Uncle!

Time to yell Uncle! The MHST has been relegated to the Shelf of Shame. After two months of toil, consternation, abject failure and losing some hair I am throwing in the towel. I must apologize as this could have been a pretty nifty project, but I have exhausted my tribal knowledge base and am just plain stumped as to what to try next.

Maybe at some future time I will trip over some unrelated project that suddenly like a missive from the Oracle at Delphi reveals the root cause. It is likely some simple thing -- I just don't see it.

Yesterday I fiddled and fooled with signal levels out of the I and Q channels as well as the quadrature LO level. This was to assure that each ADE-1 was not being overdriven which could result in spurs. All that did was reduce the amplitude of the spur (and the desired signal) but the spur always slightly stronger than the desired signal.

Thusly the MHST joins a host of other failed projects with a prominent place on the Shelf of Shame. It was a hairbrained idea that never made the grade. That said I remembered the urban legend story of Thomas Edison. One day a very shaken assistant came into Edison's office and said: "Sir, I have some very bad news, the storage warehouse containing many of your projects burnt down."

Edison smiled and said please repeat what you said. The assistant did so, and Edison said Thank God, and went on to say that the warehouse contained stuff that didn't work. He just didn't have the heart to rid himself of all that junk and now it was done for him. So maybe I am having an opportunity much like Edison.

Sometimes despite what you know you can't make things go. Sayonara MHST!

73's

Pete N6QW

Lissajous Figures

I covered this before but JIC (just in case). Inputting signals to your DSO and invoking X versus Y functionality you can derive a relationship between signals such as Phase difference. A 90-degree phase difference is critical in the SDR world. 

The 1st line and middle set of three figures is where two signal inputs are shown for a square wave. The last figure in this middle set is for a 90-degree phase shift, our tilted square shown yesterday. The last figure in the first set of three is the circle which as we saw yesterday from the I and Q output of the sound card was not a perfect circle indicating not 90 degrees.

These graphs have a technical name called Lissajous Figures (some suggest pronounced Leesa Juice) and are old school and approaching over 200 years old (circa 1815).  

For those who served in the US Navy and had to do navigation, Nathan Bowditch is a name that invented those figures for navigation. I had to take a course in Navigation while a Midshipmen. I was supposed to be in the Pacific off the coast of Oahu, but my plot was in the Gobi Desert. Another reason why I didn't serve aboard ship and in the Seabees!

Them that know can make it go

73's

Pete N6QW

Note: Pi/2 represents a 90-degree Phase shift. Ask Microshaft Co-Pilot.

Data along the path to resolution...

No cigars or celebrations just yet! But some data points to ponder. One input from a blog reader was that the LO quadrature signals were not quadrature, or 90 degrees out of phase. 

Using the XY function on my Siglent scope if you have two sine waves exactly 90 degrees out of phase the resulting plot is a perfect circle. But the output from a Si5351 is more like a square wave and two square waves 90 degrees out of phase produce a tilted square.

This is the XY Plot of CLK0 vs CLK2.

The Tilted Square is indicative of a 90 Degree shift between CLK0 and CLK2. So, check that off the list.

Another reader input was that the quadrature signals coming from the Sound Card on transmit was an issue. Below is a photo of the I and Q outputs from the Sound Card on transmit. There is slight difference in amplitude which I think can be corrected in the Pulse Sound App. But what I see is about a 90-degree shift and very good-looking waveforms.

Amplitudes are Different but Correctable

Pulse Audio Panel Adjustment ~ Closer

Sine Wave Phase Shift: Not a Perfect Circle!

We now have some interesting data for further analysis in that we can see a sine wave output on transmit for the I and Q channels and we have the ability to balance those output levels using the Pulse Audio Control Panel. I also believe using the QUISK embedded tools we can make the I and Q a perfect circle on transmit.

What we are doing is an issue elimination process on the road to problem resolution. Not close, but sure a learning process.

Them that know can make things go. 

73's

Pete N6QW

 

So What is Happening?

You smell a burnt resistor, you see a discolored resistor and you see no voltage on the other side of the resistor. You conclude it is a defective (smoked) resistor. But that is just one part of the issue and next question follows the "WHY" is it toast.

Our burnt resistor is an easy problem to define as we have sensory tests to tell us exactly its condition: smelly, discolored and open. The Transmit issue with the MHST is similar but different in that it appears only on transmit, can be heard 300 miles away and is consistently linked to the actual desired transmit signal. 

