® MPD VHF portable
How I modified a GE MPD VHF Handie-Talkie (150-174) to 2 Meter HAM band. Copyright 1998, Sterrett Carter
DISCLAIMER: This document is for informational purposes ONLY! If you choose to follow the steps outlined herein, you do so at your own risk. I cannot, nor will not, be responsible for damage to equipment caused by the modifications YOU make to the radio as a result of your reading this document. OVERVIEW: The GE-MPD is a robust commercial radio which continues to be supported by Ericsson Communications in Lynchburg, VA. Parts and manuals are available from the manufacturer. The Parts Identification section can be reached by telephone at 804-368-3277 08:00 to 17:00 eastern time. The manual for the MPD that I have is LBI31677 (service) with LBI31627A (maintenance) bundled together. The manual for the MPD-Scan that I have is LBI31677 (service) with LBI31628 (maintenance) bundled together. Both of the VHF MPDs are available in 136-160 split which requires only programming, not the special steps in these instructions, and 150-174 split which is covered below. MPDs are manufactured in the UHF region, similar steps could be taken with those radios. The MPD-Scan is a MPD with 4 buttons on the front panel which control the scanning function. The buttons are labeled SCAN, ADD, DEL, and KYBD. Programmed properly, the MPD-Scan allows you to scan any/all the channels in memory and with a Priority-1 and Priority-2 channel, all of which are user programmable from the front panel of the radio. The radio is *capable* of (rated at) 5 watts output and 48 channels. When manufactured, the radio was rated weather resistant' for blowing rain. Each channel is programmed with: Transmit frequency Receive frequency CG - CTCSS for transmit and/or receive (independently programmable and can be defeated from the top keypad). GE calls CTCSS "Channel Guard", Motorola calls it PL®. CCT - "Carrier Control Timer" (settable in increments of 30 seconds). TN - "Tone" (when set, the radio will "beep" when channel is changed). H - High (Y) or Low (N) power - not switchable after disconnected from the programmer. OS "Oscillator Shift" to help eliminate Receiver spurs (called "birdies" in scanners). STE - "Squelch Tail End" which inverts the CTCSS phase to minimize the squelch "crash" on the receiving end of your transmission. TXL - "Transmit lock" to keep you from transmitting if there is a signal on frequency (recommend value of NO or you will be waiting for a repeater to drop carrier before you can transmit). 8 character Alphanumeric channel designator which is displayed in the LCD. A "Home" channel which is the channel the radio goes to when the HOME key is depressed (recommend channel 1). The default "power up channel" which is the channel which the radio defaults to when initially turned on (recommend a using your call sign for property identification purposes with a frequency which you will remember). The default "power up volume" setting. WHAT IS NEEDED (BARE MINIMUM): 1. A dummy load capable of handling 10 watts for 10 minutes. 2. A watt meter capable of measuring 10 watts in this frequency range (144-174 MHZ) 3. A receiver (Scanner or 2-Meter HT). 4. A charged battery for the GE-MPD. 5. PC software for the MPD series of HTs (File name is CNV.exe), the PC to radio interface box (same as for the MPA HT and the S-8xx series mobile control heads) 6. The correct programming cable to go between the PC interface box and the radio "mike connector" located above the PTT. This is the same cable as the MP-A radio. OR Access to someone (or some company) who has the software, interface, interface cable, and equipment to do all the programming and adjustments to the radio. WHAT WOULD BE NICE TO HAVE: 1. A frequency counter. STEPS FOR THE CONVERSION: 1. Write down: A) The 48 frequency pairs and channel designators you wish to have in the radio. B) The transmit CTCSS needed (recommend enabling STE if using CTCSS). 1) I didn't program a receive CTCSS at all. C) Whether this is to be HIGH power or LOW power channel. D) The "Home" channel (recommend Channel 1 for simplicity) E) The "Power Up" channel (recommend a using your call sign for the Alphanumeric channel designator for property identification purposes with a frequency which you will remember). My power up channel is receive only on the the local NOAA weather frequency with a receive CTCSS of 131.8, this enables the radio to stay silent' on this frequency unless I want to listen to NOAA weather. To defeat the CTCSS just press both ends of the Channel Selector at the same time for 1 second. F) The "Power Up" volume setting (1-low to 30-HIGH), I use setting 15 as a good compromise. G) The power output levels you want for HIGH and LOW power. I use 4 watts (High) and 1 watt (Low) to cut down on battery consumption. 