HT1000 Background Noise Issue

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HankRock
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HT1000 Background Noise Issue

Post by HankRock »

I have tried everything to no avail, so maybe you guys can help me out here.

I have a customer who purchased a set of 6 used UHF HT1000. I programmed them and sent them back. 3 times now he has brought them back complaining that they can't understand any transmissions due to the mics picking up all the background noise. I've done hundreds of these radios, used them for years and never had this issue. I know there is no gain control and I've tried adjusting the levels, but what am I missing here?

Not sure if the previous owner changed something and I just don't see it?
sjxts3000
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Re: HT1000 Background Noise Issue

Post by sjxts3000 »

A wind-porting or background noise reduction speaker mic may help, but you're not going to get too far with the old HT1000's without the noise cancelling RSM.
KG4INW
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Re: HT1000 Background Noise Issue

Post by KG4INW »

To me, it sounds like the Jedi microphonics issue: http://batboard.batlabs.com/viewtopic.php?t=61634

Or this old thread: http://batboard.batlabs.com/viewtopic.php?t=55273

Probably will be difficult to obtain the official noise kit from Motorola but you might be able to find one somewhere, or follow the advice to try to remedy it yourself, if it is indeed the microphonics issue.
HankRock
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Re: HT1000 Background Noise Issue

Post by HankRock »

I don't believe it's the same issue here as it's not a whistling or wind like noise, but the actual background noise they are picking up. Like the mic is too sensitive. They state they can here someone talking like 10 feet away from the person transmitting. It's a construction company so there is a lot of noise in the background that it picks up. I had them try using Motorola NMN6193C RSMs with no change in the issue so it's not the internal mics.

I'm tempted to buy these back from them and sell them MTS2000's
motorola_otaku
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Re: HT1000 Background Noise Issue

Post by motorola_otaku »

Anti-static foam wrapped in copper or aluminum foil is an excellent DIY remedy for Saber and Jedi (HT1000) microphonics.
KG4INW
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Re: HT1000 Background Noise Issue

Post by KG4INW »

HankRock wrote:I had them try using Motorola NMN6193C RSMs with no change in the issue so it's not the internal mics.
What about trying NMN6191s since those are noise cancelling? However, I haven't come across HT1000s that were that sensitive before.
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Bill_G
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Re: HT1000 Background Noise Issue

Post by Bill_G »

They have the crunchies aka microphonics. Super common problem. Squeeze the radio as you PTT. Put a good grip on it, and then alternate relaxing your hand slightly and tightening again. Or press the front panel with your other thumb during xmit. Draws the gremlins out every time. Take it apart, and tighten everything. Grease the rubber seals on the covers. Reassemble.
HankRock
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Re: HT1000 Background Noise Issue

Post by HankRock »

Bill_G wrote:They have the crunchies aka microphonics. Super common problem. Squeeze the radio as you PTT. Put a good grip on it, and then alternate relaxing your hand slightly and tightening again. Or press the front panel with your other thumb during xmit. Draws the gremlins out every time. Take it apart, and tighten everything. Grease the rubber seals on the covers. Reassemble.
Again, I don't believe this is a microphonics issue. It is not static or bad sounding transmissions. It is overly sensitivity. It must be something in the tuning!
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Bill_G
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Re: HT1000 Background Noise Issue

Post by Bill_G »

Humor me, and give it a try. Squeeze a radio and listen to it in another radio.

Case and Point - Our tech had been chasing "interference" on a mall security system, but getting no where locating it. I was tasked with putting fresh earballs on it, and within seconds of listening to them in their office, I was taking their speaker mics apart, greasing the plastic housings where they mated, and putting them back together. Bingo. "Interference" gone. Almost every transmission perfect after that. Then, I got to chase down individual GP300 portables with similar crunchies from the twisting in the leather pouches they had issued the officers. Torque was applied to the radio housing with each step they took. We set up a schedule to have all their portables serviced.

That said, you may want to check their transmissions on a service monitor to verify they are operating narrow band. They may be programmed narrowband, but the alignment may be set for something louder than that. I've seen it before. Usually the factory setting are too low, but someone may have aligned them incorrectly eons ago thinking he was making them better by letting them get to 3.5khz deviation.
RFI-EMI-GUY
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Re: HT1000 Background Noise Issue

Post by RFI-EMI-GUY »

Have you checked the deviation balance? AKA modulation compensation.
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