Gum on your shoe --- the Bitx40

Have you ever stepped in Chewing Gum?

The questioned posed is more like the result rather than the question --- no matter what you do it sticks and is just there, never to leave. So it is with my involvement with Bitx40 --- no matter how hard I try, there always seems to be an email in the queue asking me a question. Most recently there have been a flood of questions about the use of OLED displays on the Bitx40.

 

First asking me has some really negative aspects especially since the information is not being shared with the greater Bitx40 community such as would happen if posted on the Yahoo group reflector. Despite what  I tell my XYL that "I know everything", I don't and thus posing your question via the Yahoo group will give you the benefit of the "group grope" to wrestle with your question. I don't subscribe to the reflector so I may give you info that has been proven wrong.

 

The other negative aspect is asking me to do work that you should be doing. One ham made an inquiry about the 240X320 Color TFT display and I found out later he didn't like my suggestion that he start with some basic stuff like learning to swim before attempting to compete on the Olympic Swim Team. He loaded some one else's code and got it to work but then wanted me to make changes for him. I have declined to do so.

 

One scary experience is that my OLED implementation on the Bitx40 was done with a Nano, the OLED and Adafruit Si5351 board which was all external to the Bitx40. I have shared that code on my website at www.n6qw.com/Phase7.html --- keep in mind when I bought my Bitx40 the "digi" module was not offered for sale. Thus the external homebrew digi-board with the OLED is what I used.. The scary part is that individuals have "ripped up" their VU2ESE supplied board and "haywired" in the OLED using my code. One report I got was the OLED displays OK but the Bitx doesn't seem to change frequency and the computer noise in the Rx masks everything. I asked did you put a scope or frequency counter on CLK0 to see if you are getting RF and what frequency is it? I am thinking that the overwhelming computer noise is masking the real signals. I have had no reply.

 

Now that is another bad aspect as I never imagined someone would cobble up Farhan's board as my implementation was a standalone board. The other negative by connecting directly into the Bitx40 , power rail you are opening up the possibility of noise. My outboard digi has the additional isolation. Bill N2CQR on his blog soldersmoke.blogspot.com has covered active decoupling to resolve the noise issues with the OLED'S.

 

I don't mind helping but in the future will ask that Bitx40 questions be posted on the yahoo Bitx40 (actually Bitx20) group reflector.

 

The really Good News the Bitx40 is taking the World by storm!

 

73'S

Pete N6QW

Cool Stuff from N6QW

Cool Radios from the N6QW Laboratories!

 2/4/2017 ~ Request for AGC circuit being used. This was supplied to me by PD7SSB who came up with modification to my 20M Shirt Pocket Transceiver Project. It is an audio derived circuit. I have no details for implementing an RF/IF derived circuit such as the W7ZOI Hycas.

2/5/2017 ~ More on the AGC
Tribal knowledge here. The 4.7K Ohm Resistor connected to the output and feeding the diode was replaced by a 25K trim pot in series with a 3.3K fixed resistor. I found that there was too much "AGC" action with just the 4.7K ohm as shown on the schematic. The 25K pot was wired as a variable resistor (If you have to ask how to do that --turn off your soldering iron). Thus the range is 3.3K to 28.3K --now giving you a span of adjustments. Hold off  sending me an email as there will be some who suggest just using the 25K pot with one end to ground and the center wiper to the diode and the other end connected to the LM386 output. That is not what I did and I leave that to others for experimentation. The photo below the schematic is actually what is on the schematic including the microphone amplifier, audio amp, AGC and S Meter circuitry.

 

 

 

 

N6QW Two Band XCVR:  Mic Amp, Audio Amp, AGC, and S Meter Board

 

73's
Pete N6QW

Secrets to Homebrewing ~ Revealed!

Secrets to Successful Homebrewing -- An Art!

Many years ago there was a joke going around about the person who widely advertised "Become Rich Quick!" Send $2 and discover how. As the story goes a reply would be received in the form of a postcard ( at that time 3 cents) which simply said "Do What I Did!" 

