Wednesday, October 11, 2017

Simpleceiver Plus SSB Transceiver ~ A new DifX

A Move to the Simpleceiver SSB Transceiver.

 

The Simpleceiver Plus SSB Transceiver is on the Air!

 

10/22/2017 ~ The Simpleceiver Plus SSB Transceiver 1st QSO with W1AW/6

It does not get any better than this -- imagine my surprise when at 9:30 AM PDST on 7.185 MHz I heard W1AW/6 calling CQ --several times. I could resist no longer. Gave him a call and the Op Marty, called me back. Boom! The Radio Gods Have Spoken. My very 1st QSO with the Simpleceiver Plus SSB Transceiver and it is with W1AW/6. This was a special events station at San Ramon, CA  (SF Bay area) in connection with Pacificon (a Ham Radio Event). I was running 500 MW with the EMRFD Driver board and my report was 5X8.
 
Needless to say the most amazed person was me! San Ramon is about 350 Miles form the N6QW Newbury Park Laboratories. So OK -- here is a photo -- it looks like crap but works like a bomb!
 
 

The EMRFD Driver Board is at the Top Center off the bread board. I did not even have the TR relay set up so the Driver board is connected to the antenna and I was using an outboard receiver where I could switch my droopy dipole between the board and the external Rx. Today I need to get the TR relay installed and the LPF. You can see I was all set to install the LPF (The three toroids were wound just this morning and are lying just to the right of the board.)
 
This was an exciting day -- the Simpleceiver Pus SSB Transceiver has many innovations and what you see in the photo above is pretty much the Superhetrodyne Receiver with a  few relays, a microphone amp and the driver board. Go get off the couch and heat up that soldering iron!

More Photos -- had to add a small T Type attenuator pad on the EMRFD driver stage when I discovered a RF feedback problem when it is used with an outboard linear amp. The issue was I had to lower the gain on the pre-driver to prevent the RF Feedback but that then lowered the receive gain of the stage. The Pad lets me run more gain on receive and solves the RF feedback issue.

The RF Amplifier board used both on Rx & Tx

The IF Block that uses the relay switching for Rx and Tx

The EMRFD Driver board with a 5.5 dB T Type Pad on the input [ 2X 15 Ohm and 1 X 75 Ohm]

W3NQN LPF

PD/BM with the single 2N3904 Microphone Amplifier


I now have it rigged up with 2 in-line amplifiers and it will run 200 Watts output. Several additional contacts were made today at 10 watts with stations in Arizona and Nevada. Go Simpleceiver Plus SSB Transceiver! So far about a half dozen contacts today.
 
73's
Pete N6QW
 

10/21/2017 ~ Addendum On the RF Stage Switching

Works flawlessly and produces 1.64 Volts Peak to Peak across a 50 Ohm load which is 6.72 Milliwatts. Next I will test the EMRFD standard driver stage (2N2222 and 2N3866) to follow this stage and see what that output looks like. It may be enough to try some QSO's. The output is clean and sounds really good. Yes I did look at the signal with my homebrew SDR receiver and Power SDR. This is exciting.
 
73's
Pete N6QW
 

10/21/2017 ~ First Look at Switching the RF Amp Stage for Rx and Tx

Here is a first look at using our J310 Dual Gate MOSFET Stage to also work as the Transmit Pre-driver stage. Again the surplus Omron G5V 5 VDC SPDT relays are doing the heavy lifting.
 
 
The above schematic is my first prototype and I will be wiring that up today. The beauty of the relay switching is that we use the inherent circuits of the Superhetrodyne receiver blocks in the Transmit stages. This means minimum building and ease of construction. Stay tuned we are inching closer to an on the air transceiver.
 
73's
Pete N6QW
 
 
 
 

10/20/2017 ~ Houston we have Ignition -- The Simpleceiver Plus SSB Transmitter Portion of the Transceiver is Working and Exhaling RF!

 

Exciting news! The Transmitter is working and for your own amusement and amazement you can see it working here. It was an exciting day at the N6QW Newbury Park Laboratories.
 
 
 
 
Some noteworthy mentions. The relay switching of the IF block module works beyond my expectations. Plenty of RF coming out of the block which now has me thinking the receiver RF amp stage could similarly be switched with two relays so that it would function on both transmit and receive. Two more blocks (low level driver stage and LPF) would yield an actual working 300- 400 MW QRP transceiver. I also found that the LSB BFO frequency seems spot on but the USB needs to be adjusted. I need to go back into the code and adjust the frequency so that the USB does not sound pinched, which you can hear on the video.
 
Keep in mind that by adding just a simple one transistor microphone amp and adding now 4 relays you can turn the Superhetrodyne receiver configuration into a working SSB transceiver.
 
 
In the next post I hope to  get a chance to include the schematic of the microphone amp and how I wired up the RF amplifier with the two additional relays. For those who can't wait visit my website at www.n6qw.com and link on to the LM373 transceiver project and one of the linked schematics is the microphone amp.
 
73's
Pete N6QW


 
 
 

10/18/2017 ~ Troubleshooting the Simpleceiver Plus SSB Transceiver

Soon we will be having a complete transceiver and that is usually where the fun begins. No, at this point I am not addressing the fun side when you make contacts; but the agony when something isn't working and it drives you nuts. We all know that fun!
 
I want to share with you two stories from my earlier life that while they are not directly related to ham radio none the less tell a powerful story about when confronted with trouble shooting problems.
 
Taking the time machine back to 1966 I was a Lieutenant in the US Navy [For those who wonder I was USN not USNR.] Being chronically sea sick I was assigned to the US Naval Civil Engineer Corps. (SeaBees guys). In 1966 I headed a small group of principally Chief Petty Officers (most were Master Chiefs and thus at the highest enlisted rank) who each had a specialty in the construction trades. These specialties included builder, utility man, electrician etc. Our job was to assemble stateside, a complete camp that would be shipped to South Vietnam. Typically we were given a number like a 500 man camp at location X and then we would essentially assemble the parts for a "Giant Heathkit" that would be shipped to location X.
 
Because the Vietnam War was ramping up so quickly, we were forced to purchase COTS (Commercial Off The Shelf) products such as pre-engineered buildings. Perhaps you heard the term Butler Building which happened to be a specific manufacturer. But there were others like Strand Steel or Soule and others. These buildings were typically 40 X 100 square feet and while all manufacturers had s stock 40 X 100 foot buildings, the actual steel support structure was different and the "bents" typically were spaced differently and the anchor bolt patterns were different.

A 500 man camp may have a half dozen of these buildings. Often slabs were poured before the actual buildings arrived on site. In one of these "kits" might be buildings of several different manufacturers. Thus we got a lot of grief from the field battalions about the wrong pads for the right buildings.
 