I think back to the early 1960's SBE-33 SSB Transceiver that had a receive "birdie" just above the high end of the 40M Band. The SBE Engineers never did fix it but instead highlighted its usefulness in determining the dial calibration. Quote: "If you hear this signal at the specified location, then your dial calibration was right on." We can't use that logic or excuse with the MHST.

Yesterday I diddled with the VWS code for the Arduino Sketch so that the Quadrature Outputs are on CLK0 and CLK2 versus CLK0 and CLK1. Long ago there were issues with using CLK0 and CLK1. There seemed to be a shift to using CLK0 and CLK2 for LO and BFO. Here is a link to a quadrature application issue using CLK0 and CLK1 -- you decide, but I decided to change to CLK0 and CLK2. See below.

CLK0 and CLK2 ~ 90 Degree Phase Shift

The change improved the situation but did not resolve the problem. I do consider this a positive change. The photo was taken at the output side of the Si5351 while connected to 10K trim pots which are in line before application to the ADE-1's using the center wiper as the feed point. This lets you fine tune the LO signal inputs to the ADE-1's so that they are balanced.

If I were smart enough and had extensive software skills, my next step would be to use a different code approach so that the Pi Pico would follow the QUISK directives but generate a single LO at 4X and then rely on a 74AC4 to provide the quadrature output at 1X. That works with the Soft Rock Transceivers and works on my other SDR without having the funky signal to ride along.

We must be thankful for such problems as it keeps us out of the bars and from getting into all sorts of other trouble.

Them that know can make it go.

73's

Pete N6QW

The Noodling Process

The Noodling Process is a deliberative approach to solve a problem involving a fault tree analysis. The old Italian Mechanic is merely describing a symptom when he says: "She don'ta work". That gives no clue to a solution or where to start. Thus job #1 is to describe the problem. But accurately formulating a problem statement is a result of gathering data and analyzing that data t0 arrive at something more substantive than the observation of our old Italian Mechanic.

Our somewhat real-world crass analogy: It took some time to figure out that Mary Jo, our 300-pound close friend, had to have two Bob's Big Boy hamburgers first, before she could be enticed into the back seat of a 57VW Beetle. 

Try to image 450 pounds of raging teenage hormones in the back seat of this 57VW. Scary?

To formulate a real problem statement requires assembling known facts.

* The mainboard with the ADE-1's is a known design and works with QUISK. Other rigs using this same board design + QUISK do not have the issue.

* The MHST works on Receive using the VWS package and the receive function works perfectly with the Pi Pico and the two sound cards. 

* The QUISK software has functionality to abate image signals in both transmit and receive. I was able to null out any images on the receive side, but that same internal QUISK process for transmit has no effect on the mystery signal. (Could this be a clue that it is not an image but an extraneous spur?)

* I can see the signal on the Half Moon Bay SDR receiver site which is 300 miles away from me. Thus, this is not something to be ignored as we know the 85th Harmonic of N2CQR/KK4DAS DCR project was picked up by the FCC monitoring stations in Bali and the Northwest Cape in Australia.

* The problem is only observed in transmit and since the two ADE-1's are bidirectional, wiring errors do not seem to fit into the equation. Working perfectly on Receive also tends to eliminate a bad set of ADE-1's.

* The offending signal appears stronger than what is intended as the primary signal. Using a station receiver with a 1-inch antenna located about a foot away reflects a 10dB difference with the stronger being the undesired signal. Incidentally, the frequency spacing is about 30kHz away and observed higher in frequency.

(Mental Note set up the Siglent scope for FFT and observe the pattern on transmit.)

* In looking at signal mixing we have the quadrature LO signals at 7.2 MHz and the I and Q streams which are in the audio range and limited to maybe a max of 6 kHz. So, a 5th harmonic of the I and Q streams mixed with the LO signal would give a signal substantially removed from the intended signal. But past experience would say the 2nd or 3rd harmonic of the I and Q would be more of a problem but not observed.

* This is when apples to apples comparisons are important. A fellow knowledgeable ham sent me an email this morning that I should turn off any unused clocks on the Si5351. Shazam a lightning bolt from the Radio Gods. In most of my use of the Si5351 based on some of the earliest applications, only CLK0 and CLK2 were used for the LO and BFO. It was suggested to avoid using CLK1. Initially I did note that the VWS package used CLK0 and CLK1. So aside from the mystery issue I am going to go back to the Arduino sketch and put the quadrature signals on CLK0 and CLK2 and turn CLK1 to off.  

