Somehow, this video fits well with the SolderSmoke theme. It may be that Uri cheerfully acknowledges that the lathe can kill you (the same is true of much of our gear). Or it may be his repeated use of the term "Bob's your uncle" (has he been listening to SolderSmoke?). Whatever the reason, this beautiful video fits here. This is from Uri Tuchman's channel: https://www.youtube.com/@urituchmanpigeon. Uri is in Germany. Thanks Uri!
Derek wrote:
Bill,
Here are some cards from earlier (in some cases MUCH earlier):
https://soldersmoke.blogspot.com/2023/11/some-short-wave-listener-qsl-cards.html
It is a thing of beauty. You can see all four stages in there. There is the Bandpass Filter in the upper left. Below that is the VFO. In the center you can see the SBL-1 mixer. Off to the right is the audio amplifier. FB Chuck!
Chuck KE5HPY writes:
Allow me to add an endorsement of the joy and practicality of the DC receiver. Whether XTO, VFO or DDS, ring diode mixer, or Polykov, the DC IF concept is a real winner. They really deliver wonderful audio and clarity that is very satisfying for homebrew builder.
Homebrewing is not for the faint of heart! Accept the challenge! Build stuff!
Our question: Did Doug DeMaw ever build an SSB transceiver? Starting in September 1985 he wrote a five part series on an SSB TRANSMITTER for QST. But he prefaces it by asking, "Why would anyone build an SSB transmitter today?" He says it would be fun "for the experience and understanding it would provide." But not for use, you see... And it is not a transceiver.
Bill's theory about DeMaw, SSB,CW and sideband inversion: He was a CW guy so sideband inversion did not really matter. He could get it wrong and still make it work.
Pete's Bench:
Brilliance and the TR3. https://www.youtube.com/watch?v=2C-eYB8yFzg&t=13s
A tale of woe. Done in by a light bulb.
Thanksgiving dinner and SSB transceivers. https://n6qw.blogspot.com/2024/11/11292024-how-to-homebrew-thanksgiving.html https://www.pastapete.com/
Hybrid plans: https://www.youtube.com/watch?v=zKUjHZMf3Fs&t=5s
Dean's Bench:
Travelogue – Falcon 9 Launch
Building a homebrew T Match tuner for the end-fed long wave – sourcing the parts, winding the coil – taps, testing
VWS Makers Projects
SDR Receiver Project – starting in January
VWS Pico Balloon – Traquito - Traquito - WSPR Pico Balloon
Revisiting the 10M DSB rig
Soldersmoke listener challenge – build a DCR with KK4DAS – overview then one board a week
SHAMELESS COMMERCE DIVISION: Mostly DIY RF. Please subscribe to our YouTube Channel. And use the Amazon link on our blog. Become a Patron via Patreon (on the blog). SolderSmoke is now on Blue Sky and Threads -- follow us or at least like us there. Please turn on automatic downloads on your podcast app -- most podcast apps will only store a few episodes. This will help bump the numbers, which will improve visibility. Please give the show five stars and, if possible, a nice review on your podcast service, That will help with the discovery rate for people looking for new podcasts.
Bill's Bench:
Is "The Ground" a Myth? ARRL VP says Ground is a Myth: https://www.youtube.com/watch?v=KdX-978tvkY. Bill disagrees. Helicopter story. Refrigerator story. Original single wire telegraph system. https://en.wikipedia.org/wiki/Single-wire_earth_return
Front Panel and Freq Counter for the Mythbuster II.
Another Tale of woe: A mysterious audio problem on the 15-10 II rig. Done in by.... Duh! Comparing sideband suppression with Mythbuster I. Differences in Hfe? Notes on Mythbuster II build.
TinySA Ap -- A cure for Fat Finger Syndrome? : http://athome.kaashoek.com/tinySA/Windows/ How to get and load the Ap (you might want to start watching at 1:11) https://www.youtube.com/watch?v=zu4X5dyUlpo&t=2s General info video on the TinySA Ultra: https://www.youtube.com/watch?v=6C24RnYNOWQ&t=1143s
For the DR shack -- I got a Swan SWR-1A on E-Bay.
-- Scott KQ4AOP trying to track down the DeMaw SSB transceiver mystery. On the DC Receiver: This was my first receiver build and, it was great fun. When you finish the build and prove you are able to tune through the band, you are welcomed into the secret society! The build is the initiation.I am happy to print and ship the PTO if needed.
-- Bill WA5DSS has built a High School Direct Conversion Receiver!
-- Grayson KJ7UM liked the 1971 video on old THERMATRON AM radios: https://soldersmoke.blogspot.com/2024/11/basic-radio-circuitry-1971-film.html
-- Chris KD4PBJ sent nice electronic care package.
-- Walter KA4KXX is honored that Dean named his dog for him (Walter was just kidding)
-- Thanks to Bob W8SX for FDIM 2024 interviews.
