RADIO HABANA CUBAULTRA-SIMPLE TRANSMITTER

Dxers Unlimited for 12 June, 1999with Arnie Coro, radio amateur CO2KK

Single IC 74HC240 Transmitter Parts List

C1 and C2 are mica or ceramic.

L1 and L2 are air-wound from #14 wire, with an inner diameter of 3/8 inch. You use a BIC Ballpoint Pen asthe coil form (then after winding the coil, just remove the coil form, and you have an "air wound coil" thatlooks nice)!

RESISTORS: Standard carbon type, they may be 20 percent tolerance. If they are better tolerance, like 10percent or 5 percent, it's OK too.

R1 22K ohms 0.5 w R2 330K ohms 0.5 w R3 470 ohms 0.5 w

Ultra-Simple Transmitter, Dxers Unlimited for June 12, 1999 http://www.radiohc.org/Distributions/Dxers/ultra-simple-transmitter.html

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R4 47K ohms 0.5 w

CAPACITORS: The 0.1 mfd capacitors should be DISK CERAMIC for better RF response but epoxy typeswill work, too.

C3 0.1 mf 50 volts or more C4 0.1 mf 50 volts or more C5 22 pf ceramic, or better yet, mica or silver mica C6 47 pf ceramic, or better yet, mica or silver mica C7 20 pf Variable C8 47 pf ceramic, or better yet, mica or silver mica C9 0.1 mf 50 volts or more

0.1 mfd capacitors can be epoxy type used for bypass.

You may use smaller resistors, but the half-watt type are easier to handle and solder, especially if you are juststarting in learning how to assemble electronic circuits.

The IC dissipates a lot of heat when running from an 8 volt DC source, so you MUST glue it to the printedcircuit board, in order to use the copper foil as a heat sink.

You can see how this is done in the picture of the fully assembled rig above.

Questions? Send e-mail to Arnie CoroReturn to Dxers Unlimited for June 12 1999To RHC Homepage

Ultra-Simple Transmitter, Dxers Unlimited for June 12, 1999 http://www.radiohc.org/Distributions/Dxers/ultra-simple-transmitter.html

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