MGC- Amateur Radio's Biggest Secret

Greetings Earthicans,

    Every once in a while you become alerted to a new technique that can completely change how you operate your radios. Automatic Gain Control - AGC, is a feature of a radio that more or less regulates the volume of the radio. When you receive a very strong signal for example from a homebrew QRP BITX with a slinky antenna, it will automatically lower the volume so it doesn't hurt your ears. Also when you are surfing the dial and come across the weak signal of a Kill-A-Buck 2,000 Transceiver with a beam larger than some states, it will bump up the volume so that you can hear them. 

    The other day while "listening" to my wife tell me all about the drama down at the nail salon, I was tuned in to the Solder Smoke Podcast #247 listening to Bill Meara N2CQR and Pete Juliano N6QW giving their professional quality review of the ICOM IC-7300. Then they started discussing AGC. It was during this conversation that the topic switched over to Manual Gain Control- MGC

    The BITX series of radios was gifted to all of humanity by Ashhar Farhan VU2ESE. It is basically a bare-bones radio that does not have all of the bells and whistles that today's appliance operators have come to depend on. This makes the BITX one of everybody's favorite radios. I think that the national motto for the wonderful country of India is "If you don't like the BITX, then you are wrong!" You got to love India, this is the country that gave us Indiana Jones and the Indy 500. If you are a member of the BITX Community or wish to be a member of it, then you should really check out the digital temple to all things BITX the BITX 20 io group.  The BITX is a bare-bones rig but it was designed from the get-go to be hacked and modified. One of the first things that a lot of people add is AGC. You can get an add-on AGC kit and hook it up to your BITX. Another option is to find some schematics for an AGC module and brew your own in the haze of a cloud of solder smoke, just like this group of young and respectable men did in their VW Microbus on their way to their local amateur radio club meeting. 

    When Ashhar Farhan VU2ESE designed the BITX he hid a neat little feature called Manual Gain Control MGC. In fact, nearly all receivers and transceivers feature MGC. Yet you will never read about it in any manual. Why? The powers that be don't want you to know about it. It is a closely guarded secret. This secret is up there in importance as other big secrets like the formula for Coca-Cola, the recipe for Kentucky Fried Chicken, and the location of Jimmy Hoffa. Now we have three very important homebrew heroes that are willing to share the secret. For them to share with us they had to fight off armies of drunken Eskimo Lerechauns from Swaziland, and after that, they endured financial hardships because they had to retain the services of the world-renowned law firm of Duey Cheetim & Howe. 

    Here is the secret. I will tell you and I will probably disappear. Just from writing about it, I have the CIA, NSA, MI6, and the Girl Scouts beating down my front door to silence me. Are you ready? Be forewarned, once you gain this knowledge your eyes will be opened for the first time and you will never be the same again. 

    When you are surfing the dial and you bump into a really loud signal that threatens to blow your drums, reach up to your radio and find the volume control and turn it down until the sound coming from the speaker is at a comfortable listening level. When you encounter a very weak signal, again reach for the volume control and adjust the volume higher until the sound is at a more comfortable level. 

    That is it! When using MGC the audio volume can be quickly and easily adjusted to the level that YOU prefer. Not some algorithm or black magic hoodoo stuff that is happening inside an IC chip that is deciding for you the audio that it thinks you want. The best thing is MGC is completely free. You don't have to add modules or write some code for it. You already have it on your radio! It's time to take back the controls of your radio, and YOU decide how loud you want it to be. Next time you talk to Ashhar VU2ESE, Bill N2CQR and Pete N6QW, thank them for liberating you from the cerebral processing control that the black arts of AGC that dominate our day-to-day lives. You are now free to choose your own volume. 

    (Disclaimer- I'm pretty sure that Ashhar, Bill, and Pete did not invent the volume control but they support its use, and they are important figures in the amateur radio community and that is good enough for me. Also, MI6 isn't really beating down my door. MI6 is in the UK so they are probably eating fish and chips while monitoring the 50 trillion CCTV cameras that are in operation in England.) 

