My Manhattan-style Termination Insensitive Amplifier Production Line

 

You gotta love the name, right?  It sounds like some sort of psychological condition.  Perhaps someone who just doesn't care  if his girlfriend breaks up with him, or is indifferent to getting fired.   

But no, we know that that's not what it means. 

I recently had to make three sets of TIA amps for my new 15-10 rig.  First, I decided not to use the boards provided by Todd of Mostly DIY RF.  You can see one of these boards above the tin shears in the picture above.  Note how compact it is.  Even though you would need two of these (one for receive, one for transmit) to get what you need for a bilateral rig like the BITX,  using these boards (as I did on my 17-12 rig) saves you a lot of space.   But this time I wanted to build a rig that is TOTALLY DIY RF.  So out came the tin shears and the super glue. 

First I decided on the Manhattan pad placement.  I used a pattern that had worked on previous rigs. Pete is right -- I use a lot of TIAs (but no, I have no tattoo of the circuit anywhere on my anatomy!).  I scaled it down a bit, thinking that I could come a bit closer to Todd's compactness.  

Knowing that I would need three sets,  I first made three boards.   Then it was just a matter of soldering in the components:  I did resistors, then capacitors, then, finally, the transistors.   In this way I was able to put together the three dual TIA amps in a couple of morning build sessions.  It was kind of tight and I had to be careful to avoid wiring errors or unintentional shorts.   But it worked. 

I like the TIA circuit.  It lets me select the gain of a stage by simply using two resistor values from W7ZOI and K3NHI's chart.  And with this circuit I know that it will look like 50 ohms both ways.  This is really important on bilateral rigs like this.  

I don't think there is anything wrong with using BITX-like bilateral circuits or TIAs or LC VFOs.  This is all for fun right?  I just like using these circuits.  

My friend Pete is right in pointing out that the bilateral concept did not originate with the BITX -- it has been around for a long time, going back at least as far as the Cosmophone.  But I think Farhan's BITX definitely moved it into the solid-state homebrew mainstream.   Three cheers for Farhan for doing that.  

Yet ANOTHER Homebrew 15-10 SSB Transceiver (Video #1)

A homebrew 15-10 SSB Rig for the Dominican Republic:

This is my second build of this rig.

I am using a 10 pole crystal filter that I built for the first build, but did not use. I am also using the tuning capacitor from a Galaxy V's oscillator -- I like the anti-backlash gears and the reduction drive. This rig is built on a pine board covered with adhesive copper tape. It has been built stage-by-stage on copper-clad boards using the Manhattan construction style.

The structure of the rig is basically that of a BITX rig -- the RF and IF amplifiers are Termination Insensitive Amplifiers.

Soon the receiver will be completed. I will then build the stages needed for the transmitter portion of the transceiver.

I will take this rig with me to the Dominican Republic.

The System Source Museum (Computers, Maryland)

Thanks to my friend Bob KD4EBM for alerting me to this.  Bob provides some very useful background: 

https://museum.syssrc.com/

(Just north of Timonium, colocated with the future home of the National Electronics Museum)

System Source has a computer museum displaying technology from the inception of computing. Founders Bob Roswell and Maury Weinstein opened ComputerLand, a predecessor to System Source, in 1981. Rapid advances in technology in the early 1980’s made some ComputerLand inventory obsolete before it could be sold. Bob and Maury’s old ComputerLand store on Redwood Street had a bank vault in the basement, so they filled it with vintage tech.

Wow, that bank vault in the basement is really intriguing.  We need to find more of those.  

The Usagi guy's 6AU6A T-shirt is pretty cool.  I also liked his reference to Tracy Kidder's book "The Soul of A New Machine."  I happen to be re-reading that book now.  I'm struck by the complexity of even the computers of the late 1970s.  At one point Kidder notes that there is only one guy on the hardware team who has a complete grasp of how the hardware in the new machine actually works.  The software was probably even more inscrutable.  And of course, things have gotten a LOT more complex.  This is the big reason that I have decided to stick with simple, analog, discrete component, HDR rigs that I can understand.  To each his own.  One look at the wiring on some of those old computers tells me that this is not for me.  

RIP Arno Penzias -- Co-discoverer of the Big Bang Cosmic Background Radiaton

 

Penzias on the right

Here it the Penzias Obituary:

https://www.npr.org/2024/01/24/1226572843/arno-penzias-obituary-big-bang-theory

I think this is one of the best troubleshooting events in radio history:  they thought at one point that what they were hearing was the result of pigeon poop in the antenna.  Turns out they were hearing radiation from the birth of the universe. 

And here is a wonderful 2014 6 minute podcast with Penzias and his co-discoverer Robert Wilson:

 

https://www.npr.org/2014/05/20/314239930/big-bangs-afterglow-two-scientists-recall-their-big-discovery

IMSAI Guy Looks at Counterfeit Chips

Like some of the commenters, I had been scratching my head wondering why someone would go to all the trouble of counterfeiting electronic parts.  It just didn't seem to make economic sense.  Perhaps they were just marketing factory rejects?   But no,  IMSAI Guy shows in the video above that it is a lot more insidious.  It turns out that this kind of crime DOES make economic sense (see comments).  So be careful out there. 

Here is another one IMSAI Guy did yesterday, looking at other faked chips: 

Thank you IMSAI Guy! 