-- Tony G4WIF insomnia driving him to podcasts. Amazed by quantity of food eaten on Thanksgiving.
-- Nice comment from Trigger about the podcast.
-- Clint says "valves" when he means THERMATRONS. Kindly asks about "Oooo Thats Awesome"
-- Eric 4Z1UG faced with a new challenge. Get well soon OM.
-- Sam WN5C and his Chat GPT AI Elmer.
-- Paul VK3HN on using AI for electronic design. I dunno... Apocalypse Now in the DR?
-- Tommy SA2CLC FB old military gear on QRZ site. Helps with HP8640B repair.
-- Mike WN2A nice comments on Chappy Happy's FB Tezukuri DC RX https://soldersmoke.blogspot.com/2024/11/tezukuri-and-chappy-happy-amazing.html
-- Allison KB1GMX. Good info on ground truth.
-- Phil W1PJE Had to throw out 15 test leads. Fake wire!
--Todd K7TFC Thoughtful comments on AI and ChatGPT, Help with TinySA Ap
-- Steve KW4H Boatanchor guy. Likes that we often scratch our heads trying to understand.
-- Nick M0NTV built a 40 meter DC receiver: https://soldersmoke.blogspot.com/2024/12/a-40-meter-direct-conversion-receiver.html
-- Dave AA0KU asks about CCI amp (AN762) Also woking on Drakes.
-- Jack (Dhaka Jack!) F4WEF/AI4SV Good thoughts on how to bolster SolderSmoke's ratings.
--Tobias thinks the decline IS ALL HIS FAULT!
-- Tony VE7JUL building a TJ DC RX. Go Canada! Dean says: 3D print PTO former at 110%
-- Jim KI4THC getting his uBITX on the air.
10S November 23, 2024 1517Z SV1AER Kostas in Athens. Said a very sincere “Oh my goodness! Congratulations! That is not a very common thing!” when I told him rig was homebrewed. Nice fellow. Great response.
Another FB video from Mike WU2D.
But you know, I too find myself kind of opposed to front panel on-off switches. I power my rigs with small DC supplies. I just turn on the supply when I want to use one of the rigs. I don't have or need a switch on the front panel of the rig.
I especially liked Mike's use of the gate dip meter and, of course, the Q meter. FB OM.
Scott KQ4AOP put a comment on a recent SolderSmoke Blog post that I found especially encouraging and apprportiate. He was writing about his experience building the High School Direct Conversion receiver.
Scott wrote:
"This was my first receiver build and, it was great fun. When you finish the build and prove you are able to tune through the band, you are welcomed into the secret society! The build is the initiation. I am happy to print and ship the PTO if needed."
The 3d printed form for the tuning inductor is often a show-stopper for prospective builders. Scott offers to print out a form for you, and send it to you.
Scott's mailing address is on his QRZ page. His e-mail address is: streez55@gmail.com
Thanks Scott!
Here is a post I did early this year on Scott's receiver:
My receiver doesn’t work right!
What should I do?
First,
relax. You will be able to get it to
work. The design is good, people around
the world have built this receiver, and you will be able to get it to work. But homebrew radio is not plug-and-play
radio. Sometimes a new receiver needs
some tweaking, peaking, and coaxing.
Realize that the 40 meter band has its ups and downs. The downs usually come at mid-day. The sun’s position high in the sky causes a build up of the D layer of the ionosphere. This tends to absorb radio waves. So signals are often weak at mid-day. Signals will be much stronger in the morning, and in the evening.
Can you hear the “band noise” when you connect your antenna? This sounds like hiss or static. Some of this is the result of thunderstorms in Brazil. Some of it is from events far away in the cosmos. Some of it comes from the weed whacker down the block! But if you can hear this noise, that is a very good sign that your receiver is working. The signals you are looking for will be stronger than this band noise.
Where are you tuning? Your receiver tunes from about 6.8 MHz (with the screw all the way our) to about 7.8 MHz (screw all the way in). But we are only really interested in the ham frequency band between 7.0 MHz and 7.3 MHz. Try to tune your receiver near the middle of the tuning range (with the screw about half-way in). You should hear morse code from about 7.0 to 7.06 MHz. Then you should hear strong digital signals at 7.074 MHz. Tuning further up (screw going in) you should start to hear hams speaking to each other using Single Sideband. At first they will sound like Donald Duck.
Sometimes you will only hear one side of the conversation. That is normal. The other station may be either too far away from you, or too close to you. You may be outside his or her skip zone.
One very
obvious thing to check: How is your
battery? Is it drained, or is it still
at about 9 volts? You may need to
change it.
How is your
antenna? It doesn’t have to be fancy or
elaborate. 33 feet of wire will
do. But it does need to be up in the air
a bit. And you need to have the 33 foot
counterpoise wire connected to the ground (on the PC board). With many pieces of consumer electronics
antennas are kind of optional – the devices will often work without them. Not so with ham gear. Antennas are important. If you are not receiving signals, it may be because of your antenna.