 

Well I could tell you to do what I have done; but that would undoubtedly be a disservice in that simply repeating what I have done has no guarantee and you didn't even have to spend the $2.

 

So for free -- you know how good free is -- are some suggestions for the would be or seasoned homebrewer on being successful in your builds.

 

1. Getting organized by having a good information storage and retrieval system. A well established library, collections of data sheets, and cataloged project articles are worth their weight in gold
2. A suitable well lit workspace where you can stop a project and return to it later picking up where you left off. I remember an article about a ham who had very limited space in his home save for the family laundry room. Clever guy that he was he built a swing down work table that was above the family washer and dryer. When he wanted to build something he simply let down the chains on either end of the hinged table and instant workbench. That worked very well once! Seems his XYL (like my XYL) absolutely hated ham radio. His XYL literally waited in the bushes until he just had everything ready to go and she would come in with the laundry basket and announce it was time to do the laundry. Of course they had a top loading washer --so his bench had to be put back. Find a better solution than this chap.
3. Tools and Test Gear -- take a tip from Tim Allen (Star of Tool Time and also a ham today) and get the best tools and you do need something more than a 1920's voltmeter for test gear.  There have been many suggestions on a minimum tool set and test gear and if you navigate over  to http://www.n6qw.com/Bitx40.html there are several pages devoted to getting a good stock of basic tools and info on test equipment.
4. Junk Box. Start now by collecting common parts in your junk box. You will not find a Radio Shack open at midnight when all you need is a 10K 1/4 resistor. Several years ago I wrote an article on how to stuff a junk box. You can find it on my website http://www.jessystems.com under Konstruction Korner. This is a recommendation on what you should have in the bins.
5. Start with a small project like building the Michigan Mighty Mite one transistor transmitter as this has many benefits starting with low part count (less than 10 parts), low cost as many of the parts cost pennies, short build time, and UNDERSTANDING --yes not only build it but take the time to know what is the function of each part. Finally 9 out of 10 builders smoke the transistor for various reasons. Thus another few pennies and you are back in business. Smoking a set of finals in your Yaseu, ICOM or Kenwood will cost well  over $100. A small project is easier to troubleshoot!
6. If it is a receiver you want then start with a direct conversion receiver (low part count, good sensitivity, easy build) and get that working. A DCR is a very usable rig! Once you have that going you can move up to a superhet with a crystal filter and other goodies. In 2015, Ben KK6FUT and I wrote a series of articles on the LBS (Lets Build Something) which is a project that did exactly that and the bonus literally all of the DCR was incorporated into the Superhet.
7. A word here about the Bitx40 which is a pre-built complete radio including a digi LO and LCD for an amazing price of $59 delivered from India. This is a good starter project as there is much support and documentation to assist the builder. Costing only $59 and pre-built save for mounting in the customer supplied enclosure, this satisfies many of the criteria mentioned earlier.
8. KEEP NOTES and RECORDS of settings, wiring diagrams, modifications, parts substitutions and as built sketches. You simply cannot remember all of this in your head!
9.  Finally :Do not be afraid to ask questions from suitably knowledgeable people, in fact ask lots of them. Asking WHY leads to understanding and wisdom =. (Tnx Rob)

That is it --secrets revealed.

 

73's

Pete N6QW

Very Interesting ~ ?????

 

 

 

 

 

 

 

 

 

 

 

 

Pete N6QW

 



SolderSmoke Podcast 193 ~ Insight and Comment

All Information is Good Information!

Someone once told me that and I have firmly come to believe that. Not that the information in itself may be good; but it is good to know that certain individuals believe something (which maybe erroneous) that you now know where they stand. The other side of the good information is that you may be presented with thoughts or concepts that perhaps were unintended in what you personally have presented. An example is to merely say "hook it up" and run the test failing to mention that the test needs to be run with a dummy load. You know to hook it into a dummy load; but that may not be clear to others.

