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Before yesterdaySolderSmoke Daily News

Radio Items Picked-up at VWS Winterfest 2024 Hamfest

11 March 2024 at 14:23

As always, click on image for a better view

Above you can see what I picked up at the Vienna Wireless Society's 2024 Winterfest Hamfest.Β 

-- On the left in the blue box is an MXM Industries SuperRX/TX 40 transceiver. It is a kit from a Texas company.Β  Β Superhet receiver with IF at 455 kHz.Β  Crystal controlled CW transmitter on 7040 kHz.Β  The oscillator works, but so far no receive signals.Β  I will have to troubleshoot.Β  Does anyone have a schematic?Β 

-- 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.Β  Β Box may be useful.Β 

-- 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.Β 

-- On top of the Weekend Projects book you see a "Crystal Holder" from Gross Radio of New York City.Β  W1UJR has some good history on this company:Β Β https://w1ujr.com/written-word/gross-radio-company-circa-1931/Β  This device seem to be intended to hold in place a raw piece of quartz!Β  Cool.Β 

-- To the right of the books there is a serious-looking VFO.Β  One dollar!Β  Deal!Β  It is a CB VFO, but the markings say it puts out 5.44 to 5.99 MHz.Β  So it should be useful.Β  The dual speed dial is very nice.Β Β 

-- Above the VFO is a nice step attenuator from the "Arrow Antenna" company of Loveland Colorado.Β 

-- Further to the right are some Electric Radio and Antique Wireless Association magazines that Armand WA1UQO gave me.Β  Really nice.Β  The AWA mags have a very thoughtful piece (warts and all) on Jean Shepherd.Β  And the ER pile has an article by Scott WA9WFA that mentions my work on the Mate for the Mighty Midget receiver.Β  Thanks again Armand!Β 

-- I also got some ADE6+ surface mount mixers.Β  The price was right!Β 

Thanks to VWS for putting on this great hamfest!Β 

N6ASD Builds a Zinc-Oxide Negative Resistance Transmitter (and a Spark/Coherer rig)

6 March 2024 at 12:46

I saw this video and post on Hackaday this morning:


I got the fellow's callsign fromΒ  his Morse CQ.Β Β 
It is N6ASD in San Francisco.Β 

Check this out from his QRZ page:Β https://www.qrz.com/db/N6ASD

My journey into the world of amateur radio began in a very primitive way. My first "rig" comprised of aΒ spark-gap transmitter and a coherer based receiver. A coherer is a primitive radio signal detector that consists of iron filings placed between two electrodes. It was popular in the early days of wireless telegraphy.

Spark transmitter (using a car's ignition coil to generate high-voltage sparks):

Coherer based receiver (using a doorbell for the "decoherer" mechanism):

When I keyed the transmitter, a high voltage arc would appear at the spark-gap andΒ this produced (noisy) radio waves. The signal would beΒ received by the iron-filings coherer on the other side of the room. A coherer is (usually) a one-shot receiver. You have to physically hit it to shake the filings and bring the detector back to its original state. That's what the doorbell hammer did. It would hit the coherer every time it received a signal. It amazed me to no end. A spark created in one room of my house could make the hammer move in another room. Magic!

Soon after this project, I started experimenting with *slightly more refined* crystal detectors and crystal radio circuits. As most of you would know, these amazing radios don't require any batteries and work by harnessing energy from radio waves. I guess these simpleΒ experiments instilled a sense of awe and wonder regarding electromagnetic waves, and eventually, this brought me into the world of amateur radio in 2015.

My main HF rig is an old ICOM IC-735. The only modification on this is radio is that it uses LED backlights (instead of bulbs):

Icom IC 735

With space at a premium in San Francisco, the antenna that I have settled for is an inverted vee installed in my backyard (and it just barely fits). I made the mast by lashing together wooden planks. For this city dweller, it works FB:

I have recently gotten into CW, and it has definitely become my mode of choice.

I'm a self-taught electronics enthusiast and IΒ love homebrewing radio circuits. I'll be sharing more info about them soon.

Thanks for checking out my page. I hope to meet you on the air!

73,
N6ASD

Β 

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