* The working HB SDR uses a Si570 with a single output a 4X which is run through a 74AC74 to produce a quadrature signal at 1X. So, this is not apples to apples. This opens the possibility of running the Pi Pico at 4X and running a single output through a 74AC74 which is already on the MHST board. This would provide another check on just where the issue is originating from. 

The problem statement is now leading us to the following.

The MHST transceiver has an issue with transmit is that a spurious signal is being generated approximately 30kHz from the desired signal. The nature of the signal does not respond to abatement using the embedded tools in the QUISK software and is identified as being potentially spurious and not related to the I and Q Stream.  (However, the I and Q stream may still be an issue.) The problem is the signal, and the solution is to initiate progressive steps identified from this analysis to observe the effects if only to eliminate potential issues and narrow the scope of possibilities.

The Isley Brothers said it best 

Them that know can make it go.

73's

Pete N6QW

My Other Homebrew SDR.

The issue of the extraneous signal coming from the MHST has reached the point where it is time for a break from this project. NOODLING will afford me the time to think more about the causal factors. It just does not make sense and obviously I must be missing something.

I broke out another HB SDR which has an almost identical main board but does not have the extraneous signal issues. But this board uses the Softrock package in QUISK and not the VWS.

I also hooked it up to a 0.11KW amp, the AN 762 from CCI. In the afternoon it was like shooting fish in the barrel and great signal reports.

5W HB 20M SDR Transceiver

HB 20M SDR with an external AN762 Amp

I might even resort to cutting a new mainboard on the CNC and using all new parts -- it is a drastic move, but nothing so far has fixed the issue.

RIP Pope Francis and we are saddened at your passing. The current Washington crowd must be sad too --- out of the news cycle for at least a week. But then again, a simple solution: Manufacture some sort of crisis to move the news cycle back to Washington. 

Them that know can make it go.

73's

Pete N6QW

Happy Easter!

Religious beliefs aside it is a great day for Chocolate lovers and a great time for being with family. I have many fond memories of my four kids especially ones associated with holidays. 

My eldest son now 56 when at about age 7 one Easter Sunday came screaming into the house and I was trying hard to decipher the problem. It seems like he ate too many jellybeans at one time and his teeth were stuck together. My mind quickly turned to the soldering iron or a very large screwdriver. But then reason took over and the most important thing was to have him calm down. In time the salvia melted the jellybeans, and he was good to go. The things as parents we see, makes you go bald.

I was sent the above video by my #3 son, and it is worth watching at least two times. As I watched the video, my thoughts turned to 50% of our population who are cheering the actions of those in control. All that whacking is hiding the actual processes of cleanup. With certainty they have no clue of those processes as they only can focus on events that they think make this nation great. If they only knew. Whacking is a term that takes me back to western Pennsylvania where that definitely did not involve wholesale budget cutting.

The moral of the video: Watch whose butt you are kissing.

Them that know can make it go.

73's

Pete N6QW

An Exciting New Toy to be released from https://www.mostlydiyrf.com... The Mouse Knob!

But 1st, the MHST had its first 40M QSO yesterday with a check in to the Jefferson Noontime Net. The temptation was too great and that weird in band signal is not totally gone -- but the MHST does work and now a real incentive to get it working 100%.

But the real news of the day which I proudly present forthwith is the "Mouse Tuning Knob". I have wanted this capability for a long time on my SDR Rigs and arising from the depths of the Silicon Forest is the Mouse Tuning Knob. This is a real boon for those of us with Fat Fingers and whose eye hand coordination may be on a downhill slide.

Some detractors of SDR complain about the lack of knobs, especially a Tuning Knob. Complain no more! This is so cool and a real aid to those of us with FFS. The Mouse Tuning Knob is revealed.

I am just an Alpha Tester and had no involvement in its development, but this is one sweet tool. Sign up for Todd's newsletter at his website. https://www.mostlydiyrf.com as the product release will be announced via that newsletter.

Once again to respond to the detractors from the Howdy Doody Peanut Gallery, the K7TFC creation has been tested on Linux based and Windows based SDR software as well tested with high end SDR Software such as Thetis and SDR Console (watch the video). It may be yet a bit before you have one in hand as this is an Alpha Test of the prototype. However, that does not prevent you from signing up for the newsletter or also contacting K7TFC to express an interest in acquiring The Mouse Knob.

