BCD536HP Base Antenna Issues

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Doublea626

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So I got A Tran 1410 Discone and mounted it next to my 2 meter antenna (same mast/above by 3 feet). The coax goes in the house very close to the 2 meter coax (problem?). Upon plugging the discone to 536, I get audio clipping, and then audio drop on the 536 (not transmitting on 2 meter); and the scanner audio is bleeding through to the 2 meter radio's channel in the mixer I use- Is this some sort of feedback loop since evrything ties back to a mixer and antennas on same metal mast?? btw-I don't have it plugged directly into the wall, rather a power bar. And the adapter gets super hot (radio gets pretty warm too).

Any help would be appreciated
 

RFI-EMI-GUY

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You may very well have a ground loop problem and if the scanner is connected to the mixer without an isolation transformer you may damage something. I would unplug scanner from the mixer right away. The scanner wants to see a speaker or an isolation transformer. If either terminal of the audio out is grounded you may damage something.

 

Doublea626

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You may very well have a ground loop problem and if the scanner is connected to the mixer without an isolation transformer you may damage something. I would unplug scanner from the mixer right away. The scanner wants to see a speaker or an isolation transformer. If either terminal of the audio out is grounded you may damage something.
Thanks- It was working perfectly fine with the stock antenna, but once I introduce the LMR 400 to the discone, I get loud clips when turning the 536 on/off. Even into the mixer the same way. I also noticed when I power off the scanner and unplug the BNC, I hear a hum. Something's all crossed up...
 

RFI-EMI-GUY

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you are providing another ground to the scanner via the LMR400. Nothing wrong with a ground. In fact it all needs to be properly grounded. But is your setup is like 90% of the folks using a mixer or a sound card, you have inadvertently grounded one side of the scanner speaker amp which is a bad thing.
 

Doublea626

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So a ground loop isolator be a solution? What would you suggest? btw I have not been able to ground the mast yet... That will have to be soon!
 

RFI-EMI-GUY

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See Notes: Use the link in my first reply to see the radio shack isolation transformer on RS webpage.
"Notes

The typical radio output will be an 1/8 inch mono jack. Always use the Line Out, Record Out, or Tape Out when available on the scanner. This provides a constant audio level to the streaming computer and allows you to listen to the scanner's local speaker whenever you wish. Failing that, use the Headphone jack, not the speaker output. You can monitor your scanner via the streaming computer's speakers.

The typical computer sound card input will be an 1/8 inch stereo jack. The Line Input is desirable and is usually color-coded blue. Some computers, particularly laptops, only provide a Mic Input and this is usually color coded red.

Line output of the radio to line input on the computer is the best connection as this gives the cleanest audio and still allows you to listen to the scanner on its local speaker. Once you set the audio level, you don't have to touch it again since the volume control does not affect the line output.

Uniden scanners must be programmed properly so that each channel is set to Record = ON to allow audio to flow to the Rec or Tape Out jack. If you skip this step, the feed will not get audio from the scanner on those channels.

Newer Uniden scanners label the line output “Rec” (for Record out) and is located on the rear of the radio and is color coded green. The Record output needs to be turned ON via the software to activate it for use.

If you need to connect the headphone output of the radio to Mic in on the computer you will need to watch your audio levels on both the radio and computer. It is very easy to overdrive the audio.

Avoid using the speaker output of the radio because the output level maybe too high for the computer input and cause distortion. If this is all you have, keep the volume level low, between 1/4 to 1/2 volume.

The use of an audio isolator can help to eliminate hum between radio and computer due to different a.c. power grounds. Radio Shack has an isolator listed in #Related Links. It is an audio transformer that blocks d.c. continuity between the scanner housing and the computer case.



Monitor the desired frequencies to ensure that the scanner does not receive radio interference from computers and computerized equipment nearby. If necessary, move the scanner around or re-orient the power, audio, and data cables to avoid picking up stray radio energy from devices in your shack. You'd be surprised how dirty some devices are."
 

RFI-EMI-GUY

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Since your discone and your 2 meter antenna are on same mast. you are getting a ground somewhere, probably through the 2 M radio. Fix the ground loop and then ground everything to ARRL, Motorola R56, NEC, Polyphaser. SINGLE POINT GROUND SYSTEM tied directly to where your AC meter gets its ground.
 

Doublea626

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Since your discone and your 2 meter antenna are on same mast. you are getting a ground somewhere, probably through the 2 M radio. Fix the ground loop and then ground everything to ARRL, Motorola R56, NEC, Polyphaser. SINGLE POINT GROUND SYSTEM tied directly to where your AC meter gets its ground.
Thank you so much for the info!
 
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