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The GRONK Radio Standardized Interface Method
By Matt Lechliter W6XC of the GRONK Radio Network
HTML'd by Mike Morris WA6ILQ
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Motorola MSF 5000: The GRONK Radio Standardized Interface Method By Matt Lechliter W6XC of the GRONK Radio Network HTML'd by Mike Morris WA6ILQ |
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Overview:
Our standard interface modifications for the MSF5000 stations are detailed below. The result is compatibility with GRONK and Cactus Intertie specifications. Most internal functionality is bypassed since it cannot serve this purpose. However, extensive modification is undesired should factory-stock operation be desired later. A simple programming change or even the flip of an existing switch can restore the station to internal repeat in the event of external controller failure or other calamity. This keeps your system on the air (perhaps in a degraded mode) and keeps the channel poachers at bay.
Let's be honest. The MSF 5000 is an over-engineered station concept. It began Motorola's departure from commonality between base-station and mobile infrastructure design. Lines like the Motrac, MICOR and Mitrek/MSR2000 all shared basic design between mobile and station. Their packaging was the greatest difference. The MSF5000 was the first station design unproven in field-mobile applications. It's not what we were used to, yet a great design nonetheless if managed well.
MSF stands for "Maximum Station Flexibility". As Motorola's hot new item in the early 1980s during the first microprocessor computing boom, it was to support many modules all connected by common bus architecture (MUXbus) to perform many different tasks and interfaces. These modules, naturally, were options from Motorola.
Beginning as an EPROM-programmable version (the "CLB"), it was later upgraded. The later "Analog Plus" ("GFB") and "Digital Capable" ("CXB") stations were PC-programmable and some supported Motorola's SECURENET encryption packages. Gradually as they're replaced, these stations of both versions (Analog or Digital-capable) have become available to us hams, but their makeup is unlike other radios previously encountered. The two versions shall henceforth be referred as "CLB" for Analog EPROM type or "CXB" for Digital type. Note that the "GFB" was a exportable (non-SECURENET-capable) variation of the "CXB", the "RUB" was a Canadian "CXB", and the "RLB" was a option-limited "CXB" (limited by marketing, the hardware was the pretty much the same). For the purposes of this document they are all equivalent to the "CXB".
Interface to the non-Motorola world came through the "WildCard" option. These
were bridges between the MUXBUS control signals and a combination of logic levels
(COR, PTT, etc) and some audio pathways. The WildCard module even included a small
breadboard-like area that could be used to build small circuits on the WildCard
or to simply bring wires out to external devices. WildCard modules aren't the most
plentiful goodies in the world. Obtaining one is half the battle. Documentation of
the item is the other half. The author has a module but as yet not obtained any docs.
Note from WA6ILQ: There are several vintages of "Wild Cards" including the
QLN2914A (which was known as "Option C232AA, C232AB, C232AG or C233AB when
factory installed)". The manual on that one is
6881114E40-C.
While WildCards would work, there's a better and simpler mousetrap. Thankfully, it's fairly straightforward in either CLB or CXB stations. Ham applications rarely need anything offered by the station's internal controller and associated options. It falls short for most needs and reaches beyond others. Plenty for some, however those of us implementing MSFs in "California Linking" architectures (as they've come to be called), need little from the radio besides exactly that: a raw full duplex radio. The remainder is handled via external controllers. Our controllers are painstakingly designed by ourselves, and over the various generations are purpose-built to our architecture and needs. This modification procedure below suits exactly that.
The CLB Stations:
CLB (Analog) Stations are easy to interface. A handful of signaling points and test points gives you everything. The difficulty with CLBs is having them programmed. This requires the R-1801A suitcase programmer (with the 4KB option), the appropriate R-1801A EPROM set that contains the program for the MSFs and the MSF PROM Programming Adaptor that lets the R-1801A program teh 2732 chip. All of these are scarce birds. Some folks offer programming for a price, while other kind souls do freebies with the cost of chips and/or postage as their only "fee". Note that 2732 family EPROMs are getting scarce, you should expect to have to provide one to be programmed - and there was one MSF PROM Programming Adaptor for the 12 volt 2732s and another for the 21 volt 2732s). Make sure that you find out what adapter the gentleman has and provide the proper voltage 2732 chip.
So, let's explore where we apply solder. Listed below are the connections:
| Connection | Function | Notes / Description |
|---|---|---|
| TP4 | Transmit Audio tap | Flat TX audio point of injection (non-pre-emphasized). Be careful when injecting audio here: this is the output of an op-amp that has a very low output impedance and it will resist any changes. Also, disconnecting the output pin of this op-amp may cause the power-on diagnostic tests to fail. |
| TP3 | Receive Audio tap | Direct unprocessed/ungated audio from the receiver quadrature detector (non-de-emphasized). |
| TP9 | Station Local PTT (Push-to-Talk) | This is an active-low or low-true signal used to key the transmitter. Typically, it is unaffected by an internal time-out timer, but be sure to double-check your programming when having codeplug EPROMs made. It is also available at the front Mic/Control connector. |
| A.G. | Audio Ground | Tied to Logic Ground (L.G.) |
| TP6 / TP7 | Carrier Squelch Indicator | Internal noise squelch logic output, 2 circuits available. More notes in the text below. |
| U829-15 | Private Line (PL) / Digital Private Line (DPL) Indicator | RX1 Audio Gate Control. |
The internal audio processing circuitry of the station is bypassed completely. This is common of "California Linking" methodologies regardless of radio make or model. We refer to it as "Flat Audio". The terminology started with Motorola manuals and the practice extends back to the early 1960s and linking efforts of that time in Southern and Central California.