Them that know can make it go!

Easy on the Jellybeans and Cadbury chocolate eggs when you raid the grandkids Easter baskets tomorrow. Happy Easter and enjoy the time with the family especially your XYL or Partner. This year I will miss hearing "stay out of the chocolate bunnies!"

73's

Pete N6QW

 

Troubleshooting the MHST

If one constantly repeats the same test repeatedly without changing a thing, then why would you expect a different result each time you run the test?

I have another homebrew SDR transceiver that closely resembles the MSHT. It too uses QUISK and an identical mainboard. The same Driver, and Final and a steerable single BJT amp. The single difference is this one uses the SDR LLC interface while the MHST uses the Pi Pico. The actual QUISK rig selection for the Pi Pico is the VWS Package and for this one it uses the Soft Rock USB. 

The Pi Pico uses the Si5351 and the SDR LLC the Si570. The Pi Pico turns out a quadrature LO at frequency directly and the SDR LLC is at 4X and run through a 74C74 D Flip Flop which results in a 1X Quadrature signal stream.

SDR Using the SDR LLC Controller and Soft Rock Package

 

Yesterday was spent comparing the two rigs, The SDR LLC does not have that nasty signal that exits with the Pi Pico. The SDR LLC produces a single transmitted output at the correct operating frequency. The externals to the Mainboard, i.e. the same two sound cards are used with both rigs, so any difference is the QUISK hardware specific software and or bad components on the main board. This may be a ADE-1 issue.

So, using essentially the same mainboard what could cause the issue with the Pi Pico? A bit of Noodling through the scenarios we get the two items as above, the hardware specific software (VWS versus Softrock) and one or both bad ADE-1's on the mainboard. The LO drive level to the ADE-1's was checked and they were consistent from board to board.

A brute force test would be to decouple the SDR LLC controller from the 2nd unit and sub in the Pi Pico. This would resolve several questions. If it works sans the SDR LLC Controller and VWS Package, then we know it is a mainboard issue with the MHST. If it displays the same erroneous signal, then we have two possibilities with the Pi Pico board or the VWS package. 

The reverse is a check too if we can get the MHST to work with the SDR LLC then that proves the mainboard is OK and that narrows the choices to the Pi Pico and the VWS package. 

Since both alternatives involve some dis-assembly and temporary hookups, which of the two options is better to arrive at the answer.

Green Board Lower LH Corner is the SDR LLC Board

Them That Know Can Make Things Go!

73's

Pete N6QW

MHST an update.

I wish I could report I made two hundred 40M contacts on the MHST including DX to Western Samoa, but alas that is not the case. The issue is the transmitted signal and not receive. 

While I can abate the spurs and image signals using the QUISK tool, one additional frequency is getting transmitted. It is stronger than the operating frequency, of the opposite sideband and is not touched by the QUISK controls. I can even see it on the Half Moon Bay SDR site which is 300 miles from here. 

Thus, the transmitter remains a problem for me. I need to do a bit of research and see if any other homebrewers have seen this effect. 

Them that know can make it go.

73's

Pete N6QW

April 15, 2025 -- Tax Day.

If you are just now wading through the shoe box of receipts to prepare your 2024 Income tax, this might be a tough day. Elon has you in his sights for waste fraud and abuse. Certainly, no pressure on you.

I once was audited in the 1970's and spent a whole day with an IRS agent who you could tell had one goal -- find a problem and make her day. That year I must have fit the profile of those they wanted to investigate. At the end of the day, she said I didn't like the way you handled some expenses associated with a piece of rental property I owned. 

After pounding away on her calculator, she said you owe $100 in back taxes. I sat there astonished! I had to take a day off of work and certainly the 8 hours she spent trying to nail me was more costly than $100 she was about to recover. Then in a piece of coordination I have never seen before, 3 days later I got a Bill from the State of California for $21 in back taxes.

Here is an example of what she went after. I claimed $56 in telephone charges with calls to the Management company who did the property oversight. I showed her the Telephone number of the company and then my phone bills with that number and the cost. 

She grabbed the documents from my hands and added up all of the calls and that came to $54 -- where is the extra two dollars she asked. On one bill I noted that I spent $2 in a phone booth as I called during my lunch hour while at work. (This was before cell phones.) She said I am disallowing $2 since you have no real receipt. Why would I lie about $2? We are back to those days again.

