Can someone please help me with this.
I have built this circuit https://www.electro-tech-online.com/custompdfs/2012/11/3063-1.pdf
it uses the Mk484. i am trying to tune it to 457kHz.
It has a coil and ferrite bar. The coil is made from 80 turns of 3 strand litz wire. I have calculted this to be 32uF.
There is a tuning capacitor of 160pf that i have had to wire in parallele to enough capacitors to get me to 3.8nf.
Now my calculation is that this should be tuned to some where near the frequency i am after.
I have a bug transmitting on 457kHz and I can hear its pulsed output on the speaker. the trouble is that it is not very loud and if i move the bug any further than 5 inches away from the coil the signal is lost.
Can someone please tell me what I am doing wrong? I just can not seem to move past this stage
Thanks
I have built this circuit https://www.electro-tech-online.com/custompdfs/2012/11/3063-1.pdf
it uses the Mk484. i am trying to tune it to 457kHz.
It has a coil and ferrite bar. The coil is made from 80 turns of 3 strand litz wire. I have calculted this to be 32uF.
There is a tuning capacitor of 160pf that i have had to wire in parallele to enough capacitors to get me to 3.8nf.
Now my calculation is that this should be tuned to some where near the frequency i am after.
I have a bug transmitting on 457kHz and I can hear its pulsed output on the speaker. the trouble is that it is not very loud and if i move the bug any further than 5 inches away from the coil the signal is lost.
Can someone please tell me what I am doing wrong? I just can not seem to move past this stage
Thanks