The connection points chosen are conveniently available on the station control board. All but one are "Test Points" as their "TP" designators suggest. Motorola designed this station even for us without even knowing it... quite a pleasant realization it was. TP4 injects audio directly with a data-quality tap point for transmission. Be careful when injecting audio into TP4: this is the output of an op-amp that has a very low output impedance and it will resist any changes. Also, disconnecting the output pin of this op-amp may cause the power-on diagnostic tests to fail. TP3 is the equivalent in the receiver chain: raw, unsquelched audio. An audio compensation network is suggested but not required between detector and controller. Generally, two 10K ohm resistors (1/4W) and a 0.068uF in parallel with the second resistor (controller side) provide the proper shaping. This will vary with the cable type and length used.
Next is an oddity that is common to the MICOR, MSR and MSF stations. Two noise-squelch circuits exist; one serves as 'Repeater Squelch', the other as 'RX1 Squelch' (or 'Receiver Squelch'). These two settings are elements of the "Receiver Qualifier" primarily used in internal repeat operation. One controls the actual gated audio while the other is a logic reference for "holding in" the repeater's transmitter (repeater PTT).
TP6 is 'RPTR Unsquelched Indicate' and TP7 is 'RX1 Unsquelched Indicate'. TP7 is the preferred signal, the audio control signal. Unlike TP6, TP7 attempts to follow the MICOR squelch concept of hysteresis to provide decent squelch action. Not exactly the MICOR squelch itself, but close unless you're a purist. These signals are active-high or high-true signals. Use a 2N7000 buffer or at minimum a diode to protect the internal circuitry from damage. Most parts on the control board are unsocketed - not fun to change. Don't attempt it unless you have a decent solder-sucking iron.
The next interface point is where most folks give up. While it's easy to use an outboard PL decoder like the ComSpec TS-32 or the newer TS-64 that takes the fun out of it. An MSF handles this already, right? Why not use it? The trick is finding where. Not easy at first since there isn't a testpoint or other discrete line saying "Here I am!" - until one looks closer. Part of the codeplug programming allows specification of audio gating control from the receiver. It can be either CSQ only, CSQ + PL/DPL or PL/DPL only. The last option is key. Specifying option 'C' (Coded Squelch) turns the RX1 Audio Gate Control line into a PL Decode Indicate line. This line is found at U829 pin 15 on the controller board, an active-high/high-true signal. You'll have to tack-solder to the IC's leg, but it's worth the effort. If done cleanly, no harm and no foul. Buffer it with a 2N7000 or diode as with the CSQ indicator, and there you have it: separate COR (TP6) and PL decode (TP7) lines.
CLB Codeplug Programming:
The station codeplug can be programmed as a repeater or base station. Either option will allow use of the preceding procedure. When programmed as a Repeater, the "Acc. Dis" or Access Disable switch is used to disable internal (in-cabinet) repeating. The radio then acts like a base station. Making a Base Station codeplug works fine also. The aim of a Repeater codeplug is merely to alleviate having to switch codeplug EPROMs if the external controller is removed for service. Up to your tastes.
| CxyCLB7106A (base) or CxyCLB7106AT (repeater) (where x is the power and y is the band) |
||
|---|---|---|
| Field | Data | Notes / Description |
| Station transmit frequency | (your TX freq) | Frequency in MHz |
| Station receive frequency | (your RX freq) | Frequency in MHz |
| Transmit Code | (your tone) | Specified by Motorola PL code or DPL number, i.e. 4Z (136.5) or D411 |
| Recieve Code | (your tone) | Specified by Motorola PL code or DPL number, i.e. 4Z (136.5) or D411 |
| LINE-TOT | x.x | Wireline Timeout Timer (in seconds) |
| LOCAL-TOT | 0.0 | Local PTT Timeout Timer (entering a value of zero disables the timer) |
| RPT-TOT | x.x | Repeater (internal) Timeout Timer |
| RPT-DOD | x.x | Drop Out Delay (hang timer or carrier delay timer) Used only on the in-cabinet repeater |
| PTT PRIORITY | LR (Local then Repeat) | PTT Priority, Local first and Repeat second suggested |
| RPT. ACT. | SC | Rpt. Activate Qualifier (initial keyup, SC = CSQ and PL / DPL) |
| RPT. HOLD | C | Repeater Hold-in Qualifier (during hang time) |
| RX AUDIO | C | Receiver Audio Gate Control Qualifier (must be C) |
| TX AUD/DAT. | NO | Not used in our application |
| LOC. AUD/DAT. | NO | Not used in our application |
| RPT. AUD/DAT. | NO | Not used in our application |
| AUTO I.D. | (your callsign) | Internal Morse Identifier Callsign (in-cabinet repeat only). Entered as text, for example "WB6SLR" |
| ALARM OTA | ENABLED | Alarm Tones Over the Air (audible notifcation of PA problem, etc.) |
| ALARM WIRE | DISABLED | Alarm Tones Over the Wireline (Not used in our application) |
The above fields are as used by the R-1801A suitcase programmer in building a codeplug. Other parameters can be specified, but are beyond this article. Consult the R-1801A owner to determine exactly what you need to provide.