K0IYE's Thoughts on Homebrewing and Workshops

Click on the image for a clearer look

I like Frank Harris K0IYE's book so much that I don't mind posting about it frequently.   "From Crystal Sets to Sideband" is must-read material for all homebrewers.  

The picture above is especially significant.  I first came across it in the old pulp-style magazine called World Radio.  The picture, like Frank's book, is truly inspiring.  

This week I stumbled across a relatively new chapter in Frank's book.  Chapter 3A deals with his approach to homebrewing (Luddite, analog, HDR) and his advice on how to set up a home ham-radio workshop.  There is a lot of wisdom in this chapter.  

The opening paragraph of Chapter 3A really grabbed me.  Check it out here.  Click on the text below for a better view: 

Click on the image above for an easier read

Frank's advice on what to do when you get stuck on a problem is right on the mark, and a bit counterintuitive, but very true: Do something else for a while. 

Click  here for all of Chapter 3A:

 https://www.qsl.net/k0iye/CHAP3A.html 

Chapter 3B also looks great. 

And click here for the entire book (including a Spanish translation!) 

https://www.qsl.net/k0iye/

Thank you Frank for sharing with us all of this wisdom.  73 OM   

Some Great Reading Material -- Links to Radio Publications

 

https://www.worldradiohistory.com/Home-DX.htm

My fellow Hambassador Dave WA1LBP sent this to me today (from Taiwan, I think).  Lots of great  ham radio and SWL info in these many publications.  The one that caught my eye was "The Modulator,"  an ARRL publication done by the 2nd District in the 1920s.  Really interesting.  I will sent this to Lyle, W7QCU who has an interest in radio from this era.   

Here is the link:  https://www.worldradiohistory.com/Home-DX.htm

Thanks Dave!  73! 

Listen to this great contact with KA1BWO on 10 meter AM -- 1800 miles with 4 watts AM

Joe KA1BWO is a well-known AM operator who moved West to Idaho several years ago. We had a very nice contact on 10 meter AM on January 14, 2024.  See the video above. 

I was using an old CB rig that I had converted to legitimacy on 10 meters using the mod developed by Jerry K5JC:  

http://www.jcoffman.net/WB5RUA/10_meter_AM_conversion_w_Photos.html

I was running 4 watts on AM to a Hex beam. The signal path was over 1800 miles from Virginia to Idaho.

Andreas HB9BLA's Ideas on Building a Lab or Workshop

Lots of great ideas on workshop or lab design from Andreas, the guy with the Swiss accent.  Andreas is HB9BLA.  I liked all of this, especially his idea on books.   

A while back Andreas was interviewed by Eric Guth on QSO today: https://www.qsotoday.com/podcasts/hb9bla

Thank you Andreas!  

Clock Chimes from Japan - Contact with JA0LBE

This contact with Masa was a lot of fun.  2300Z January 14, 2024.  15 meters was obviously in great shape.  Suddenly I started hearing clock chimes.  The sound seemed to be coming from my rig.  Then I looked at my watch and realized we were at the top of the hour.   Masa-san's clock chimes were being picked up by his microphone.  The microphone was in his I-pad, which he was using to connect to his ham radio station.  Very cool. 

This email came in from Masa: 

兼子政彦 <>	Sun, Jan 14, 7:54 AM (20 hours ago)
to me

Hello Bill

Thank you very very much for your Email attached the video of our QSO.

Your homemade transceiver is working excellent! I was very surprised to watch the video. I checked transmitting of your equipment is very good this morning. And this evening I understood receiving was also very very good. Congratulations on your homemade equipment.

I have tried remote operation for several months. But I’m afraid my transmitting is not good.

Thanks for your video, I could tell following things. Thank you so much l appreciate it.

My remote signal has almost no blinking up,I felt.

There are about 2 seconds latency on my transmitting.

Most important thing I realize is English conversation over the phone is very difficult for me. I need to learn intonation and pronunciation of English much more.

Again thank you very much for your Email,I appreciate it.

Have a nice day. And good night from Japan.
73!

JA0LBE, Masa in NAGANO

QRP Trigger Warning! 500 kW from WLW (great video)

Wow, this video will make you appreciate the simplicity of QRP! 

My favorite part was when they required the use of "dark welding goggles" for whoever was charged with a visual check of  the tube filaments.  

Thanks to Hack-A-Day for alerting me to this wonderful video. 

QF-1 Variable Capacitor Problem -- What Should I do?

For years I have been heartlessly slaughtering innocent Heathkit Q multipliers, just to get these variable capacitors. Dean KK4DAS has joined me in this mayhem. And recently Wes W4JYK has also started hunting down QF-1s.

I am sorry to report that my love for this variable capacitor has taken a hit.  The capacitance is perfect.  And it has a reduction drive built into the shaft.  But I have found that that reduction Drive has a form of backlash. It is really just a dead spot that you find when tuning in a signal. Turning in one direction, all is good.  But when you then try to turn in the other direction, you have to turn the shaft a bit before the cap blades begins to move (see video above).  This makes tuning SSB signals a bit difficult. 

What should I do? Should I pull out a Dremel and cut off the reduction drive, then use a better (external) reduction drive to move the vanes? Any other ideas?

These are the kinds of problems that homebrewers face...