08-04-2019, 07:37 PM
Hello everyone,
I realize this thread is about three years old, but just in case someone here is interested I had built an AM transmitter/modulator using the method described by Joe Sousa with the 6AS6. In my design I used an EF80, however, as this is fairly common and easy to obtain. It can be modulated at G3 and by using the differential method with an output transformer it will produce a very nice linear modulation up to 100%:
Please check out my article on Radioforum.org:
https://www.radiomuseum.org/forum/linear..._ef80.html
It is in German but if there is interest here I would be happy to translate it to English.
Since I have many P- valves I designed the whole transmitter using P valves (apart from the EF80) like PCF80 and it has a PM84 as a modulation level indicator.
This design will also work very well with EF89 and EF85. The EF183/184 valves do not work well with this method, however.
I also have a version that has an output stage that uses a PCL200 that delivers about 1W PEP. Here is an image of the transmitter:
In the image you can see the PM84 in front. IN the back row from Left to right:
PCL200 linear output RF Amp, EF80 AM modulator, 90V Stabilizer
The middle row:
PABC80 amplifier and rectifier for the PM84 indicator, PCF80 AF amp. and carrier oscillator.
Looking forward to your feedback
Semir
I realize this thread is about three years old, but just in case someone here is interested I had built an AM transmitter/modulator using the method described by Joe Sousa with the 6AS6. In my design I used an EF80, however, as this is fairly common and easy to obtain. It can be modulated at G3 and by using the differential method with an output transformer it will produce a very nice linear modulation up to 100%:
Please check out my article on Radioforum.org:
https://www.radiomuseum.org/forum/linear..._ef80.html
It is in German but if there is interest here I would be happy to translate it to English.
Since I have many P- valves I designed the whole transmitter using P valves (apart from the EF80) like PCF80 and it has a PM84 as a modulation level indicator.
This design will also work very well with EF89 and EF85. The EF183/184 valves do not work well with this method, however.
I also have a version that has an output stage that uses a PCL200 that delivers about 1W PEP. Here is an image of the transmitter:
In the image you can see the PM84 in front. IN the back row from Left to right:
PCL200 linear output RF Amp, EF80 AM modulator, 90V Stabilizer
The middle row:
PABC80 amplifier and rectifier for the PM84 indicator, PCF80 AF amp. and carrier oscillator.
Looking forward to your feedback
Semir
