UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Heathkit DX-40/DX-100 Modern High Impedance Microphone?

g4aaw pete · 7th Apr 2022, 9:58 pm

If you get the two-connection type of electret element, the voltage source can be inside the transmitter. An isolation capacitor (4.7uF) is then connected from the voltage source point to the AF input of the circuit.

Call me crazy, but I took voltage from the H.T. supply via 150kὨ and put in a string of forward biased diodes (five) to set the voltage to 3v.

7th Apr 2022, 9:58 pm	#16
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Re: Heathkit DX-40/DX-100 Modern High Impedance Microphone? If you get the two-connection type of electret element, the voltage source can be inside the transmitter. An isolation capacitor (4.7uF) is then connected from the voltage source point to the AF input of the circuit. Call me crazy, but I took voltage from the H.T. supply via 150kὨ and put in a string of forward biased diodes (five) to set the voltage to 3v. Attached Thumbnails __________________ Regards Pete