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Title: Another Tiny Transmitter Post by: WA4WAX on February 01, 2019, 09:41:01 PM About 1 watt. CW only, but I guess one could mod it. Got a couple of 1S4's??
Title: Re: Another Tiny Transmitter Post by: ka1tdq on February 03, 2019, 03:59:50 AM At 1 watt, maybe just screaming at the B+ supply would do it.
Jon Title: Re: Another Tiny Transmitter Post by: PA0NVD on February 03, 2019, 08:58:02 AM Or no tubes at all and talking in a carbon mike in the ground of the antenna system
1912, Moretti Spark gap, Marzi carbon microphone, 1 kW AM!!!! Title: Re: Another Tiny Transmitter Post by: PA0NVD on February 03, 2019, 08:59:44 AM forgot the pic.
Title: Re: Another Tiny Transmitter Post by: kb3ouk on February 03, 2019, 10:12:29 AM If it could handle the voltage, you could almost put the carbon mic in series with the B+, it is only 90 volts and the battery voltage on a telephone line is typically 45 volts or so, so it might work. The variable resistance of the carbon mic under audio would vary the plate voltage, which would modulate the transmitter.
Title: Re: Another Tiny Transmitter Post by: PA0NVD on February 03, 2019, 10:40:14 AM The Marzi microphone is a complex construction that can handle a few amps of RF using a stream of carbon powder to avoid heating. In the old days of AM, it was common to put a carbon mike in the antenna system to modulate. In order to handle high currents, many microphones were used in series or parallel, see the Lorenz microphone
In the B+ line it will not modulate well, the impedance is too low. But I did put a circuit for a carbon mike substitute in the Military section. When using a bigger transistor and more current, you can directly modulate the transmitter with an AF output transformer in reverse. Title: Re: Another Tiny Transmitter Post by: Opcom on February 03, 2019, 01:01:45 PM Back in the day I can imagine them employing a small boy for a few pennies a day to stand there and empty that cup of carbon back into the hopper while the thing was live. :P AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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