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G8HQP Dave · 14th Jul 2011, 6:37 pm

I did say broad brush!

My guess is that battery valves are mainly pentodes because they need all the gain they can get, and distortion is secondary. There is a battery triode (DCC90?) which was intended for VHF.

6146 is large signal, and I said that is complicated. Triodes are used for VHF (and up) receivers because of noise. Noise is not such an issue in transmitter PAs. Instead, you need to reduce anode-grid capacitance so use tetrodes/pentodes. Why these tend to be tetrodes rather than pentodes I don't know - someone will tell us! 6146 is really an HF valve which happens to extend up to 175MHz.

14th Jul 2011, 6:37 pm	#22
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Triode vs Pentode I did say broad brush! My guess is that battery valves are mainly pentodes because they need all the gain they can get, and distortion is secondary. There is a battery triode (DCC90?) which was intended for VHF. 6146 is large signal, and I said that is complicated. Triodes are used for VHF (and up) receivers because of noise. Noise is not such an issue in transmitter PAs. Instead, you need to reduce anode-grid capacitance so use tetrodes/pentodes. Why these tend to be tetrodes rather than pentodes I don't know - someone will tell us! 6146 is really an HF valve which happens to extend up to 175MHz.