In the 20's and 30's, most all AM transmitters were low-level modulated. The Power Amplifier stages operated in class "B" mode. In the 40's, high level plate modulation became the norm because the total efficiency was far higher. The modulators operated in class "AB" mode and the RF power amplifier operated class "C".
In 1958, RCA started producing their Ampliphase transmitters which were somewhat more efficient.
In the mid 60's, Continental developed their version of the Doherty amplifier. The efficiency was a little bit better than the Ampliphase.
In the early 70's, Gates started producing their "MW" series of transmitters which used Pulse Width Modulation. Gates called it PDM ... Pulse Duration Modulation. The efficiency was far, far higher than anything before and the transmitters sounded better than anything previously available.
During my career, I have maintained transmitters which operated in all of these classes.
In 1958, RCA started producing their Ampliphase transmitters which were somewhat more efficient.
In the mid 60's, Continental developed their version of the Doherty amplifier. The efficiency was a little bit better than the Ampliphase.
In the early 70's, Gates started producing their "MW" series of transmitters which used Pulse Width Modulation. Gates called it PDM ... Pulse Duration Modulation. The efficiency was far, far higher than anything before and the transmitters sounded better than anything previously available.
During my career, I have maintained transmitters which operated in all of these classes.
NMR(MRI) shimmy(gradient) coil amplifiers - few hundred amps, quite a few hundred volts - used to design some...
EDIT: sorry solid state
Have seen THE TUBE GU101A, used to feed particle accelerator - disassemblable for service...
300 kW plate dissipation up to four used see attach
EDIT: sorry solid state
Have seen THE TUBE GU101A, used to feed particle accelerator - disassemblable for service...
300 kW plate dissipation up to four used see attach
Attachments
Last edited:
Thanks for the history Frank. I knew there was more to it. The 1978 Harris (Gates) TV transmitter I worked on was modulated at about the 1 Watt level followed by linears. The 1956 RCA it replaced grid modulated the 'final' which was followed by an optional grounded grid linear to boost 10 KW to 25KW. In the early days they ran at 25 but as the tower got raised they eventually ran about 8 KW.
The RCA modulation amp would impress the audio guys as it was 4 6146s in parallel stacked on top of 4 more parallel 6146s and made 400 Vp-p of video driven push-pull like a solid state audio amp.
G²
The RCA modulation amp would impress the audio guys as it was 4 6146s in parallel stacked on top of 4 more parallel 6146s and made 400 Vp-p of video driven push-pull like a solid state audio amp.
G²
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.