The Problem Appears to be Fixed
Aside from installing a new Codec board and taking a tip from Hans Summers g0upl, today the 600 Ohm to 600 Ohm Isolation transformers arrived and were installed. That cured the hum problem and I will make another video to demonstrate the improvement. The Trick is to separate the grounds. Thanks Hans!
Shown above are the two Isolation transformers (sold as Modem Transformers from Jameco Electronics -- Triad Transformer is the Manufacturer-- about $6 each). Phasing is important and that is why you see the dots (as supplied) on the transformers. Hard to believe that what you see above is the front end, the quadrature LO, phase splitter and the I & Q Detectors. The audio amp (2N3904/LM-386-3) is also on this board.
In passing I do know that the I & Q is working very well. After modifying this board and the Teeny 3.5 board to add the isolation transformers I powered up the unit --and all I was receiving was USB -- Inadvertently I had the I & Q reversed.
The two black wires going to the ADE-1's is actually a chunk of shielded cable from a pair of defunct Sony Walkman earbuds. I made it extra long just in case I did that. I will now trim the wires and tidy things up. On either side of the J310's RF amp stage I will be adding a couple of relays on the RF Amp to use this circuit as the Rx RF Amp and as the Tx RF Pre-Amp just like in the Simpleceiver Plus V2.0. I purposely left space on this board to do that. You still need to have the isolator installed on the audio output out of the Teensy 3.5.
Can't wait to get this working as a transceiver.
11/16/2017 ~ Some Progress on Fixing the Whine Burble Noise
Part of the problem was the Teensy Codec Board. I had a second board and the above video shows the improvement. We are not out of the woods yet. There is still a bit of background hum which may be resolved with the addition of the 600 Ohm to 600 Ohm Isolating transformers on the front end output similar to what Hans Summers has done with his QRP Labs receiver board. I already have a small fortune in hardware so a few more bucks almost seems like pocket change. The flies in the face of my 1st station which cost me $20 in 1959. I had to mow a lot of lawns to amass $20.
With a large Tip Of The Cap to Charlie Morris ZL2CTM who has done some pioneering work in building SDR SSB Transceivers as evidenced by his superb videos on You Tube --I decided to try my hand at replicating Charlie's work. ZL2CTM has most kindly provided me a great deal of assistance and supplied the all important sketch code and many photos and schematics that he used.
Charlie has been successful with his rig. But I have not been so lucky. I simply cannot put my finger on the root cause but in hopes of those more skilled at this SDR stuff will immediately know the answer. View the video and "Tell Me What You Think".
The main issue is the terrible background noise that is present on the audio output. If the "whine and burbling background noise" could be resolved --this would be one heck of a rig.
By way of background the rig consists of a front end comprised of a pair of J310's configured as a DGM RF amplifier, a 40M Band Pass Filter, a homebrew ferrite core balun signal splitter, two ADE-1's as the I & Q Detectors and a SN74AC74 that is used as the divide by 4 quadrature LO. Also on the main board is an audio amplifier using the 2N3904 and LM386-3.
The SDR board has the Teensy 3.5, the Audio Codec Board, the Si5351 and some relay switching so the Line In and Line Out I & Q can be routed to/from the board. For a Display I am using the 1 inch square OLED.
After connecting everything up and listening -- it was awful and a terrible whine and burbling noise was evident which called for a disciplined trouble shooting process. The first thing I did was hook up the front end as a Direct Conversion Receiver and routed the output of the I & Q Detectors to the Audio amp (1 channel at a time). The sound was crisp, clear and no evidence of any problems. While the SDR board was bypassed, I was using the LO signal from the Si5351 and the OLED for reading the frequency. Thus the clean signal was not impacted by any OLED noise and what also was evident -- nothing was coming through the Si5351. The outlier was the Teensy 3.5 and the Codec Board.
