As I get ready to build the SolderSmoke Shack South, the Radio Gods (well at least YouTube) keep sending me these workshop videos. Today's is also for a shop specializing in the repair of vintage audio gear, but the lessons-learned and observations are also applicable to a ham radio workshop. This fellow's shop is in New York City, where space is very limited. Check it out. Lots of great ideas here.
Wow. Really great test gear, and an amazing parts collection. This guy even gets a "nice workshop" comment from Mr. Carlson. Pac1085 seems to be in Rochester N.Y. and he says he specializes in the repair of vintage audio gear. He should have more subscribers. Does anyone have more info on him?
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.
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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:
Above you can see what I picked up at the Vienna Wireless Society's 2024 Winterfest Hamfest.
-- On the left in the blue box is an MXM Industries SuperRX/TX 40 transceiver. It is a kit from a Texas company. Superhet receiver with IF at 455 kHz. Crystal controlled CW transmitter on 7040 kHz. The oscillator works, but so far no receive signals. I will have to troubleshoot. Does anyone have a schematic?
-- Behind the MXM there is a nice box marked "Diode Detector" I opened it up and there is just a solid state diode and a 50 ohm resistor to ground. Box may be useful.
-- I got a couple of books: "Weekend Projects" 1979 from ARRL, and "A History of QST -- Volume 1 Amateur Radio Technology 1915 - 2013" 2013 from ARRL.
-- On top of the Weekend Projects book you see a "Crystal Holder" from Gross Radio of New York City. W1UJR has some good history on this company: https://w1ujr.com/written-word/gross-radio-company-circa-1931/ This device seem to be intended to hold in place a raw piece of quartz! Cool.
-- To the right of the books there is a serious-looking VFO. One dollar! Deal! It is a CB VFO, but the markings say it puts out 5.44 to 5.99 MHz. So it should be useful. The dual speed dial is very nice.
-- Above the VFO is a nice step attenuator from the "Arrow Antenna" company of Loveland Colorado.
-- Further to the right are some Electric Radio and Antique Wireless Association magazines that Armand WA1UQO gave me. Really nice. The AWA mags have a very thoughtful piece (warts and all) on Jean Shepherd. And the ER pile has an article by Scott WA9WFA that mentions my work on the Mate for the Mighty Midget receiver. Thanks again Armand!
-- I also got some ADE6+ surface mount mixers. The price was right!
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