- Joined
- Jun 13, 2018
- Messages
- 869
I don't know JWT.... sounds like you encounter'd one of the last of a dead breed- the AM Fanatic. I dare say that unless you told him you were using a 'rice box' transceiver, he never would have known. I wouldn't say a thing........ 
True, there is a real "quality" about a true plate modulated AM signal*- its got the full range of audio highs and lows- in a 8-10 KHz wide signal. Unless you are an AM broadcast station, this doesn't matter since we are into communications, not audiophile stuff. That's why we have single side band, and use audio compression.
With plate modulated AM- the big transformer 'real AM' league-- 50% of its power is going to be wasted as carrier. If you throw in an extra sideband, there goes another 25%..... its a pretty inefficient mode. And unless someone looks at you with a scope, its darn hard to tell how you are achieving AM.... but maybe they can also feel all that heat coming off your transmitter.
Today you can run a low level AM signal thru a Class AB1 amp, going QRO and no will be the wiser.
AM techniques with tube transmitters can/did run the gamut. Screen, grid, plate; some poorly design'd circuits even produce nice sounding signals with a downward modulation.
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* When I was a student I used to moonlight as the engineer-DJ-custodian at a campus AM radio station. 1000 Watts from a 4-1000 Eimac final.... the modulator transformer came from the audio section of an ancient BC-610E.... and it was pure, sweet plate modulation !
My program sign-on was Debbie Harry's - "Blondie's"- Atomic-- I would turn off the overhead lights and delite in watching the slightly gassy 4-1000 flash blue in time to her music...........
Lauri
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True, there is a real "quality" about a true plate modulated AM signal*- its got the full range of audio highs and lows- in a 8-10 KHz wide signal. Unless you are an AM broadcast station, this doesn't matter since we are into communications, not audiophile stuff. That's why we have single side band, and use audio compression.
With plate modulated AM- the big transformer 'real AM' league-- 50% of its power is going to be wasted as carrier. If you throw in an extra sideband, there goes another 25%..... its a pretty inefficient mode. And unless someone looks at you with a scope, its darn hard to tell how you are achieving AM.... but maybe they can also feel all that heat coming off your transmitter.
Today you can run a low level AM signal thru a Class AB1 amp, going QRO and no will be the wiser.
AM techniques with tube transmitters can/did run the gamut. Screen, grid, plate; some poorly design'd circuits even produce nice sounding signals with a downward modulation.
____________________________________________________
* When I was a student I used to moonlight as the engineer-DJ-custodian at a campus AM radio station. 1000 Watts from a 4-1000 Eimac final.... the modulator transformer came from the audio section of an ancient BC-610E.... and it was pure, sweet plate modulation !
My program sign-on was Debbie Harry's - "Blondie's"- Atomic-- I would turn off the overhead lights and delite in watching the slightly gassy 4-1000 flash blue in time to her music...........
Lauri
.
.
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