help request with simple live mic tx

[Stefano Zorzanello]

Dear list,

as a newbie I ask you for your help with the attached file. For a 
sound-installation purpose I'd like to transmit a weak signal, which is 
generated live, over a particular FM frequency. In my attempt based on a 
grc file found here 
https://wiki.gnuradio.org/index.php/Simulation_example:_AM_transmitter_and_receiver 
<https://wiki.gnuradio.org/index.php/Simulation_example:_AM_transmitter_and_receiver> 
I get errors even if I change the vector lenght to 2 of [short to float] 
and [multiply const] blocks, and I don't know what values to change in 
order to make it work.

Any help is greatly appreciated,

thank you

stefano

system:

HackRF one

Raspberrypi + usb card for input

GRC 3.8.2.0

HackRF-FM-Transmit-STEF01.grc
Description: Text document