Back to our Master Chief Petty Officers --a unique breed all of their own. One of them came to me and said I am going to lunch, I am going to drink until I get drunk and I will solve this problem by tomorrow! He then said I assume you have no questions about what I am going to do. The next morning when I came to work there he was and he looked like hell -- obviously he had a lot to drink. Then he says about 11:00 PM the prior night he came to the office (half in the bag) and developed his solution. It was brilliant!
 
The solution involved creating a new universal drawing for the 40 X 100 foot concrete slabs that had embedded anchor bolts spaced apart for every pre-engineered building we used. Thus when the slab was poured extra anchor bolts were installed in the slab. When the building showed up --you simply used the magic decoder chart and cut off the anchor bolts that were not needed. About a half hours worth of work with a torch and you were ready to install any building that was delivered.
 
After that I frequently encouraged the Master Chief to take a long lunch hour! He was the guy who changed the Bill Of Materials to 29 common items. Initially we had four different sizes of hinges in the kits --he asked --WHY? Supply one size of hinge and it will work anywhere. We stopped supplying 4X4's and if you needed a 4X4 make it from two 2X4's This was advanced base construction not building luxury homes in Beverly Hills. The guys in the field appreciated this too as the parts shortages went way down as you only had to deal with 29 items!
 
We not only assembled the kits but we bought the parts --I can tell you there were over 5000 of those buildings that were bought! His solutions saved us countless man hours.
 
The next story took place after I had left the Navy and was working for Boeing in Everett, WA, home of the 747 manufacturing plant and the world's largest building by volume. I joined Boeing when 747 Ship #1 was going final assembly. You can't imagine the energy and excitement that filled the plant. Ship #1 typically is not sold, but is used as a flight test vehicle. As an airplane is moved down the assembly line it frequently is raised on special jacks so that access can be gained to areas that are not accessible in the normal mode.
 
As luck would have it as Ship #1 was nearing completion of final assembly it slipped off the jacks and one of the jacks penetrated the wing in the area of one of the fuel tanks. Disaster! Catastrophic was a common catch phrase. Most of the VP's could only think about the hit to the stock and their incentive compensation. Some of the brilliant young engineers suggested that in a month they could cut off the wing and install a new one. A month? Well finally someone said lets ask Bill Geist (he was my boss's boss).
 
Bill came down to the final assembly area and started laughing at what he heard being suggested. Geist ran the manufacturing line for the B-17 during WWII and planes slipping off jacks was routine. He said here is how you fix that problem --boom it was about 16 hours worth of work, which was the standard fix for a B-17 jack impalement. Once again Tribal Knowledge to the rescue.

Bill's comments were that this was Ship #1 and it would never be sold --so who cares if there is a patch on one the wings --not even visible. The program had only a slight 16 hour delay. The VP incentive stock was not hit and they even spun the story about the amazing Boeing Engineers! Bill Geist was not an engineer but sure knew how to build and fix airplanes.
 
So there is a ham radio aspect to these two stories as it applies to what we do in our hobby. Almost always there is a simple solution to  trouble shooting a problem. You might have to drink a bit to find it; but don't start by ripping everything apart. Also only change one thing at a time! Spend time thinking about what could be the problem and what clues lead you to the answer. Don't raise the bridge --lower the water.
 
 
73's
Pete N6QW
 
 

10/16/2017 ~ Response to some questions.

The Ghost in the Machine has struck again and now it seems I can't respond to questions that are posted. So I will do it this way
 
  1. I used two relays for some specific reasons. One is of course thinking they would be better for the isolation issue and 2nd -- That is what was in the Junk Box. I do think this isolation is an issue as I found that was a problem when I used the diodes. The diodes did not prove as good as the two relays.
  2. Following on to Jan's comments. Yes a pair of TIA amps does involve six transistors just as the J310's would require 4 for a pair of amps. Jan, I guess my approach has always been that there is never a single point solution. Often I see and hear comments that the TIA is the only amp that should be used or that the Bitx is the singular approach to building a transceiver. Today I have one Bitx and only one that uses the TIA amps. Thus about 20 or so other transceivers  use other approaches. The bottom line is to foster experimentation and trying new things.
 
 
73's
Pete N6QW 

10/16/2017 ~ J310 Spice Model & Photo of IF Amp Block

I received an inquiry about how to find the LT Spice Model for the J310. I am not sure that LT Spice has updated the library with the J310 --keep getting a message about it being 764 days since I updated my LT Spice. Guys there is a very good reason why I don't do things like that -- I updated my Arduino IDE and none of my old sketches would work and in fact I lost some sketches. That was a disaster!
 
Now if you look carefully at this blog page you will see that long ago I added a Search Block. If you type in J310 Spice Model it will take you to a page about two years ago called Simpleceiver 7 and on that page is a link where you can find the spice models for many devices including the J310. [Do I have to do all of the heavy lifting? ] Anyway that page has now been updated to the following link:
 
 
So I guess it is now time for me to remove the Search Block as it obviously is not being used!
 
I have installed the two relays on the IF block module. I also installed a 7805 which provides power to the two relays -- tried it initially with just a 78L05 -- too much current draw with two relays. The 7805 is sitting next to one of the relays. I have yet to install the RG-174U cables which are used only on transmit but if I switch the relay --the receive signal is not in the loop-- so my quickie test tells me I wired it correctly. You can also see the board with the ADE-1 Product Detector / Balanced Modulator installed.
IF Block Module with Relays
 
Next to the ADE-1 is a blank area for the microphone amplifier which is the next build. Once I have the Microphone Amp built I can test the low level transmit stages. See there was a method to my madness. We are getting closer to having the transceiver built. Keep in mind how I earlier said that once you have the Superhetrodyne built that you were about 65% of the way to having the transceiver --now you can see why I said that.
 
 
Stay Tuned for more excitement!
 
73's
Pete N6QW 
 
 

10/14/2017 ~ Switching the IF Block Module ECN #2.

In an earlier series of posts I detailed how to keep the IF Amplifier Module and Crystal Filter intact and arrange for the switching of the signal direction using diode steering. My first attempt at doing that raised some issues about signal isolation and thus am changing that approach to using two simple small relays. The schematic for that change and the notes explain how it works. The relays also make it easier to retrofit the board --lots less wiring and lots less parts. The relays are SPDT from Omron G5RV - 5 Volts. They were bought surplus form All Electronics here in California. I think the price was under $1 each.
 

 
 Hope you can read the drawing and the notes. Engineering Drawing was not one of my strong suits when I was in College.
 
We are getting much closer. I will install the 2nd relay tomorrow and take some photos so you can see.
 
 
 
73's
Pete N6QW

10/12/2017 ~ A Question about the J310 Configuration

Jan Ciger posted a question about why use the J310 as the basic amplifier circuit as deployed throughout the Simpleceiver Plus project, versus using the Termination Insensitive Amplifier building block from Hayward and Kopski vintage 2009. That is a good question and so I will attempt an answer as to the "why".
 
