If it was allowed,  
this small assembly could be used to send walrus on the 27 MHz.  
To do this, we just need to wire the whole, as shown in the diagram below.  
A switch would make us broadcast  
and we would then be left to manipulate our "ti" and our "ta".

Implantation of components :
Printed circuit ( track side )
List of components :  
R1 , R2 : 4.7 K - D1 , D2 : 1N4148  
C1 : 10 mF / 25 Volts - C2 : 100 nF - C3 : 8.2 nF - C4 : 1 mF / 25 Volts  
P1 : Potentiometer 100 K