In the QUSIK software is some embedded functionality to address images of the signals that result from the mixing process. There are buttons to address the Received signal images as well as the Transmitted images. This process is done across the entire band so that about every 50KHz you essentially set up a database of compensations to eliminate images. 

The Receive side has been done and in a terminal window you can see the compensations being applied. The Transmit side has yet to be tackled and I can see already we have a significant image about 30 kHz away from the frequency in the QUISK window. So how do I know that? Well, I plugged the MHST into a dummy load and tuned across the band and listened on an outboard receiver. Trust me it is there and needs to be addressed before putting the MHST on the air in transmit.

So, for the next several days that is the task at hand. 

BTW claiming a new set of golf clubs is likely not a legitimate business expense. But fixing the XYL's crooked teeth probably OK.

Them that know can make it go.

73's

Pete N6QW

April 14, 2025. The Tax Man Cometh Tomorrow.

A bit of progress yesterday as we found a wrong connection on the Receiver path which was a result of when I added the IRF510, the right wire was in the wrong pace. With that fixed we will look to see if we can make some on the air contacts. The Pout as I predicted is 4 watts. 

IRF510 Final Amp/LPF

IRF510 & 2N2219A Driver

Steered Amp, 2N2219A & IRF510/LPF

We are getting closer to our goal of a minimalist SDR transceiver run off of a Raspberry Pi5 SBC. As can be seen in the photo above -- not a lot of components. If this could be done all in SMD then a very small footprint. But even with Manhattan style not that big.

Them that know can make it go. 

If you have a tax refund coming, it will probably have to be reviewed by Teflon Elon before they cut you a check. 

More on proving who you are. The Voter ID project will most likely require a separate Voter ID Card if you don't have a Passport or Real ID. So, you best get some certified copies of your birth certificate as you will need that to get a Voter ID. Or if you do nothing you have achieved the goal of the Voter ID --- you won't be eligible to vote. 

73's

Pete N6QW

So, You Want to Build the SSB Jr.

 So, you got caught up thinking hey I could build a SSB Jr. Well, pilgrim think twice as the trick pony is the phase shift network. Back in the day you could just buy one from Barker and Williamson the Model 350 known as the type 2Q4.

They can be found on eBay but hold on to your butt -- this one cost $100.

You would be better served by researching the work of Rick Campbell, KK7B who designed the R2 and T2 which are phasing type receiver and transmitter boards. Campbell used operational amplifiers coupled with precision capacitors and resistors in his design. Components to build a complete rig based on his design can be had for the cost of the 2Q4.

When it rains it pours. I did build the IRF510 RF Linear amp and as I predicted about 4 watts to a dummy load. That said there is now some sort of anomaly on the receive side -- a perfect definition of SNAFU. Well, it does keep me out of the bars and/or getting into all sorts of trouble.

I am attending a Grief Group and the group leader in the last session was adamant: Don't take any sort of major action for the next 12 months -- you know selling your home, moving to Tahiti or hooking up with a 45-year-old divorced mother of two teenage sons. 

I suspect purchasing a FLEX 6700 would also fall on the counselors list. But somehow an 82-inch wall mounted LED monitor along with the FLEX6700 and a 1500-watt legal limit amp is making a significant statement about your station!

Them that know can make it go.

73's

Pete N6QW

History provides us an answer.

History is a marvelous teacher which a large segment of our society recently ignored, and we have the chaos we have today. As my mom used to say: "a leopard doesn't change his spots". So, it is with ham radio as historical events serve us well as we try to troubleshoot our rigs.

Early SSB transmitters did not use crystal filters and our amazing SDR rigs today are direct descendants of those efforts using phasing techniques. The W2EWL converted ARC-5 SSB mobile rig and the SSB Jr. from the GE Ham News are the history.

The SSB Jr. used three tubes less the RF drive coming from either a Crystal Oscillator or VFO. Before you hit the send button yes, the "IMP" from Joe, W4IMP   was also a three-tube circuit and later converted to solid state.

Basically 1/2 of a 12AU7 is a Microphone amp which passes audio through an RC Phase Shift Network to create an I and Q signal streams and then amplified by two sections of the 12AT7. The 2nd half of the 12AU7 (the other half of the Mic Amp) amplifies the RF Drive operating at frequency, like 7.202 MHz. 

