Podcasting since 2005! Listen to Latest SolderSmoke
Wednesday, January 31, 2024
My Manhattan-style Termination Insensitive Amplifier Production Line
Tuesday, September 26, 2023
F6CRP's FB Homebrew Receiver
Sunday, May 28, 2023
Jerry KI4IO (Wizard of Warrenton) Describes His ALL ANALOG Phasing Transceiver -- Bob Crane FDIM interview #3 (audio)
Wow, this one really resonated with me. Jerry had me won over when, early in the interview, he described his decision to dispense with the Si5351/Arduino combo: "I said the hell with this digital stuff!" I hear you Jerry. I feel your pain OM.
Jerry then goes on to describe a rig with bits of circuitry from some legendary sources: The Ugly Weekender transmitter. SSDRA and EMRFD. W7ZOI's 1968 Direct Conversion receiver.
Jerry discusses the "presence" of the direct conversion receiver. And he decries the pernicious effects of AGC. (Indeed, real hams MANUALLY control the gain.)
The Wizard of Warrenton then shares some important tribal wisdom: After building that new piece of gear, leave it on the bench for a couple of weeks. Beware of "radio infatuation" (what a great term -- we will have to include this in the lexicon). Jerry points out that while at first, the new rig will seem just perfect, with time time the need for improvements and modifications will become apparent.
Jerry also has connections to India and Nepal (where he helped Father Moran). See: https://www.qrz.com/db/KI4IO
Here is W8SX's interview with Jerry:
http://soldersmoke.com/KI4IO23.mp3
Thanks Jerry! Thanks Bob!
Wednesday, April 26, 2023
Retro QRP Rigs of the 1960's, 70's, and 80's -- Video by Mike WU2D
Monday, April 3, 2023
Technology and Methods from Wes Hayward W7ZOI
http://w7zoi.net/oldtech/ponder.html
Thanks to Tony G4WIF for spotting this gem and alerting us. And thanks to Wes for all of this.
Friday, February 10, 2023
SolderSmoke Podcast #243 -- HI7/N2CQR, uBITX mods for 10 meters, High-School Direct Conversion Receiver Project Launched (Success!) Mailbag
February 10, 2023
SolderSmoke Podcast #224 is available.
http://soldersmoke.com/soldersmoke243.mp3
Video here: (32) SolderSmoke Podcast 243 (video) Hi7/N2CQR, uBITX, Success with High School Receiver Project - YouTube
Pete N6QW had technical difficulties this morning. He insisted that the show must go on. Pete will be back for the next episode.
Travelogue:
Bill in the Dominican Republic for all of January.
HI7/N2CQR Eastern
tip of the island. uBITX and dipoles.
20, 17, 10. CW and
SSB. SSB was tough and I had reports of
RF getting into the signal.
Went to CW.
Worked VWS Mike KA4CDN, and Walter KA4KXX on 20CW.
Finally moved up to 10 CW. Lots of contacts. Even though uBITX very QRP
on ten.
I am modifying the uBITX now.
Copper tape shielding to keep RF out.
Low power out not
the fault of the IRF-510s. The problem
is the 2N3904s.
Will replace with 2N2222 in To-18 cans.
Dean KK4DAS putting KD8CEC software into Arduino. I gave up.
Who sent me this orphan uBITX?
SolderSmoke Shack South in final phase of construction.
SHAMELESS COMMERCE DIVISION:
Patreon!
Bezos Shopping!
DC Receiver Project
Local High School radio club.
Simple: Like
Herring Aid 5 and Wes’s original.
Farhan’s four
stages:
BP Filter, Diode Ring, PTO, AF amp.
Simple Colpitts PTO SURPRISINGLY STABLE.
Simple and easy.
No chips. No complicated circuits.
Guys have helped test out the design: Rick N3FJZ, Walter KA4KXX,
Daniel VE5DLD, Stephen
VK2BLQ and others.
First session last night: We demonstrated build of the PTOs.
They worked (thank God).
Open Circuits book.
Envelope Detection Controversy
Save the Antenna – Book “Losing the Nobel Prize” K1JT
MAILBAG
--Dean KK4DAS 10 meter DSB!
Tiny SA ULTRA! FB
--John AC2RL on Elmer W3PHL DSB guy
--AC3K reports inventor of Fender Stratocaster guitar was a
ham: W6DOE
--AF8E was doing POTA.
I worked him. He said my rig had presence. FB
--Alain F4IET FB DSB rig with mic in Cigar can!
--Daryl N0DP worked him on SSB. He is homebrewing
--Steve N8NM was in for repairs but is on the mend.
--Rick G6AKG working with sub-harmonic mixers and logic chips
--Paul HS0ZLQ Built DC receiver but looking for something
else to build. No DSB!
