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Old 24th Nov 2010, 9:13 pm   #3
G8HQP Dave
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Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
Default Re: Low noise amplification with mulitple valves

You only get the advantage if you don't have to share the signal power between the devices. Valves have such a high input impedance that you can sometimes get away with this. However, the advantage may be illusory as you can get better noise performance just by using higher gain valves, instead of paralleling loads of lower gain ones.

If you do parallel valves, don't forget that the maximum grid leak resistor has to be divided by the number of valves. This may limit what you can do.
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