The I/Q audio plus RF is magically mixed through the actions of T2, T3 and L1 and L2 and the Diode Mixer (G1-G4). The Pots R16 and R17 enable balancing the inputs to the diode mixer so that the final product is a SSB signal. The result is amplified by the 6AG7 and thereby on the air. Pots R5 and R12 also are involved in providing AF Balance. R5 assures that audio stream to the RC Phase Shift Network is balanced and R12 assures the I and Q streams from the 12AT7 are balanced.

Yes, immediately there are 4 pots that require frequent fiddling. That is one of the reasons why the shift from Phasing to Filter topology -- too much fiddling. But the advent of Digital Electronics, embedded computers and improved component stability has now reversed the shift back to phasing and digital signal processing. So, if you really want to diddle with the receive and transmitted signals then SDR is the path.

Now the history part and a little insignificant item known as a DPDT switch which you can see right below T3. This is how you select Upper or Lower Sideband. The switch mechanically reverses the I and Q signal streams which results in a Sideband inversion. 

In my early work using the ADE-1's I found that often you had to invert the Sideband in the QUISK software so that when you selected LSB in fact you would be receiving LSB. Since there was no DPDT switch, it was merely a case of how the circuit was originally wired. Then I discovered that while I fixed the receive part there was a sideband inversion on transmit.

My fix to this problem was a DPDT relay that would reverse the sideband only on transmit. So now with the relay-- LSB on Receive and LSB on Transmit. When I read the manual closely, I realized that QUISK also had a button to have the software switch the sidebands on Transmit and so no relay needed. RTFM!

Yesterday I had a head scratcher as I noted that I had USB receive when the QUISK button was on LSB. What in the hell is going on here? Sure, enough the Receive sideband selection in the QUISK software had not changed but the real signal did. 

After about 10 Minutes I realized that the answer was right under my nose. If we go back to the schematic, we have a case of raise the bridge or lower the water. In the SSB Jr. at the time it was developed, about 75 years ago, it was far easier to reverse the audio stream than the RF stream. But changing either one would switch the sidebands. 

The Phased RF signals coming from the Si5351 CLK0 and CLK1, are terminated in SMA connectors and a 6-inch length of Shielded cable interconnects to SMA connectors on the main board. In the process of doing some work on the main board I had inadvertently reversed the cables from the Si5351 to the main board. It was staring me in the face and regrettably the last thing I checked.  Switching the cables back to the original configuration fixed the problem.

I sure wished that a simple cable switch could fix other issues that face all of us today.

Them that know can make it go.

73's

Pete N6QW

April 11, 2025. Power Output from an IRF510

Power Output from an IRF510 Final Amplifier Stage is like predicted gas milage of your conventional car or for those of you who still own a Tesla -- the range of travel on a single charge. (There is still time to dump your M3.)

But 1st a short observation from the parking lot of my local Albertson's. I drive a 20-year-old car whose EOL may be rapidly approaching. While my XYL was with us, a huge part of my savings and income went to her care. I did not mind that in the least. Simply stated: It was a part of the original deal. Thus, I tuned out any thoughts of new cars and the new-fangled features. Back to the parking lot.

Opposite to me as I pulled into the parking slot was a rather large Tesla, black in color and had fully tinted windows. This car arrived at about the same time mine did. Then as if by magic the rear door opened upwards like a gull wing. It was like a symphony of motion. 

The driver alighted first, a small, attractive, well-dressed Asian woman who quickly moved to the rear door opening to assist the second Asian (more mature) yet similarly appearing woman to alight from the car. It was definitely a choregraphed and rehearsed action. 

Boom it came to me in a flash -- a dutiful daughter-in-law chauffeuring the mother-in-law. The gull wing door certainly eased the departure from the rear seat. A scene you don't forget concerning rank has its privileges. If it was the driver's mom, she would likely be in the front seat!

A little-known fact is that there is a significant Asian population in Newbury Park a result of the large bio-technical firm AMGEN and the location of a division of the company who builds the Si5351, Skyworks Solutions. Both operations employ this knowledge worker labor segment.

Back to the IRF510. Our IRF510 for a given set of Biasing and Drain voltage has a derived transducer gain. This is typically expressed in DB. Yesterday's post suggested my IRF510 design would produce better than 3 watts output. But any output from an IRF510 is also dependent on the input level. If we suggest a transducer gain of 10dB you ask what that looks like.

For clarity we are talking about power gain not voltage gain. So, our driver stage produced 12 Volts PTP and that comes to 360 milliwatts. If the output from the IRF510 was 3.6 watts (3600 milliwatts) then we have the following for our calculation.

