Total posts : 45366
Neil, I’ll keep looking forward to your tests when you have time.
I ended up trying again with the Nortronics Bias Transformer in place of L4, only this time I used only half of the windings of the primary and secondary and the result is good. Modulation is equal in level to an SStran AM3000. For A – B comparison the Ramsey is at 1640 KHz and the SStran at 1680 KHz and the sound quality and level are equal.
I have another question regarding R33 & R34, two 10-ohm resistors that can be removed for higher power mode, but there are two questions about those resistors aside from their affect on power.
1.) When they are in the circuit they would tend to slightly attenuate the modulation being fed to L4 where it mixes with the RF;
2.) When they are in the circuit the impedance of the combined RF and modulation (Q3 & Q9) is 20-ohms, whereas the combined impedance without R33 & R34 is 0-ohms.
That difference could change the matching and distortion characteristics, and I’d like an opinion on that.