Podcasting since 2005! Listen to Latest SolderSmoke
Wednesday, August 6, 2025
CuriousMarc Fixes the HP-182C Power Supply -- But More Fun to Come!
Monday, August 4, 2025
ElectroBOOM! CuriousMarc Tries (and fails) to fix an old HP182C Oscilloscope -- Words of Wisdom for all Homebrewers
It will be great to see, in subsequent episodes, how Marc makes it work. It is really great to see someone present an unvarnished view of how troubleshooting really works.
Thanks Marc. 73
Here is Marc's YouTube channel:
Thursday, May 1, 2025
Alan Wolke W2AEW's FB Homebrew SolderSmoke Direct Conversion Receiver
It is really and honor to have Alan Wolke W2AEW build one of our receivers. Alan is a true wizard. Armed with an amazingly popular YouTube channel, he has taught electronics and ham radio to thousands of grateful viewers worldwide. A Field RF Application Engineer for Tektronix, Alan has a special knack for showing us how to get the most out of our test gear.
So many times have I gone back to videos that Alan made years ago, just in an effort to refresh my memory on the insights that he shared. For example, it was from him that we learned how the diode ring mixer really works -- what it really means to say that this mixer multiplies signals by 1 and -1. Alan even showed us how to get our 'scopes to display the multiplication. This was all very cool and very typical of Alan's work. His videos have been an important reference for this direct conversion receiver effort.
On this project, Alan dug into his junk box, only to discover to his dismay that he didn't have the AF transformer that we recommended. I am sure that Alan could have whipped up several alternative circuits that did not require the transformer, but he wanted to build the receiver the way we recommended, so a slight delay took place while Mouser filled his order.
Alan did build the circut modularly, stage-by-stage, using the Manhattan method, but he admits to giving in to his temptation to use a very small board. This may be the most compact of our 60+ DC receivers. In an encouraging reminder that even the great ones worry about unwanted feedback, Alan writes:
Why am I always compelled to build as compactly as possible? I hope feedback doesn’t bite me in the butt!Join the discussion - SolderSmoke Discord Server:
Documentation on Hackaday:
https://hackaday.io/project/
SolderSmoke YouTube channel:
Wednesday, February 12, 2025
SolderSmoke Direct Conversion Receiver Challenge -- Bonus Video -- Using an Oscilloscope to Test Your Receiver
SolderSmoke Challenge – Bonus Episode – Using your oscilloscope to test your DCR
New homebrew radio builders often struggle with test and measurement. You can build a board perfectly but if you don’t have your tools setup correctly you won’t be able to tell if your board is working, or worse you’ll thing it is not working when it is working perfectly. In this bonus episode Dean, KK4DAS takes us through the basics of configuring and oscilloscope to test the boards, particularly the PTO oscillator, buffer, and the mixer.
We say this often, but if you really want to learn about oscilloscopes and test and measurement there is no better resource than our friend Alan, W2AEW’s YouTube Channel. Check it out!
Alan Wolke, W2AEW’s YouTube Channel:
https://youtube.com/@w2aew?si=
Join the discussion - SolderSmoke Discord Server:
Documentation on Hackaday:
https://hackaday.io/project/
SolderSmoke YouTube channel:
https://www.youtube.com/@
SolderSmoke blog DCR posts:
Wednesday, May 8, 2024
Why we have "BW Limit" Switches on our Oscilloscopes
Dean KK4DAS asked me why we have these switches on our 'scopes. I didn't know. Dean asked Alan Wolke W2AEW. Alan knew:
Alan Wolke wrote:
Interesting background on the 20MHz vertical BW selection. This feature has existed on the vast majority of all oscilloscopes since the 50s or 60s (both analog & digital). When I explored the history of this, I spoke to some of the folks at VintageTek.org, and wound up having a chat with THE engineer that did it first! Tt was John Addis, designer at Tektronix.
At the time, Tektronix was located in Portland Oregon. While working on a wideband vertical preamp for a new scope (the 7A11 vertical plugin for the 7000 series scope), John Addis was plagued with interference from the local television broadcast station in the 50MHz band. So, he popped in a 20MHz low pass filter that he could switch in/out so that he could complete the work on the preamp. Since it was deemed useful, it was left in the design.
And, since Tektronix added a switchable 20MHz low pass filter in their scope, and Tek was the leader in oscilloscope technology, other manufacturers followed suit, and this feature has "stuck" as a staple in vertical setting controls.
The main reasons you'd use this filter would be to improve the signal to noise ratio (SNR) for signals when their frequency content is below 20MHz. You've probably noticed that, even without any signal connected, the thickness of the trace is thinner when you engage the 20MHz filter.
---------------------
Alan sent a link to a Wiki page about the 7A11 that John Addis was designing. Alan says this places the initial inclusion of the 20 MHz BW Limit filter to the mid 1960s:
https://w140.com/tekwiki/wiki/7A11.
Thanks Dean, thanks Alan!
Friday, October 6, 2023
A Pretty Good Troubleshoot -- Fixing the Transmitter in my 75/20 meter Mythbuster Transceiver -- Mind the Gap!
All of a sudden the transmitter in my 75 & 20 meter dual band homebrew Mythbuster transceiver stopped working -- there was no output at all. I went into troubleshooting mode.
The first clue was that the receiver was working fine. This meant that many stages of the rig were taken out of suspicion: It probably wasn't the VFO, the first mixer, the BFO/Carrier Oscillator, the second mixer, or the bandpass filters. Nor was it any of the receive sections in the bidirectional amplifiers I was using.
Suspicion fell on the power amplifiers and on the transmit sections of the bilateral amplifiers.
