XTL2500 RX_FILT_AUDIO pin behavior

[aaknitt]

From the manuals I've been able to find online, it appears that pin 21 of the accessory connector provides a fixed level audio output. I'm trying to reverse-engineer a rats-nest fire station speaker system, and it appears that one of the radios may have an external audio amplifier wired to this pin. The external amplifier then drives a couple speakers throughout the station. However, I've been told that the audio level of the speakers changes with the volume control on the radio. I'm not done digging into the system to figure out what exactly is wired to what, but is it possible (either via CPS option or a hardware modification) to get the pin 21 output to change with the volume control?

Thanks,

Andy

[tuckerm]

Pin 21 + ground (Pin 1 I believe) will give you a fixed level audio regardless of what the volume on the radio is set at. I use it for recording radio traffic off the XTL that ties into an accountability software.

[aaknitt]

Sounds good, thanks.

Andy

[Bill_G]

If the PA volume changes with the vol knob, they tied into the speaker.

[Jim202]

Pin 21 + ground (Pin 1 I believe) will give you a fixed level audio regardless of what the volume on the radio is set at. I use it for recording radio traffic off the XTL that ties into an accountability software.

These are the correct pins for fixed RX audio on pin 21 and ground on pin 1 or pin 14 for a low or mid power XTL mobile. Have used these connection pins for many years on the low or mid powered XTL mobile radios. If you have a high power radio, then the DB25 accessory connector needs to be used. Those pins are pin 9 for the RX fixed audio and pin 10 for ground. This RX fixed audio pin will not change the output level with the volume control.

Bear in mind that there is a DC bias voltage on the fixed RX audio pin, so I would suggest that you use a coupling capacitor of a 1.0 uf size or slightly larger. Put the plus side toward the XTL radio if you only find a polarized electrolytic capacitor. You don't need much for the voltage rating. A 15 volt rating will be more than enough.

Jim

[Aliraza1166]

that includes H35 and H37 already. You cannot but a XTS5K that is not factory capable of H35.????