Archive for the ‘Building projects and kits’ Category:

2018-11-26 Two 6 uH RF Chokes

from FB group Building Transistor Radios 2018-11-26 https://archive.org/stream/ETIA1983/ETI%25201983-03%2520March_djvu.txt Two 6 uH RF chokes The photo shows two different RF chokes, each about 6.4 microhenrys. The one on the left is a ferrite bead, made by Fair-Rite, Cat. # 2643000801. These were about 12 cents apiece from Mouser.com. Yes, the wire passes through the small hole

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2018-11-25 One Transistor FM Receiver Schematic Part 1

From FB group Building Transistor Radios Larry Daniel 2018-11-26 This is the original schematic posted by Larry. GM is a gimmick capacitor made of two short lengths of solid hookup wire, twisted together for a few pF capacitance. List of RF Chokes for the ham bands Larry said he used an RCA SK1008, then corrected

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2018-11-24 The Rise Of The PCs

from FB group Vintage Transistor Radios 2018-11-24 Early on, I built and upgraded many PCs when they became popular. Some for myself and friends, but most at work. Before that I was maintaining and repairing terminals and other equipment attached to mainframe computers. It started out small with TRS-80s and Apples but really took off

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2018-11-19 Depth of Loop Antenna

from FB group Building Transistor Radios 2018-11-19 I shared my loop antenna – see photo, and it is somewhat 2 dimensional. The arms are 762mm across but the depth of the windings is only about 35 mm. Compare that to the ferrite loopstick at the other extreme, it’s 10 mm diameter but 100 mm long.

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2018-10-08 Air Band Radio Kit HMOOABRA_4.3 Part 5

from FB group Building Transistor Radios comment 2018-10-08 Bob Johansen Receive frequency? I can’t receive a signal, so the receive frequency is not known. This receiver has no tuned circuit in the RF side of the NE612, other than the bandpass filter made up of the coils on the PCB and their capacitors. The bandpass

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2018-10-07 Air Band Radio Kit HMOOABRA_4.3 Part 3

From FB group Building Transistor Radios comment 2018-10-07 Bob Johansen I don’t have a way of calibrating an RF signal level. Back when I worked on Aircraft radios we had General Radio VHF signal generators, attenuators and RF signal strength meters and a Panoramic spectrum analyzer. This would have been a piece of cake to

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2018-09-11 Vectronics Aircraft Radio Kit

I got the Vectronics VEC-131K aircraft band radio kit in the mail yesterday and warmed up the soldering iron to assemble it. It came at a decent price, so some of my complaints seem to be cost cutting measures. It comes with a decent assembly instruction manual, but some of the pages including the schematic

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2018-09-02 Mims Mistakes In Audio Amplifier

From FB group Building Transistor Radios, 2018-09-02 I already see one mistake. On p.27, Audio Mixer. The R6 is only 1k. The voltage divider R5 and R6 will give a voltage less than 0.6 at Q1’s base, which means Q1 will not be forward biased enough and the circuit won’t work or else sound distorted.

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2018-03-02 One Transistor AM Radio

FB group Building Transistor Radios In JF1OZL’s voluminous archive I found his version of a MW receiver.  It is labeled [2] …. MW-RADIO (see link).  He used a long wire antenna, and an IF transformer with the ceramic capacitor removed for the tuning coil.  He also said to use a ferrite loopstick, which is what

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2018-01-09 Regenerative Radios Are Too Difficult

For FB group Building Transistor Radios Bob Johansen After building several of the regenerative receivers, I think I figured out the reason why regens are so difficult.  The circuit has to do so much with very few parts.  If one part value is changed to improve one thing, it adversely affects something else.  The tickler

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