Fundamental to the answer is how I build things. Several days ago I responded to Johannes in downtown Freiburg suggesting he build a second receiver that was not so nicely packaged on a single board. My suggestion was that he build another one made up of modules i.e. audio amp module, RF amp, Product Detector that in effect becomes a test bed.
 
Thus we introduce the  rationale for the concept of an Experimenter's Platform. By building in modules, it is possible to try new circuit elements without destroying the whole project. Another key factor is the use of you tube videos. You can film a baseline of performance and then when you make a change you film that as well. Boom you now have documented data like when you go to the eye doctor and are being fitted for glasses. Is lens A better than lens B?
 
A second point is that we started the Simpleceiver Plus Project with the concept of a very basic and universal common circuit template. The  building block layout for the RF amplifier (Transmit or Receive) was essentially the same as for the Product Detector as well as the IF amplifier blocks. This made possible the use of very common parts and a limited number of parts values. The use of LT Spice enabled fine tweaking of a circuit dependent on its use. I could evaluate an RF amp circuit using the J310's and then see how that works for the IF amp. Further I could adjust the gate voltage (or introduce a signal on Gate #2 when used as a Product Detector) and see the performance change depending upon the specific application.
 
Now I am beginning to understand the real issue! I am not a Farhan, Hayward or Kopski!  Nor am I well known in the ham community as they are. So why would I suggest the use of J310's configured as a Dual Gate MOSFET versus simply pressing on with the well documented and frequently mentioned TIA?
 
Obviously many homebrewer's have heard that Dual Gate MOSFETs are like ancient technology --so much so that RCA no longer makes the venerable 40673. Most DGM's made today are surface mount so another "bad feature". The TIA (Termination Insensitive Amplifier) circuit was specifically developed for use in bi-directional radio transceivers --so again why in the world would you use J310's --and who is the N6QW guy?
 
For your Dining and Dancing pleasure I have prepared a chart that compares some of the features and benefits of the two circuits.
 
 
In looking at the chart it depends what lens is in place ( A or B). The TIA has many fine attributes and is well known and revered in the EMRFD community. Besides the  J310's have not been used in  a broad band mode but rather specific use of LT Spice enabled the performance to be fine tuned for a narrow band of frequencies.
 
For the most part they are comparable in performance. There is one aspect that I do find as being a difference and that is the ability to use AGC or manual gain. There are several You Tube Videos where I demonstrated the manual adjustment of the stage gain in the RF and two IF Amps -- I thought that was pretty impressive!
 
Now for a moment back to the Experimenter's Platform. It would be an easy matter for someone with this burning question to simply substitute TIA amps for the J310 amps and decide which is better. I have built a 20 Meter transceiver using the TIA amps where initially I set the gain for the 15 dB (using the 1st set of resistors in their chart). I was underwhelmed with the performance in that there was insufficient gain and the receiver sounded deaf.
 
When I changed the two resistors (from the data table) in the TIA application note so that the gain was 24 dB then that was more like it. Initially I thought I had a wiring error or bad parts --nope 15 dB per stage was not enough. Keep in mind that you have 6 dB of conversion loss in a SBL-1 and there is loss in the SSB filter. By my WAG I had lost about 15-18 dB of gain in the two SBL-1's and the crystal filter.  Adding about 18 dB of gain (15 to 24 = 9, and 2 X 9 =18) made it work.

I hate to say this --but it is gain across the whole topology that is the key factor --hold back the gain of the front end (because you amplify the noise as well) and make up that gain in the IF and audio stages. Thus you may get the point of my having adjustable stage gain capability for the RF and IF amps.
 
While I have not measured any noise figure ( I don't think I would even know how to do that) but I can tell you and others have commented --the signals seem to "pop" out of nowhere and the background noise between stations is low. So I guess that counts for something.
 
For those who may not believe N6QW actually built a transceiver using the TIA amps see below. [So OK stop drooling --- it does look like a rather nice layout!]
 
 
Now Jan, back to your question. You need only to listen to the current You Tube videos and ask do the J310's configured as a DGM sound OK? After all it is how it works and not so much what is under the hood.

Maybe a more fundamental question would be would I ever use a TIA circuit again? The answer is it depends but more than likely not. My first choice would be the J310's followed by the Bidirectional circuit I developed using the Tri-Quint MMIC amplifiers. The Blue Rig at the top of the masthead has the MMIC amplifiers for one of the stages.  Given what is the Simpleceiver Plus project (a clue is in the name), the J310's were a clear choice.
 
Thank you Jan, for your question as I am sure others would want to know why I did what I did.
 
73's
Pete N6QW
 
 
10/11/2017 
 
It is always best to start with a block diagram and this is shown below. You will note the blocks that are highlighted in yellow which reflect what is built so far. Noteworthy much of the built receiver becomes the transceiver.
 
I have posted several videos of the Simpleceiver Plus receiver configuration and I believe what you heard reflects the performance built into the design. Now look carefully at the block diagram you will see that many of the circuits are used both on transmit and receive. So this should be a huge flashing billboard that by working on the receiver and having it perform well will carry over to the transmit side as they are the same circuits.
 


What is not shown is the control/switching circuitry which will be detailed in subsequent postings. Thus it is imperative that you have the receiver working just as you heard on the you tube videos before starting the transceiver.

The next few days I will spend cleaning up the Simpleceiver Plus bread board by removing the original Product Detector and installing the ADE-1 onto the bread board. the plan is to take detailed photos so you can follow along with your build. We are getting closer.

73's
Pete N6QW

Wednesday, September 13, 2017

Simpleceiver Plus Superhetrodyne ~ An Ultimate form of DifX

The Simpleceiver Plus Superhetrodyne!

 

 

10/10/2017 ~ ADE-1 Product Detector Fitted to the Simpleceiver Plus

I have temporarily installed (polite words for hay wired) the ADE-1 Double Balanced Mixer in place of the original J310's used as a Dual Gate MOSFET Product Detector. This was done to facilitate the transition to the SSB Transceiver. You can listen for yourself in the two you tube videos below. I am satisfied with the result and this greatly simplifies the build -- a lot less parts and ease of transition from receive to transmit. The ADE-1 has but four connections with Pin 6 being the BFO input and Pin 3 is the RF input and Pin 2 is the IF output (AF in this case). Pins 1, 4 and 5 are grounded
 
 
 
 
 
 
I have had some further communication from Johannes in downtown Freiburg, Germany. He has completed his Simpleceiver Plus SSB transceiver and sent along some photos. I am including several of the photos. First I want to complement him on his building of the filter. The curves show what can be achieved -- and he for the most part used the method I described to build the filter. So if he can do it so can you -- this was the first ever homebrew filter for him! Johannes first started with the suggested cap values and then with a bit of judicious experimentation achieved the shape factor below. Of significance is that it has a good ripple factor (maybe less than 1 dB) and it is symmetrical which says that it should work well on either sideband.
 