Power Gain in DB = 10*log(power out/power in)

Gain = 10*log (3600/360) or 10*log (10) = 10dB.

If our transducer gain is 13 dB then the power output is 7.2 watts.

Gain = 10* log (7200/360) = 10* log (20) = 13dB.

If our transducer gain is 16dB then the power output is 14.4 watts.

Gain = 10* log (14400/360) = 10* log (40) = 16dB.

Now we can lower the water or raise the bridge, but these gain figures were based on the 360 Milliwatts of input. Transducer gains of 13 or 16dB are like 51 MPG on a Toyota Camry LE -- only achieved when the planets are aligned every 150 years. These gains are possible but NOT typical!

In my experience, 10dB of transducer gain is the more likely output. So, what is the solution and that comes in the form of more drive to the final and/or raising the Drain voltage. For those whose left hand is permanently welded to anything Bitx you will recall the Bitx40 board had the capability of supplying 24VDC to just the IRF510 for more power output.

Let's see what would happen with a 10dB transducer gain but with a 500 Milliwatt drive signal. 

Gain = 10* log (5000/500) = 10* log (10) = 10dB. 

To get 10dB of gain the Pout is 10 x Pin so I automatically knew the output was 5 watts. Now to see 5 watts the output across 50 Ohms has to be about 45 Volts PTP or 45^2 = 2025 and that times 2.5 = 5000 milliwatts or 5 watts.

A 13 dB transducer gain at 500 milliwatts input would be 10 watts output. That I have never seen with 13.8 VDC on the Drain. 

Thus, assuming a typical 10dB transducer gain you would expect less than 4 watts of RF with 360 Milliwatts of drive.

I will try to cut a board on my CNC today since the IRF510 amp is one of my stock boards.

Them that know can make it go.

73's

Pete N6QW

Video of Driver Stage ~ Yes, 360 Milliwatts output on 40M.

 Them That Know Can Make It Go!

MHST 2N2219A Driver!

Our next phase will be the Final Amp using the IRF510. I expect about 3 or so watts on 40M.

73's

Pete N6QW

April 9, 2025. The MHST Driver Stage

Just as many homebrewers rely on Bitx circuits for use in their rigs, I like to use and reuse stuff I have designed. The MHST Driver stage is straight out of the P3ST Project. A quick hookup to the steerable amp produced 12 Volts PTP. A power calculation results in 12^2 = 144 and that value times 2.5 = 360 milliwatts.

So, OK if you can only think the old way. The 12 Volts must be divided by 2 for the Peak Value or 6. That must be multiplied by .707 to yield 4.242 Volts RMS. Next, you square that and divide by 50 (Ohms) to yield 0.35989128 watts. Or 359.89128 milliwatts. Duh, you really want to do all that or just square the PTP and multiply by 2.5.

Compact Driver Stage for the MHST

MHST Driver Stage Schematic

Tomorrow I will post a video of the output with the Driver stage.

You ask about the Real ID adventure with the California DMV -- A TOTAL BUST!

Despite having an appointment, I waited in the cattle line for 1 hour just to get inside the door and then another half hour to get to a station. I actually had two pieces of business with one of those being to get a revised "pink slip" with only my name on it as the XYL is a SK. In order to replace the car, which at 200K Miles and nearly 20 years old it's time, you need to have a clean title. That part went OK.

But I got nowhere with the Real ID. Two problems: my expired Passport is now with the Dept of State being renewed. I gather if you have a valid passport -- the whole process is shortened. The alternative is to provide a birth certificate and two utility bills. Well, I have a birth certificate, but the DMV said it was not a certified copy but only a copy. So, I have to await the Passport -- about a month and also, I had to contact the Pennsylvania Department of Health and order a certified birth certificate. 

BTW that Pennsylvania birth certificate process was the same as CA for the Real ID. I had to supply a photo of my Driver's License and two supporting documents. BUT you cannot just take photos with your phone as that is too high of a resolution. So, I had to scan the documents and drop the resolution so I could upload the documents. 

At this point you almost want to give up on the Real ID as the Passport will let you fly. Then the light bulb went into very bright as now I know why old what's his name is pushing for voter ID. For many getting the Voter ID will be as difficult as getting a Real ID and they will simply stop voting. What's his name is hoping to only have his acolytes vote in an election. The Voter ID has impact on suppressing the vote.

Them that know can make things go.

