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New Technology for 2020 ~ A Scratch Built Hardware Phasing SSB Rig

A Hardware SSB Phasing Transceiver!

N6QW makes yet another attempt to lure you into the homebrew world!


April 18, 2020 ~ New Posting  Soon!

This thread is getting large and when I post tomorrow it will be on a new posting and contain some updated technical info. So you will want to tune in.

Covid-19 Practical Tips.

I am disciplining myself to lots of washing, not only my hands; but my clothing. So after a stop at the grocery store and after pulling into the garage, I sprayed my shoes with Lysol and immediately took off my jacket and pants and into the washer. Ooops I forgot to put down the garage door so there I was in my undershorts loading the washers. One of the neighbor ladies was passing by and made it a point to say" Hi Pete" Are you OK? To which I replied I am OK. So first tip close the garage door when you are stripping down to your skivvies. Also wipe down the car seat and steering wheel.

Second problem! I forgot that my really nice Sony earbuds were in my jacket pocket so they got washed too. I spotted them in the washer when I moved the pants and jacket to the dryer (I did have pants on this time). 

I was bummed out because they really worked well. So then I thought -- What if I placed the earbuds in a plastic baggie with a heaping teaspoonful of uncooked rice. Boom this morning the rice looks like it had grown a bit and I now have a working set of earbuds.

I have resisted using the credit card for every purchase; but have been buying groceries with cash. (The theory is if you don't have the cash you don't buy it.) 

My process for the cash once I hit the ATM is to place the cash in a plastic baggie and a quick spray of Lysol and then  seal the bag. I wait 24 to 48 hours before opening the bag. This may be likened to when the teenage boy hears from the gal that she is safe; but he still uses protection. There is conjecture about the safety of using cash -- I hope at least my cash has been sanitized.

I must question if the emperor (with a small e) is attempting to incite civil war by his tweets on liberating states. He is only inciting his base and this approach will likely cause grave harm. Is it now time for the good guys to be counted? Want a metric --- look at the rise in gun sales?

73's
Pete N6QW

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April 17, 2020 ~ A Giant Step Forward!

A kind soul (Mike) took pity on me and reworked my feeble design into a workable circuit that gives a flat response across 270 to 2700 Hertz with the required 90 Degree phase shift. I wouldn't have found it in a million years. And so to Mike: "When you know stuff you can do stuff"

The Plot at 2200 Hertz --- nice!

I will now build this circuit and run some tests to prove the design. This is a major leap forward. Thanks again Mike!

BTW the emperor (with a small e) has no plan to ramp up testing across these United States. His neglect may result in your death. Think about that if you voted for him! 

73's
Pete N6QW


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April 16, 2020 ~ Still noodling circuits.

The 2Q4 was a marvel 70 years ago but am not so sure today. I see some issues with low frequency response and have even moved away from the Modem Transformer coupling. I have spent two days with the LT Spice simulations and cannot see any light at the end of the tunnel.

I see the emperor's ( with a small e) approval rating has dropped by 6 points in just a month. I guess he won't tout that when he blabbers at the daily briefings. 

Take stock when more people get infected and die because of his ill conceived plan to open the country -- his ratings will plummet. It is time to jump ship! The lack of leadership is obvious -- perhaps he may lack leadership gene's! #TOT



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April 15, 2020 ~ Part II Quadrature Audio

I took some photos of the Quadrature Audio Plots of the 2Q4 Circuit Simulation at four frequencies: 270 Hz, 300, Hz, 1000 Hz and 2700 Hz. The amplitude and 90 Degree Phase Shift look pretty promising in the simulation. But the real proof is a hardware build and the actual physical testing. 

I reset the inductance value of the simulated 600:600 Modem transformer to a value at 1000 Hz which if you solve the equation for Xl = 2*Pi*F*L where Xl = 600 and F = 1000 you are left with L which is 95.5 Millihenry.







This is the plot at 270 Hertz.

This is the plot at 300 Hertz

This is the plot at 1000 Hertz

This is the plot at 2700 Hertz

There are some observations that will require further analysis and evaluation. From what I see the equal amplitude of the two plots at a specific frequency is governed by the adjustment of R5/R6 which simulates a 1K trim pot. I do note that it is about a 75% to 25% ratio. I can't explain that. But it does seem to hold over a 10:1 frequency range such as 270 to 2700 Hertz.

