Archive for March, 2019:


from FB group Vintage transistor Radios April 3 Are all ‘polyvaricon’ tuning capacitors the same? They’re all about the same size. Charles Vesser Japan Industry Standard… The few that I have examined were 140 pF antenna and about 70 pF oscillator. In parallel give 210 pF. They’re probably made to match up with the loopstick

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From FB group transistor radios Mar 29 Lin Holcomb One never knows what secrets the US government has hidden. They could have some other plans for using the WWV stations. Decades ago I worked for a radio engineer, and we had a frequency counter traceable to NBS (now NIST). He noticed that the frequency of

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2019-03-26 Fukushima Daiichi NPP Article

From “You traveled to Fukushima to film. What was your big takeaway from there?” “I found it incredibly chilling to be there. The plant itself is very strange. You don’t smell or see or touch radiation, so you don’t know. But [there’s] this whole process of getting completely suited up, and there are literally

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2019-03-22 Tuned Circuit For 702 kHz

from FB group Building Transistor Radios Stoffel van Aswegen I used the free Android app ElectroDroid to do these calculations. For 702 kHz, a 220 pF fixed capacitor (NP0 or C0G) and a 230 microhenrys coil are needed. The standard ferrite loopstick is 230 uH, but you can wind your own on a coil form

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2019-03-19 Radio Alignment Questions

From FB group Building Transistor Radios Mar 20 Bob Kirsch Any recommendation for doing a complete alignment? Documents? I used a HP sweep gen decades ago but I don’t have one now, just an old signal gen. I thought about building a sweep gen but I need to get a few parts. I have bought

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From FB group Building Transistor Radios 2019-03-19 John Ferguson Yeah, I used to use the Sylvania ECG and the NTE catalogs to cross-reference transistors. But then I got some better product manuals from the makers, especially Motorola and National Semi. And I got hold of the professional industry documents. ECG and NTE give a ‘one

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2019-03-15 The Tape Recorder 6V6 Making Crackling Noise

from FB group Building Transistor Radios Tuck Choy I was a reel to reel tape recorder fanatic when I was a kid, and had a recorder with a 6V6 output to the spkr. The first thing I did was modify the recorder to add an external spkr. One time I plugged in a clip leads

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2019-03-14 Pi Day!

3.14 is Pi day.

2019-03-13 Regen Receiver Schematic

from FB group Building Transistor Radios post by Tuck Choy. I sharpened and lightened it to make it more readable. From EPE Mag. Sep 2005 by Thomas Scarborough. Since only four of the 6 inverters of the CD4069 are used, the CD4001 or CD4011 quadruple NOR or NAND gates should substitute, if the other unused

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2019-03-12 Dipper, Wavemeter, Receiver Added Pt. 2

Update 2019 Mar 12 – I continued to add capacitors and variable resistors along with switches to change them similar to the VK2ZAY video on YouTube. By switching the capacitor and trimmer resistor, it can now act as a receiver. I clipped a 2 meter long piece of wire to the tuning capacitor and with

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