Steve Hartley g0fuw sent me an email about an event in the UK called YOTA which also had a link to a video about the event. (YOTA = Youngsters On The Air). After seeing what these youngsters were doing -- they probably have the answer. The problem is this "oldster" doesn't! Help????
I did pose the problem on the PJRC Forum (Teensy gang) and even contacted the head guru at Teensy -- aside from one response from the forum which was not helpful nothing else has been heard other than to sell me another piece of hardware while helpful did not totally resolve the issue. Help????
This project has been a frustration to me personally as I just don't know enough about the Teensy 3.5 to lay a finger on the problem. Perhaps it is not a bad device --but I upgraded to a Teensy 3.6 and the results were worse --an important clue that the problem is a Teensy hardware issue.
Has anyone reading this blog been successful with the Teensy 3.5 -- ZL2CTM has had good luck but he too is scratching his head.
11/13/2017 ~ Last Posting on the Simpleceiver Plus SSB XCVR
Thanks for riding along but now it is time to move on --Perhaps Part 15 Low Power Neighborhood FM radio stations using a Arduino and Si5351 in an FM Mode much like VU2ESE. It is a whole new world out there. I can only hope the readers have enjoyed this project as much as I have.
11/12/2017 ~ A Few More Photos Before Painting JuliYellow
Note new email address as of 11/12/2017: firstname.lastname@example.org
An approach for indicating USB/LSB --The Red Square. Works for Me. So far have had a bout 10 contacts and the Rig is doing exceptionally well.
11/11/2017 ~ On the Air QSO with KC6FZY.
The Simpleceiver Plus SSB Transceiver is nearly complete and the documentation will ultimately shift to my website http://www.n6qw.com. Most likely there will be no more posts about the project as I have been politely told -- enough Pete! Despite that input this rig is one of the better ones I have built.
11/09/2017 ~ First QSO with the Simpleceiver Plus SSB V2.0
The wiring of the V2.0 was completed today and the very first QSO was coast to coast with WA3RSL, Frank in Appomattox, VA. The QSO was at 1445 PDT on 7188 kHz. Frank was running a Yaesu FTdx3000 with an ACOM 1000 and a 5 element wire beam. On this end I was running the V2.0, the intermediate amp and the SB200. The Pout was close to 800 Watts and my usual antenna was the droopy dipole. WA3RSL was of course 5X9+ and I also got a 5X9 report --including a comment on the nice sounding audio.
Top View of the Simpleceiver Plus SSB V2.0
This is the Simpleceiver Plus V2.0 SSB Transceiver prior to painting and finishing off the case.
This project has turned out to be one of the best transceivers I have ever constructed -- and the circuitry is so simple. Stay tuned for more reports of on the air QSO's
11/08/2017 ~ Simpleceiver Plus V2.0 Construction Photos
First look at the front panel layout of the Simpleceiver Plus V2.10 SSB Transceiver being boxed up. Work remaining includes building the Low Pass Filter and the power relay switching wiring plus build the back panel. If we can get the LPF built we can do some on the air testing. I am impressed at the sensitivity and how good it sounds.
This posting will now show some details of the V2.0 Build as we progress through the process. By way of review the V2.0 build consists of two PC boards which are stacked one above the other. Here is the breakdown of the two boards
Bottom Board. This is the main board consisting essentially of the following elements: The 40 Meter Band Pass Filter, The RxTx Mixer (ADE-1), The 9.0 MHz IF Amplifier block (two sets of J310'c configured as a Dual Gate MOSFET), The Product Detector/Balanced Modulator (ADE-1), The Audio Amplifier and The Microphone Amplifier. The IF Amplifier Block is relay switched so that the signal is passed through the block in the same direction on both transmit and receive. This one board forms the basis of the transceiver and all this circuitry is packed onto a board 4 X 6 inches.
The last photo show the board with all of the circuit blocks starting on the lower right side with the band pass filters moving to the lower left hand corner with the Surface Mount 2N3904 Microphone amplifier. The first photo shows the PC board on the bed of the CNC Mill. Noteworthy is that much of the wiring is routed underneath the PC Board which is mounted on the base plate using 1/4 inch aluminum pillars This really cleans up the wiring and helps with unintended coupling and feedback paths.