With the output going to a dummy load, I put the rig into transmit mode and put a bit of audio into the mic jack. Then with the 'scope I started to work my way back from the antenna jack. I wasn't seeing anything. Then I got back to the transmit side of the TIA amplifier between the crystal filter and the mixer. There was a strong signal at the input, but nothing at the output. Bingo! I had found the faulty stage. But where, exactly, had this stage gone wrong?
There are three transistors on each side of a TIA amp (see schematic above) -- I just started from the input of the first one with my scope probe and moved through the circuit. Finally, at the output of the last of the three amplifiers, the signal stopped. I knew I was very close to the problem.
Looking at the components, suddenly I could see the problem: At the output there is a 47 ohm resistor (R2 in the circuit diagram above) and a .1uF cap in series. The cap went to a Manhattan pad. But when I looked at it closely, the lead was kind of floating above the pad. See it?
And when I moved it, the connection between the 47 ohm resistor and its pad seemed quite flimsy.
I quickly replaced both components and was back on the air.
I don't really know how or why the lead to that capacitor broke. Maybe I had bent it repeatedly, to the point of weakness, and, over time, it just let go.
Whatever the cause, I found this to be a satisfying troubleshoot and repair. It required me to think a bit about what could be wrong, and to use some test gear to zero on on the faulty component.
Thursday, July 6, 2023
The TEK 465 'Scope Used to Create Pong and the Apple II
Monday, May 1, 2023
Apex Surplus in Los Angeles
Tuesday, April 18, 2023
CuriousMarc Powers up (and Explains) Old Cathode Ray Tubes
Saturday, July 24, 2021
Thursday, December 31, 2020
So Many Wonderful Things on W7ZOI's Site
There he is. Wes Hayward, W7ZOI in 1957. I had never seen this picture before. I found it on Wes's recently updated "shackviews" web page: http://w7zoi.net/shackviews.html .
There are so many treasures on that page, and on all the other portions of Wes's site.
Some highlights for me:
-- Wes's description of the station in the above picture.
-- On his page about Doug DeMaw, Wes mentions that after Doug edited Wes's 1968 article about direct conversion receivers, Doug built some himself, experimenting with different product detector circuits. Having used Doug's mixer circuit in many of my rigs, and having recently experimented with different product detectors for my HA-600A, I kind of felt like Doug was watching over my shoulder, guiding me along as I experimented.
-- Wes's use of a digital Rigol oscilloscope. Makes me feel better about giving up on my Tek 465.
-- The page about Farhan's visit to Wes, and the awesome gathering of homebrew Titans that ensued...
-- Wes's meeting with Chuck Adams.
Thanks Wes. Happy New Year and best of luck in 2021!
Tuesday, September 8, 2020
Builds Oscilloscope at age 12! Nick has THE KNACK
Thanks to Grayson Evans for sending us this very encouraging video.
It is from Tektronix; I wonder if Alan W2AEW provided some ideas and inspiration?
More stories like this: https://www.tek.com/stories
Saturday, April 8, 2017
Discrete Dead-Bug O'scope Pong
Monday, October 17, 2016
Oz Tektronix 'Scope Repair (in Juliano Blue)
Rob is a braver ham than I. When my Tek 465 quit, I tried to fix it, but quickly chickened out.
Very nice that he painted his in Juliano Blue.
Dear Bill and Pete,
Thursday, September 29, 2016
Video: Sweeping a Filter with a FeelTech Signal Generator and a Rigol Oscilloscope
This short video shows how I used my new FeelTech Signal Generator (90 bucks shipped from China) and my trusty Rigol oscilloscope to display the passband of the filter in my Armand HROish receiver. Feedback on this test procedure would be appreciated.
Saturday, September 10, 2016
Alan Wolke Talks 'scopes on "The Workbench" Podcast
George KJ6VU is a long-time supporter of the SolderSmoke podcast. He has recently teamed up with another ham and launched a podcast called "The Workbench." This morning I listened to Part I of their interview with the legendary Alan Wolke W2AEW. It was great. As I was listening to Alan I was soldering together a crystal filter for my new receiver, and using my RIGOL 'scope to check the results.
I liked Alan's description of how they made images of 'scope patterns in the days before the advent of Digital Storage Scopes (Polaroid!). I also liked Alan's scorn for those who use the "Auto" switch on the 'scopes. The host's reaction to Alan's description of a $300,000 Tektronix 'scope was also fun: "For that price I want to be able to drive a car into it and put a swing set behind it!" Indeed.
Recommended listening:
http://hamradio360.com/index.php/2016/08/30/ham-radio-workbench-5-oscilloscopes-part-1/
Wednesday, March 9, 2016
A Knack Victim's Midlife Crisis
Monday, April 21, 2014
Clocks, CRTs, HV supplies: Eric has The Knack!
Nice interview by Jeri Ellsworth. This fellow definitely seems to have the Knack. At the end of the video he shows a high voltage supply that he is WEARING AROUND HIS NECK!
Here's Eric's site: http://tubetime.us/
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
Thursday, January 23, 2014
BITX 20/40 Build Update #5: It is ALIVE!
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
Wednesday, January 22, 2014
Digi 'scope, Analog 'scope
Carl (M0ICR ex 2E0TEC) saved the day with my Tek 465 -- he sent the replacement HV multiplier that put the 'scope back in action. (Ace Tek repairman Tad WA1FQO made the repair. Tad sells Tek scopes on E-bay -- check out his products: Search for fqo63 on ebay.)
Carl notes a number of similarities between our workbenches and recent projects. All he needs now is a Drake 2-B!
Alan Wolke said he'd be interested in my reactions to having both a digi scope and an analog scope on the bench. I can already see areas where one might be a bit better than the other. The Tek is better at watching a fast moving audio or SSB waveform. But the Rigol doea all kinds of math tricks. Check out the FFT function shown on Carl's page: http://iqrp.net/
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