Modulated 3,579545 MHz QRP foxoring transmitter.
pa0nhc 20180515
Preliminary data.

The use, copy and modification of all info on this whole site is only permitted for non-commercial purposes, 
and thereby explicitly mentioning my radio amateur call sign "PA0NHC"
as the original writer / designer / photographer / publisher.

Warning:>>> DO NOT use this little milliwatt transmitter as a driver stage for a power amplifier <<<
It is meant as a recreational foxhunt / foxoring transmitter, with very limited range, connected to a low efficiency antenna system.
This transmitter is ultra simple, after an idea of the ARRL. The 100% modulation is simply done by switching on/off the ports of the 74HC240.
The drawback of this simplicity is: WIDE modulation bandwidth, only limited by the Q of the antenna tuning circuit


Plug and play. Reliable. Pure solid state, no software.
Narrow 38x130 mm Double sided PCB, 
Fits inside a 20cm long 50mm dia. PVC sewage pipe.
All wired components, no SMD, clean RF-design.
Xtal oscillator unit for adjustment-free, accurate and stable carrier freq.
Two three position slide switches, for setting of the tone frequency and the on/off rhythm. Up to 9 different combinations.
The range is abt. 300m when at 1.5m height, with a 1m long wire as antenna, and a 1m long wire as counter poise.
Also useable with a short whip, and a grounding pin.
Range adjustable by changing the antenna length.
Includes a simple Hi-Z antenna tuner, and LED tune indicator.
100% AM tone modulation + carrier switching, 50% duty cycle, for low power consumption, and easy reception when its received signal is weak.
Mean current consumption abt. 40mA @ 6 to 9 Vdc. (peak values 70 / 13 mA whith modulation on / off).
Stable operation until the battery becomes really empty (5.5 V).
Up to 5 hrs operation with 9V alcaline battery.
Clean output, with output filter for 2nd harmonic = -60 dBc,

Pse read "Assembling". 

This  130 x 38 mm factory made PCB is available.

Downloads :   SCHEMA      Partslist    Assembling