The NSN6054A looks like a normal speaker from the front, but the side view shows just how deep it really is. The bracket is NOT a common bracket. The cable is seven conductors and has a male DB-25 plug on it. These two photos by WD9HSY.
     

Several external RF power amplifies were an option on the MVA and which one came with it depended on the band and split. There were ones for low band, high band and UHF, but all were single band (to my knowledge, Moto has never offered a dual band amplifier, but I have seen several MVAs that have been cabled to aftermarket dual band amplifiers).

There are several different RF power amplifiers that are part of the MVA kit:

• Low band: (I do not know the part number, anybody have it?)
• High band: N1274, 40 watts, came in two splits: 132-150.7 MHz and 150.7-174 MHz.
• UHF: N1275 was rated as either 30 watts or 35 watts, depending on which catalog you read. I've seen 406-420 MHz and 450-470 MHz splits, and I suspect that the amplifiers followed the radio splits and came in 470-494 MHz and 494-512 MHz splits as well.

Moto offered amplifier kits such as the NLD7701 (136-150 MHz), the NLD7702A (later changed to PLD8000A, both built for 150.8 - 174 MHz), the NLE8911 (406-420 MHz), the NLE8912 (450-470 MHz), the NLE8913 (470-494 MHz) and the NLE8914 (494-512 MHz) consisting of the amplifier and all appropriate cables.

The 4-pin power cable that plugs into the back of the MVA uses a standard polarized Molex connector, but I do not know the Molex, DigiKey or Mouser number. The Motorola part number for the cable is 3005442T03, but Motorola does not list the connector as an orderable part by itself.

The lock at the bottom front of the MVA used different keys depending on if the MVA was a standard product or delivered with a specially ordered fleet - i.e. If you are going to purchase one on eBay make sure the unit uses one of the standard keys (I've seen them with both a MOT-1 and with a 2135), comes with a key, or plan on buying a half hour of your local locksmith's time to make a key).

The manual number is 68P81062C75, but the schematic has been scanned for you: Page 1     Page 2

There are 2 small switches on the back of the MVA. One is in series with pin 7 of the radio accessory connector and allows selection of the radio speaker versus an external speaker (up for internal radio speaker, down for an external mobile speaker). Trust me, you will want the external speaker. The other switch is relevant only on a 99 channel radio and causes the display to flip over when the radio is inserted into the MVA so you can read the channel right side up. This feature is dependent on the "MVA FLIP" option being enabled in the codeplug (i.e. in the RSS).

The NTN5612 has a plain front panel as shown in the photo below left - just the transmit and charging complete vertical LEDs on the right, and the Moto logo. In contrast, below right is a photo of an NTN5613 - to the left of the up/down channel rocker buttons is a 2-digit green LED display (early red ones were were almost unreadable in bright sunlight). I've seen one with an LCD display that was quite readable in the day, and illuminated at night, but I do not know if that was one persons personal hack, was a Moto special product, was a late production item, or a prototype that escaped into the field.

The mobile microphone plugs into an RJ45 connector on the left side. The microphones specified in the manual are the same microphones as are specified for a Maxtrac:

• HMN1056D Microphone, Compact Palm
• HMN1035C Microphone, Heavy-Duty Palm
• HMN3013A Microphone, DTMF

The black protrusion on the left front is the volume control.

The back of the MVA has a DB25 female connector, the two DIP switches mentioned above, a 4-terminal DC power connector and a mini-SO-239 coax connector:

DB-25F Pinout: View is looking at the face of the socket, or at the back of the plug that is inserted into it.
Pin Assignment 1 N/C 2 Ground 3 Ground 4 DATA 5 PA Squelch 6 N/C 7 External Speaker 8 External Speaker 9 Pac RT out switched		Pin Assignment 10 N/C 11 A+ 12 N/C 13 N/C 14 Microphone 15 PTT 16 16.5v 17 Busy		Pin Assignment 18 N/C 19 N/C 20 PA Audio 21 PA Audio 22 N/C 23 Ignition Switch 24 A+ 25 N/C

Note that the speaker runs both leads hot above ground. More details on that potential "gotcha" on the Genesis index page. The NSN6054A External Speaker with its internal 12-Watt audio amp is part of the MVA kit and plugs into the DB25. Unless you have an extra quiet car like a Rolls Royce don't even try to run an MVA without the amplified speaker.