Johannes Final Filter



Below are two photos of Johannes finished Simpleceiver Plus SSB Receiver. I suggested to him that he build a second version only this time instead of a single board to construct the radio in modules and install them on a bread board. The reason for this is that this then becomes an experimenter's platform where you can test filters, RF stages, product detectors, audio amplifiers, LO's and Display's. I have one of these and it makes for any easy task to check out new circuits in a complete radio.
 
I should mention that Johannes is using an AD9850 for the LO and a local crystal oscillator for the BFO. His next step is the Si5351 for both the LO and BFO
 
 
 





 
I must apologize for some delays in getting circuits published and moving along with the project. But I think the way forward has a clear path.
 
73's
Pete N6QW
 


10/05/2017 ~ Data on the Crystal Filter Build

Johannes in Freiburg, Germany has successfully built a 12 MHz Crystal Filter using the process suggested in this blog. From the git go it was an iterative process and not simply a matter of reaching into a plastic bag and pulling out four crystals and you are there. His "final filter" is data based using analysis and drawing inferences of what needed to be changed and doing so in a very measured fashion. If a prospective builder is not up to investing the time to do this, then you best purchase a commercial filter!
 
In May of this year the Chief Radio God himself, Wes Hayward W7ZOI published a document regarding our beloved computer crystals and how the physical sizes of the quartz devices are much smaller today (reducing costs, automated production methods notwithstanding) which in turn affects their use in crystal filters.
 
My Synopsis of his paper = Harder to Do--but still doable! There is another factor and that is something shared with me by the one or two homebrewer's who  were actually successful in building a crystal filter using the Dishal method. Both shared that it was the brand (manufacturer) of the crystal that made a difference.
 
One individual shared his research indicated only CTS Knights Crystals worked and could  reliably follow the parameters spit out by the program. I am not sure what brand of crystals Johannes used but the brand I use is ECS. So some of the differences in capacitor values from where I suggested you start very likely relate to the different manufacturers. The values I specified will put you in the ball park; but you very likely will need to adjust the cap values to put you in the correct section and row.
 
What you will see next is data from Johannes that starts with the values from the blog. Then through a process of measured changes and further data analysis, Johannes reported he found "the sweet spot". His data mining found that his 68 PF clearly marked caps were 68 and 73 PF after measuring them. It is important the values used be really close in value (where there are multiple caps) and close to values specified. 135 PF is not 120 PF!
 
Secondly as you go through the process of refining the cap values --change one thing at a time or you will never be able to track what causes a significant change and or improvement.
 
Sorry can't figure out how to rotate this --note the 68 & 73 PF caps

 
Here Johannes changed the Matching to 200 Ohms and tries three different values for the
end capacitors -- still too wide but ripple appears better.

 
 
One of the early runs -- Several Subsequent Runs Addressed the Band Pass Ripple
This filter is a bit wide --but a starting place!





 
Here Johannes changed the caps and you should be able to see that in large measure the
filter bandwidth is driven by the three capacitors to ground. Compare to the chart above.







This is the "final filter" and the much narrower bandwidth






Finally we have a photo above of Johannes "test setup" that he is using. I would suggest that perhaps he should take one more step as I think the filter is sufficiently narrow for use in the Simpleceiver Plus. He now may want to go back and adjust the matching transformers as his last run was with a Z in/out of 200 Ohms. Don't touch the caps but try a run at 100 Ohms (7 turns to 10 turns --- 49 and 100. 100/49 = 2:1)
 
I would bet after that impedance change the top of the curve would look a bit like the fashion model "Twiggy" -- kind of flat on top.
 
 




73's
Pete N6QW

 

 

News  Flash ~ A heads up from Charlie ZL2CTM.

A supplier has integrated an OLED display right on to an Arduino Compatible Microcontroller board and I think the price is about $10 USD. This open up some possibilities for shrinking our rigs down really small. Check this out below. Don't know how well it works or if there are RF noise problems but this is a huge step. The processor operates at 240 MHz and as you know the standard Arduino operates at 16 MHz. It also includes a Wi-Fi chip and USB interface. That is all I know.
 
 
 
 
73's
Pete N6QW 

10/4/2017 ~ Some follow on regarding building Crystal Filters

One of our builders has shared information with me regarding his efforts to build the crystal filter using the method I previously described. Later I will be posting some data that he shared with me; but wanted first to discuss some observations and cautions regarding the actual building of the filter.
 
The data shared with me showed a filter that had a bit of ripple and was too wide for good SSB usage. But the filter shape overall put in the ball park and a really good start. As I suggested in the earlier posting changing the matching transformer ratio will smooth out the ripple. So it was that his ripple did improve by making that change. But that still left a filter that was too wide -- shades of Dishal.
 
The filter bandwidth is markedly affected by the values of the 5 capacitors --less capacitance  = wider bandwidth. The two outer capacitors were specified as 68 PF and the three caps to ground were 120 PF on either end and a single 150 PF at the middle.
 
  1. First and foremost you must use capacitors that are close in value by 1 to 2%. Our builder used two capacitors marked 68 PF on the outer interconnects; but on actual measurement one was 68 PF and the other 78PF. It is important that both caps be either 68 or 78 PF --not one of each. Thus you might have to do some capacitor sorting to arrive at values that are very close to each other. The same holds for the 120 PF caps and the 150 PF.
  2. A critical point once you have an initial plot is to not change too many things all at once! My advice to the builder was to first address the ripple factor, which he did and his plot results indicated that there was an improvement in the ripple (flatness at the top of the curve). So that is a key piece of information. You could see the change by changing only one element!
  3. The builder next changed the two outer capacitors (getting them closer in value and I think moving them to 100 PF). There was some change in filter bandwidth but it was still too wide. So another piece of data for you in that we can see that the bandwidth is very likely more affected by the caps to ground (120 PF and 150 PF). He will be running those tests.
  4. Our builder also thought his generator (an AD9850) might be presenting something other than 50 Ohms input. Resist changing anything on the generator until you can see the bandwidth shrink. Keep in mind it would be the ripple that would be more affected by an impedance mismatch more so than the bandwidth.
  5. This iterative process is not done! Once the bandwidth has been shrunk then you may need touch up the ripple factor. But our builder's experience is invaluable in identifying that change only one thing at a time so you can readily see the effects of the change.
  6. What I haven't discussed is that after the change you might find that the center frequency of the filter will shift. I saw that in the plots our builder sent me. Knowing the Center Frequency will be required in order to set the frequency of the BFO for USB/LSB selection. As a starting point once you find the Cf --then pick frequencies 1.5 KHz above and below that for the BFO input.
  7. The process in #6 is a starting point for finding the BFO frequencies. What I usually do is to connect a separate RF generator to the BFO port and then listen by ear what sounds the best. You would be amazed at how accurate that computer between our ears can discern small differences. If it sound natural you are probably very close.
Later I will post some of his plot data so you can see the initial filter and the final results.
 
