Sunday, July 6, 2014

Grenade Transmitter



The Parts List for the Shortwave Transmitter:

  • R1 - 33K ohms, ¼ watt, carbon.
  • R2 - 4.7K ohms
  • R3, R6 - 100 ohms
  • R4 - 22 ohms
  • R5 - 100 ohms, 1 watt, or greater.
  • C1 - 47 to 470 pF, or greater, silver mica or disc ceramic. Better yet, a trimmer capacitor, to slightly change frequency ±1 KHZ.
  • C2 - 10 to 140 pF trimmer.
  • C3 - 100 to 220 pF, silver mica or disc ceramic.
  • C4 - .01 to .05 µF.
  • C5 - 300 - 800 pF, or (? ? ?) variable capacitor. Use an Arco TC-4610 (260-900 pF) compression trimmer.
  • C6 - .01 to .1 µF.
  • C7 - 1000 µF or greater, electrolytic, 25 volts or greater.
  • X1 - Fundamental mode crystal, 5 to 8 MHz.
  • T1 - On an Amidon T50-2 toroid core, primary is 26 turns of #28 magnet wire closewound, secondary is 2 turns wound over the primary windings.
  • T2 - On an Amidon T50-2 toroid core, bifilar wind 6 to 8 turns of #18 magnet wire. See note 1 for details.
  • L1 - 2 mH or greater, .5 ohm or less resistance. Use the inductor from Radio Shack p/n 270-0030A HD Noise Filter. One could also use the 4 or 8 ohm secondary of a medium sized audio transformer, or the secondary side (6 to 24 volts) of an AC mains power transformer.
  • L2 - .7 µH.   Wind 7 turns of #16 magnet wire on a 5/8 inch diameter form, then remove form.
  • L3 - 1.4 µH.   Wind 11 turns of #16 magnet wire on a 5/8 inch diameter form, then remove form.
  • Q1 - 2N2222
  • Q2 - 2N2907
  • Q3 - IRF510 or IRF511 (Radio Shack p/n 276-2072A)

... and this is another Audio section without compressor/limiter

LF-section without compressor/limiter

A slight modification in the LF/RF section of the Grenade transmitter

How to winding and installing a Toroid Coil
The transmitter's low-pass filter uses a high-Q toroid inductor wound on a T37-2 form (T37 means the powdered-iron form is .37-inches in diameter). When winding the Toroid Coil, the numbers of turns are counted inside the form (not on the outside). That means, if the instructions call for a 12-turn coil, you must pass the wire through the centre of the core 12 times. When winding this coil, be sure to pull each turn up tight before starting the next. If the coil is wound loosely, its inductance increases - a condition that may reduce transmitter output power. Count turns on inside of form. Tin leads with solder before installing. Pull each turn tight before winding the next. Finally, before installing the Toroid Coil be sure to tin both leads with solder. The coil wire is coated with heat-strippable enamel insulation that breaks down at soldering-iron temperatures. If you touch the tip of an iron to the end of the wire for several seconds, the insulation should start to melt, allowing solder to adhere to the copper underneath. If your iron is not hot enough to start this process, carefully scrape the insulation off with a small hobby knife and tin. If necessary, refer back to these instructions at any time during assembly

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