The Motorola MT500 Series Index Page

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Back to Home The Motorola MT500 / PT500 Series of Hand-held and Portable radios
compiled by Mike Morris WA6ILQ
Web page maintained by Robert Meister WA1MIK
I know nothing about this equipment so please don't ask!

An eight frequency PL model.
The PL/Carrier switch is in the lower right corner
An eight frequency PL and scan model.
The Scan/PL/Carrier switch is in the lower right corner

Does anyone have an original brochure or catalog sheet for the MT500 or the PT500?

The MT500 was the follow-on radio to the HT220 handheld, was first introduced in February of 1977 and used many of the existing accessories. The MT500 series was produced for only a few years before the MX series was introduced. The MX was the primary handheld radio during the period that saw the end of the crystal controlled radios and the introdution of the synthesized radios.

Like the HT220 the MT500 came in two versions - Slim-Line (sometimes called "Basic") and Omni (sometimes called "Universal"). The Omni / Universal models are thicker, allow larger (higher capacity) batteries and have a speaker-mic connector on the side, while the Slim-Line / Basic models has the jacks for speaker/earpiece and antenna on the (crowded) top of the radio. The additional thickness allows for a second layer of circuit board(s) for optional features - additional frequencies, higher power PAs, or even a multichannel scanner.

Speaking of antennas, here's a cross-reference list (7kb PDF) that lists and identifies the various units.

An additional difference is that the both the Basic and Universal radios came in two different heights of cases - short and tall cases. The additional 5/8 of an inch was used for smaller options like PL.

Since the PT500 is a MT500 in a "lunchbox" case with a big pack of "D" flashlight cells ora rechargeable battery (very popular with railroads, pipline crews, road crews, etc) those folks working on the PT500 radios will find the handheld manuals useful. Click here for an oblique view photo of an 8-channel PT500. Click here for a top view photo of an 8-channel PT500.

There used to be a web site at www.mt500.com that had a great deal of information on these radios but it went away in mid-2003. Also, there used to be a web page that gave information on the channel elements at http://users.leading.net/~radiotr/MT500 but it's gone also. If anyone knows who ran those web pages we'd be happy to talk to them about rehosting their information.

Like other Motorola radios of that era the MT500 RF section comes in multiple frequency ranges or splits for each frequency band. Unfortunately the split is not encoded in the model number.
For low band, the published splits are 30-36, 36-42 and 42-50 MHz. The manuals don't mention a 25-30 MHz range but I've seen one on 26.62 MHz (a media remote pickup channel) and several folks that I trust have told me that they were available in a 25-30 MHz split.
Supposedly there were mid band MT500 radios for Europe. If so, they would probably be in two splits, 66-77 and 77-88 MHz.
For high band there are three splits, 136-150.8, 150.8-162, and 162-174 MHz. I've seen several MT500s on US Navy Shore Patrol channels in the 140-141 MHz.
For UHF there are four splits, 406-420, 450-470, 470-490, 490-512 MHz. There were some SP radios on 512-524 MHz during the 1984 Olympics here in Los Angeles.

Where the prior models (the HT200 and HT220) used crystals the VHF and UHF models of this radio use small "Channel Element" in the receiver and transmitter, the low band MT500s continued to use crystals. A channel element is a plug-in module containing the crystal and a complete temperature compensated oscillator followed by a tripler-buffer. The multiplier chain following the channel element multipies up to what the exciter or receiver mixer needs. BTW, the transmit elements (either a KXN1083A or a KXN1042A) have five pins and the receive elements (KXN1075A) have only three pins. The crystals themselves are in a HC-49/X package.

Like all crystal controlled radios the MT500 radio is power miser, especially in receive. The average draw is about 11 milliamps squelched and 70 milliamps at a loud volume. In transmit the low power MT500 radios draw about 450 mills, and the high power radios draw just about an amp. Synthesized radios draw much, much more power. The 11 ma idle drain was a big selling point to the US Forest service for their firetower radios that ran on storage batteries.

The serial tag on the back of the radio

The MT500 Model Number:

Numbers that are in [brackets] refer to notes at the bottom of the tables.

Sample model number: H34BBU-3184AN

H 3 4 BB U

Radio Type Transmit
Power Frequency
Range Series Feature Set

H
Hand-
held

or

Z
Special
Product [8] 3
66-88 MHz:
?

146-174 MHz:
2 W

403-470 MHz:
1.5 W 1
30-50 MHz BB
MT500 B
Slim Line / Basic
(Thin Case)

4
25-50 MHz:
6 W [1]

66-88 MHz:
?

136-174 MHz:
5 W

403-512 MHz:
4 W 2
68-88 MHz
[2] U
Omni / Universal
(Thick Case)

3
136-174 MHz

4
403-512 MHz

Sample model number: H34BBU-3184AN

3 1 8 4 A N SPnn

Squelch Bandwidth [4] Channels Variation [5] Revision [6] Shipping Package [7] Special [8]

1
Carrier
Squelch 0
Wide Band
(15 kHz
Deviation
Very Rare!) 1
Single channel 0 A (blank)
a warranty replacement radio,
shipped bare (no battery, antenna, etc.) SPnn

2
2-tone
paging
decoder [3] 1
Narrow Band
(5 kHz) 2
2 Channels 4 B A
Shipped with Alkaline battery and antenna

3
PL
squelch 4
4 Channels C N
Shipped with Nicad battery and antenna

6
6 Channels D ?
There was an option to ship with a Mercury battery and antenna. I don't know what that code was.