73's
Pete N6QW

9/27/2017 ~ Early Simpleceiver Plus SSB Transceiver Concepts

Any designer worth his salt will look to ways of simplifying any circuit without compromising performance. Thus some thoughts about the design simplification as we move to the SSB Transceiver configuration.
 
The first simplification (change) has been previously discussed and that was to change the active device product detector comprised of two J310s to that of a packaged Double Balanced Mixer such as the SBL-1, TUF-1 or ADE-1. I will be using the ADE-1 as I have a stock of those. All of those devices are 7 dBM which means they need a max of 1.4 Volts Peak To Peak of RF Drive which is easily done with the Si5351. I will be providing a hookup schematic --so untie that knot in your underwear.
 
Further simplification was pursued in the form of keeping the basic IF Amplifier Block Module (the 1st IF Amp, Crystal Filter and 2nd IF Amp) as a unit and electronically switching the signal direction through the Block Module so that it would operate both on receive and transmit.
 
This also simplifies the circuit ahead and following that block module. Ahead we have the SBL-1 [or other DBM] which now is both the Receive and Transmit Mixer stage with the LO always connected to the device. Following the IF Block is the 2nd DBM which on Receive is the Product Detector and on Transmit is the Balanced Modulator. The LO Port on this DBM is always connected to the BFO. Additionally the IF Port connects to both the input of the Audio Amplifier and the output side of the Microphone Amplifier. Again keep your cool as those schematics will also be provided.
 
Now I want to focus on how to electronically switch the IF Amp Module so that the signals pass through the amp stage on both transmit and receive and this is shown below with my initial noodling. You are encouraged to trace the signal paths based on how the diodes are biased. Note: check Charlie Morris, ZL2CTM current crop of You Tube videos and he is doing the same thing with a SSB transceiver he is now building that uses both a SSB Filter AND an SDR Back End.
 
You'll need about four each of 22K 1/4 Watt resistors, two 1K 1/4 Watt resistors, four diodes (any of those shown) and six 10 NF caps plus one additional Double Balanced Mixers. All input and outputs are at 50 Ohms. The output of the 2nd IF amp might have to be adjusted to 50 Ohms (as I don't recall what is in there now) .
 
Keep the leads short and I must apologize to those who have designed boards for the Superhetrodyne that this approach might have been nice to have been known earlier.
 
The notes try describe how the forward / reverse biasing of the diodes causes the signals to be steered in a single direction through the block yet take advantage of the bilateral nature of the Double Balanced Mixers.
 
The RF Amplifier Design could be simply replicated for the low level transmit pre-amp stage. Again diodes could steer the signals from/to the BPF to either the receiver RF amplifier or Tx Pre-Amp stages. The Band Pass Filter which is always connected to the SBL-1. Diode Steering could be also employed to switch in various banks of Band Pass Filters if you chose to operate on several bands. Charlie, ZL2CTM has a video on how he is using the diodes for this purpose.
 
 
 
 

 
Once we get past the Tx Pre-driver stage next will be the low level transmit RF Amp which will use a 2N2222A and a BD139. The Final Stage will be the venerable IRF510 which will make the SSB transceiver good for about 5 watts output.
 
As I hope you can see -- once you get the Superhetrodyne receiver built the move to the SSB transceiver is not that much more difficult.

Stay tuned more schematics to come -- so unknot your underwear. [These will include the Tx Pre-Driver (you could take the J310 Product Detector and reconfigure it for this --nothing wasted), the Driver Stage (2N2222A/BD139), The IRF510 and the Microphone Amplifier ]
 
73's
Pete N6QW
 

9/26/2017 ~ Building the Crystal Filter and Other Modifications

In preparation for the Transceiver build there are a couple of changes that need to be made. The first change is that the Product Detector using the dual J310's will now be converted to a Double Balanced Mixer such as the SBL-1, TUF-1 or ADE-1. This is done so that when we go to the transceiver configuration the Product Detector will become the Balanced Modulator.
 
You can even homebrew a DBM and there are three You Tube Videos by N6QW (and others) on how to do this. I don't recommend the homebrew variety. It is very difficult to achieve the performance that you get with a commercial unit. Many homebrewer's despite the three videos got their wires crossed and the end result was a disaster.
 
I have limited time today so I want to list three things you will need to build the filter. The first is at least a stock of 25 crystals all on the same frequency. I used 12.096 MHz but 12.0 MHz will work nicely too. I paid about 30 cents a piece and these were not eBay specials (Mouser). Next you will need to build the G3UUR oscillator and the Internet abounds with info on how to do this. Third you will need a means of accurately measuring the crystal frequencies in a loaded and unloaded state. There are frequency counter modules that can be found for about $15 on Amazon and will give a readout to 1 Hz.
 
The method I will describe does not use any of the fancy software programs --you are welcome to do that, but what I  will describe gets you close. AADE, Dishal and EMRFD all have programs you can use. But I had disastrous results with the Dishal program so maybe you will have better luck.
 
Do a search on this blog for Simpleceiver 16 for my initial discussion about building the crystal filter and those values worked! Below is the schematics of two filters as described in Simpleceiver 16. I found it interesting that the values for the four crystal filter are similar to what you see for the four pole filter spit out by Dishal.

By way of review I started with my batch of 25 crystals and labeled each one (1-25) using a tape label machine I have. Next I opened a excel spreadsheet and with the numbers 1-25 made two measurements with the G3UUR oscillator. The first was to measure each crystal (using my SDR receiver) oscillating frequency in the unloaded condition. After powering up the oscillator I let it set for one minute to stabilize. Then I took reading in the unloaded state. Each reading was entered into the spreadsheet. I repeated that process only this time in the loaded state and took another set of readings. figure about 1 hour to do this.

Since there are so few crystals involved by visual inspection I noted the crystal numbers where there was no more than 50 Hz variation in frequency in the unloaded state. Next taking that grouping I looked for four that were close (within 50 Hz) in the loaded state. From these I picked the closest four and I now had the beginnings of a filter.

From my experience I have found that the four pole filters typically have a  Z in/out in the 100 to 200 Ohms range. Starting with the assumption of around 170 Ohms I built a 50 to 170 Ohm matching transformer which turns out to be a 7 Turn to 13 Turn transformer on a FT-37-43 ferrite core. [ 7^2 = 49 and 13^2 = 169 --close enough for our work].

Connecting the crystals as I have shown them I inserted a 50 resistor in series with a signal generator source to the input matching transformer. On the output transformer I connected another 50 Ohm resistor and put my scope here. Then using the generator I started a 5 kHz below the nominal center frequency (12.096 or 12.0 MHz) and then with a reading every 100 Hz made measurements to 5 kHz above. I plotted the scope output reading. You can set the scope to Peak To Peak or RMS. When I had all of these reading (which were entered into a 2nd spreadsheet), I then had excel convert the values to dBm. (PTP^2)/400 and then multiplied by 1000 gives you milliwatts. Take 10 Log(milliwatts ) and you have dBm. Plot the dBm values against the frequency and you will have the response curve. It may not be absolutely pristine but it will be "Pete's Good Enough".