Any thoughts or comments can be left in the comments section below and you may contact me at Aaron@K5ATG.com

Be safe and Don't Litter

Aaron K5ATG

The Radio Flyer

Here are some pics from today of my baby. The Radio Flyer

The above pic shows my trunk. It is made from surplus ammo can for 50 caliber rounds. It is coated in several layers of spray on the truck bed liner. I have two more that are being modified to be saddlebags on both sides of the rear wheel. The plan is to get some flush-mounted custom tail lights for a motorcycle and run a 12-sealed lead acid battery. The battery will supply power to an Arduino and the LED lights in the tail lights. Since flashing lights are noticed before steady lights, I will use the Arduino Nano to make the tail lights blink my call sign in CW. The mag mount is something that I picked up somewhere. It is a compromised antenna for an HT but the football helmet adds 7 db of gain (Each of Oklahoma University's national championships should be good for a db of gain lol, Boomer Sooner) Once the 2 saddle bags are finished they will have solar panels mounted on the top of them and these will help charge the 12 battery. At some point, I want to add more batteries so that I will have an onboard source of power instead of having to bring a separate battery for portable ops. Once I am able to add an electric assist, the battery will fit on the rear rack under the trunk. 

Here is the mount for my HT. It can easily be operated while riding. If conditions are noisy like if there is a lot of truck traffic I have a 1 ear headset that fits nicely under my helmet. The coax goes from the HT at my handlebar and snakes along the frame to the little mag mount antenna on the trunk. This keeps the coax from snagging on the chain, wheels or other mechanical parts of the trike. I'm not going to work much DX with this HT but I can get on the local repeaters. I'm net control for a weekly net and I have done this while riding the trike. In my local amateur radio club there are 4 of us who have become really close friends. Out of the 4 of us there are 3 recumbent trikes and one recumbent bike. The cities in the metro are adding dozens of miles of paved bike trails each year so the 4 of us meet up quite often and have a nice ride. At this point I am unable to ride by myself so they take me out riding and one has an electric assist and he keeps a tow rope on his trike for me. There are times when I am out riding and hit a bump wrong and my back "goes out" It is kind of hard to explain but I will lose control of everything below the waist. Temporarily paralyzed. Often it feels as if my bones have become heating elements and are cooking my muscles. My skin will feel like someone poured Napalm on me and lit me up. It is a very unpleasant sensation. Because of this I spend 99% of my time in bed. I will be homebrewing the sBITX from a folding tv tray on the side of my bed. Because the seat of the trike supports my entire back, it provides me with the only source of exercise that I can get. I'm almost 49 years old and I have had open heart surgery, my diabetes is nearly out of control, I also have Asperger's syndrome, and high anxiety, Add all of that to my back problems which are spinal stenosis in several places and my Sacrum is becoming detached from my pelvis cradle, which is why they will be putting in a cage to stabilize everything. 

So I will be out cruising the trails on the Radio Flyer and my back could go out, or my sugar will drop like crazy or my heart can act up. When this happens I have to call someone with a truck to come and pick me up. If I had electric assist then I can just turn it on and steer the trik home. I don't need the electric assist to help me go farther or make it easier to pedal, I need it to safely get me home or to a place where I can recover. For most people having an electric assist is a luxury which is awesome and there is nothing wrong with it. If it gets them out of the house then they can add a car engine for all I care. I see the electric assist as more of a necessity based on health.  As said earlier my buddy carries a tow rope on his trike and when I need help getting me home he just pulls me along. It works when he is with me. At a thousand bucks, I'm not going to be able to get electric assistance anytime soon. We are saving up for it though so never say never. 

This is an accessory mount on the side of the seat. I need to move it to the left side of the seat because I am left-handed and it will be easier for me to access everything. This would be the perfect place to mount the head unit of an HF radio. I have a mount that goes on the rear fork that will let me put on a ham stick. If I run a small wire behind me, I can do decent on the radio. In 2021 I had a 20-meter ham stick and was using a friend's KX2 and was operating "Trike Portable" and was live streaming on YouTube. I had a small pile up and was talking to people all over North and South America. I would like to have that set up more permanently and do that more often. Need to get me an HF rig first though. This accessory bar beside the seat is rated for 35 pounds so It should be possible to rig something up. 

Here is the overall view of the trike. I got it new in January 2019 and I have 3,100 miles on it. I try to get on it every chance I get because it is good exercise and it is a lot of fun. 
Well, that was too much information but hopefully, it will let everyone know what my life is while I make my own custom sBITX. 
'72

Aaron K5ATG

Aaron@K5ATG.com

The sBITX - My maiden voyage into the art of homebrewing. Part I

     Every once in a while a new product comes out that you just got to have. While you are drooling over the listed features you think to yourself "Wow, not only are the NSA, CIA, Homeland Security and Girl Scouts of America flex their financial and covert might at tracking every move and thought that I make, so does HF Signals out of India." When  Ashhar Farhan VU2ESE announced the sBITX I couldn't help myself. I'm a big fan of HF Signals. They are the ones that sell the most famous electronic creation of Farhan VU2ESE, the BITX series of radios. I have the BITX 40, uBITX (pronounced MICRO BITX, not U BITX), and the Antuino. So when Farhan announces a new project, well that is clickbait for me. I have to check it out. 