 

For three years now I have participated in a monthly podcast along with Bill, N2CQR who has been at it for 10 years and is one of the original founders. Check out Bill's blog http://soldersmoke.blogspot.com for a link to the latest podcast (#193). The subject matter of the blog --yep ham radio with an emphasis on homebrewing, current technical topics and a trip across our respective work benches to share projects we are  building. I tend to favor the newer technologies (digital VFO's) and Bill likes the older type (Analog VFO's). We had thought this was a good approach as it offered our listeners a range of topics or how to perform a task using different technologies. (A comment here: I see Bill drifting more and more toward the "digi" stuff.)

 

Usually the podcast starts by Bill asking me what number is it -- and I respond much like the Rock Jock's of the 1960's by shouting with enthusiasm the current number. I guess I always wanted to be a rock jock --a dream of mine that was fulfilled by my daughter who actually was one!

 

Hopefully our format shares technical knowledge and even our tales of woe as we  smoked parts and most importantly to include projects by our listeners. In fact Bill's blog is mostly about projects being built around the world with many of the projects directly relating to subjects covered in the podcast. At one time we ran a series about the Michigan Mite Mite a single transistor transmitter using colorburst crystals. Bill (mostly Bill) and I even supplied crystals to those wanting to build the project. We did supply about 50 crystals and we know of many being built using their own crystals. So we do think our efforts have been impactful across the world of ham radio.

 

The last several podcasts have highlighted a currently world wide popular ham transceiver known as the Bitx40. This amazing complete built 40 Meter SSB transceiver comes to you pre-built, delivered to your door for an amazing price of $59 --and that includes a digi LO and LCD display! Bill has built two  and I have built one!

 

But the real thrill of this radio is the ability to customize the project and there is even a "hack page" provided by the manufacturer to collect these mods/improvements, to which both Bill and I have contributed. I have even created a series of web pages to assist the 1st time builder to get the Bitx40 on the air. You can find that here Bitx40 from N6QW  We believe about 2000 of these radios are now in ham shacks across the globe. We have VU2ESE, Farhan to thank for this wonderful project and the idea of how to spread the ham radio gospel.

Two other recent technical highlights discussed reverse polarity protection and the use of active de-couplers to remove noise from audio circuit resulting from the use of OLED displays. Perhaps the message to us is that these were too simple technically to even merit a word let alone a discussion.  Inputs like this would help guide a selection of topical discussions.
 

Since we do the podcast monthly at times it may stretch to five weeks and to alert the podcast fans Bill will send notice the various reflectors in essence saying "we're back at it." So was the case yesterday when SS #193 was announced to the world.

 

On one particular reflector there were several negative comments about the podcast including a derisive comment about my "wanna be rock jock announcing" of the podcast number. Further comments involved the lack of technical content and it not being very useful. That is good information! Unlike our current POTUS 45 we are not thin skinned about negative comments nor have we banned any listeners!

 

Instead what would be helpful is if listener's would share with us the good, the bad and the ugly! If my shouting into the microphone is offensive to many of the listeners then it is an easy fix. Just tell us. But if you laugh a bit while I say it --let me know. As to technical content let us know that too. If you would like to know about Hilbert transforms or how does a Double Balanced Mixer perform a commutating action to demodulate a signal --we can do that too. Although a treatise on 3rd order linear regression might lose a few listeners. But let us know. The podcast is for you not us!

 

So to those several hams that had the courage to input negative comments we salute you and say thank you. But we'd also like to hear from others who may share those same negative (or positive) feelings about what Bill and I do. Let me assure you will not be banned from the podcast nor will you have to show proof of license.

 

73's

Pete N6QW

You Never Know ...

Yes! Ham Radio Is a Very Small World!

As many who have read this blog for the last year or so know that my XYL is not in the best of health and as such we typically have a medical appointment almost every week. I literally have an autopilot button on my car's dashboard that says UCLA Healthcare Center, Thousand Oaks and boom we get there almost automatically.