Next is the shape of the sine wave -- it seems to hold true over the audio range (some early simulating presented a skewed sine wave). The same appears to be true relative to the 90 Degree shift. But, when we have hardware we can actually test how true is the phase shift over the audio range. Based on some comments I have read --I should not hold my breath or maybe that is the case.

Constant Audio Frequency Gain Level over the 270 to 2700 Hertz frequency range may be an issue. The 2N3904 amplifier started life as a microphone amplifier that was peaked so it would have a better response at the low frequencies and to remain flat for the rest of the curve. Late Info: I have been doing some experimenting and have an initial approach that gives only a 7 mv Peak difference between 250 Hertz and 2700 Hertz. That should improve the "presence" factor. Will post that schematic tomorrow.

Since we want to be certain this rig passes the 40M FLEX Radio SDR police criteria of having audio presence and not "yellowy" at low frequencies, I am still wrestling with that issue. A cursory look at the gain levels show less gain on the low end (270 Hz) versus what you see at the higher frequencies (2700 Hz). This is on the order of a couple of hundred millivolts. 

The good news is equal amplitudes and what appears to be a tracking phase shift. The bad news lower frequency gain levels.

We must hold the emperor (with a small e) responsible for the 610,000 Covid-19 infected citizens and the 30,000 deaths. He did not score a perfect 10 in his response! #TOT
 
73's
Pete N6QW



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April 15, 2020 ~ Quadrature Audio from 2Q4





I coupled the output of the first audio stage into the simulated 2Q4 and got two signals 90 degrees out of phase. The amplitude of the signals is adjusted by the pot shown as R5, R6. I had to adjust that pot (changing values) to give a fairly flat amplitude over the range of 300 to 2700 Hz. This took some diddling and involved making the 500 Ohm pot into a 1K  pot. A combo of fixed and variable resistors can give a fine adjustment --two 200 ohm resistors in series with a 600 Ohm trimpot would work. I also had to limit the signal input to no more than 500 mv.

Later I will publish a more detailed photo of the circuit and the two plots -- The second trace is blue and hard to see but they are indeed 90 degrees out of phase. Super progress. 




Now what I haven't investigated is the angular shift from 300 Hz to 2700 Hz. Amplitude looks ok but haven't evaluated any phase shifts. If I did this in hardware with an audio oscillator -- I could look at the Lissajous figures from Ports A and B on my Rigol Scope.

Each day it is more obvious that the war against the Covid-19 is being fought by individual states with science, metrics and input from the professionals. The WH briefings are irrelevant!  Look to those  Governor's on the East Coast, Mid-West and West Coast to lead us, to keep us safe and to see us through this. #TOT

73's
Pete N6QW


April 14, 2010 ~ Homebrew 2Q4


We have a Constitution not an emperor or king!



So Ok the Model 2Q4 Audio Phase shift network is long in the tooth having observed it 70th birthday! It is also marginal by today's standards maybe achieving a maximum of 35 dB of opposite sideband suppression. Yes it was advanced technology for 1950 but today is can be likened to doing brain surgery with a rusty spoon. 

It is a fairly simple circuit and so the "illuminati"   would say --Too simple and thus no good. Sort of like to the Wright brothers --that bicycle won't fly!



Many would say -- you are wasting your time and you could do it with Tayloe detectors and polyphase networks. On the rare occasion that I actually removed my EMRFD from its position as a book end and in looking through section 9.32 or was it 9.23 I noted how the authors approached the subject. They simply categorized it by dB of suppression. If you want 20 dB then do this and if you want 60 dB then do this. 

Now that made sense to me in a slightly different light. Suppose you just wanted to experiment and as a first goal build a phasing transmitter. Then as a next goal measure the sideband suppression (hey that would be novel). Finally as a third goal tinker with what you have to see the real limits of what you have built -- you know what makes things better and what makes things worse. 

This is a learning journey --what else are you going to do while hunkered down? A polyphase network has tons of parts whereas the 2Q4 has 8 parts!

Now as I have found in the past with many of my projects, many modern hams are basically lazy! So to remove that excuse I have collected the part numbers from Mouser for what is needed to homebrew a 2Q4. In most cases there are specific part numbers for the exact component specified (like the capacitors) but in other cases such as the resistors you might have to add a couple of values. 

