Background Hissing

[Aaron, N3MBH]

Hello James,
There isn’t really a setting in alsamixer for this. I would just make sure that your outputs and inputs are set first to a reasonably level in software (alsamixer) so you get better dynamic range, then adjust your pots on the SVXLink card.

Outside of that, I would suspect 1 of 2 things. Either you are getting RF introduced back into the input audio via your sound card or cabling, or you just have cheap sound cards. I have some sound cards that introduce hissing. If you can try to test input and output on a computer and see if the hissing is present. For the first item, try running into a dummy load to see if you can attenuate your TX signal enough as to not effect the RX side.

73,
Aaron – N3MBH / WRFV871

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[James, VE1JCS]

Just an update, I checked what you mentioned and could not correct the problem. What i did find that eliminated the problem was shorting out the 1k resistor on the Repeater input (R13) That seems to correct the problem?
So i just soldered in a jumper pin on both inputs resistors thus allowing me to short out the resistor if required. It also gave me more audio, but was able to adj. that down by using the potentiometer

James VE1JCS

[Aaron, N3MBH]

James,
Glad to hear you found a solution. Yeah unfortunately when interfacing hardware together you can encounter some strange situations like that. I know when interfacing my ICS board to my Motorola repeater, I had some issues with it holding the PTT active after the initial key up with was baffling me. Ended up having to remove an LED that was functioning as voltage divider in my case can causing the pin to float.

73,
Aaron – N3MBH / WRFV871

OpenRepeater is offered free of charge. Find out how you can support us.

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