If you adjust the matching transformer to say 100 ohms which is a 2:1 the Turns Ratio will be 7 Turns to 10 Turns. You might find that there is an improvement in the pass band ripple as the Z in/out mostly affects the pass band. Next you can try 200 Ohms with a 7 turn to 14 turn (7^2 = 49 and 14^2 = 196) which gives you a 4 to 1 transform. Pick the value that gives the best curve.

 

Further experimentation could be done with the 68 PF caps at each end as these caps impact filter bandwidth. Larger values will narrow the bandwidth. Give that a test drive.

Now on my website I have posted DuWayne's [KV4QB] Sketch for his Arduino/Si5351 Board and that can be found at http://www.n6qw.com look for the link that says KV4QB sketch. It is in notepad format.

Should mention that Johannes has added more parts to his Simpleceiver Plus board and he is getting close to firing up his Simpleceiver Plus Superhetrodyne. In his build of the crystal filter he built used the G3UUR oscillator and went through a process similar to what we described to characterize his crystals. The Photo of his board shows the board populated less the four crystals, matching transformers and the capacitors. He is getting close. Nice work.



73's
Pete N6QW

 


9/24/2017 ~ An Email Report from PA3GUP

In my posting of 9/20/2017 I had shared that Jelle, PA3GUP had built the Simpleceiver Plus DCR and  was working on the Superhetrodyne. Well he has finished the Superhet and sent me an email along with a photo of hos build. I am sharing his email (with his permission) so builders can hear about the performance from someone other than myself.
 
PA3GUP's Simpleceiver Plus Superhetrodyne



Here is the text of Jelle's email:
 

Hi Pete,

Success on the 9Mhz IF and filter build!

I put it all together yesterday, trinket with the LO / BFO offset and
ended up with a BFO of 8998500Hz (LO = RF + BFO).

Although a keen eye spots 12Mhz IF Amp written on 2 boards in the photo
its really tuned for 9Mhz.

Plenty of gain and loud audio, I use the 2N3904 + LM386N AF amp.

The pots on the IF amps are about have way.


Why did I join in? A while back I stumbled up on the soldersmoke
podcast, so I googled you work and found the simpleciever on youtube.
What struck me was how quiet it was between stations. I found the JH8SST
version also with the AGC. And then when you announced a series on the
Simpleceiver from DCR, Super to TRX I got really exited. Also I had
almost all the components needed in my bins.


Observations:

The DCR has a very good performance with few components.

The DCR is quieter then the superhet, noise wise. Of course I would say.

In the superhet I use a MCL TFM-2 mixer (saved from an old cable TV Amp).

The noise from the LM386N I reduced by adding a 1K resistor between pin
1 and the cap, effectively reducing the gain.

On the product detector I have followed your original design but I did
not have the 100mH inductor and put in 100NF caps and a 10mH.


For first time builders, go to hamfests, get your self some copper clad
board, FT37-43, T37-2, T50-2, T68-2, T37-6, T50-6, T68-6 and BN43 pig
nose cores. And look on internet for deals.

I got all my SMB connectors and cables in the pictures from hamfests and
old cable TV Amp boards.

Yes costs! For this Simpleceiver project I was lucky and only bought a
handful of 12Mhz xtals. But others I know are still gathering parts.

I find the 'muppet' Manhattan style very easy for building RF circuits
because it follows the schematic closely. And it is QUICK! I keep a
stack of 1"x1/4" single sided copper clad board strips so I can cut it
when I need an isolated solder point. I stick it on with superglue.

On equipment: I have a simple CRT scope, 2 multimeter's, a frequency
counter and a RC meter both simple home build PIC devices. That could
now easily be done with an arduino HI.


Now! Back on the original path and constructing the 12Mhz xtal filter. I
also will explore the uBitx version with the 8 xtals.

Thanks Pete for this opportunity!

Question: The output level of the SI5351. Any level tuning needed? [I set it for 8 Ma]

Best 73

Jelle PA3GUP

Thank you Jelle, for sharing your project. I also heard from him today and he shared the following: Initially his Superhet build was with the 9 MHz Commercial Filters. He has now built the 12 MHz Crystal Filter so we will be anxious to hear how that is going.
 
I must apologize as some personal circumstances here on this end has caused me to have a bit of delay in publishing the Crystal Filter info. That is at the very top of the list which should arrive shortly on the blog and I should also mention that I will be changing out the product detector that uses the dual J310's to a double balanced mixer like the TUFD-1 or SBL-1. So builders should add a DBM to the list of things needed. This change is to simply the build of the transceiver variant where the DBM will serve both as the Product Detector as well as Balanced Modulator.
 
73's
Pete N6QW

9/20/2017 ~ Builder Feedback on the Simpleceiver Plus DCR

I really enjoy hearing from project builders and getting feedback on what they have experienced or variations they have tried. It is all about what is in the junk box or trying new things. Jelle, PA3GUP has shared his Simpleceiver Plus DCR build and you can see his work in the photo below.
 
PA3GUP's Simpleceiver Plus DCR


 
If you look carefully at the build you can spot the circuit module blocks and a really good practice is to solder a shield between the sections of the Band Pass Filter. I saw an evaluation of BPF's with and without the shield and the impact was not so much at the operating frequency but at much higher frequencies. So if you want a "Tight" BPF -- install the shield. I have installed the shield in some radios -- but I was just lazy when I made the BPF for this project.
 
Noteworthy is that Jelle is already constructing the Superhet and has chosen to use a commercial 9.0 MHz crystal filter in place of a homebrew 12 MHz filter. The IF amplifier circuit shown in the post of 9/16/2017 was modified by changing C1 to 68PF and C2 to 360 PF with all other values kept the same. Jelle reports that his LT Spice Simulation shows a max gain of 27 dB and a min gain of 14 dB. I had done a earlier simulation at 9 MHz using similar values with essentially the same results. We are looking forward to hearing more from PA3GUP once he completes the Superhetrodyne.
 
DuWayne has sent me code for use with his board (which I should note is a bit different, and better, then my code) I will post that on my website and will advise when that happens. His code will enable adding some features such as a signal generator mode and battery voltage measurement should you embed the board in portable equipment -- like I said better!
 
 
73's
Pete N6QW
 

9/19/2017 ~ Feedback on the Simpleceiver Plus DCR

First let me once again mention the Arduino/Si5351 Circuit board available from KV4QB that can be found here: http://kv4qb.blogspot.com/ I can attest that these are 1st rate boards and WILL shorten the critical path. Thanks again DuWayne for designing the boards and making them available.
 