NSN6054A external speaker pinout:   (this is the DB25M plug on the end of the speaker cable)

The NSN6054 series of speakers was designed for use in both negative and positive ground environments, hence the "Assignment" of "-12vDC" and "+12vDC". Despite the misleading text, this is a 12vDC amplifier, NOT 24vDC !   In a normal vehicle installation pins 2 and 3 end up at ground potential and pins 11 and 24 end up at +12vDC.

Pin	Color	Assignment	Comment
2	Black	-12vDC	jumpered to pin 3
3	Brown	-12vDC	jumpered to pin 2
5	Green	Squelch	Voltage on this pin turns the audio amplifier inside the speaker on & off
11	Red	+12vDC	jumpered to pin 24
20	White	Audio in	Audio from MVA
21	Blue	Audio in	Audio from MVA
24	Orange	+12vDC	jumpered to pin 11

Yes, the are two power leads in parallel for the positive side, and two more for the negative, just because of the current drain. The MVA provides a +DC voltage to pin 5 (the squelch lead) to automatically switch the speaker amplifier on & off based on breaking squelch. This is a DC power saver feature so the internal amp in the speaker wouldn't be on all the time. If you want to use an NSN6054A without the MVA just put a 470 ohm 1/4 watt resistor between pin 5 and pin 11 (or pin 21).   If in a vehicle then wire pin 5 to switched +12vDC (from the ignition switch) through the resistor.
For what it's worth, as of mid-2009 the NSN6054A is still available from Motorola at about US$105.00
Courtesy of WD9HSY here are two photos of the interior. The two metal brackets that hold the circuit board in place also function as heat sinks for the 12 watt audio amplifier.
     

MVA Power connector pinout:

Pin	Assignment	Color
1	+12vDC (Vehicle Battery)	Red
2	Ignition switch +12v (when equipped with the PAC-RT option (the mobile extender) switching the ignition on caused the mobile extender to drop into off-line mode.	Yellow
3	Headlight switch (usually is connected to the tail-light wire so it gets 12v when either the parking lights or the headlights are on). When connected to +12 this lead causes the display to dim.	Green
4	Ground	Black

As mentioned above, the power cable is still available as of mid-2009 as part number 3005442T03.

Modifying the Battery Charger in the MVA
The MVA has a rapid-charger circuit in it that is designed for Nickel-Cadmium based battery packs. The "basic" MVA is trickle-charge only, the "enhanced" MVA will do rapid charging. That circuit has the same problem that is described in the article on modifying the desktop rapid charger. I suggest that you go read it, then come back here. In short, if you drop an NiMH battery into any unmodified charger for even just one charge cycle you can overheat it to the point of permanently ruining it. If you are going to use nothing but NiMH packs for the rest of the life of your MVA you can just change the value of one resistor from 15k to 22k and be done with it, but if there is even a slight chance that you would stick a NiCD pack in the MVA you will want to change R45 for the MiMH pack, then mount a SPST mini-toggle switch and wire it to shunt a 47K or 51K across the 22K resistor (resulting in an effective value of 15K) then label the switch positions as "NiMH" and "NiCD". See the schematic below (the charger circuit is identical to the one in the regular desktop rapid charger, but the component reference numbers are different).

Here is a closeup photo of U4 and R45. The big black object in the lower right corner is the microphone jack. Once you remove R45 you can install other components using the nearby feed-thru holes, as there's one at each end of it. Personally, I'd remove the surface-mount R45, mount the mini-toggle switch mentioned above, wire the two resistors to it, and then run wires to the R45 feed-thru holes.

To be added: (contributions of information are welcome!)
Does anybody have any of the following that they would be willing to contribute?)
The model numbers for the previous "box" style Convertacoms.
Digital photos of:
The previous "box" style Convertacom (empty).
The previous "box" style Convertacom with a radio in it.

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This page originally posted on 11-Apr-2007 by Mike Morris WA6ILQ.