kodera2tI've got IR5, it's "heptode"=7 electrode vacuum tube. The structure is two additional electro-inserted pentode. Two additional electrode can work as local oscillator and as a whole, this tube can serve "frequency conversion". More exact explanation is available at wikipedia.
More than 40 years ago, pocket battery radio was made with this tube and 1R5 was widely utilized. I quickly wired "breadboard superheterodyne radio".
IFT (intermediate frequency transformer) for vacuum tube is hard to find, so I simply use ones for transistor expecting it will work as I expected. (the difference between vacuum tube trans and transistor is current tolerance. Thin wire in Tr trans may burn out for high current, but it will work in battery tube,,, I hope). The configuration is, IR5 for mixer/local oscillator, 1T4 (later I changed it 1L4) for IF amplifier, and 3A5 for IF amplifier and AF amplifier.
One thing I had to do is check capacitors of unknown variable capacitor and IFT.
It is quite important to know values for completing circuit. Otherwise we have to struggle in the complete dark (and will lose)
.... And finding parameters and making......
And... it works as above picture!
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Wow that's a rare one. I may have seen a data sheet for such a beast but I only worked with a maximum of pentodes.
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Haha! Yeah, it's very useful tube speficied for frequency conversion. Oscillator+mixer all in one!
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