8
8 Channels E

Notes:
[1]: There was no low power low band radio that I know of. The 41 series radio produced 3 watts on a 12.7 volt Mercury battery or 6 watts on a 15 volt NiCD batery.
[2]: I've never seen a mid band (66-88 MHz) MT500 or the book for one.
[3]: I've been inside a 2-tone radio to change the reeds. It was a -2110CN and the radio was not an SP radio.
[4]: This is the 1960s-1980s definition of narrowband. These days it's considered wideband.
[5]: I have no info on the translation of this column. I've seen radios with "0" and "4".
[6]: Think of this as the hardware version. You need a "C" radio or later to run DPL.
[7]: This column was dropped on some serial tags (like the one shown above).
[8]: a -SP suffix specifies that the radio was a Special Production (or Special Product, or Special Purpose, take your pick...)... If a radio model number ends in SP followed by any number or numbers then it was a special factory modification. It could be as simple as a yellow or orange case for a railroad or it could be a special IF frequency, or a special channel count or dual PL or... You would need the exact manual (or manual supplement) to know what is going on with any but the most obvious SP radio.
If the first letter of the model number was a "Z" then the radio was part of a special production run, not a modification of a relatively small number of radios.
And some were shipped with "-SPnn" suffixes and some with "SPnn" (with out the "-") like shown above.

The MT500 Manual Library:

Thanks go to Brian Alesio, Skip Clark and Eric Lemmon for their contributions...

The "A" revision manual covers VHF (H23BBB, H33BBB, H23BBU, H33BBU) and UHF (H24BBB, H34BBB, H24BBU, H34BBU) units.

The low band radios (H31BBB and H31BBU) came out later and are included in the "B" revision of the manual. By the way, this manual pair is a good example of the later manual (the "B" revision) having less info on some topics that the earlier one (the "A" revision). If you are working on MT500s you will probably want to download both manual versions.

Where the prior models (the HT200 and HT220) used crystals the VHF and UHF models of this radio use small channel elements, the low band units use crystals. BTW, the transmit elements (either a KXN1083A or a KXN1042A) have five pins and receive elements (KXN1075A) have only three pins.

Since the PT500 is a MT500 in a "lunchbox" case with a big battery those folks working on the PT500 radios will find the handheld manuals useful.

(no number) Line drawing of an Omni radio 17 KB PDF donated by Eric Lemmon WB6FLY

(no number) Parts and Accessories list 1.91 MB PDF donated by Eric Lemmon WB6FLY

6881012C50-E MT500 Series Operating Guide 628 KB PDF donated by Eric Lemmon WB6FLY

6881012C55-A
6881012C55-B HB and UHF MT500 Theory and Maintenance / Troubleshooting / Service Manual
"A" version 6.13 MB, "B" version 3.7 MB both donated by Eric Lemmon WB6FLY
The "A" version manual covers VHF (H23BBB, H33BBB, H23BBU, H33BBU) and UHF (H24BBB, H34BBB, H24BBU, H34BBU) units. The low band radios (H31BBB and H31BBU) came out later and are included in the "B" version manual. By the way, this manual pair is a good example of the later manual (the "B" revision) having less info on some topics that the earlier one (the "A" revision). If you are working on MT500s you will probably want to download both manual versions.

6881012C56-B Supplement to 6881012C55, VHF 2 and 5W Service Manual 3.4 MB donated by Eric Lemmon WB6FLY

6881012C58-B UHF 403-512 MHz (1.5 / 4 Watt) Service Manual 4.5 MB donated by Eric Lemmon WB6FLY

6881013C35-O MT500 Convert-A-Com model N1248A Operating Instructions 145 KB PDF donated by Eric Lemmon WB6FLY

6881013C40-C MT500 Convert-A-Com model N1248A Theory / Service Manual / Troubleshooting / Instruction Manual 4.6 MB donated by Eric Lemmon WB6FLY

6881013C45 Timeout Timer Service Supplement (another list says "Time-Out Timer Option")

6881013C55 Single Tone Service Supplement

6881013C60 Selective Call Options Supplement (one list says Supplement, one says Manual)

6881014C45 UHF 1 watt RF Output - Option H606AD

6881014C90 Multiple Tone Private Line Options MT500 2,3,4,5

6881016C15 UHF 4 watt RF Output - Option H606AE

6881016C20 UHF 1 watt RF Output - Crossband Operation - Option H610AA

6881016C25 UHF 4 watt RF Output - Crossband Operation - Option H610AB

6881016C30 UHF 1 watt RF Output - Option H611AA

6881016C85 Unit ID, Emergency Call and Time-Out Timer ("TOT") Theory/Maint/Schematic

