Friday, 4 July 2014

QRP Transmitters

 

7W on 7Mhz Vasantha VU2VWN's QRO? VFO controlled 40m Tansmitter. Loved by South Indian hams and they modulate the whole tansmitter (and the 40m band - hi!) with AM. My friend Sunil VU2TES who send this circuit said that he worked about 60 countries (in 1993) with 5W CW.

LM317 Voltage Reguletor TX What? Yes, extreemly simple single chip, tansmitter. Ideal for low frequency hamming. If you can get 5W/AM by modulating this simple TX, that will be your Top Band Chat-Box.

Logic Chip Tx Very simple Transmitter that can be used on 20, 15 or 10 meter band. Out put is about 500mW. Xtal Control. Only active component is a 74HC240 Octal inverting buffer!

5Watt Transmitter Simple Transmitter that can be used vertually on any band. Out put is about 5W. Single transister and driven by a TTL Logic chip. Xtal Control.

Tuna Tine Transmitter40m Xtal control two transister nice little transmitter that was orginaly built in a Tuna Fish Can. That does not mean that you too should built in one of those, but it is a nice idea for a simple case isnt it? How about a Pepsi or Coke Can (I have seen AM/FM BC radios made in those - factory stuff!)

Pippin 40m 2Transister TX40m Xtal control two transister nice little transmitter by G3PTO. It is simple but gives 1W Output in to a 50ohm load. The author says "The PA transistor has a "Stove Pipe" heat sink attached and has been left running continously for more than 1 hour without any complaint from the PA stage"

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