November 2014 – Page 2 – SolderSmoke Daily News

DDS amplifier

Tony, G4WIF, asked about an amplifier to boost the output of the AD9850 chip. Here is Dr. Juliano’s prescription:

You might find that once you plug that DDS into a circuit you may not quite get 1 V pk to pk and in fact after about 10 MHz it really starts to sag. See the attached drawing as you can put this “afterburner’ on the output of the DDS. The isolated output is good if you are interfacing with “toob” type equipment –it can be left off if you are doing SS or just left in place. This is the output from the amp and as you can see fairly clean.

73’s

Pete N6QW

Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Digitizing my BITX17 with an Arduino and an AD9850 chip

This is only temporary! My analog, discrete, hardware-defined BITX17 was NOT harmed or even modified for this little experiment.

Background on the use of Si5351 — code and integration with Arduino Nano (video)

I somehow missed this one. Here Pete talks about how the use of the Si5351 in ham radio has been evolving, who has been working on it, etc.

Pete Goes Superhet with the Si5351 generating BOTH VFO and BFO (video)

Congrats to Pete for his amazingly fast development of a 40 meter superhet receiver using a single Adafruit Si5351 paired with an Arduino Nano for ALL of the frequency generation. No more VFOs, no more crystals. It sounds great! Amazing stuff.

BIG Amplifiers with SMALL Microcontrollers and LOTS of Tribal Knowledge

Hi Bill,

I wanted to forward to you a slightly edited email I sent to one of our podcast listener’s as I think this is a really good example of some “Tribal Knowledge”.

—————————————————————————————————————————————————————————————————————————–

Hi OM,

Ham radio publications are much like the Internet –all that is published must be scrutinized. One such publication had a beautiful QRP to QRO amp using a 3CX800A7. A few watts in and 800 Watts out. My daughter was in FM radio broadcasting and I told her to introduce herself to the station engineer and to look out for any pulls – then the floodgates opened –about a week later I had a 3CX800A7.

So I started to work on the amp. The circuits just didn’t make sense and parts were missing that would make it work correctly. I contacted the author and here is what he shared. He built the amp but never did get to proof the final article. In fact he sent me his notes and sketches which were correct. Thus I could have never built that amp using just the article. I built it for one band, 20 Meters. It has a tuned input and a Pi-L output so is quite excellent on harmonic reduction.

Oh BTW this amp caused me to learn about PIC Microcontrollers. You cannot hit the 3CX800A7 with HV voltage until the cathode is warmed up (must be a female tube). That time delay is 3 minutes. I could not find a suitable time delay relay with a 3 minute delay that didn’t cost an arm and a leg. So that is when I thought about using the PIC16F84 as a time delay relay. Later I ported that over to a 12F675. The cost was less than $10. In the 3CX1500A7 amp ( another free tube) I have two microcontrollers in there. One is used for a three second step start on the filaments (don’t want to shock the filaments with inrush current) and the second for the 3 minute delay before starting the HV step start sequence.

You can see the “Big AMP” on my website at http://www.jessystems.com.

There was only one problem – I was worried about the cooling of the tube so I made sure there was plenty of air which I dump into a very small sub-chassis and the exhaust is out through the tube. Well “Dah” large volume in and small port for exhaust and you have a jet engine sitting on the desk top. Man it was loud – I would wear headphones when it was working. When I built the 3CX1500A7 amp I used a larger plenum so not as loud.

There are several key points I want to make about tribal knowledge:

Turn off the soldering iron and spend a good deal of time “noodling” over the circuit so that it is clear what each function will do and that all the wires connect to something.
Contact the author and ask lots of questions and you might be surprised to find out the published design is not what was designed!
Look for uncommon solutions to build problems. Many times parts used in the articles are so unique that only one exists in the whole world and it is installed in the authors unit.
The amp was built in 2000 and the use of the PIC16F84 as a time delay for an amp was a bit leading edge but don’t be afraid to employ some advanced technology into your projects. [Today an Arduino built into the amp could do time delay, temperature control of blowers, SWR sensing, grid trip protection and even warm your coffee.]
In the Big AMP I figured out how to keep the blower going for about 1 minute after the amp is turned off to “cool down” the tube. The point here is to think about not just the amp itself but refinements to make that $600 tube last for a very long time thus filament current inrush protection and tube cool down.
Don’t forget SAFETY – there is 2000 Volts @ 1 amp running around chassis–it is an electric chair sitting on your desk top. I included a microswitch that when the top cover is off it de-energizes the HV circuits. See if you can spot it in the photos.

