MT1000 internal speaker

[Norman]

Hi everyone. My MT1000's receive audio is fairly distorted. I uncased the radio and the ultra-thin speaker's diaphragm looks a little warped. It's not ripped but I'm guessing it may have been exposed to excessive moisture and left to dry more than once, contributing to the raspy audio especially at higher volume levels. I'd like to try replacing the speaker (p/n 5005155Q03) but saw that its no longer available. I see that the flex assembly (p/n 0102700J81) which includes a new internal speaker is available but its $65.00+tax & shipping and my flex cable is fine.

I looked on eBay but there aren't any sellers for either part at this time. I'd appreciate it if someone could let me know of a source for an new speaker or one which is compatible with the MT1000 (same physical size and impedance).

Thanks, and 73

Norman

[DJP126]

You might check the center of the speaker and clean out any metal filings that might be there. This was a big cause of distortion and speaker rattle when I worked on these at the depot.

[Norman]

Hi Dave. Thanks very much for your advice. I tried cleaning off any small debris by gently blowing on the speaker diaphragm. None really there and still no improvement. This is a former fire department radio and In addition to the slightly-warped diaphragm, perhaps a small amount of corrosion from dampness worked its way into the coil/magnet.

The design and audio quality of this radio remind me of the old Expos. I had two of these (one on VHF and on on UHF). Both lacked lower-frequency audio response and sounded a bit raspy -- probably because of the wimpy speakers.

Turns out the internal speaker from a P110 is a tad smaller in diameter than that from an MT1000. It is, however, as thin so I pulled one from a spare P110 housing and transferred the flex cable to it. I hate breaking one thing to fix another, but I wasn't really using the 110's housing. Because of its smaller diameter, it's now tacked down in place by only the long spring-steel clamp (foot?) and pressure from the flex cable. The other two clamps don't even make contact with the edge of the speaker. The front face seems to help hold it in place.

It sounds much cleaner with the "new" P110 speaker -- even at higher volume. I'd love to someday do it right with a correct (perfectly-fitting) speaker. I'll keep looking. I like the MT1000's 99-channel capacity but I wish I had invested in an HT1000 instead. The audio on those sound great.

Thanks again for responding and congratulations on your tenure with my favorite company. That's quite an achievement.

Norman

[Norman]

Okay -- not to beat a dead horse, but thought I'd share a tip which helped resolve my problem with my MT1000's raspy sounding audio.

Yes, my MT1000's original internal speaker's paper diaphragm was somewhat buckled due to repeated exposure to moisture. Replacing the speaker element helped but speech still had an annoying buzzing sound at medium to high volume.

I figured out that there is virtually zero clearance between the black cloth pad behind the radio's front housing (grille) and the speaker. It was pressing against the speaker diaphragm interfering with the speaker's "throw" and causing an annoying "buzzing" sound at peak volume levels.

I made a gasket using some very thin strips of foam around the perimeter edge along the speaker's surface (where it rests against the cloth pad). This little bit of clearance (about 1/64") allows the diaphragm to move freely without hitting the housing. The audio's now distortion-free even at full volume.

[wx4cbh]

For what it's worth, both my MT1Ks have a white nylon or plastic ring that matches the speaker's outer edge mounting surface. It's about 1/64th thick and is white, similar material to the speaker insulator that goes on the back side of the speaker but thicker. The ring is what gives that spacing that norman is referring to in the previous post. If you leave it out, you'll get the center of the speaker vibrating against the cloth.

I have no idea why so many 1ks are missing the spacer ring, but for whatever reason most are, and the part isn't even shown in the parts breakdown because I've looked for it. Could it be that the ring is a factory fix for speaker clearance problems on the assembly line? If so, how come it ain't in the book? Was it a part from another portable series that was used by the depot or local shop techs when a buzzing speaker complaint showed up? I've had these two radios since they were new, and both were maintained in the local MotherMoto shop, so who knows.