    A simplified description of the sBITX is a uBITX and a Raspberry Pi 4 computer get together and some magic happens. 

    The following is a list of features of the sBITX as borrowed from the HF Signals website:

Home station, at home

• The big compact: Although compact, it has the largest display shipped with a transceiver, a capacitive, touch screen of 7 inches.
• All software to run modes like FT8, RTTy, PSK31 is integrated into the radio, without any messy configurations, setup, etc. to deal with.
• It switches soundlessly from transmit to receive and between bands due to its electronic filters and T/R.
• Band-stacking VFOs with 4 memories on each of the 8 bands, 9 convolution digital filters for the best audio experience. 
• High-performance electronics with a passive-FET front end, 8 crystals filter, and a low phase noise, temperature-compensated crystal oscillator. 
• The built-in, editable macros that make it a breeze to work DX or compete in contests. 
• Add an HDMI monitor or use the browser from your PC/tablet to have a large-screen experience of all the features of this amazing radio. 

Go POTA, Go SOTA, Go Wild

• The sBITX will neatly slip into your backpack with its compact size of 10 inches X 6 inches X 2 inches and weight of under 4 pounds (less than 2 KGs) with room to spare. With its 40-watt transmit output, it is the most powerful radio you can put into your backpack. 
• It is armed with an XT60 power connector that you can use with lightweight 3S LiPo batteries to provide hours of field operation (The receive current is 600 mA, the transmit current can go up to 8A depending upon the drive settings.)
• The built-in mic and the onscreen keyboard, macros makes it easy to operate all modes, voice/digital or CW without a key, mic or an extra computer in the field.
• It has an accurate real-time clock to time FT8 transmissions and log the contact made. 
• The built-in logger eliminates the need to carry the logbook too. 

High-Performance Radio

• Bulletproof hybrid superher with passive-FET KISS nixer.
• Brickwall crystal filter with 8 crystals.
• 80 db close-in dynamic range, 90 db wide dynamic range.
• Low phase noise, temperature compensated reference oscillator.
• 30-40 watts output on all bands from 80 M to 10 M
• Transmit IMDR of 30 dB (from PEP levels)
• Silent, fanless operation
• Noiseless electronic T/R and band switching.
• Built-in 2 tone transmitter to tune the antenna and measure IMD

FT8

• Built-in FT8 that works out of the box
• One-touch operation. Touch to call CQ or start the contact.
• Automatically logs all the QSO's into the built-in logbook. 
• Built-in, high accuracy, real-time clock. 

CW/RTTY/PSK31 with logging and Macros

• Totally noiseless, fast electronic T/R without noisy relays.
• Built-in N1MM style Macros support Running and S&P
• Uses Fldigi with its high-performance decoder in the background.
• Raised cosine CW keying with perfect shaping.
• 9 ring-free Convolution filters from 3 KHz to 100 Hz.
• Use the onscreen touch keyboard or add a USB/wireless keyboard for effortless CW sending. 

SSB

• The sBITX uses convolution SDR technology and a 7-element crystal filter to provide superb sound quality with punchy clarity.
• Built-in microphone and touchscreen PTT as an alternative to plugging in a mic
• It works with any other mic (standard audio jack)
• Transmit IMD of 30 db
• Receiver with variable receiver bandwidth from 3KHz to 1.8 KHz.
• Built-in two-tone generator to align external linear amplifier or tune your antenna

Logger and Logbook

• The sBITX has a logger and a logbook with RDMS support.
• N1MM style logger with macros and automatic logging of contacts with the frequency, mode, time, automatically filled in.
• Use macros on CW/RTTY/PSK to send out standard messages with the press of a button/key.

Telnet

• See the spots, DX clusters on the radio with built-in telnet to DX Clusters, Reverse Beacon, PSK Reporter, etc.

