Re: [Elecraft] K2 and K3 Microphone Input Impedance
On 1/6/2011 2:55 PM, George Jan wrote: It is not critical at all - should be at least 10 times the microphone impedance. Actually, the current applicable IEC Standard DEFINES the impedance of a microphone as 5X its rated load impedance. And yes, a higher input Z is better -- the rated impedance is a minimum value. Most professional mics have an impedance of 150-250 ohms, and most pro mic inputs have an input impedance of at least 1K-1.5K ohms, and there are excellent technical reasons for values of 5K ohms or greater. 73, Jim Brown K9YC Member, AES Standards Committee and WG on Microphones __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K2 and K3 Microphone Input Impedance
Wayne et al. I am surveying various rigs to see what their microphone input impedance values might be. I note the K3 schematics show just about every audio path including the microphone's path terminated in 10k ohms or so. In the KSB2 I see 1k ohm (or 180 ohms if /ATTEN is asserted). Was there a compelling reason for having different termination values, 10k vs. 1k, between transceiver model lines? Thanks. John __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 and K3 Microphone Input Impedance
John, I would not select a radio on the input impedance of the microphone input! It is not critical at all - should be at least 10 times the microphone impedance. Pro-Audio from as far back as the antique Western Electric unbalanced systems of the 40s tend to be in the range of 1 k to 10 k. Mostly depends on what the designer wants to emphasize. Lower would tend to reduce noise pick-up. Higher would tend to load the mic less thus improving S/N. Probably neither value is significant. George AI4VZ -Original Message- Was there a compelling reason for having different termination values, 10k vs. 1k, between transceiver model lines? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 and K3 Microphone Input Impedance
Rest assured George, the mic input Z is not a rig selection criteria for me. This is for a completely different item I am developing to adapt my mics to various rigs including the K2 and K3. John On 1/6/2011 5:55 PM, George Jan wrote: John, I would not select a radio on the input impedance of the microphone input! It is not critical at all - should be at least 10 times the microphone impedance. Pro-Audio from as far back as the antique Western Electric unbalanced systems of the 40s tend to be in the range of 1 k to 10 k. Mostly depends on what the designer wants to emphasize. Lower would tend to reduce noise pick-up. Higher would tend to load the mic less thus improving S/N. Probably neither value is significant. George AI4VZ -Original Message- Was there a compelling reason for having different termination values, 10k vs. 1k, between transceiver model lines? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
