With the above post in mind...
Looking at this from the Handset perspective
Grey cable is your direct inject
Direct inject, is a lot like Tape Monitor Loop - it is a high drive level interface that allows you to use the signal present in the line to be equalized and sent to an amplifier to be then reproduced with good fidelity thru your speakers or headphones.
Your Mic amp is a lot like the Phono amp in a typical stereo receiver, it takes your audio from your mic element - filters and amplifies it greatly at the same time - a process of emphasis and de-emphasis (tonal filtering and amplification) and brings it to a level that can be considered acceptable as "Tape Monitor Loop-level Drive" so it can be sent to Pin 4 of your Audio amp - which by the way, needs a drive signal level of 3 to 4 VOLTS Peak to Peak to work, so you can now see how that mic amp needs to take a simple cone speaker coil that produces an output power voltage level signal of roughly 300 to as much a 750 mV (That's Mili-volts (mV) or even Micro-Volts (uV)) and put it into that same audio amp.
There is another problem with Bandwidth of the audio - and is why the Dynamic element approach is used because the requirements the other people want - your listeners - including your neighbors and the FCC. At least they want you to keep your stuff out of other peoples stuff and you can do that kind of stuff without having to use expe$ive stuff to make your Stuff sound better than anyone else's stuff...
STUFF_MODE=Quit_Stuffing_It. SET %Strawberry.Fld% as %0% UNITL %0% = %Strawberry.Fld% X %1%
QUIT_STUFFING_IT=On
Ok, the mic amp is setup to filter down your audio to just get your voice out there with not much else in fidelity to accomplish this.
You have other areas that use filters that Restrict or tone down your signal in both dynamics (Starvation and Limiter action) and tonal response (Your C148) as well as other Capacitance in-line both at the mic amp and at the output of the Audio Amp.
You can tweak some of these values to even make the typical Dynamic Mic element sound better than ever, but for now, let's just get you and your Mic input, to quit squealing...
In the Drawing above...
Looking at this from the Handset perspective
Grey cable is your direct inject
Direct inject, is a lot like Tape Monitor Loop - it is a high drive level interface that allows you to use the signal present in the line to be equalized and sent to an amplifier to be then reproduced with good fidelity thru your speakers or headphones.
Your Mic amp is a lot like the Phono amp in a typical stereo receiver, it takes your audio from your mic element - filters and amplifies it greatly at the same time - a process of emphasis and de-emphasis (tonal filtering and amplification) and brings it to a level that can be considered acceptable as "Tape Monitor Loop-level Drive" so it can be sent to Pin 4 of your Audio amp - which by the way, needs a drive signal level of 3 to 4 VOLTS Peak to Peak to work, so you can now see how that mic amp needs to take a simple cone speaker coil that produces an output power voltage level signal of roughly 300 to as much a 750 mV (That's Mili-volts (mV) or even Micro-Volts (uV)) and put it into that same audio amp.
There is another problem with Bandwidth of the audio - and is why the Dynamic element approach is used because the requirements the other people want - your listeners - including your neighbors and the FCC. At least they want you to keep your stuff out of other peoples stuff and you can do that kind of stuff without having to use expe$ive stuff to make your Stuff sound better than anyone else's stuff...
STUFF_MODE=Quit_Stuffing_It. SET %Strawberry.Fld% as %0% UNITL %0% = %Strawberry.Fld% X %1%
QUIT_STUFFING_IT=On
Ok, the mic amp is setup to filter down your audio to just get your voice out there with not much else in fidelity to accomplish this.
You have other areas that use filters that Restrict or tone down your signal in both dynamics (Starvation and Limiter action) and tonal response (Your C148) as well as other Capacitance in-line both at the mic amp and at the output of the Audio Amp.
You can tweak some of these values to even make the typical Dynamic Mic element sound better than ever, but for now, let's just get you and your Mic input, to quit squealing...
In the Drawing above...
- I apologize for the rough sketch, but there are factors and noises that can crop up into your work.
- Including, the shared shielding line that provides the SPEAKER ground return and the TX pin 3 grounding toggle contact - with your audio inject line.
- You can try using the Audio Shield to the TX Pin 3 - but cannot guarantee that the shield of the audio cable with not put your TX pin 3 to ground by another means as in your antennas coax cable
- - because many pieces of equipment use ground in some form or another - the Radios own Pin 3 may ground to the SHIELD of the mic radio thru your equipment.
- - so to make the connections correct, yet quiet, you'll need to see if TX pin 3 wire and lug can be your audio shield ground only when you need to TX.
- Why?
- This deals with CENTER lug In RX mode;
- you may wind up with a hum you can't get rid of because of the noise loop you can have between your audio equipment and your radio - the run length can act as an antenna and induce this noise into your work.
- - because many pieces of equipment use ground in some form or another - the Radios own Pin 3 may ground to the SHIELD of the mic radio thru your equipment.
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