minimum sample delay

[Polymer]

@bbsailor -
I get "server not found" error with the link, even with the base address.
Sometimes this happens with US websites whwn accessed from Europe.
Could you please test from your location!?

Works ok from Australia

Thanks. Just tried via a proxy server, it works! Might be geo-blocking or similar.

[6666]

"... Carl mentioned in another thread to disconnect Rd with an operating PI to check resonance..."

Thanks

[KingJL]

is there a schematic error with Q5/6 bases?

I don't believe there is. I created the circuit in LtSpice and the circuit works... It implements a low noise preamp with a gain of ~150. I had to substitute Q4 (better performance could be obtained with a better match for Q4). The circuit offset is controlled by R14.

[bklein]

Your Q5 is right but the schematic doesn’t show the “dot” b-c.

[green]

Carl's method of measuring resonance is most accurate, as the result will have included ALL of the capacitance (intended and unintended) of the TX circuit (i.e. coil, MOSFET, cable, internal wiring/routing, etc.). Also the correct damp resistance is not just a function of resonant frequency, but more importantly a function of the ratio of inductive reactance relative to capacitive reactance (which corresponds to the ratio of L to C as well as frequency). In other words if 2 coils have the same resonant frequency but different ratios of L to C, they require different damp R values.

Where is Carl's method described ? thanks

Rd=pi*L*resonant frequency

[KingJL]

Your Q5 is right but the schematic doesn?t show the ?dot? b-c.

Actually, it does. Look carefully, it is easy to miss... I almost missed it myself.

[bklein]

Ahhh ok, see it with my ipad blowup. What are the three line traces? Special shielding, or?