When you pull the flat RX audio off the 16 pin accessory socket on the back of the 900 MHz Maxtrac, is that the companded audio or is it normal audio after the de-companding circuit?
If you want to run hearclear on your repeater you don't want to compand the companded audio!
Thanks,
George
KJ6VU
Maxtrac audio output with hearclear
Moderator: Queue Moderator
You are correct that you only want hear-clear enabled in one place, and that's probably NOT the repeater if all the users have it turned on.
The flat RX Audio on the accessory jack picks up de-emphasized audio out of the RF board's detector circuit. There is no way to access any of the hear-clear circuitry from the accessory jack.
The hear-clear circuitry is located in the control head of the 900 MHz MaxTrac and consists of two halves: one is in series with the front panel mike jack where it feeds the logic board, therefore it only processes audio from this source; the other is in series with the audio that feeds the top of the volume control and headphone audio pin on the mike jack, so the controlled audio that goes back to the audio amplifier on the logic board will be processed by hear-clear.
If you use the front panel mike jack for all your repeater functions (the only thing missing is a COR signal and that can be routed to an unused pin and brought out), then you can enable or disable hear-clear as you see fit, and it will do the appropriate processing.
Bob M.
The flat RX Audio on the accessory jack picks up de-emphasized audio out of the RF board's detector circuit. There is no way to access any of the hear-clear circuitry from the accessory jack.
The hear-clear circuitry is located in the control head of the 900 MHz MaxTrac and consists of two halves: one is in series with the front panel mike jack where it feeds the logic board, therefore it only processes audio from this source; the other is in series with the audio that feeds the top of the volume control and headphone audio pin on the mike jack, so the controlled audio that goes back to the audio amplifier on the logic board will be processed by hear-clear.
If you use the front panel mike jack for all your repeater functions (the only thing missing is a COR signal and that can be routed to an unused pin and brought out), then you can enable or disable hear-clear as you see fit, and it will do the appropriate processing.
Bob M.
Hi Bob,
So are you saying the following...
If the mobile unit transmits hear clear when you pick off the rx audio on the 16 pin accy connector on the back, that is discriminator audio and has not yet hit the hear clear de-companding (expanding?) circuit yet?
In my system we will have a 900 Mhz repeater tied to a UHF repeater and multiple UHF link radios all of which of course don't run hear clear except the 900. So, routing the accy socket flat rx audio to the non hear clear radios is a bad thing because I would be passing companded audio. Is that right?
If so, I would have to pick off the audio from the control head after the hear clear de-companding circuit.
Thanks for the help.
George
KJ6VU
So are you saying the following...
If the mobile unit transmits hear clear when you pick off the rx audio on the 16 pin accy connector on the back, that is discriminator audio and has not yet hit the hear clear de-companding (expanding?) circuit yet?
In my system we will have a 900 Mhz repeater tied to a UHF repeater and multiple UHF link radios all of which of course don't run hear clear except the 900. So, routing the accy socket flat rx audio to the non hear clear radios is a bad thing because I would be passing companded audio. Is that right?
If so, I would have to pick off the audio from the control head after the hear clear de-companding circuit.
Thanks for the help.
George
KJ6VU
Yes, that's it exactly. The flat audio on the accessory jack is right off the discriminator (technically it's a quadrature detector but old lingo is hard to drop sometimes) and the audio here would be compressed if receiving a signal from a station with hear-clear enabled.
You can pick up everything, except a COR signal, from the mike jack. The headphone audio signal is actually picked up from the top of the volume control after the hear-clear circuit has straightened out the audio.
Similarly, you can inject line-level audio (0.1-0.5VRMS) into the mike jack and it will get compressed by the hear-clear before modulating the radio. This also isolates any PL/DPL encode/decode signals so they stay completely inside the radio.
If you have the desire to take everything from the front panel mike jack, you can wire a COR signal to an unused pin and it will come out on pin 1 of the RJ45 connector. This lets you get everything from that one connector and you can ignore the accessory jack entirely.
Bob M.
You can pick up everything, except a COR signal, from the mike jack. The headphone audio signal is actually picked up from the top of the volume control after the hear-clear circuit has straightened out the audio.
Similarly, you can inject line-level audio (0.1-0.5VRMS) into the mike jack and it will get compressed by the hear-clear before modulating the radio. This also isolates any PL/DPL encode/decode signals so they stay completely inside the radio.
If you have the desire to take everything from the front panel mike jack, you can wire a COR signal to an unused pin and it will come out on pin 1 of the RJ45 connector. This lets you get everything from that one connector and you can ignore the accessory jack entirely.
Bob M.