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Icom R6 - CTCSS Audio Hum?

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I briefly had an R6 earlier in the year but returned it due to an annoying audio hum anytime there was a CTCSS tone present with the received signal. This was produced both by the internal speaker, as well as when headphones were attached.

I am starting to wonder if I just got unlucky and had a lemon. Can anyone else with an R6 comment on whether their model does this?

Thanks in advance! :)
 

Gezelle007

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Was it receiving that way for every frequency that had CTCSS? Or just a certain one? Sometimes I can hear it through certain repeaters because the PL volume is turned up way to high and on other channels its not so bad.
 
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It was definitely on more than one frequency. Mostly public safety VHF/UHF traffic over repeaters. No hum on things like civilian airband. (In fact, airband reception was excellent.)
 

Gezelle007

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It was definitely on more than one frequency. Mostly public safety VHF/UHF traffic over repeaters. No hum on things like civilian airband. (In fact, airband reception was excellent.)
Yep, might have just been that radio then. I wouldn't expect it at all on the airband because they are AM and there is no need for CTCSS. So it was most likely just how that radio receives. I've had a Motorola radio plugged into head phones and you can't hear the PL at all even if there was one.
 

W2NJS

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A receiver capable of decoding PL is/should be built with a filter that eliminates all audio tones below 300 Hz. from the receiver's audio output. If you're hearing the PL tone there is something definitely wrong with the receiver.
 

hertzian

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You can hear PL tone from my R6 and R20's headphone output. The problem is that scanner headphone audio from most manufacturers, including Icom, is too hi-fidelity. Even my Pro-106 is not immune. Usually the PL tones above 150hz or so are heard.

In fact, every scanner I have ever owned is not properly designed to roll off the bass frequencies from the headphone output starting at 300hz. This problem is exacerbated by the use of hi-fi earbuds. Thus, when using earbuds, I always hear PL tones and it is very annoying.

Hearing it all the time through your internal speaker? Something is wrong there, as the speaker is usually incapable of reproducing low frequencies, or they should be very attenuated.

One solution is to use comm-quality headsets with the proper rolloff(s) - like a Kenwood HS-5. This headset works very well since it is not hi-fidelity. Unfortunately, they are large cans - but comfortable nevertheless. As for an external, perhaps try to make a custom unit from an upper-mid-range speaker you typically find in high-end stereo speakers....

It is too bad the Icom didn't incorporate the proper low frequency rolloff in the AF-Filter option, just the highs. But don't blame them too harshly - nobody gets this right, except for commercial and perhaps some amateur radios.

AND, part of the issue to look out for is that when a scanner incorporates the FM-Broadcast band, the manufacturer usually wants hi-fidelity - much to our displeasure.
 
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eorange

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Agreed with everything hertzian said. I am pretty sure I don't hear it through the speaker (will have to verify that one), but always with an earbud. Same deal with my PSR-500.

Your R6 wasn't a lemon.
 
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Hmm... thanks folks!

I'd be curious to know if your R6 passes that CTCSS hum through the internal speaker.
 

eorange

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I have been listening, and really can't hear the hum through the speaker.
 
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Okay, thanks! I'm thinking I had a bad unit as far as the internal speaker goes. One or the other I can understand, but not both.

Next question... R6 or save up for an R20? LOL :cool:
 
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Well, got a good deal on a lightly used R6 and went with that for now. Still have that R20 on the brain, maybe in the not-to-distant future... :)
 

hertzian

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Gulp. I forgot to mention that if you are using an external speaker (with or without an amplifier), when operating the R6's buttons, you might hear some blasts from the keys. You also may hear the "battery saver" ticking away - I had to turn that off when mobile and using amplified audio.
 
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Thankfully, no, haven't run into that pesky CTCSS audio hum. I do notice when tuned to the local NWS transmitter that the volume can't go above halfway or else there is a ton of speaker vibration and distortion, and a little case vibration. But their signal is cranked up, booming in, and full of bass. Turning the AF Filter to "on" alleviates a tiny bit of it. This is not nearly as bad for other local VHF/UHF signals, AM aircraft band, FM broadcast, AM broadcast. The little 150 mW internal speaker seems to do better with treble than bass. I'm sure this plays into what Hertzian was mentioning earlier...

Q: I'm curious -- how high your speaker can go before hitting the distortion/vibration? Around the halfway mark like my sample?
 
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