The top board is mounted on spacers that are about 1.25 inches above the main board. This board has the mounting space for the Si5351, The RxTx RF Amp Stage which again is relay switched to change the signal path so that is passes through the stage in the same direction on both transmit and receive. Following that stage is the EMRFD transmit driver block and finally the IRF510 final amplifier. Not seen is the aluminum plate that is 3 X 4 inches by 1/16 inch thick and forms the basis of the heat sink. This plate is mounted to PC board which has the cutout so that IRF510 is directly mounted to the plate. The overall box size now is about 4.375 inches wide by 8 inches long and 3 inches high.
The following photos show the top board and the component parts.
The above photo show the top board starting at the upper left corner with the space where the SI5351 will ne housed and below that is the relay switched RxTx amplifier stage consisting of two J310's configured as a Dual Gate MOSFET. In the lower right hand corner is the EMRFD Driver Stage with the IRF510 directly above that circuit block. If you look closely you will see the cutout in the board where the there is access to the heatsink.
The above board is the blank board hot off the CNC Mill. Additional work involved the removal of material where the IRF510 will penetrate the board. That was done on my manual mill --yes I have two of them. The heat sink is mounted to the PC Board and electrically connected so that it is actually a shield.
The above photo show how the Si5351 is affixed to the board and was taken prior to the installation of the Driver and Final stages.
I will take some additional photos as the construction progress. I am still noodling the front panel as I need to pay attention to the "ergonomics" of how the controls are arranged. Keep in mind that panel size will be 4.375 inches wide and 3 inches high. That is about 13 square inches and that must accommodate two large real estate items -- the large tuning knob and the display.
A question was asked about V1.0 and V2.0 and a comparison of their performance. I was delighted to see that both perform well and are essentially equal. The V2.0 in reality makes the rig be a compact package.
11/04/2017 ~ Simpleceiver Plus V2.0 First Transmitter Test . Take note a 2nd video was added to document the improved receiver performance with the one capacitor change (10NF) to the Drain on the 2nd IF Amp stage
We started of the day by building a surface mount version of our Microphone amp circuit that was originally developed for the LBS II transceiver.
The squares I milled out were 0.15 X 0.15 inches and the assembly is as shown above. Noteworthy this was designed over two years ago. This really works well!
Thus after building the microphone amp I hooked everything up and the output was low and the sound was garbled. Well if you look at the photo above -- there is a wire going from the 10 K surface mount resistor to ground as the SMD resistor straddles two squares. If you forget to include that wire then you get low output and garbled speech. I also found that by taking the output off of the drain of the of the second J310 Combo versus the junction of the 68 and 470 PF caps --more output and the instability issue I noted in the earlier video was in part from too low of a battery voltage. No instability with a higher voltage and the 10 nF connected to the drain.
You can see the transmitter testing here.
About another week and we should have board #2 completed ready for air testing.
11/03/2017 ~ Simpleceiver Plus V2.0 Inhaling RF.
Today was a great day as we got the receiver portion inhaling RF. I will do a bit more of peaking and tweaking and then build the microphone amplifier to test out the transmit function. We are about a week away from having a complete 2nd transceiver.
11/02/2017 ~ More Progress Photos and Notes
As of 1600 Today!
This afternoon I finished off the Audio Amp stage. The Finger Test (no not that one) produced a loud hiss on the output --thus this stage is working. Tomorrow's work plan is to add the two cables for the LO and BFO and with an outboard 2N3904 RF amp I will see if the receiver circuitry is working.
I also must modify the Arduino sketch for the 9.0 MHz IF but that is but a 5 minute effort.
