In Reply to: Re: End Of Zen schematic posted by Anand on October 30, 2001 at 09:01:58:
Hey Anand,Let me begin by saying I am no guru but...
I think the H3008 may be more suitable here.I believe the Hammond was chosen by Tom as the choke because it was a budget part that could do the job at hand while being easily obtainable, budget being the operative word here. Its a power supply choke and not a plate choke so there are some compromises (as always)in its use as a plate choke. Tom can straighten me out here.The rule of thumb for the choke I know of is preferably ~20H per 1K primary Z so if you are using a opt with a 5K primary you want ~100H. Thats not to say that 15H or 30H will not work, the extra inductance is supposed to work better.
There is another rule of thumb I have read where the opt inductance should be ~4X the choke inductance, so... if you have a 100H choke you want an opt ~400H (thats a lot!!).
Thats part of the reasoning behind the fancy materials in the opt's, higher inductance.
Now, having said all this I have seen more than one design where the choke is ~80H and the opt ~20H, which is the opposite and of course it works.
I breadboarded (new word!) a "parazen clone" 6n1p - Triode wired el84 with a PP opt as choke and 125e as opt and it worked quite well.
I guess with all the rules it still all comes down to trying it and listening to see how it works, just like what Tom did.AB
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