Archive for the ‘Meters and Test Equipment’ Category:

2019-09-30 RF Modulator

For the oscillator I used the Hartley oscillator circuit that is used in the Eico 330 signal generator. I didn’t need any of the range switches – I left that out. It used MPS6513 transistors which are cheap but very uncommon – I can’t remember ever seeing them in any schematics or in PC boards.

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2019-09-27 Phase Shift Oscillator For RF Signal Generator

2019-09-27 PSO I tack soldered the parts together for a PSO, and made modifications to get it go work at 500 Hz. My goal is to get a steady tone to use to amplitude modulate the RF signal generator that I have built (see this blog). The sine wave from this PSO is beautiful –

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2019-04-06 HP Transmission Test Set

from FB group Bell Telephone of… Apr 6 (I bought a transmission test set, TTS-4, photo at bottom.) Glenn Peters We had a HP 493something transmission test set for testing up to 56 kb/s lines. I remember seeing the symbols on the green screen, like a carriage return would look like a little ‘CR’. The

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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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2019-03-11 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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2019-02-20 Old 2N708 Transistors

Feb 20 I got 21 ‘packages’ of 2N708 transistors for $.99 a package from Goldmine-elec.com. In the box were 42 plastic zip bags, each having 5 2N708 transistors, so apparently one ‘package is two bags. Each transistor is marked with the Motorola logo and 2N708 and on the top KOREA is stamped into the metal.

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2018-12-12 LM78xx Linear Regulator Disadvantages

from FB group Building Transistor Radios 2018-12-13 Joseph Rotello I agree with some of your claims. But I know far more about 3-terminal regulators than you think. First off, your claim that they are more efficient is unproveable. There are linear PSes that are more efficient. That was the reason LDO regulators were used. You

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2018-12-03 My Fluke 75 DMM

from FB group Building Transistor Radios Joe Lima That’s good to hear. More than a year after I bought my Fluke 75 DMM (and with light use at home) I turned the switch to off but it stayed on(!!) I had to unplug the battery. Luckily it was still under the 3 year warranty, so

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2018-08-03 GE Special Speaker And Iron Particles

From FB group Building Transistor Radios, Aug 6 This also happens with the meter movements of old analog meters. The iron particles get into the magnet assembly and stop the coil from moving. The only way I’ve found that gets rid of the iron particles is to very gently put a thin piece of steel

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2018-01-31 1kHz Wien Bridge Oscillator Kit

Also photo posted to FB group Building Transistor Radios. I got several of these Wien Bridge Oscillator kits from an eBay seller in China.  They are built using the circuit from http://redcircuits.com/Page13.htm More information can be found on the wiki for this oscillator. The kits come with no instructions, so to assemble it, use this red circuits

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