I have had Ian on the SolderSmoke blog several times: https://soldersmoke.blogspot.com/search?q=%22Ian+Keyser%22
Podcasting since 2005! Listen to Latest SolderSmoke
Wednesday, April 3, 2024
Ian Keyser G3ROO and Spy Radios
Wednesday, November 1, 2023
Basil Mahon is an Author for Us -- He explains Faraday, Maxwell, and Heaviside
PERSONAL:
Born May 26, 1937, in Malta; married Ann Hardwick (a teacher of chemistry), April 1, 1961; children: Tim, Sara, Danny. Education: Attended Royal Military Academy, Sandhurst, 1955-57; Royal Military College of Science, B.Sc., 1960; Birkbeck College, London, M.Sc., 1971.
British Army, career officer, serving with Royal Electrical and Mechanical Engineers in Germany, Aden, and United Kingdom, 1955-74, retiring as major; Government Statistical Office, civil servant, 1974-96. Consultant and trainer on censuses and statistics, including work for clients in Russia, Estonia, Croatia, and Republic of Georgia.
From the Netherlands, Manu Joseph explains why he loves Mahon and Forbes' book on Faraday and Maxwell:
Sunday, October 15, 2023
Spy Rigs, Para Sets, Bugs, and Enigma Machines -- Dr. Tom Perera W1TP (video)
Saturday, August 19, 2023
Valveman -- The Story of Gerald Wells
Tuesday, June 13, 2023
How they Make Raspberry Pi 4 Single Board Computers
Friday, April 28, 2023
Who is the Man in the Portrait in Artie Moore's Shack?
Monday, April 24, 2023
Tim Hunkin on Drilling Holes (Secret Life of Components Video)
I guess that aside from being a great video, this is something of a test of technical nerdy-ism. If you find this hour long video really interesting, well, you know...
Really cool stuff from Tim Hunkin:
-- I liked the angle driller. Need one.
-- The placement of the magnets near the hole to catch the shavings was really cool.
-- Tim's reluctant admission that it is just better to buy new drill bits (as opposed to sharpening old ones) is good advice.
-- WD-40! Yea!
-- Note: No white "Boffin" coat for Tim. Just "overalls." But as I watched I found myself thinking that he could probably have used an armor plate or at least a Kevlar vest amidst all that flying metal. Perhaps a bit more eye protection too...
-- Fiddley. A useful tech term.
--Swarf: Another useful tech term: the metallic remnants (shavings) of drilling.
-- The digi readout on the milling machine looked really useful.
Finally, I loved the sign that Tim has posted in his workshop:
SMALL HADRON COLLIDER
Four Old BBC Shows on Radio: Hams, Physics, and Antique Wireless
Thursday, April 20, 2023
Artie Moore and the Titanic
https://www.facebook.com/groups/118053768802799
Friday, April 7, 2023
More Info on the Cuban Jaguey Solid State DSB Transceiver
Continuing our search for information the Cuban "Jaguey" DSB rig, Trevor Woods pointed me to Dick Pascoe's QRP column in the (below) July 1998 issue of Ham Radio Today. I think the first SPRAT article about Eric Sears' ZL2BMI DSB rig was in SPRAT 83 in the summer of 1995. This fits well with the sequence described below by Arnie Coro CO2KK.
I am still looking for a schematic and pictures of the Jaguey rig: If you can help in this, please let me know.
Speaker Made from Potato Chip Bag: Tim Hunkin's Solenoid and Electromagnet Video
Sunday, January 8, 2023
Tuesday, November 15, 2022
Amazingly Cool MONTV Video on Direct Conversion Receivers with Glue Stick PTOs
Friday, October 7, 2022
How the Diode Ring Multiplies by 1 and -1 -- "The Secrets of the Diode Ring" -- Plus another Bandsweep with the DC RX
Tuesday, October 4, 2022
Tim Hunkin's "The Radio Set" Drawing, and The Secret Life of the Radio (Remastered)
Thanks Tim!
Wednesday, September 21, 2022
Nick's "Shelf-17" Al Fresco Homebrew Transceiver -- Frank Jones Would Approve!
Tuesday, September 13, 2022
Great Technical Info and Tribal Knowledge from GQRP
Thanks to Tony Fishpool G4WIF for sending us this link.
There is a lot of great tech info and Tribal Knowledge on the GQRP page. This is all related to our discussion of how to set up an electronic workbench or workshop.
Thanks Tony and thanks to GQRP.
Monday, September 5, 2022
Why Do Some VFOs Tune More Linearly Than Others?
This has been one of the major complaints about our beloved analog LC VFOs: The frequency tuning on these circuits is often not linear. For given amount of VFO frequency dial turn you can get vastly different changes in frequency. At one end of the tuning range the frequencies are nicely spaced and tuning is easy. But at the other end of the tuning range all of the frequencies are bunched together. This is one of the problems that leads some homebrewers to defect to the sad land of "digital VFOs."
But wait. It appears that the old designers found a solution to this problem. Just look at the tuning dial of my HT-37. The frequencies are all spaced out evenly. How did they do that?