Following that series of tests will be the building of the single transistor (2N3904) microphone amp stage that will reside in the island square area of the lower left hand corner. Virtually all of the power wiring and the controls for the audio amp and audio output plus the microphone input will be run underneath the PC Board. This sure makes things a lot neater.
The steps after that is to cut the top board for the RF circuits, TR & Control Relays and the LPF.
Still noodling the Front and Rear Panel layouts but the color scheme will be Juliano Blue.
BTW I have seen some CNC Mills advertised for sale that can be had for about $300. Since I have most of the circuit board patterns stuffed in the computer cutting new boards is a short piece of work. Christmas is coming --Time to either give yourself a present or to share with your family your Christmas Wish List.
On a sad note, once again I know that as usual this year my XYL will get me another SUV present (Socks, Underwear and Vitamins).
Today I added to the wiring and a couple of notes about impedance matching. The GQRP Filter has a Z in/out of 500 Ohms and so we will need to match that impedance of the two stages. On the output side of the 1st stage we have a 2 dB pad with an output of 50 Ohms --so a match from 50 to 500 Ohms is a 10:1 match. This easily done with a 6 Turn and 19 Turn transformer wound on a FT-37-43 Core. 6^2 = 36 and 19^2 = 361 ----361/36 = 10:1. Thank You Mr.Boyer.
On the input side of the 2nd stage we have 2.2K and so we must match 500 to 2.2K or a 4.4:1 match. This again is easily done with a 9 Turn Primary (500 Ohm side) and a 19 Turn Secondary (2.2K side) Thus 9^2 = 81 and 19^2 = 361 . 361/81 = 4.45 : 1. Thank You again Mr. Boyer.
Noteworthy is that I used some 1/4 inch aluminum pillars to elevate the board above the base plate and made penetrations through the PC Board so the wiring would pass underneath the board. Look closely and you will see the two SPDT relays that are used for routing the signal through the IF Amplifier block for Transmit and Receive which was successfully demonstrated in the V.1 Prototype.
I also used my standard color code for wiring.
Red wires for circuits powered at all times --IF Amplifier block
Orange wires for those circuits powered only on receive -- Audio Amplifier
Yellow wires for circuit powered only on transmit --Mic Amp, Relays and Transmit chain
Black wires for grounds
That is it for now -- if I get a chance to add the parts for the audio amplifier we may get to test this on receive later today.
So OK many of our builders are still in the process of collecting parts for the Direct Conversion Receiver version (that was three configurations ago). But just in case you are ready for the next (and final) iteration of this project here we go.
Version 2 -- What is it? V2.0 is the Simpleceiver Plus SSB Transceiver Architecture with the following changes:
A GRQP Club 9.0 MHz Crystal Filter is used in place of the homebrew 12.096 Four Pole Filter. This gives the advantage of acquiring the matching crystals for the BFO and with a 5 MHz Analog VFO you can have a two band rig (20 meters or 80 Meters). The only change required is the appropriate matching Band Pass and Low Pass Filters. A couple of relays and a toggle switch will put you on either band. So a big plus here. Or you can leave it on 40 Meters.
Compacting the rig in physical size. I have used two 4 X 6 inch PC Board and fit all of the circuitry on these two boards which will then be stacked upon each other. The main board has the Band Pass Filter, the RxTx mixer (ADE-1), the IF block module comprised of two amps and the filter with the relay switching network, the ADE-1 Product Detector/Balanced Modulator, the Microphone Amplifier and the Audio Amplifier.
The upper (second) board will have the RxTx RF Amplifier, the driver stage and the IRF 510 Final, Low Pass filter and the TR relay switching scheme.
The Si5351/Arduino/Display will be mounted to the front panel.
The finished size should be about 4.5 Inches wide, about 9 inches deep and about 3 inches high. This is not a miniature rig but certainly small and will be painted Oasis Blue
Here are some photos of the work in progress: The grid in the lower left hand corner is for the Microphone Amp and the grid in the lower middle is for the Audio Amplifier. There are some blank spaces on the board where the switching relay will be installed