Archive for March, 2019:

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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2019-03-17

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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2019-03-11 Dipper, Wavemeter PT. 1

from FB group Building Transistor Radios Mar 11 I watched a YouTube video from Alan Yates VK2ZAY, he built a combination Dipper, wavemeter, receiver and RF generator. I built his schematic ‘right side up,’ he admitted he built it upside down with positive ground and drew the schematic, see: https://youtu.be/0pJw0m2Lz6o I didn’t attempt to build

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2019-03-10 Phones Work During Power Outages?

From FB group Orange Talk Mar 11 The old fashion ‘non electric’ phone depends on the phone line for its power. The old phone lines used to have backup power at the central office, so they worked if the power went out. But nowadays the power comes from a local box which has batteries but

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2019-03-08 Winding a Ferrite Loopstick

also links to this in FB groups Building Transistor Radios and Ferrite Loopstick Exper. I got some of these ferrite loopstick bars from Goldmine Electronics while the were on sale. They are the small kind that fit into pocket radios. Materials were the bar, a piece of paper for insulation, a roll of 32 AWG

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