"One Linear Transmitter"

Adding a visual VU-Meter.

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This information is provided for educational purposes and/or authorized usage only.



Check out the video at the bottom of the page.


Evan's comments on this TX

First: For my comments regarding the "One Linear Transmitter", which forms the basis for this TX, please see: http://www.xminusone.com/am/power/power.htm

Modifications made during this revisit:

  1. I've added a 6E2 as a VU-Meter which responds to the modulated audio.
  2. Note: I had to disassembly the 6E2, tube socket, grind new notches, then spin it to the correct position in the metal frame and reassemble it to get the indictator tube "face" to face the direction as shown in the pictures. The best one I've found that will allow you to do this is the "QQQ Japan 9 Pin Noval Top Chassis Mount Black Phenolic Tube Socket"
  3. Just like my previous "One Linear TX", I'm using a 6GH8A tube not a 6CQ8 tube. The 6GH8A triode section has a slightly higher amplification factor (46 vs 40) which modulates just a bit better.
  4. The power transformer used is the Hammond 262F6.
  5. Cabinet size is 6" X 8".

Adding a visual VU-Meter adds a pretty cool look!

Please also see my "Lessons Learned" at the bottom of this page.


Click on the image below for a larger schematic.


For a closer look at the tuning eye circuit.


The schematic above always show the latest updates. Click on it for a full view.

The pictures below may not show every update.

Click on any image below for a larger picture.

The ribbon cable you see goes to the LED's installed in the tube sockets.

All on a single 6" X 8" top!



To answer your FAQ's

Lessons learned!


If you have a transformer that is not center tapped try the E section of the circuit below to obtain some negative bias voltage.

Point E is the negative bias supply .


Are Your Capacitors Installed Backwards?




This is what the TX sounds like while listening to a 1938 Air Castle radio - with a 12" speaker.