Here is an example a 770K Ohm 1% resistor is specified. Well I was able to find a 768K 0.1% and a 2K Ohm 1% so added you get 770K Ohm at no worse than 1%. In the other case a 198K Ohm is specified and I found a 100K Ohm and a 97.6K Ohm which would get you to 197.6 at 1%. 

Now keep in mind this network and the component stability in 1950 gives you a 90 Degree shift with a 1 degree tolerance (crude by today's standards). But keep in mind many of our rigs have homebrew crystal filters that are less in performance than a commercial filter; but we still use them.

Now if you would like a list of the Mouser P/N's then email me at the  address above. I am doing it this way to gage the interest in this project. Yes, that would be asking too much to email me so...






It was fun to watch the emperor (with a small e) melt down yesterday. That "stable genius" is going to get us all killed! Noteworthy is the real leadership being demonstrated by the 15 or so Governor's who have formed coordinated alliances that rely on metrics, science and the advice of the healthcare professionals! #TOT!

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April 13, 2020 ~ More on the Phasing Rig

But first a PSA. 

If you stand with Trump; man you are in the wrong line! If he opens the US before it is an appropriate time we all are at risk of a certain death. People are saying the Trump Properties are tanking and this may be coloring his decisions.

My plan is to build a TransReceiver Phasing Rig. For the unwashed this means a separate transmitter and separate receiver that share a common link -- The Phased LO. This will be done with  the 2Q4 on the transmit side and the QRP-Labs Polyphase network  on the receive side . So a bit more hardware but a starting place. 

I am aware the opposite sideband rejection for the 2Q4 on a good day and when all of the planets align is only about 35 dB so the 40M FLEX Radio SDR Police will have some fun; but the journey of 1000 miles starts with the 1st step.

I took the 600 Ohm Impedance of the Modem Transformer and solved the equation for "L" at a frequency of 2000 Hz. That value was 48 mH. Next I looked at a Transient plot of the output across the Combo of R5+ R6 to simulate a 500 Ohm pot with the center wiper to ground. Test changing these values so that the sum is always 500 Ohm. Really neat to see the plots at the test points are 180 Degrees out of phase and of equal amplitude.

This design will be repeated for all three amp stages. I bought 10 pieces of the 600 Ohm to 600 Ohm Modem transformers for about $8. The exception is the final two stages do not have the 500 trim pots on the outputs.






73's
Pete N6QW




Easter Sunday 2020.

The 2Q4 Network and solid state audio amplifiers (3X 2N3904) graph paper layout and finished PCB.




Here is hoisting a virtual beer to you to celebrate this Easter Sunday. The beer, San Miguel, is from the Philippines and is potent --especially the kind served there and not the export version. After a short stay in the Philippines, during my naval service, I came to two conclusions: Excellent Beer and Hot Women!



So OK Guys and Gals you are stuck indoors and looking for an activity to fill time while we await the stable genius to come up with yet another really dumb idea like opening the USA too early! Or his hawking medicine with no license to do so.

So how about a hardware based Phasing SSB Transceiver? I have seen hardware based Phasing Receivers from KK7B (Rick Campbell) and in the transmitter department we have the GE SSB Junior or the Central Electronics 10A and of course the drifty HT-37 (at least mine did).

I am exploring several possibilities. My two Polyphase Phase Shift Networks arrived from Turkey (Hans Summers) as well as a real "Oldie" the B&W Model 350. I also have a slug of Tayloe Detectors coming.







My first thought is to couple the B&W Model 350,  2Q4 network with the RADIG V.2 board as an experimental transmitter. The 2Q4 would provide phased audio which would be coupled through Modem Transformers. A small relay could redirect signals so we could have selectable LSB or USB. OR as was pointed out to me by my good friend in VK land (Greg) if you switch instead the CLK0 and CLk1 into the ADE-1's -- an instant sideband reversal. I personally verified this so we have two ways to select LSB or USB modes of operation.

http://www.n6qwradiogenius.us has some additional circuits we would use.

This is a starting place and we will employ the phased Si5351 LO. For the receiver there may be a Tayloe detector hiding in the bushes.

In one of the ARRL SSB handbooks Richard Taylor W1DAX presented a design for a solid state phasing SSB transceiver. Need to dust that off. [This is when ARRL built stuff versus selling expensive radio hardware.]

Stay tuned and start thinking about parts! There, that may help erase the stupid stuff we hear from the daily briefings. 

73's
Pete N6QW

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