The folks over at Ham Radio Workbench have graciously accepted the challenge issued in our last podcast: that they scratch-build homebrew the 40 meter Direct Conversion receiver that Dean KK4DAS and I designed for local high school students. We want to help our brothers over at HRWB. For example, we may be able to supply a few of the 3D printed PTO coil forms. Here is some background information on the project.
Design Decisions in the Direct
Conversion Receiver
Why did we do it this way?
In thinking about how to design this receiver, we had to
make early design decisions on almost every stage. Here are some of our key considerations.
VARIABLE FREQUENCY OSCILLATOR:
Normally we might have used a variable capacitor to change
the frequency of this oscillator. But
variable capacitors are now expensive and hard-to-source. Our friend Farhan in Hyderabad used a simple
variable inductor for this purpose in his “Daylight Again” transceiver. The
coil form for this part could be 3D printed.
A metallic screw would vary the inductance as it is screwed in and out
of the coil.
We also decided to use the same simple Colpitts oscillator
circuit used by Farhan in his own high school direct conversion receiver. This circuit is unusual in that the feedback
capacitors are also the frequency determining elements (along with the variable
inductor). This simplified the circuit
and reduced the parts count, and proved to be remarkably stable.
For the VFO buffer we used the simple JFET buffer from
Farhan’s Daylight Again design.
Based on suggestions from other radio amateurs, we developed a simple frequency readout based on the position of the end of the tuning screw (how far in or out?).
We selected the 40 Meter band for this receiver because we
thought it would be easier to get the VFO stable on this frequency, and because
Farhan had built his receiver for 40 meters.
MIXER:
At first we hoped to use a simple singly-balanced mixer
using two diodes and a single trifilar transformer. But we found unacceptably high levels of AM
breakthrough (mostly from Radio Marti on 7335 kHz) when using this
circuit. So we switched to a diode
ring. This required two more diodes and
an additional trifilar transformer. We
believed the students would have great difficulty building and installing two
trifilar transformers so early in their building experience. So we used transformers that had been wound
in Hyderabad by a women’s collective employed by Farhan, and developed
a scheme for fool-proof installation of these transformers.
We also found that the mixer needed a diplexer at its output
– this would provide a 50 ohm termination at all frequencies and would result
in much cleaner action by the mixer and greatly reduced AM breakthrough from
Radio Marti. We used the same circuit
used by Roy Lewellen W7EL in his Optimized Transceiver circuit.
BANDPASS FILTER:
This was the simplest board in the project but it required
the students to wind two coils on toroidal cores. A simple dual-tuned circuit design would be
sufficient. We used component values
from the QRP Labs website. We showed
them how to wind the coils, and made a video about the technique. Students used a simple Vector Network
Analyzer (Nano VNA) to tune the filter.
AUDIO AMPLIFIER:
We had to make several design decisions here. First, we rejected the idea of using an IC
amplifier like the ubiquitous LM-386. We wanted this to be a completely analog
and discrete component experience. Then we rejected the idea of using a
push-pull output circuit. While this
would have eliminated the need for an audio output transformer, it would have
resulted in a more complicated circuit. In the end we opted for three simple
RC-coupled common-emitter amplifiers with an audio output transformer. There was no feedback in these circuits. We found there is a lot of gain (hFe)
variation in the 2N3904 transistors that we used. Care needs to be exercised in making sure
that transistors of moderate (but not too high) gain are used.
This AF amplifier chain probably presented a 1500 ohm
impedance to the mixer (instead of the desired 50 ohms), but we think this
problem may have largely been taken care of by the diplexer.
We found some very small (one square inch) speakers that
could be easily used in this circuit.
ANTENNA:
While the students could use a wide variety of antennas, we
recommended a simple ¼ wave antenna with a ¼ wave counterpoise. We thought that this antenna – of only 33
feet in length would provide good performance with low complexity, and would be
well suited to the “upper floor bedrooms” from which many of the students would be listening. Also, this antenna would not require the use
of coaxial cable or an impedance matching transformer. We made a video on how
to build and use this antenna.
POWER SUPPLY:
We opted for the use of 9 volt batteries. This proved to be a safer and wiser choice that
limited the kind of mayhem that could occur should a variable voltage supply be
used.
Details on the receiver can be found here:
https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver
May 29, 2023
I finished my first super het receiver. It's for the 40m band. It consists of: bandpass filter, tuned amp, diode ring mixer, wide band amp, crystal ladder filter, wide band amp, then SA602 + LM386 combo. I learned tons as i put all the components. First two amps are my design. The third amp is bga2866. The bandpass filter is what i posted a few days ago. I planned to make another one but with 2.5db insertion loss i thought it was good enough.
Posts
All Comments
Posts
All Comments