PS: At 5:00AM (left coast time) got an email from Pennsylvania -- what I submitted was good and they will send the certified birth certificate -- once they find it. It is ironic as the revised registration for my old car that I got yesterday was one of the documents submitted to Pennsylvania and purposefully I had the new registration match my Birth Certificate and the same for the DL. Beat them at their own game!

73's

Pete N6QW

April 8, 2025. Ready to add some boards to the MHST

After much gnashing, wailing and grinding of teeth, the main board of the MHST is sufficiently along to proceed with the remaining boards for the 40M MHST.

With about 3.6 milliwatts coming out of the mainboard steerable amp (1.2 Volts PTP) we need several boards to boost that output to > 300 Milliwatts to drive the IRF510. Below is a short video of how the output looks on 40M from the mainboard.

I have built several homebrew SDR transceivers over the last 5 years, but the challenges of this particular rig have really been a learning experience for me. Hopefully others will build along and gain that same experience. 

Before getting too excited bear in mind this is a minimalist SDR and translating this design to higher bands will entail additional amplification stages. It is not a matter of simply changing out the BPF and LPF and you get several watts on 10M. The higher bands will need more intermediate stages of amplification.

Them that know can make it go.

Wish me luck today with my visit to the CA DMV to apply for my Real ID.

73's

Pete N6QW

Passport Update and a visit to a charming CA town.

After waiting nearly, a month for an appointment, last Friday was the date to visit the US Passport Office in Los Olivos California. In my earlier quest to find a place to apply for a new passport this was the closest place I could find that had actual appointments open on a schedule.

Prior to the visit, I had prepared all of the paperwork and had all of the required documents including the confirmation appointment document and two checks. The next question was: Where in the hell is Los Olivos? Google Maps said 85 miles away.

I started my journey at 6AM as there is always highway construction and I was totally unfamiliar with the area. Santa Barbara is but 42 miles north of me using the Highway 101 Freeway. After passing through Santa Barbara, you take exit 101B on to Highway 154 and 43 miles later you are in Los Olivos. Near Santa Barbara there was road construction and slow traffic. Lest we also forget morning rush hour.

It was like a trip to wonderland once on the Hwy 154. It was very scenic drive and a 24-Hour headlight zone for 35 miles coupled with very thick fog. Finally, I arrived in the town some two hours later with two needs: time for a pit stop and a cup of coffee. 

Los Olivos had a very small downtown area like maybe three blocks and the Post Office (Passport location) was in a real small building. As I drove the three-block town, I was looking for a McDonalds or 7-11. None to be seen nor any kind of diner. There were many restaurants (upscale) as this was wine country and only open in the evening. Finally, I spotted the Fess Parker Inn (He was a TV star ~ Davy Crockett in the 1950s) where I inquired about some sort of diner -- they said there was only one place and that was in a competitor Inn that had a public dining room. Whew, as I now was at the pain level. 

Found the 2nd Inn and the dining room where I ordered a bagel and a cup of coffee -- $14.01. When she handed me my change from a $20 -- my distress must have been apparent as she then said -- the restrooms are over there. Whew! The printed menu listed a light breakfast at a mere $35. Tourist Trap.

My appointment was for 9:30AM and sure enough Suite B was the passport office and the size of a broom closet. 

I go into suite B and was asked by the attendant do you have everything, and I replied yes. He looks at my expired passport which would have expired on February 12, 2022, and with the grace period would appear to me that on February 12, 2025, would trigger a new passport versus a renewal. Well, the attendant says you need the renewal form not the new form. He says it is the year not the date. Who am I to question the USPS.

It was also cheaper as I did not have to add the USPS fee. So, we will have to see if that works. 

I asked myself had this been 15 years ago when we came back to California would Los Olivos been an area of consideration. That question had two answers: Yes and No. The Yes part was the small town and the opportunity to buy a chunk of land big enough for an antenna farm. The No part was that it lacked sufficient medical facilities for the XYL. Santa Barbara was like 50 miles away and just too far. Today still a No answer as it would be a big hill to climb as it is a little late to start over in a new place.

Tomorrow it is a similar appointment with the DMV as I try to prove who I am so I can get a real ID. That should be fun.

Tune in tomorrow for more exciting adventures as I try to get the documents necessary so in May, I can fly to San Francisco to see my #3 son-- a total of 350 miles. Suddenly, driving there is getting to look better. 

Them that know can make it go.

73's

Pete N6QW