PR400: Microphone muting with newer firmware

[Victor Xray]

Looking for feedback or similar stories before I depot some radios under warranty....

I have a fleet of PR400s, with new ones being added every few months. The newest radios are causing a serious problem for some users - the microphone completely mutes if the user's mouth is less than 1-2" to the radio. (Now sure you can say, just tell the users to back off a little bit, but bad habits are hard to break, especially in noisy environments and also when only a few radios are experiencing this problem.) I've tried everything from ensuring the radios are completely aligned to making dozens of adjustments on the mic gain (db) setting in the CPS - nothing solves this problem.

The only difference I can identify between the radios that have the problem and the ones that don't are the firmware versions: R03.03.03 seems to be the firmware in the muting radios, anything lower and the mic works fine even if it's literally on your lips.

Anyone else experienced this problem with newer PR400s?

[Pj]

Just a shot in the dark as I have not played with one, but are there any settings for AGC or the like that can be adjusted?

[Victor Xray]

No AGC setting, only a setting for "Microphone Gain (dB)" and I've programmed just about every value from 0 to max with no change in the mic's muting behavior.

[wavetar]

How did you program the newer radios...cloned from old codeplug, or built from scratch?

[Victor Xray]

Built from scratch; however, as part of the troubleshooting steps, I also cloned in a codeplug from a different radio (with older firmware, known working) and the results were the same.

[wavetar]

As a last resort, upgrade an older unit to the latest firmware, verify it still works properly & if so, clone it to a troubled unit. See if that fixes things. If not, you could send them to the depot, or optionally, open a GCC (global customer care) case with Motorola through MOL. If it's a 'known issue' to them, there's possibly a firmware patch they could send you to fix things up in-house.

[Victor Xray]

I found the problem today. It's not the firmware.

It's the mic element used in the latest production of the PR400s. They don't like RF.

If RF is reflected to the mic element (antenna to face to mic), the mic cuts off and/or buzzes. This can also be seen if the housing is off the radio, the mic element mutes during transmit. Drop to very low power and the problem is gone (mostly, can be reproduced with the right amount of reflection).

I confirmed it is the mic in the newer models as the problem follows the housing. I swapped housing from 3 new radios with 3 older radios and the problems follow the housings. (New radios with latest firmware and housings from older radios work perfectly. Radios with older firmware and housings from new radios now experience the problem.)

If any dealers out there have some new PR400s in the box, you can verify this problem without even programming them. Pull two out, set to high power and set to PERS 1 channel, then transmit on one while whistling or humming as you bring the radio close to your lips, you'll hear the audio cut out on the 2nd radio.

I'm not sure if sending these to the depot will solve anything, if the mic elements there are the same as in the newest radios.

Thanks, Motorola.

[Pj]

Call them up and have them take care of it. The best thing to do is start that papertrail so down the road you have the docs when there is a fix and yours is magically not "in range" or some other BS (depending on how a SRN/FSB is written up).

[escomm]

A case is already open and enroute to the engineers