--Steve AB4I – Coherer, Jagadish Chandra Bose, and Marconi
--Eldon KC5U
Worked VK5QD right after me and mentioned SolderSmoke FB
--Todd K7TFC is building the DC RX.
--Tony G4WIF and Ian G3ROO using automotive relays for
antenna switching. FB.
--Dave WA1LBP Great to hear from my fellow Hambassador (Okinawa)
Older post comments:
--Scott VO1DR was also in CF Rockey’s class! (Blog comment)
--Aurora Aug 4, 1972: Twelve people shared memories. (Blog comment)
--Will WN1SLG Googled novice call and was led to
my Novice log.(Blog comment)
Saturday, October 15, 2022
DC Receiver: 100db Gain? Diplexer? VFO in a box?
Thursday, October 6, 2022
Adding a Diode Ring to the Direct Conversion Receiver, And How the Diode Ring Works
Thursday, September 29, 2022
A Bout of Direct Conversion-ism in Northern Virginia -- DC Receivers Under Construction
Sunday, September 11, 2022
An Especially Good (Old) SolderSmoke Podcast
Thursday, September 1, 2022
New Video: Farhan's Presentation on the "Daylight Again" Analog Transceiver
Monday, August 22, 2022
Mike Caughran KL7R's Last Podcast
Mike Caughran, KL7R, SK: Well-known low-power (QRP) and homebrewing enthusiast Michael S. "Mike" Caughran, KL7R, of Juneau, Alaska, died January 22 of injuries suffered in an automobile accident in Hawaii. He was 51. Caughran may be best known as one-half of the team -- with Bill Meara, N2CQR/M0HBR -- that created and produced the weekly SolderSmoke podcast <http://www.soldersmoke.com/>. "I think people were drawn in by Mike's friendly voice and manner," Meara commented on a memorial page for KL7R <https://kiwi.state.ak.us/display/mc/Home>. A member of ARRL and the Juneau Amateur Radio Club, Caughran also wrote articles for the Michigan QRP Club's T5W newsletter and he was an active ham radio contester. "Mike was one of those people who you instantly like because of his honest, straightforward and humble way of talking and expressing ideas," said Mike Hall, WB8ICN, who edits T5W. "His co-hosting of SolderSmoke provided me hours and hours of enjoyment." Caughran was an IT professional with the State of Alaska. Survivors include his wife and son.
Saturday, May 28, 2022
"Experimental Methods in RF Design" LADPAC Software Available FREE!
We've frequently said that is pays to check the W7ZOI web site. Tony G4WIF did just that and pointed us in that direction, noting that the LADPAC "Ladder Package" software is now available for download from that site.
Homebrewers will really want to have that package on their computers. There are all kinds of useful programs in that package: software for designing crystal filters and feedback amplifiers, a program that allows you to think systematically about receiver gain distribution and dynamic range, and many other useful things.
You can get the program here:
http://w7zoi.net/emerrata.html
Also on Wes's site is this May 22, 2022 picture of Farhan VU2ESE with EMRFD co-author Bob Larkin, W7PUA.
Thanks Wes!
Tuesday, March 22, 2022
Receiver Dynamics -- How Good is my Receiver?
Tuesday, January 4, 2022
Exorcism Completed! Getting Rid of the Spur in my 17 meter SSB Transmitter using a TinySA (video)
To re-cap: The problem became evident when trying to "net" or "spot" my transmitter onto my receive frequency. Around 18.116 MHz, I could hear at least two tones in the receiver as I moved the transmitter frequency. I needed to get rid of the extra tone.
First, thanks to all who sent in suggestions. They came in literally from around the world, and this is a demonstration of the IBEW in action. I used or at least tried all of them. They were all good ideas.
Following Vasily Ivananeko's pseudonymous suggestion I rebuilt the carrier oscillator (apologies to G3YCC). I used the carrier oscillator/buffer circuit from Farhan's BITX20.
Henk PA0EME said I should look at the signal level at the input ports of the NE602 mixer. Henk was right --- the VXO input was far too high. I lowered it, but the problem persisted.
At first, I thought that the spur in question was so small that it would not show up on the air. I could not see it in the TX output using my TinySA spectrum analyzer. That was good news and bad news: Good that it was not showing up on the air, bad that I could not see it in the TinySA and use that image in the exorcism.
At first I thought that the spur was being caused by the 10th harmonic of the carrier oscillator and the third harmonic of the VXO. This seemed to fit. So, following VK3YE's sage advice, I built a little 69 MHz series LC trap (using a coil sent by AA1TJ, on a board CNC'd by Pete N6QW). That trap succeeded spectacularly in crushing the 10 harmonic. Look at these before and after shots on the TinySA:
Spectacular right? But guess what? The problem was still there.
