07-24-2014, 03:01 PM
While looking for substiute choke I looked at the specs: the max DC current is 10mA, at 70H inductnce and 2300 Ohm resistance.
While this seems like a lot of current for to SGs to pull, according to the voltage chart the SG votages are 80V while the rectifier voltage is probably 260-270V which makes the current about 8.7mA, close to the max of 10mA.
Hammond makes 20H choke for 20mA at 1.7k resistance. 20H is not 70H but it will bring the cutoff frequency from 7Hz to 12.5Hz, which is acceptable. The resistance could be brought up by serializing with a smll 600 Ohm resistor to keep the voltages though I think itbis not very important.
The output transformer will probably be 125-ACE or equivalent if I find a cheaper alternative, needs to have 87:1 ratio.
While this seems like a lot of current for to SGs to pull, according to the voltage chart the SG votages are 80V while the rectifier voltage is probably 260-270V which makes the current about 8.7mA, close to the max of 10mA.
Hammond makes 20H choke for 20mA at 1.7k resistance. 20H is not 70H but it will bring the cutoff frequency from 7Hz to 12.5Hz, which is acceptable. The resistance could be brought up by serializing with a smll 600 Ohm resistor to keep the voltages though I think itbis not very important.
The output transformer will probably be 125-ACE or equivalent if I find a cheaper alternative, needs to have 87:1 ratio.