Hackable Code, Skinnable GUI

• Full source code, circuit and explanations on github.com/afarhan/sbitx
• Write custom apps in javascript without learning SDR coding. 
• Open source, hackable SDR written in C
• Develop your own skins in UI in HTML/CSS/Javascript
• More modes and functions planned

    Hopefully, all of that information will give you a general understanding of this great and wonderful radio. See here is my situation. I'm disabled. My back has all kinds of trouble. As a result, I have to spend about 90% of my time in bed. So because of this my shack is a plastic table that is on the side of my bed, set up so that I can operate my radio from bed. Then from decades of me having to be at work by 0500 I have a habit of waking up early. Well my beautiful bride is a night owl, about the time that I am waking up, she is going to bed. Being respectful of my wife's sleeping, I try to keep the volume on the down low. So I wear headphones and earbuds when watching TV. Having to keep quiet puts a pretty good kink in operating radio while the XYL is sleeping. Because of the noise I have to be regulated to the digital modes like FT8. Well, lately I have been addicted to CW. Because of my poor hearing I use an app on my cell phone to decode the CW as a backup for when I miss something. To do this the cell phone has to be able to hear the CW signal from the radio. So I can't do CW while my wife is slumbering because of the noise. Looking at the sBITX, with the feature of decoding CW itself and tons of other stuff makes this an ideal radio for me. I could go from FT8 to SSB without having to unplug an interface and its cables. I also love to operate portable when my health allows it. With the sBITX I will be able to take my radio, a computer, and just about everything else I need in one small box. Not a truckload of stuff.  

    

    To be honest, when I heard about the sBITX it kind of made me mad and depressed. Like I said, I'm on disability, and with my low disability paycheck, I have to support my wife, my 20-year-old Autistic son with Aspergers Syndrome, and a 16-year-old daughter that I'm putting through countless drama classes because she wants to be an actress and I am doing all that I can to help her achieve her dreams. It's like I now get to go on one of those internet gatherings of like-minded people, like the BITX 20 io Group, and see those that are more fortunate than myself and are able to get this wonderful radio and then tell everyone how great it is. It is something that is out of my reach and why? It's because I sacrificed my body and my health to provide for my family. This is also the reason why I don't do Facebook very much. I get to see all of my friends and family go on these vacations and do all of these things while I am sentenced to life without parole to my bed. It sucks more than a warehouse full of vacuum cleaners. I would like to live my life also. It may be hard to understand but I'm alive but I'm not living. 

    Then from stage Left, Ashhar Farhan came into my life. He is well aware of my station in life. Even so, he got me to believe that I too could have this great little radio. I can have one by making it myself. When an amateur radio operator makes something themselves we call it homebrewing. Ashhar convinced me that I can build the all-mighty sBITX at a fraction of the cost of buying one. Ashhar first developed the BITX with the goal of having people build it themselves. Then it became another rig for people to buy. He has the same idea as the sBITX. He would rather have people build it themselves than to send out the credit card numbers in exchange for a finished radio. 

    I don't remember how it happened but yeah Ashhar got me to believe that I could build the sBITX myself. Now my experience in homebrewing is limited to making different kinds of radios. I have no history in electronics at all. If I can completely build a fully functioning sBITX radio then hopefully it will inspire others to build their own. 

    My mission is to try to learn every aspect of the sBITX and share it the best that I can here on this blog. As of right now, I need to learn a lot. Right now the only parts that I have to go towards this build is a Raspberry Pi 4 (4gb RAM) and a monitor for the Raspberry Pi 4. When Ashhar designed the sBITX he made everything open source. So everything, including the OS that is on the RPI is hackable This radio isn't just soldering a transistor to a resistor. It's about learning the code, knowing what electronic component goes where and why. Like I said, I plan on sharing everything here on this blog and on the BITX 20 io group. I'm gonna tell you right off the bat. I AM BAT POO CRAZY! That being said you can and should expect lots of failures and lots of laughs from me. In fact more failures than successes. When I fail at something I want to know why it failed and what can I do to fix it. You learn more from mistakes than you do by never failing. If that is the case then I should be a genius. I should be Aaron the Great. lol

    So PLEASE subscribe to this blog so that we can go forth on this Journey together and keep slugging away. We will succeed as long as we Don't Stop Believing. (See what I did there?) We are gonna show those street light people how to build an sBITX. Anyone can comment so please do so. You can also email me at Aaron@K5ATG.com

Check back often for updates, or just subscribe so that you will know when this blog is updated. 

'72

Aaron K5ATG