73’s

Pete N6QW

PS The amp really does exist –see below.

Pete’s Boards Come Alive as a Direct Conversion Receiver (video)

I love it when a new rig is spread out on the workbench like this, pulling in its first signals. Like First Light on on a new telescope. These are the same boards you have been seeing in Pete’s previous videos: The Si board, the mixer, and the AF amp. Now they are linked together in the form of a Direct Conversion receiver.

Pete’s “Let’s Build Something” Audio Amplifier (video)

Who needs LM386 ICs? Pete goes discrete! Love the MePads. And I knew Pete was going to test it with his finger! He’s just taking stray hum from the power lines and coupling it to the input through that Exacto knife.

Seems to me like these boards is getting close to actually receiving signals.

Pete’s Mixer (Pictures)

Hi Guys,

Just finished building the PD/BM that will be used in the final circuit of the LBS Part I. I will also upload a video of the build.

The W1REX MeSquares really work very well and greatly facilitate the build. So the newbie builder — will have one leg up by using the squares method.

73’s

Pete N6QW

Pete’s video on this circuit appears below — just scroll down a few.

Bandpass Filter Construction by Pete Juliano (video) TFMS!!!

MePads! Arduinos! Breadboards! SuperGlue! Graph paper! Noodling! Room for Relays!
TFMS (TUNE FOR MAXIMUM SMOKE!)

Another great video from N6QW. Thunder power!

Pete Builds a Doubly Balanced Modulator (Video — Part 3)

Another beautiful piece of cinema from Giovanni Manzoni’s Newbury Park Studios. Bravo Giovanni!

Pete is obviously a doubly balanced kind of guy. I liked his use of the W1REX MePads and the breadboard. Also, the balance pot and the un-balance switch are very handy innovations.
Most of all I like the way Pete’s video takes you from schematic to actual circuit.

Thanks Pete!

SolderSmoke Podcast #167: Arduinos, Amplifiers, Books, and Tribal Knowledge

SolderSmoke Podcast #167 is available:

http://soldersmoke.com/soldersmoke167.mp3

3 November 2014
Who the heck is Giovanni Manzoni?
Pete’s Bench Report:
“Let’s Build Something” Project
Arduinos and Si5351s
Bill’s Bench Report: 140 watt Amplifier Completed!
Low Pass Filter Design with the ELSIE Program
Samlex Power Supply
How I almost blew it up!
The new amp and the lids in the FT4TA pileup
Tribal Knowledge!
“Nature abhors a vacuum (tube)!” “The Innovators” by Walter Isaacson.
Carter, WA9DNF, REALLY knows which end of the soldering iron to grab!
Meeting with Thomas, KK6AHT. The two electronic cultures.
Interviews by Chris, KD4PBJ, at Two Days in Huntsville:
Glen Popiel, KW5GP, Author of “Arduino for Ham Radio”
John Henry of TenTec
Steve, WG0AT

Giovanni Manzoni
Giovanni Manzoni b. circa 1950 Civatavecchia, Lazio, Italy is a noted videographer specializing in the avante garde use of YouTube in ham radio homebrew settings. Long noted for his insistence on the use of completely home-made video equipment, Manzoni went so far as to demand that his cameras and recorders only use discrete components — he claimed that integrated circuits “freaked him out.” Manzoni’s collaborators have long been puzzled by his claim that all his videos are filmed “on location.” What he means by this remains unclear, however, in a 1997 interview in QST-Italia, he was quoted as saying “No matter where you go, there you are!”

OH NO! SolderSmoke Goes QRO! Bill’s Amplifier Project (video)

I got the Communications Concepts Inc. EB-63A amplifier working today. Yea!
Kind of ironic that the highest power amp I have ever built gave me the LEAST trouble. This just goes to show that circuit layout is very important. This amp is a proven design, with a proven layout and board. That’s why it didn’t turn into a 140 watt solid state oscillator!