 

This past Monday was no exception and the only exceptional thing is that we have been having a lot of rain the past several weeks and it was cold too! (Cold is relative at a mere 52 Degrees F.) Well at this time of year I love to wear my wool Beret as not only does it keep my head warm but also is a great chick magnet! The beret was not my headgear of choice on Monday since it was raining and my alternative was to wear my DX Engineering baseball cap. No I did not spend $9.95 and buy one; but it was sort of a consolation offering after DX Engineering screwed up an order of mine.

 

So yes it was really raining and the hat did keep my head dry and warm. Upon entering the facility we were met by Michael, a medical assistant, who has helped us before. Once we got in the exam room Michael says I see your hat with DX Engineering on it -- Are you a ham? Well it was a micro-second and I answered an affirmative yes and gave my call sign.

 

Well then Michael shares with me that he is soon to take the General Exam but his next stumbling block was what kind of a rig he could acquire while operating with a limited budget. As he was tending to my XYL, I wrote down my website, blog and the link to hfsigs.com to find out more about the Bitx40 which is an ideal entry level rig for the new ham. At $59 including shipping it is a real deal!

I wished him luck and told him he could contact me through the website or blog. I can't describe the gleam in his eye when I shared I was a ham and perhaps had an answer to his rig problem.

In case you missed the hoopla you can find out more about the $59 rig and how to make it pay.
http://www.n6qw.com/Bitx40.html

You just never know who has an interest in our wonderful hobby.

73's
Pete N6QW
 

More on Color TFT Displays ~ The Big Ones -- 240 X 320

Really Big (bigger) Displays the 240 X 320 Color TFT

About two years ago I bought several of the 240 X 320 displays and immediately was struck by how much information can be displayed on the face of the unit and  like a choice of 256K colors. Lots of customization can be had here. Unlike the 128 x 128 or 128 X 160, which I used straight into the Arduino pins, these larger displays Do Not Like to see 5 VDC.

 

They like to see 3.3 VDC and typically a "Level Shifter" must be interjected between the 5 volt Arduino Pins and the pins on the display which like to see 3.3 VDC. So this is where I get emails about running the Arduino at 3.3 VDC and then no level shifting is required. Not sure my heart is that strong to do that. The literature abounds with tricks and tips to do the level shifting.

 

One method involves a series resistor combination of a 4.7K in series with a 10K (the 10K other end is at ground). Now to the high level math. If you ran 5 VDC through the 14.7K resistor( 4.7K + 10K) the current via ohms law would be 5/14.7K = .340 milliamp . Now a bit more math .340 milliamp flowing through 10K would be a voltage drop of 3.4 volt and the drop across the 4.7K would be 1.6 volts. So at the junction of the 4.7 K and 10K you would read 3.4 VDC. Thus one end of the 4.7K is connected to the Arduino pin the junction connection of the 4.7K and 10K is peeled off to the display and the other end of the 10K goes to ground. Instant level shifter. You would need 6 such combinations of 4.7K and 10K resistors.

 

Another way is to take an IC such as a hex buffer IC such as the CD4050 and by connecting 3.3 VDC to Pin 1 (Vdd) all inputs to the IC (six total) are outputted at 3.3 VDC. Many of the wing nut jobs hate this approach because it is not bi-directional. There are bi-directional level shifters but cost more than the nominal 50 cents for the CD4050. In my application I only need a single direction and that is a down shift. Below is the pin out for the CD4050

 

 

 

Here is the display and you will get a sense of the size with the ease of readability. Did I mention about the 256K color choices?

 

 



 

So now the problem is since the CD4050 level shifter will be used --how do you hook up the display? A glib answer would be carefully! Shown below is a hand sketch of the Nano ICSP and a decode of the pins on the back of the display. Note Vcc is connected to 3.3 VDC not 5 VDC as shown on the sketch.

 



 

So yes many will have trouble connecting the dots so the magic decoder ring is provided below. Please no inquires about how to connect the output of the Si5351 --CLK0 is the LO and CLK2 is the BFO.

 

73's

Pete N6QW