Do not expect to have here the latest greatest audio tube/valve amplifier.
Having said that, it works for me and still give a reasonable audio output, understand by reasonable; it's audible but not big volume, you can keep comfortable the speaker 10cm from you ear. Let's said this is the amplifier you need in case you run out of any other device that can give you audio amplification.
Some photos and diagram bellow.
The glow:
..violet color on the heather is due to camera, in reality is more on the orange/yellow side.
The testing board
The schematic
..this worked for me, for sure there could be a lot of improvement but I just wanted to try and prove the concept. The "audio output transformer" is just a 230/9V power supply one, I tested with a 230/15 and with one with multi taps and all work but would be preferable to use a real audio one.
This also works if you remove the left side o the circuit and inject audio directly on pin 7 of the rightmost tube (with the audio transformer), at the expense of lower output.
Audio sample listening to 10.100Mhz weather station with a lot of fade.
The audio from the capture is not the greatest, a little better in real but still on the low side, I'm sure with a real audio output transformer, a higher supply voltage and some optimization would be a reasonable amplifier, but again you have other specific tubes and designs to make it better.
Have fun!
Having said that, it works for me and still give a reasonable audio output, understand by reasonable; it's audible but not big volume, you can keep comfortable the speaker 10cm from you ear. Let's said this is the amplifier you need in case you run out of any other device that can give you audio amplification.
Some photos and diagram bellow.
The glow:
The testing board
The schematic
..this worked for me, for sure there could be a lot of improvement but I just wanted to try and prove the concept. The "audio output transformer" is just a 230/9V power supply one, I tested with a 230/15 and with one with multi taps and all work but would be preferable to use a real audio one.
This also works if you remove the left side o the circuit and inject audio directly on pin 7 of the rightmost tube (with the audio transformer), at the expense of lower output.
Audio sample listening to 10.100Mhz weather station with a lot of fade.
The audio from the capture is not the greatest, a little better in real but still on the low side, I'm sure with a real audio output transformer, a higher supply voltage and some optimization would be a reasonable amplifier, but again you have other specific tubes and designs to make it better.
Have fun!
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