6881017C55-B MT500 Low Band 30-50 MHz (6 W) Service Manual 3.8 MB donated by Eric Lemmon WB6FLY

6881018C40 Digital "Private Line" Models

6881019C05 Two Channel Scanner Option Supplement

6881019C70-D Touch Code Option Supplement (AKA DTMF) 679 KB PDF donated by Eric Lemmon WB6FLY
Covers options

H713: NLN5872 - Touch-Code carrier squelch front cover, NLN5826 - Touch-Code PL front cover, NLN5877 - Touch-Code selective call front cover, NLN5960 - cable kit front cover (low band only)

H324: NLN5940 Slim-Line Touch-Code carry case

H325: NLN5941 Omni Touch-Code carry case

6881020C35 Eight Channel Scanner Options Supplement (can be set for 3-8)

6881020C40 DPL Service Supplement

6881020C80 Z33BBU1152A Service Manual (another list says this manual part number is for "Five Channel Deck, Remote Microphone Connector"

6881020C85 UHF RF Power Amplifier N1275A (35W) Service / Parts (this manual is still available from Moto for about $14.00)
This amplifier goes in line between the Convert-A-Com and the antenna. This same amplifier was used with the Convert-A-Com for the HT220 and also with the Mobile Vehicular Adapter (MVA) for the MT1000 handheld.
Note that this amplifier is made in multiple "splits", just like the handheld or mobile radio. If you try and use an amplifier that is built for a split other than the radio that is feeding it (like 406-420 MHz amplifier on a 450-470 MHz radio) you will be sorry...

6881020C90 VHF RF Power Amplifier N1274A (40W) Service / Parts
This amplifier goes in line between the Convert-A-Com and the antenna. This same amplifier was used with the Convert-A-Com for the HT220 and also with the Mobile Vehicular Adapter (MVA) for the MT1000 handheld.
The caution on the wrong split amplifier mentioned above on the UHF amplifier applies here as well.

6881024C70 H34PTU Service Manual (IPTS)

6881024C80 H33PTU Service Manual (IPTS)

6881024C95 H33/H34PTU Operating Instructions (IPTS)

6881057C80 MT500 Options Manual...
Covers:

MDC (both 600 and 1200)
MODAT
Touch-Code (DTMF)
Touch-Code Automatic Number Identification (ANI)
Time-out Timer
Digital Private Line (DPL)
Transmit-Only "Digital Private Line"
Multiple-Tone Private Line
Two-channel Scanner
Eight-Channel Scanner (also covers 2, 4, 6 and 7 channel)
Single-Tone (AKA Tone Burst)
Selective Call
Selective Call Supplement (both VHF and UHF)
Intrinsically Safe (both VHF and UHF)

6881102C04 NSN6027A 12 Watt Amplified Speaker for MX3xx and MT500 series Converta-Com N1248A (866kB)
Note that there were (are?) NSN6027A and NSN6027A-1 units. There are some differences - three capacitors are different values, one resistor was added, and better insulators were used on the power transistors.

6881102C29 Single-Unit Battery Charger (standard rate - i.e. not a rapid charger)

6881102C45-D Speaker-Microphone accessory model NMN6081A (straight cord), NMN6082A (coiled cord), NMN6089A (coiled cord with "quick disconnect" plug (for motorcycle, etc)) (121kB)

6881102C49 External Speaker-Microphone and Antenna

6881102C55 Single-Unit Rapid Battery Charger - Slim Models

6881102C69 Surveillance Microphone and Earpiece

6881102C57
6881103C06 Multiple-Unit Rapid Battery Charger
Both books have the same title - one is probably slimline the other omni, but the list said "Multiple-Unit Rapid Battery Charger" for both.

6881103C11-A Single-Unit Rapid Battery Charger - Omni Models (349kB)

"Omni" Charger Model Table

Model Input Voltage Color

NLN4569B 117V AC Shadow Bronze

NLN4571B 234V AC Shadow Bronze

NLN5594A 117V AC Shadow Black

NLN5595A 234V AC Shadow Black

NLN6897B 117V AC Stellar Blue

NLN6899B 234V AC Stellar Blue

"Omni" Battery Application Table

Battery Type

NLN4463 MT500 Rapid Charge

NLN6761 HT210/HT220 Standard Rate Charge

NLN6900 HT210/HT220 Rapid Charge

NLN8232 HT220 Rapid Charge, Intrinsincally Safe

TT-402 National Service Technicians Guide 1979

? Motorola National Service School Course "MT500 Handie Talkie Portables"

? PT500 Advance Information Digest 2.22 MB (a National Service Training Document dated August 1978) donated by Eric Lemmon WB6FLY
An interesting document, that, among other things, tells you how to modify a PT300 battery pack so you can use it on a PT500.

Unless otherwise noted all of the publications in the above list have been discontinued by Motorola.

Contact Information:

The author can be contacted at: his-callsign // at // repeater-builder // dot // com.

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This page originally posted on Monday 30-Sept-2011

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.