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Author Topic: Audio recording both sides of a communication  (Read 392 times)
N6MDM
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Posts: 1




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« on: December 21, 2001, 08:30:45 PM »

I am sure that this is a well-known technique, but can anyone tell me how, generally, one sets up to record both sides of my radio traffic?  Recording the recieved part seems easy, but what about my side?

I have an Icom M710 if that helps.

Thanks!
Michael
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W8MW
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Posts: 310




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« Reply #1 on: December 27, 2001, 10:04:33 AM »

Hi Michael. As with most audio recording endeavors, a good place to begin is to identify the desired application for the final product.  For example, a recording of this nature might be made only to document the content of the radio communication with little concern for the audio quality.  On the other hand, if you want to make high quality recordings, more sophisticated techniques and better hardware are called for.

Most modern amateur transceivers have built-in monitor circuits that let you hear the transmit audio.  This makes it simple to record both sides of a QSO.  Just run the rig's Line Out or Spkr out into your recorder's Line In input.  Very nice results can be achieved once all the levels are set (and you confirm that there are no hums, buzzes or RFI).

But I suspect your rig may not have the monitor.  If that's the case, you may need to use a mic on the recorder and capture everything acoustically instead of electronically.  It should be possible to find a position for the mic that lets it "hear" your voice plus audio from the speaker.

Recording hardware will have a lot to do with the results you get. A lot of hams who are into audio are using mini-disc recorders. I can't recommend a specific model but do suggest that any recorder you buy should have both Mic In and Line In capability.  Cassette machines are a viable option too.  I get excellent results from my Marantz PMD201 which is a  portable unit with a history of field service in broadcasting.  

Hope some of this was helpful!  
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W4CNG
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Posts: 177




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« Reply #2 on: December 27, 2001, 11:16:20 AM »

I am using a Stereo Cassett deck to do my recording.  I use the speaker output for one channel.  I use an external speaker on my station (better quality audio)  Take the speaker output (unless you have a line out that would feed your computer or tnc for digital modes) and get a 3-8 ohm to 500 ohm transformer (radio shack).  Install a 25 ohm 5 watt pot (radio shack) across the speaker.  Wire the 3-8ohm side of the transformer to the wiper and ground.  This gives you level control.  Wire the secondary to the recorder input.  Do a quick test with the RX output of your radio set to a comfortable level in the shack.  Do a 1-2 minute recording adjusting the level control on your recorder to 12 o'clock or 50% gain.  Adjust the 25 ohm pot for good input level.  Play it back and see how it does.  

Then key your rig and talk near to your rx speaker and see if you get a recording using the speaker as a microphone into the same channel.  If you get even a little it is not bad.  Elsewise you are going to need a second mic feeding the other channel of the recorder to hear your side.

Since I am into Lo-Fi audio I have a complete TX audio path that ends with a W2IHY 8ch EQ.  There is a headphone output (8ohms) with a volume control on the unit that gives you the ability to listen to your audio before going into the rig.  I did the same thing with this as on the RX side to record the TX side.  One more 25 ohm pot, one more 8-500 xfmr.  Adjust levels and you are on board to TX/RX recording.

Good Luck Steve W4CNG
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KA7GKN
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Posts: 147




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« Reply #3 on: August 29, 2002, 08:34:32 PM »

I use a mini-disc recorder the sony mzr700 series you can find these at best buy. actually the sharp mini disc series might be better for you since they have a record volume adjust capability.sony is auto adjust
take the line out audio from the radio to the line in of the mini disc and then for on air playback take the line out of the mini disc to the line in of the radio

using a mixer may make the operation easier especially
if your radio does not have the line in/out capability I'm not familiar with your particular model. you can adjust the mixer eq to adjust for playback fidelity and levels if that's your desire.
behringer mx602 is a good starter mixer on sale now a days for 60 bucks..and it's rf proof

good luck and have fun

marty       ka7gkn@arrl.net
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