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Old 5th July 2008, 11:48 AM   #1
noyan is offline noyan  Turkey
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Default Plate choke material, why to use amorphous core?

Hello,

-Interstage transformer or output transformer should deliver all frequency spectrum of sound. That is why, the core of it should be fit to high, mid and low frequency spectrum. For me understandable why people using amorphous cores.

-If i am not wrong, the reason of using a plate choke is to supply DC voltage to anode of the driver tube but meanwhile also to stop the flowing of the music signal (sound) to the positive polar. The inductance value of the choke transformer should be big enough to prevent flowings of very low frequencies (15-20 Hz and up) over the choke to the + polar of supply. What is the reason for using amorphous core transformer as choke inductor??? Ordinary silicon steel should work excellent. Am i wrong???

Thanks!
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Old 5th July 2008, 08:06 PM   #2
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Seems to me the core material is where hysteresis and saturation
may affect a choke at low frequencies. Which material is better???
I don't know...

The technique of the windings is critical for the higher frequencies,
else there may be self resonant effects...

Suppose we just use big iron with simple windings, and wire a
gyrator in series with that to intercept the higher frequencies?

This would not really help with transformers, only chokes.
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Old 5th July 2008, 08:41 PM   #3
JoshK is offline JoshK  Canada
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It could have to do with the load that it presents to the tube.
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Old 6th July 2008, 09:26 AM   #4
noyan is offline noyan  Turkey
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Default plate choke core material

So, the important thing is this choke should have air gap and inductance should be sufficient. Core material is not important???
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Old 7th July 2008, 05:04 AM   #5
Tweeker is offline Tweeker  United States
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Core material matters, of course. Were just saying it might not matter as much beyond M6. Diminishing returns as per usual, not to say it wont make any difference.
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Old 7th July 2008, 12:25 PM   #6
noyan is offline noyan  Turkey
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Default plate choke

Thanks. What is your point that, the foil should be low impedenced, if i am not wrong understand. Actualy i wondered if i can use high impedenced 50-60H plate choke (1500 Ohms DC resistance) and driver tube plate current is 60mA. Then voltage drop on the plate choke will be 90V. This will help me also for biasing output tube. Driver and output tube direct coupled and powersupply units are independend. If i use 1500ohm coil do you think it make oscillation or any other trouble?
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