MTS2000 and overdriven receive PL on RX

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k7kcn
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Posts: 9
Joined: Sun Oct 31, 2010 11:34 pm
What radios do you own?: APX8K XTS3K XPR6550 MTS2K-VU8

MTS2000 and overdriven receive PL on RX

Post by k7kcn »

Hopefully this is not a repeated topic, searched but came up blank.

Using several MTS2000s on VHF receiving a transmission with a PL of 146.2 the PL seems to completely overwhelm the voice audio and make the transmission unreadable. If the transmitter's PL is changed up or down the received voice audio is OK, but the sour-spot seems to be 146.2, where the business has all of their radios and several frequencies setup on.

I have tried this with different make and models of transmitters with one MTS2000 handheld receiving as well as the one transmitter with multiple MTS2000s and the issue reproduces. Mobile-mobile is OK, portable to mobile is OK, mobile orportable to portable is not. This issue is not apparent on different brands and models of portables.

I have had a friend at a MSS try this out with UHF and 800 versions of the 2000 and apparently it reproduced with the 146.2 PL.

Is there any internal setting that can be changed (similar to clock shift) to get rid of this? The customer doesn't want to go through their entire fleet, repeaters, and change all the programming to get rid of this issue.

-K
g8tzl2004
Posts: 1128
Joined: Wed Sep 08, 2004 10:13 am

Re: MTS2000 and overdriven receive PL on RX

Post by g8tzl2004 »

I had a sort of similar problem with a HT1250 and receiving a signal with a PL of 110.9Hz.

My original posting was on Sept 7 2011 " HT1250 - RXing a PL tone of 110.9Hz causes super loud hum"

The problem was only when you were receiving a signal encoded with a 110.9Hz PL and when the receiver was set up for just carrier squelch (rather than PL squelch).

If you read the thread you will see the fix which involved adjusting the Baseband Offset using the Global Tuner software.

For me, a more simple fix that worked was to just set up the channel using RX PL 110.9Hz decode as well as TX PL 110.9Hz encode but then set up the separate squelch setting as Carrier Squelch rather than PL Squelch...that removed the super loud hum completely.

The problem came about because I wanted to receive a repeater using carrier squelch (so I could hear any other activity on the same frequency) while the repeater put out a constant TX PL of 110.9Hz. I'm surprized that Motorola did not resolve the problem in the radio design phase...I have never seen that problem with any other make of commercial radio!!!
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