Attenuation problem in connecting radio output to Line In on computer

Discussion in 'The Projects Forum' started by KE5TJL, Dec 1, 2014.

  1. KE5TJL

    Thread Starter New Member

    Dec 1, 2014
    I'm a ham operator who needs help. I am trying to finish a project where i can remotely connect from my laptop to my home computer which is connected to my HF radio. This is in part to help ham friends that are in the hospital, or unable to get on the air. The problem is that I want to take the HF radio audio out (an 8 ohm speaker jack) and connect it to my Line In on the computer right beside it. I connect a straight through cable and I can hear some on the laptop but the audio is not very good , it actually sounds distorted and a lot of bass on the audio. I think I need to insert something like resistors to make the 8 ohm audio on the same level of the Line In of the computer. I know it is 8 ohms on the speaker jack, but I can't find out anything about the Line In. Any suggestions or a simple schematic would help. Thanks in advance!
  2. iimagine

    Active Member

    Dec 20, 2010
    Google 'speaker to line level'. All you need to do is reduce the voltage down to line level voltage.
  3. MrChips


    Oct 2, 2009
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
    radio shack sells a 500 ohm to 8 ohm transformer that will do the job. for more on interfacing to sound card, there has been many articals on the internet for interfacing radios to computer for psk 31 and other digital modes.
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
    You should use a transformer in this path. The trick is to avoid an Ohmic connection between the sleeve of the HF Rig Phone Jack, and the sleeve of the Mic input jack. If you don't have transformer isolation, there is a strong likelyhood of a bad ground loop between the chassis of the HF rig and the ground on the laptop...