Re: Ubitx - carbon mic
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The earpiece in the telephone makes a good dynamic element
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in a microphone but because the Bitx is designed for an electret microphone and the electret elements are so common, I also consider it a waste of time to go outside the design of the radio as far as microph9nes are concerned. You have me beat in regard to years of telecom service. {;-> Bob ¡ª KK5R -------------------------------------------- On Sat, 12/22/18, MVS Sarma <mvssarma@...> wrote:
Subject: Re: [BITX20] Ubitx - carbon mic To: [email protected] Date: Saturday, December 22, 2018, 9:37 AM Don'y bother. I had 40yeasrs of experience in Indian Telecom.?I get your point , sir.?regardssarmavu3zmv On Sat, Dec 22, 2018 at 8:00 PM Bob Lunsford via Groups.Io <nocrud222@...> wrote: The telephone I referred to for using the earpiece is here and note that the device across the earpiece was "shunted to keep from hearing the dialing impulses." -------------------------------------------- On Sat, 12/22/18, Bob Lunsford via Groups.Io <nocrud222@...> wrote: ?Subject: Re: [BITX20] Ubitx - carbon mic ?To: [email protected] ?Date: Saturday, December 22, 2018, 8:54 AM ?Careful reading will show that I was not ?talking about the Wiki "Mouthpiece" ?which is a carbon unit but about the ?EARPIECE which is an earphone that ?closely resembles a dynamic microphone ?element. ?I worked in the telephone industry. ?First with General Telephone i 1965 and ?later for DoD as a system installer in ?foreign countries. The telephone "earpiece" ?is from a phone of the late '60's era. ?I hold one in my hand as we speak. ?Bob ¡ª KK5R ?-------------------------------------------- ?On Sat, 12/22/18, MVS Sarma <mvssarma@...> ?wrote: ? Subject: Re: [BITX20] Ubitx - carbon ?mic ? To: [email protected] ? Date: Saturday, December 22, 2018, ?2:02 AM ? Not earpiece but ?mouthpiece. ? On Sat, Dec ? 22, 2018 at 5:17 AM Bob Lunsford via ?Groups.Io ? <nocrud222@...> ? wrote: ? Try the earpiece from an ? old cradle type telephone. ? The carbon mic element is not ?advisable since it has an ? inherent hiss that may have to be ?filtered out. ? The earpiece has a diode-looking ?device across the ? terminals, probably two diodes ?back-to-back to keep the ? switching clicks from blasting the ?telephone user. Remove ? this to avoid introducing some ?unknown/unwanted result. ? The earpiece is about 600 Ohms from ?what others have told ? me. Therefore, you will probably need ?a one-transistor amp ? for impedance matching. The amp ?previously cited may do ? it. ? Bob ¡ª KK5R ?-------------------------------------------- ? On Fri, 12/21/18, iz oos <and2oosiz2@...> ? wrote: ? ?Subject: [BITX20] Ubitx - carbon ?mic ? ?To: [email protected] ? ?Date: Friday, December 21, 2018, ?9:51 AM ? ?Has anyone tried a carbon mic ? ?with the ubitx? How to wire it? The ?Shure 104C manual ? seems ? ?an interesting starting point. |
Bob Lunsford