2. YOU MUST "read" the radio then change its "personality" (configuration) with the desired programming. *OR* Configure the software to tell the radio EXACTLY what it is (eg. 150-174 split radio for the Ham 2 meter band). Do not attempt to configure the radio for the desired split', tell the software what the radio actually IS, then override the frequency lockout using the steps in 2-A A) Program the software with all the above information. If the software responds that the frequency is "OUT OF RANGE" when the programmer uses the ENTER key after typing the frequency, use an undocumented feature of the programming software to "force" it to accept the "out of range" frequency. This feature is CONTROL-E instead of the ENTER key. 3. Load the radio with the "personality" (programming) using the F5 (program) key. 4. Test the radio to make sure it is transmitting: A) "On frequency" using the frequency counter on the lowest programmed transmit frequency. B) At no more than 5 watts using the watt meter on a HIGH power channel. C) At the LOW power output you want also using the watt meter D) With the VCO locked on frequency using the receiver while transmitting. You are listening for the "telltale" audio squeal of an unlocked VCO while transmitting or the radio will blink the display and beep at you if the VCO is severely unlocked. 5. If the radio is transmitting with more than 5 watts and/or is not at the LOW power wattage you want; A) Adjust the "tracking" settings through the following keystrokes from the main menu of the software. F3 (utilities), F2 (maintenance), then F1 (reconfigure) from the main menu. B) In the reconfigure screen use the PageUP or PageDOWN key to change to a HIGH power channel and adjust the power output level to what is desired by keying the radio and noting the power out, change the OUTPUT POWER. number, save the value and retest. *Note that HEX value on paper.* C) In the reconfigure screen use the PageUP or PageDOWN key to change to a LOW power channel, use the channel UP/DOWN selector on the radio to select the same channel and test. Adjust the power output level to what is desired. *Note that HEX value on paper.* D) Exit without storing the values and go to the "TRACKING" section of the software using key strokes F10 (back) then F6 (track). On screen will be LOW, MED, and HIGH values in vertical columns, change the LOW frequency values to the values you noted in steps 5B and 5C (above). Write the changed "tracking" values to the radio, reload the "personality" into the radio and retest the power output on HIGH and LOW power channels. That is all I had to do to convert' my MPDs. I did not have to adjust the VCO at all. I did experiment with the SQUELCH settings in the TRACKING area of the radio but did not have to change them from their previously programmed value. NOTES: 1. It is a good idea to replace the internal Lithium "memory retention" battery (BT-1) after they read the radio into the software but before you have the radio "converted"/programmed. These batteries have a shelf life' of approximately 3-5 years depending on how long the radio sits with a dead battery or without a charged battery attached to it.. Once the radio loses ALL power, it will lose all of its memory, will beep...beep...beep, display *****'s in the LCD, and will REQUIRE reprogramming. 2. The POWER output gets higher as you increment (raise) the number and lower as the number is decremented (smaller). 3. The SQUELCH gets tighter (closes) as you decrement (lower) the number and opens as the number is incremented (raised). 4. Request that the person programming your radio PRINT the 'personality' (configuration) for you to reference later if necessary for reprogramming (also see note 5 below). Use the F3 (Utility), highlight the file for your radio then press F6 (Print) key from the main menu to print. 5. Request that the person programming your radio save (copy) only the 'personality' (configuration) FILE on a floppy disk *for you to keep* for reprogramming later. Giving you this file WILL NOT violate the software copyright nor the licensing agreement for the software. It will make it easier and faster to reprogram/reconfigure the radio next time. 6. The O.E.M. antenna performs about the same as other 6 inch "duckies" on Amateur bands IF the previous owner(s) did not cut it for their frequency. GE-Ericsson makes a "test" adapter to screw into the antenna port which adapts the radio to a BNC mount. (see #7 below) 7. The 'long' bettery pack (3.75 inches tall) is factory rated at 1600 to 1800mah. The short battery pack (approx. 2.5 inches tall) is factory rated at 1200mah. They both can be 3-hour fast charged'. 9. Convert the Antenna connector to BNC notes. Some D.O.A., but rebuildable, battery packs (both sizes) are available from the author. E-Mail for details.
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Copyright © 1998, 2004, Sterrett J. Carter - Last edited: 06 May 2004