Several days ago I posted information from Johannes in Freiburg Germany where he designed boards for the Simpleceiver Plus project. Yesterday I am happy to report that Joh has populated the boards and now has a working Simpleceiver Plus Direct Conversion Receiver. Congratulations Johannes as you now have experienced JOR -- The Joy Of Reception.
 
In typical ham fashion Johannes reported he first started inhaling RF at midnight, on his kitchen table using a 12 foot chunk of wire for antenna. It doesn't get any better than that! He sent some photos of his build which I will now post so other can see his work.


Starting with the naked board ...

 
 This is what resulted ...

 




 
 
We have since heard from Johannes beyond what he sent in these photos and he is continuing to work on the project beyond just the DCR and will soon start by populating the board with the Superhetrodyne components. So far he is a pretty happy camper. Thank Johannes for sharing with us. 
 
I am aware of several builds in progress with the Simpleceiver Plus DCR. I would be happy to post photos of projects now in work. Send me your photos to n6qwham@gmail.com
 
My next posting will be "how to build the crystal filter". Also don't overlook the possibility of using a commercial filter for this project.
 
 
73's
Pete N6QW


9/17/2017 ~ More Exciting Information on Circuit Board Availability!!!!!

 
The critical path item for the Simpleceiver Plus project whether it is the DCR or final SSB Transceiver is the LO/BFO using something other than  cranky/rickety/drifty/old school Analog circuits for tuning the rig. The critical path is the move up to the Digital LO/BFO  with the Arduino and Si5351. If it sounds like I disdain the analog stuff --I do! But my position is well known.

[There are solid technical reasons to migrate to the Arduino/Si5351 aside from my flippant comment about old school and that has to do with the Frequency Scheme in the transceiver. Firstly the Crystal Filter frequency is rather high @ 12.096 MHz where most of the commercial ones in your ICOM's, Yaseu and Kenwood's were below that -- like any where from 3 to 10 MHz. This has to do with the practicality of crystal stability where a 50 PPM crystal at 3 MHz is 150 Hertz and at 12 MHz that number is 600 Hz. The stability of the crystal filter is an issue --and these are crystals not some coil and cap.


The second reason is where the LO is placed. Good design practice typically will place the LO above the incoming frequency by the amount of the IF. So our Si5351 is operating at 19 MHz (7 + 12) for the 40 Meter Band. Essentially in the mixer stage we have the LO - the Incoming = 12 MHz. Now the 2nd product out of the LO is the sum frequency of the LO + the incoming and thus we have a component at 19 + 7 = 26 MHz. The 26 MHz is easily filtered out of Band Pass and Low Pass Filters operating at 7 MHz -- as is 19 MHz. The issue here is the alternative input LO at 5 MHz where that is awful close to the 7 MHz Band Pass and Low Pass Filters --not so easily removed.


The third problem given the LO above is good design practice -- have you built a stable 19 MHz VFO lately? Building one at 5 or 7 MHz has challenges --forget the 19 MHz. That is why even though some commercial transceivers were single conversion the VFO was mixed with various crystals to produce higher frequency outputs beyond say a 5 MHz VFO to achieve the desired higher frequency injection frequencies. If you are going to use that approach you just added a whole additional level of complexity. I used the 7 MHz VFO for the DCR as a quick and dirty way to demo that the DCR works. I would not use that approach with the SSB Transceiver.


So given the issues of design practice, unwanted mixing products and stable signal generation you are directly pointed to the Arduino and Si5351. By the way if you are contemplating operating in the just newly authorized 630 and 2200 Meter bands -- the Si5351 can operate all the way down to the 30000 Meter band where your dipole length would be 45720 feet long or about 8.66 miles! Try building that analog VFO to run that rig. Read on for a great solution.]
 
But where does that leave the homebrewer's who want the digital LO/BFO but have never built one and thus while knowing which is the hot end of a soldering iron are not sure about the SDA & SCL pins (A4, A5) on the Arduino.
 
I hinted a bit of this in a earlier posting and now it is time to share. One of our supporter's and in his own right a homebrewer "Supreme", DuWayne KV4QB has designed a universal LO/BFO board that installs the Arduino and Si5351 while making provisions on that board so that a range of displays and peripherals can be connected to the Arduino/Si5351. DuWayne's effort makes your job much easier. The bonus -- he is making available for sale the circuit boards shown below:
 
 
For information on how to acquire the board see DuWayne's blog. You will also see an array of displays that can be used with his universal board.

 http://kv4qb.blogspot.com/

 
DuWayne is selling just the board and the builder/homebrewer must supply all of the other parts and components. But the board is the Critical Path. Contact DuWayne direct regarding acquiring the board(s). Again this is a Universal Board and can be used on any project and not limited to the Simpleceiver builds.
 
Grab one before they are gone. A big Thank You to DuWayne! Largely through KV4QB's efforts the singular obstacle to building the Simpleceiver Plus is now gone! So get off that couch and start building.
 
73's
Pete N6QW


9/17/2017 ~ New builds of the Simpleceiver Plus DCR

Yesterday I received an email from Johannes in Freiburg, Germany regarding his build of the Simpleceiver Plus Direct Conversion Receiver and Superhetrodyne and has allowed us to share his build information. Should mention that Johannes is pursuing a license and is using the project as a means to expand his ham radio knowledge.  There are several photos showing board layouts and parts placement. Joh mention that Microsoft Paint can be used with the templates.
 
 
 
 
 

 

 
 
These boards sure would make implementing the project a much easier task. Thanks Johannes.  A
 
As advertised I will shortly be detailing how I built the crystal filter. Stay tuned.
 
 
73's
Pete N6QW

9/16/2017 ~ Another ECN (ECN#2) Upping the Gain of the 12 MHz IF Amp

Kind of pressed for time today. But had an inquiry about the tank network in the 12 MHz IF stage. Essentially the two 47 PF caps are in series and so they look like about 24 PF which is now in parallel with the 5.13 Uhy coil. I used the 47PF because that is what I had in the junk box and the simulation in LT Spice looked OK.
 
This inquiry caused me to go back and tinker a bit more with the LT Spice and if you adjusted the  two caps (C1 and C2)  that now have an effective capacitance around 31 PF and based on their ratio to achieve 31 PF -- the gain is raised by about 12 dB for a total of close to 30 dB.. The circuit  with the pot adjustment to minimum, the gain goes down to 10 dB. The 30 dB in practice may be way too much --but its better to have gain in the circuits following the mixer than ahead of it. In one of the videos (Part II) it was shown that increasing the gain of the RF amp stage ramped up the noise and I commented about not having it wide open. 
 
Major Hint: Install the capacitors (C1 & C2) as shown otherwise you will not see the increased gain. You are effectively picking off the voltage between the 350 PF and Ground. The 350 PF technically is in series with the 100 Ufd (C7) to ground and the effective value is C2 since C7 is so much larger. If you are having trouble with the concept, think of a resistive voltage divider and if you swap ends of the resistor combination and measure at the junction of the two resistors you get different voltage readings depending what end goes to ground.
 