I had been thinking that this success may have resulted from Hallicrafters' engineers using the series-tuned Clapp circuit. Here the main frequency determining element is a series-tuned LC circuit and not the parallel tuned LC circuit that we see in the more commonly used Colpitts circuit.
But hold on -- how could that be? The frequency bunching problem that we attributed to the Colpitts circuit must also exist in the Clapp, right? I went back to SSDRA where there was a good discussion of Colpitts and Clapp VFOs. The advantage of the Clapp was said to be in its use of a larger value coil which helped minimize the effects of stray inductances. But there was no mention of the Clapp offering improved linearity in tuning.
I have in front of me two transceivers: The Mythbuster uses a 9 MHz Clapp circuit (see below). The 17-12 rig uses a Colpitts Circuit. I checked the tuning linearity of both. Both appeared quite linear in tuning, with no real difference between the two.
Then I looked at the tuning capacitor in the Mythbuster 17-12 rig. It came out of an old Hallicrafters transmitter, probably the HT-44. I looked closely at the stator and the rotor plates. Both are curved. I'm guessing that this may yield a more constant change in capacitance for a given movement of the main tuning dial.
Next I opened up the VFO on the Mythbuster. (It is the VFO from an old Yaesu FT-101.) I couldn't see the stators very well but it appears that their shape is different from the square shape we often see in variable capacitors. Could it be that this variable capacitor was also made to provide linear tuning?
Back in 2013 Norm Johnson wrote about all this in the Antique Radios.com forum:
A capacitor that has uniform increase in capacitance with rotation will have the stations at the high end of the band squeezed together. Another type known as the straight-line frequency variable capacitor has, as you might guess, a characteristic that gives even spacing of frequencies with shaft rotation. These were popular in the 1920's but weren't very good for superhets where you needed to have a dual section capacitor that would tune both the RF and local oscillator, and have them track each other properly. The midline variable capacitor is more compatible with a superhet, and easier to make both sections track properly. This is the type that you see in most receivers from the late 1930's to the end of the tube era. They don't have quite the equal spacing between stations across the band that the old straight-line frequency caps had, but they're much better than the variables that change capacitance linearly with rotation.
I wrote an online calculator that helps in the design of the tuning. It shows what frequency range you'll get with a specific type of variable capacitor, including the effects of padder and trimmer capacitors. It also displays a dial scale that shows how the frequencies are lined up accross the dial.
http://electronbunker.ca/eb/BandspreadCalc.html
Steve W6SSP also provided some really good info back in 2013:
There are three types of open, variable plate caps;
SLC= straight line capacitance where the capacitance varies linearly,
these are the most common and have half-circle plates
SLF= straight line frequency where the plates are tapered to allow
for linear tuning of the frequency
SLW= straight line wavelength, you get the idea...
SLF and SLW caps have oblong plates.
The effect on tuning a receiver can be dramatic. One example is the
Hammarlund SP series of receivers where the ham bands are very
compressed at one end of the tuning range. They used SLC caps
in the VFO. On the other hand rigs like the Kenwood TS-520
and FT-101 series have linear tuning across each band. These use
SLF variable caps. Most old 1920's battery radios used SLW
where stations were identified by their wavelength.
Steve W6SSP
The Drake 2-B also has perfectly linear tuning. I looked at the manual: "The tuning condenser is of special design..." I'm guessing that they used an SLF variable capacitor. The 2-B had no need for ganged capacitors -- the "preselector" was tuned via a separate front panel control.
I looked at the tuning dials on my Hammarlund HQ-100 receiver. It is fairly linear in its tuning, but not as linear as the HT-37 or the Drake 2-B; on all of the tuning ranges the frequencies seem to spread out a bit at the lower end. My guess is that Hammarlund used the midline variable described above by Norm Johnson. The HQ-100 did use a ganged variable cap, with one section tuning the RF amplifier and the other tuning the local oscillator.
Monday, June 6, 2022
SolderSmoke FDIM Interviews: Hans Summers G0UPL Talks about the QDX and His New Balloon Tracker
Thanks to Bob Crane W8SX for getting us this wonderful interview with Hans G0UPL. Its really amazing to hear Hans talk about how many QDX rigs and Baloon Trackers have been sold by QRP Labs, and how quickly they sell. Really great. Hans's comments on the realities of the parts shortage was also very interesting.
Listen here (about 7 minutes): http://soldersmoke.com/2022 G0UPL.mp3
Wednesday, June 1, 2022
Marconi the Fascist
For obvious reasons Marconi stories pop up in my news feeds. This morning an article from Wales reminded me of a very dark and disheartening aspect of Marconi's life: his fascism and his participation in the persecution of Jews.
There have been at least 14 stories in SolderSmoke extolling the technological virtues of Marconi. I even met his daughter Elettra while in Rome and wrote it up for the blog. But it is just wrong to sing Marconi's praises while ignoring his fascist involvement.
His fascism wasn't even separated from his radio work. He won fascist honors and he won his appointment to Mussolini's Academy of Italy because of his radio work. Take a look at this quote:
The article from Wales: