When I watched Doug N0WVA’s in action I was struck by how much more sensitive his was than mine.
I think this is do to the LC ratio in the main tank circuit. In my original version I used the variometer that I had in my junk box. It was about 4.5 uH. Doug used a hand-wound coil of about 35 uH.
For construction details on Doug’s receiver and variometer go here:
https://aa7ee.wordpress.com/2015/02/07/n0wvas-one-fet-regen-optimized-for-ssbcw-sounds-great/
For construction details on Doug’s receiver and variometer go here:
https://aa7ee.wordpress.com/2015/02/07/n0wvas-one-fet-regen-optimized-for-ssbcw-sounds-great/
So mine was heavy on the C, and light on the L. I think the larger coil makes it easier to couple the antenna to the receiver. I notice a lot of discussion in the online regen community about suitable LC ratios.
So I built a version more like Doug’s. I built my own variometer — that was a lot of fun. It is easier than it appears — Do not be deterred! And indeed the new receiver is much more sensitive.
On this second receiver I measured an Minimum Discernible Signal of -115 dbm. On my ET-2 receiver it was only -93 dbm. The improvement was very noticeable. I could even copy 40 meter AM signals at the top of the band. And on SSB I was actually having trouble with overload — the signals were too strong for the oscillations of the regen.