The CXB (and similar) Stations:
Like the CLB, a CXB is fairly straightforward. Our approach is the same but the exact execution is different. A few changes in the design make use of an external board almost necessary for noise squelch, but our choice of PL indicate signals increases. Programming is also far easier by using a PC and RSS instead of the R-1801A suitcase. The MSF 5000 RSS is very useful in that it can mimic a Diagnostic Metering Panel (type with a display matrix) to observe MUXBUS activity. DMPs are nearly a must-have for MSF owners. Unlike the CLB, a CXB can be multi-channel easily. For those where this serves a need, a definite asset. Programming them up isn't terribly difficult in the RSS.
Here we have the CXB connections:
| Connection | Function | Notes / Description |
|---|---|---|
| TP4 | Transmit Audio tap | Flat TX audio point of injection (similar to a CLB). Be careful when injecting audio here: this is the output of an op-amp that has a very low output impedance and it will resist any changes. Also, disconnecting the output pin of this op-amp may cause the power-on diagnostic tests to fail. |
| TP3 | Receive Audio tap | direct unprocessed/ungated audio from RX quadrature detector. |
| TP9 | Station Local PTT (Push-to-Talk) | also avail. at front Mic/Control connector. |
| A.G. | Audio Ground | tied to Logic Ground (L.G.) |
| U802-58 | Carrier Squelch Indicator | internal noise squelch logic output to ASIC. |
| U810-9 | Private Line (PL) /Digital Private Line (DPL) Indicator | RX1 Audio Gate Control. |
| TTRC Systems Connector P2900-9, Junction Box DB-25 connector pin 9 | Red/White Wire | TTRC Spare Output bit, assign to MUXA3B2 in RSS for PL-only operation. |
| JU-18 (default strapping) Center | RX1 Audio Gate Control Selector | Programmed Qualifier default or CSQ Only) Use of the internal squelch is possible, but not recommended. Unlike the CLB, no test-points exist for either of its circuits. (RPTR or RX1) Tacking a line onto the ASIC or NPN driving it are possible, but not worth the trouble. A good, clean MICOR squelch circuit will perform better, be it Link-Comm's RLC-MOT or a do-it-yourself version. Sneaking an RLC-MOT into the Control Tray with the SSCB is certainly doable, cleanly at that. Feed it with audio from TP3. |
| U802-58 | Input to the I/O ASIC from the RX1 Squelch circuit. | This is a high-true signal. If used, be sure to buffer it. Take extreme care not to blow the ASIC with ESD. Q1510 is an SMD NPN transistor and drives the ASIC from the squelch circuit. It is on the bottom side of the board. It is not something to tamper with unless you have a good feel for SMD work. |
My strong suggestion is to forget the CXB internal squelch altogether. Stick an RLC-MOT (or your home-brew equivalent) in with double-sided tape on an open part of the SSCB tray. Wire it with TP3 as RX detector tap, and use as base-level-set and buffer for RX audio to your control system. It provides its own audio gating if needed by your controller. Without component changes however, the recovered audio is sufficiently flat for most applications. De-emphasis can be added if desired. Refer to your RLC-MOT documentation for those details.
The PL Indicator signals are three:
Something to remember, a useful bit of information. The SSCB CPU & ASICs are interchangeable with the TTRC CPU & ASICs. The 68HC11 CPUs of both contain the same 'bootstrap' program to reference their external EPROMs. Any old 68HC11 won't work. So, in your spare time, cruise eBay and pick up one or two TTRC Logic Core boards. They'll have all 3 chips. Be very careful when inserting or extracting PLCC chips, however. The sockets are easily damaged. Always use the proper extraction tool! DO NOT USE A SCREWDRIVER.
In closing, using the MSF in amateur applications is easier than it looks at a first glance. Basically you program it as a simple in-cabinet repeater, then disable the repeat function with the "Access Disable" ("Acc. Dis") switch. Once that is working to your satisfaction you connect in your external controller - be it a Scom, NHRC, Arcom, Link (RLC), a Palomar or your own homebrew unit. If your controller dies or has to be disconnected for any reason you simply flip the switch to re-enable the in-cabinet repeat.
Contact:
Matt Lechliter W6XC: grandnationalradio //at// gmail //dot// com
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Article text © Copyright 2010 by Matt Lechliter W6XC.
Hand-coded HTML © Copyright 2010 by Mike Morris WA6ILQ.
Notes about TP4 added 08-Dec-20 by Robert Meister WA1MIK.
This page originally composed on 18-June-2010
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.