I scrutinized the situation once more. I realized that the spur would be more visible if I put the TinySA on the input of the transmitter's PA (a JBOT amp designed by Farhan) as opposed to putting it on the output. Watching the spur and the needed signal move in the TinySA as I tuned the VXO, I realized that they were moving in opposite directions. This indicated that the spur was the result of a carrier oscillator harmonic MINUS a VXO-generated frequency (as the VXO frequency increased, the spur frequency decreased). Looking at my EXCEL spread sheet, I could see it: 8th harmonic of the carrier oscillator MINUS the main output of the VXO.
To confirm this, I plugged the values into W7ZOI's Spurtune program. Yes, the spur popped up and moved as predicted.
For further confirmation I shut down the carrier oscillator by pulling the crystal from the socket, and then just clipped in a 5.176 MHz signal from my HP-8640B signal generator (thanks KB3SII and W2DAB). Boom! On the TinySA, the spur disappeared. Now I at least knew what the problem was: a harmonic from the carrier oscillator.
Following good troubleshooting practice, I turned off the gear and went to bed. When I woke up, an idea came to me: Before launching into a lot of filtering and shielding, just try running the carrier oscillator at a lower voltage, seeing if doing so might reduce the harmonic output. I disconnected the carrier oscillator board from the main supply and clipped in a variable voltage bench supply. Watching the signal on my TinySA, I watched as the spur completely disappeared as I reduced the voltage from around 13V to 10V (see video above). The main signal frequency level did not change much. I tested this by listening for the hated extra tones. They were gone. Exorcised.
Key lessons:
-- Spur problems are difficult to troubleshoot. Armstrong's superhet architecture is, of course, great, but this is definitely one of the pitfalls. Single conversion makes life easier. IF selection is very important. Choose wisely!
-- When looking at the TinySA as you tune the rig, pay attention to which way the spur is moving. This provides an important clue regarding the combination of harmonic you are dealing with.
-- The TinySA is a very useful tool. It seems like it is easier to use than the NanoVNA (which is also a fantastic tool).
-- It can be fun and rewarding to re-visit old projects. In the years between original construction and the re-look, new test gear has become available, and the skill and experience of the builder has improved. So problems that once seemed insurmountable become fix-able.
-- Thinking through a problem and thinking about possible solutions is very important. It pays to step away from the bench to think and rest. Rome wasn't built in a day. Here's a rough block diagram that I drew up (noodled!) while trying to figure out this problem:
Tuesday, December 28, 2021
How to Fix the Spur Problem in my 17 Meter SSB Transmitter?
In the 2004 QST article I discuss a problem I had with "spotting" or "netting." This is something of a lost art, something that you had to do back in the pre-transceiver days, when running a separate transmitter and receiver. This was how you got the transmitter on the receiver's frequency. Essentially you would turn on the carrier oscillator and the VFO and let a little signal get out, enough to allow you to tune the VFO until you heard zero beat on the receiver. My problem was that around one particular frequency, I would hear several zero-beats. This made netting the receiver and the transmitter hard to do.
Important note: This is really just a problem with the "netting" or "spotting" procedure -- the problematic spur does not show up in any significant way in the output of the transmitter. I can't see it on my TinySA. But it is strong enough to be heard in the unmuted receiver sitting right next to the transmitter. And that creates the netting problem.
In the QST article, I said that I noticed that the problem seemed to be centered around 18.116 MHz. As I approached this frequency, the tones -- desired and unwanted -- seemed to converge. That was an important clue. In the article I said I thought that I could eliminate the problem with just one trimmer cap to ground in the carrier oscillator, but looking back I don't think that this really fixed the problem.
I recently took a fresh look at it. Exactly which frequencies were causing the unwanted signals that appeared in my receiver?
I used an Excel Spread sheet to find the culprits.
Tuesday, November 2, 2021
Farhan's Amazing Knack Story: From a Boyhood SW Receiver to the Design of the sBITX SDR
-- Farhan talks about his practice of taking the pictures of new rigs with the new rig sitting atop the book that was most important in its design and construction. FB.
-- I was really blown away by Farhan's presentation of how the uBITX advertisement was inspired by and in many ways based on the Heathkit ad for an HW-101. Amazing.
-- I learned a lot from Farhan's discussion of SDR theory. I pledge to spend more time with this. I really like Farhan's hybrid HDR/SDR approach.
-- But I have a question: Farhan seems to say that we'd need a big expensive GOOGL computer to do the direct sampling HF SDR. But doesn't the little RTL-SDR do just that? Without a GOOGL?
-- Great to see Wes's AFTIA being used in the sBITX.
-- Really cool that Farhan has his mind on VHF transverters when designing the sBITX. I liked use of the TCXO module to free up one of the Si5351 clock outputs. FB. And great to include an idea from Hans in this rig.
Thanks very much to Farhan (who stayed up until 3 am to do this!) and to the RSGB for hosting.