My Lafayette KT-195 AM Broadcaster circa 1962 was designed with screen modulation.
But you modified the Lafayette to plate modulation, why was that?? Because of modulation quality??
http://heartandhoof.com/mram/KT-195
Good screengrid modulation is not as easy as it looks. But once you have a good modulation ............................ !!
In Post # 2 I described how I use Stereotools by Hans van Zutphen to achieve a very "bring-it-forward-so-it's-clear-even-in-a-noisy-world-sound," but I do one more thing that adds Final Sizzle to the AM radio sound.
Both the AMT3000 and AMT5000 have on-board limiter/compression controls, and these do "the rest of the job" with good processing.
The limiter "caps-it-off" right at the top of modulation so that no peaks over-modulate, and the compression, set very slightly, brings the overall sound up an extra measure so that everything stands out.
I like to tinker. The modulation wasn't the greatest so the mod was an attempt to improve the transmitter.
The method is similar to the Heising Modulator which uses a choke coil instead of a transformer. In my case, the audio output transformer serves as the choke.
Now, the modulation as viewed on the ocilloscope looks more symetrical and can reach closer to 100%.
Plate modulation is preferable to screen modulation. The moslt likely reason that screen modulation was usued was to eliminate bulky modulation transformers and make kits from Heath more affordable. I had a Heathkit Cheyanne that used screen modulation. I actually got good reports though the carrier bounced all over the place. Looked like SSB though it was regular United States of America AM.
Transmitter: TH-5 + wire
Processing: Mackie 1402VLZ to Orban 424-A to TH-5
Content: Oldies, Doo Wop, OTR, Greaseman
Overall Impression: Took it down after my first TH fried. Am moving the studio to the front room.