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In Reply to: RE: Trusty McShaned Eico HF87 posted by Eli Duttman on August 15, 2016 at 13:42:03
Thank you for your kind words. The HF 87&89 use a fifty ohm 10 watt resistor between the voltage doubler caps and the B+ filter/storage capacitor do you have a recommendation for a specific choke to replace the resistor, or any other ideas to reduce the ohm value of this resistor to reduce the DC resistance of the power supply?
Follow Ups:
like what's in the Mac Mc240 and the Citation 2.Now I had a 50 ohm choke in there at 1hy.I took it out and put in a .5hy at 30 ohms..The B+ went up 2.3 volts.having a choke there really improves backgrounds,clarity,and overall control of the amplifier.I'm going to use the HF89 bias scheme and the reason I like the older bias schemes where they use a balance and bias pot,it is so much easier to bias because you aren't chasing the bias so much.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
What is the current capacity of the choke you used? I have never measured the voltage drop across the 50 ohms to see how much current is flowing.
300ma on the .5hy at 30ohms and the 50ohm choke was 1hy at 240ma.Those low Mu and low DCR chokes have a an effect on low level resolution that can't be denied IMHO.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
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