 
 
 

 
Got to run -- have fun.
 
73's
Pete N6QW 

9/15/2017 ~ More circuit details on the Superhetrodyne configuration.

Here is some info on the circuits shown on the Block Diagram aside from the circuits used in the Direct Conversion Receiver. Below is the IF amplifier blocks and interconnections. Not shown is the Crystal Filter detail but that will be coming soon.
 

 The IF Amplifier Block.

 
Show above is the interconnection of the IF amplifier block into the Simpleceiver Plus Superhetrodyne. On the input side the matching transformer is connected to the "IF" side of the SBL-1 which are pins 3 and 4 connected together. The LO is connected to Pin 8 on the SBL-1 and the Band Pass Filter Connects to Pin 1. Pins 2,5,6 and 7 are connected to ground.
 
Inquiring minds will fire off some emails to me so here is the math. A match from 50 Ohms to 170 Ohms is 1:3.4. If you take a 7 Turn winding squared that is 49 and if you take a 13 turn winding that is 169. (Thank You Mr. Boyer my 8th grade math teacher who required us to know the squares of the numbers from 1 to 20.) Thus 169/49 = 3.44 which is close enough for government work. If you match 170 Ohms to 2.2K Ohms that is 1:12.94 and easily done with 5 turns which is 25 and 18 turns which is 324/25 = 12.96. And of course 50 to 2.2K Ohms = 1:44. Three turns squared = 9 and 20 turns squared = 400. 400/9 = 1:44.4 -- again close enough. (Thank you Mr. Boyer)
 
On the output side of the 2nd IF amplifier this is connected to the input matching transformer (3 Turn side) of the same product detector as used with the DCR. Later this connection will be made to Pin #2 of an ADE-1 Double Balanced Mixer.
 
So you are scratching your head a bit. When we transition to the SSB version I would have to build another J310 DGM configured as a Balanced Modulator and similarly supply Carrier during transmit into Gate #2 and audio into Gate #1.
 
If we use the ADE-1 it can be used in a bi-directional mode and the audio port to the audio amp input is now input from the microphone amp output. Another consideration is to use some relays at the input side and output side so that the Input / Output Ports are switched depending on whether you are transmitting or receiving. This would now only require one filter which really makes things a lot easier and simplified. Not a done deal but now in the plan.
 
 
73's
Pete N6QW

9/14/2017 ~ Further Exploration of the Simpleceiver Plus Superhetrodyne!

Part II of the Simpleceiver Plus Superhetrodyne receiving tests. Added a filter cap in the audio amp to reduce hiss level and explored the three gain controls on the RF and IF Amps. Dramatic is a good word!
 
 



 
Part II Simpleceiver Plus Superhetrodyne
 
 
Part III Simpleceiver Plus Superhetrodyne
 
 
 
Later today I will post some information on the 12 MHz IF Amplifier Stages and Pete's Magic Crystal Filter. The RF Amplifier, Band Pass Filter, Product Detector and Audio Amplifier schematics were detailed in the prior post.
 

For those keeping score above is the "Block Diagram" of the Simpleceiver Plus Superhetrodyne Receiver. Note that the modules that were in the Simpleceiver Plus DCR simply move over. Just a note the DCR has the 2N3904 and LM380 --that will work perfectly. I used the NE5534/LM380 as it was available. I also used duplicate modules so I could keep the DCR intact for other experimentation purposes. Thus the Superhetrodyne is all duplicate modules that are in the DCR. In the event any questions come up about the DCR -- I can still fire it up on the bench.
 

 
 
 
This is the IF stage and is good for 18 dB of gain (R9 = 13.3K) and drops to 9 dB with R9 set to 3.3K. This gain drop is demonstrated in the above video. On the output of the 1st stage following the 2 dB Pad is a 50 to 170 Ohm matching transformer into the Crystal Filter. On the output side of the Crystal Filter which is 170 ohms you need a 170 Ohms to 50 Ohms and then a step up to 2.2k from 50 Ohms. That would mean TWO transformers or you could just match 170 Ohms to 2.2K or 1:12.94. This is an easy match if you have a 5 Turn primary and an 18 turn Secondary. 5^2 = 25 and 18^ = 324. 324/25 = 12.96. That my friend is close enough for US Government work.
 
On the output of the 2nd IF stage there is no pad and this feeds the Product Detector. In the transceiver this will feed the 50 Ohm Port on the SBL-1 or ADE-1. Do not skip THE MATCHING TRANSFORMERS!!!!!!!!
 
Below is a peek at the Crystal Filter(s) which I will cover in a subsequent blog post. Focus on the 4 Pole Filter.
 
 
 
 

73's
Pete N6QW


 
 



 
Before jumping into the SSB Transceiver Configuration, I want to make an interim stop by focusing on building the Superhetrodyne Receiver. This was done for several reasons including the possibility the builder is only interested in having a receiver and will use some other form of outboard transmitter. I can see it now -- a Simpleceiver Plus Superhetrodyne coupled with a Heathkit DX-20. Or maybe a Harvey Wells TBS-50 Bandmaster. Possibly even an SB-400 is your cup of tea.
 
The basic configuration is the J310 DGM in the RF Amp stage just like in the DCR followed by a Band Pass Filter (again like in the DCR). The next stage is a packaged DBM like the SBL-1 or the ADE-1 as that will serve as the receiver mixer (later also used as the transmit mixer stage). The next stage is the IF amp block comprised of the 1st IF stage , (J310 DGM) a four pole 12.096 MHz homebrew crystal filter and then a 2nd IF Stage (J310 DGM). For the Product Detector it is the same as used in the DCR. The audio amp is the NE5534 driving the LM380. Thus there are four blocks all using the J310's configured like a DGM. We will use the simplified "good enough" crystal filter method for building the crystal filter. You are encouraged not to use the Dishal or other arcane methods.
 
 
When we shift to the SSB transceiver I will most likely use an ADE-1 for the Product Detector and it will also serve as the Balanced Modulator with minimum wiring needed to serve both functions.
 
The LO and BFO signals (Arduino Nano & Si5351) are supplied by the same code used for the DCR with only minor value changes (and getting the USB/LSB to display correctly). The DCR had the BFO signals (USB/LSB) set to zero and the frequency being generated for the LO had no BFO offset.
 
Drum Roll Please! Here is a short video of the Simpleceiver Plus Superhetrodyne working today and being used in an A/B test with the SoftRock SDR. Bottom Line --simple circuitry and worthy of a build. The next several series of blog entries will detail the circuits in the Superhetrodyne Receiver and fleshing out the SSB Transceiver configuration.
 
 
 
 
Strap in --this is going to move along quite quickly.
 
73's
Pete N6QW