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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 11th Oct 2014, 1:56 pm   #21
SurreyNick
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Default Re: Optimum working anode voltage : Circuit design

When trying to use original 1920s and early 1930s baseboard mount components I'm discovering it still is an expensive hobby! Especially as I refuse to 'break' original receivers to rob them of components. If only there were an affordable source of these

It's a valid and interesting point about there being no one optimum bias condition and artful design involves a compromise between maximum gain, maximum power output, minimum distortion or minimum noise.

For someone with limited experience such as myself the scarcity of practical experience and knowledge is in itself an additional challenge, which is why I rely so heavily on the collective of this forum - even when that means running the risk of becoming a nuisance!

David sums it up neatly when he says "Practice is like having a machete and chain-saw for hacking your way through a jungle. Theory is like having a map and a compass so you can tell which way you're going and which way you want to go. Without the whizzing blades you're not moving, without the paper and the magnet you'll just wear yourself out going in circles. Neither is better (or worse) than the other, but together they're unbeatable."

I just want to make sure I have the right map, or in this case 'circuit' in my hands before I start hacking. I thank the contributors to this thread and I will follow the advice. I will also, for the testing stage before I finally mount the components on the cabinet face, consider how I might incorporate some form of adjustment into the circuit where I can vary the voltages and bias to each of the valves until the set is balanced at the optimum for the components I have.

Nick
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Old 11th Oct 2014, 1:59 pm   #22
G6Tanuki
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Default Re: Optimum working anode voltage : Circuit design

The "best working voltage" will depend on the precise application you intend to use the valve for, and the circuit in which it's placed.

Audio/radio-frequency voltage- and power-amplifiers have different requirements, as do regenerative, anode-bend or leaky-grid detectors. If you're considering the valve's function as a mixer a whole different set of 'bests' come into play!

Are you after greatest voltage-gain? Greatest power-gain? Most-linear operation (lowest distortion/cross-modulation) or best function as a detector? Class-A, B, or C?

There's no single 'best'. Honestly!
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Old 11th Oct 2014, 2:05 pm   #23
SurreyNick
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Default Re: Optimum working anode voltage : Circuit design

Yes. I think I'm beginning to get the point
This is why I am now wondering, having got the components, I can lash it all together and using some sort of variable adjustment in each valve circuit I can play with the anode and bias voltages of each valve until I have a balance that works best for Radio 5 Live...
(R5L because the receiver is a gift for my wife and it's the station she invariable listens to).
Nick.
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