toggle quoted messageShow quoted text
Thanks Dave! Just time for the 4H
kid's build, we're finishing up Monday
I love this radio stuff.
On 7/27/2018 7:30 AM, nm0s_qrp via
I had a chance to check out a Murania that one of out builders had
put together, that he reported low audio. On examining it, I
found that the regeneration loop was too large, and the receiver
was in full oscillation.
When the receiver is oscillating, it makes a large RF signal that
is detected in the receiver IC, and drives down the AGC voltage.
This cuts the gain of the IC. So, to set up the
regen, the loop needs to be about the diameter of a pencil, no
larger, and exactly perpendicular to the board, and to the
ferrite rod. That is neutral feedback. If you then twist it
slightly either way, it will increase or decrease the feedback.
It is hard to hear a change in volume with strong stations,
because the AGC flattens out the volume. If you hear whistles
as you turn the tuning knob, it is oscillating, and the
regeneration is too high.
Hopefully this helps some other builder!
73 Dave NM0S