Base on the information provided by the manufacturer, the primary impedance is 5.5k ohm,
As the impedance of the transformer cannot be measured by a simple muitmeter, I can only reply on the provided information.
I am not very sure it is 100% correct.
I think frequency affect the impedance of the transformer,
any idea on how to measure the impedance of the transformer ?
I do not have a oscilioscope. To determine if 4.7uf is sufficeint or not, I used the internet site which provides sounds in 30Hz. See if I can hear the signal (sound) pass thro the transformer to the headphone. Any other suggestions?
English is not my mother language, I am sorry if I present my idea in a strange way.