WA1LMV
Advanced Class License
Rick Swenton
Licensed since 1969

Click Here to see the WR1ABM Avon Repeater Photo Gallery from the mid 1970's.

WA1LMV/R Tower with me at the 60 ft. level. Picture at right.

Repeater System:

WA1LMV/R
Burington, CT
On the air in 1978 as WR1AIB. Burlington Site decommissioned March 2003

52.01 MHz. In / 53.01 MHz. Out
162.2 Hz. tone
crosslinked to
442.925 MHz. In / 447.925 MHz. Out
110.9 Hz. tone

This repeater used a custom designed and built 8085 controller. The hardware and software is full-featured. The controller supports speech, accessories, time scheduling, autopatch with speed dialing, radio and landline control, remote bases, diagnostics, video display terminal, and much more. I can even turn on the flood lights at the repeater site.

I wrote the 140 page software program in Z80 assembly language. It assembles down to a 17k machine language program in EPROM. The software is a full-blown real time operating system with 5 hardware interrupt levels to simultaneously process DTMF commands from the receivers, DTMF commands from the phone line, buffered type-ahead commands from the terminal keyboard, background timer processing interrupt, real-time error trapping (boundary checking for program counter and stack pointer) and a fail-safe heartbeat interrupt.

Here are the features in detail:

• Two main receiver inputs for COS and PL

• Two aux receiver inputs for COS

• Audio gate control outputs to control the mixer gates

• Two main transmitter outputs

• Two aux transmitter outputs

• MCW messages and ID with programmable speed and pitch

• ID Timer with polite ID and broadcast ID

• Phoenemic based speech synthesizer with unlimited vocabulary

• Separate main receiver time-out timers with PL override

• Separate main and aux receiver timers for access and release delays

• Aux transmitters inactivity dump timers

• Autopatch with inactivity dump timer

• DTMF regeneration and speed dialer with speech readout

• DTMF mute of audio gates

• Reverse autopatch with announce

• Dial-in landline system control

• Courtesy tones with programmable MCW character and pitch

• Aux receiver and transmitter status tones

• CRT console with command line, menu and status display

• Full control over any input or output

• Interrupt driven background timing system

• Foreground priority based task driven master processor

• Two interrupt driven DTMF decoders with buffered type-ahead

• Interrupt driven terminal type-ahead buffer

• Watchdog timer / fail-safe processor in hardware and software

• Time of Day alarm clock / calendar with hourly chime, speech readout and event scheduling

• Programmable macro commands for speed key commands.

• Direct memory access through console or DTMF with speech readout

• Remote base synthesizer control with programmable frequency banks, mode and power control

• Detects presence of speech and clock chips and emulates functionality in software if not detected

During the winter of 2003, the tower guy wires were hit by a tree branch that had fallen during an ice storm. The guy wire broke and the tower came down. Fortunately nobody, including the residents of the associated house were injured. The tower fell in an optimal direction. Now it's time to clean house at the site to make way for paying customers.

Thanks to my friend Don Nelson, K1ZSG, for his assistance and generosity for all these years.

Here are a few pictures of the decommissioned equipment arriving at my house along with some old pictures of when the system was in service.

Two 20 AMP power supplies (left) under the keyboard, the CRT monitor (center), the RCA Series 1000 Low Band Transceiver below the CRT, and the controller and mixer (right).

Controller (top) and mixer (bottom).

Top View of the heap.

A "pre-micro controller" picture of the rack sometime around 1990. At the top is a custom antenna rotator controller that runs an Aliance U100 motor. It takes commands from the logic system and can position the motor from 0 to 360 degrees in 10 degree increments. Next is a rack mount RCA SuperFleetfone low band RX followed by the 16 channel audio mixer.

Before the microprocessor controller, there were 15 logic boards controlling the system. From top to bottom: The 16 channel custom audio mixer, two banks of 5 logic boards. The first 5 are the repeater logic, the second 5 are the control system. A bank of 5 more boards in the white panel were expansion functions. The binding posts above the main logic rack are +5V and GND for the Logic Pen. (Remember those?)

The older system had a Teltone 3-board DTMF decoder and a Wescom Hybrid for the Autopatch. Below that is the two meter remote base consisting of a Standard HT transceiver board and a GLB Synthesizer interfaced to the repeater logic. Last is the GE MASTR Royal Exec transceiver, the original RX and TX for 52.01 / 53.01.

Development of the new controller hardware. The controller could accept control input simultaneously from the CRT keyboard, two radio receivers and the phone line. Software was written on the Heathkit H89 computer.

Inside view of the controller. The computer board (the lower one) is a control board from a Kodak blood analyzer. It has an 8085 µP running at 5 MHz, up to 64K of EPROM and plenty of I/O ports. The upper board is the additional circuits that add two DTMF decoders, a DTMF encoder, speech synthesizer, time of day clock, watchdog timer and audio tone circuits.

View of the enclosure.

Screen shot of the video display from Feb. 23, 1991. Notice the single letter control command menu, the display of the various timers, and the display of the I/O port signals shown as ones or zeros

Here's a blast from the past. This is my Ham Radio Shack as it appeared in 1973. Starting at the top left corner is a barely visible Heathkit Mohegan shortwave portable. Next is a Heathkit Signal Generator. The black panel with the six knobs is a stereo tube type homemade amplifier connected to the adjacent Scott FM tuner with a homemade stereo demodulator. On the middle shelf is a homemade oscilloscope and phone patch console, a low band 30-50 MHz tunable monitor, and a Glalaxy three channel cyrstal controlled 2M FM transceiver. On the bench is a National Ham Band receiver. On the table on the right is a Polycom 6M AM transceiver, an SBE-33 Low Band SSB transceiver, A Halicrafters SX-99 Shortwave receiver and finally a Heathkit Marauder low band SSB transmitter. Under the bench visible behind the chair is a Collins 32V1 low band AM transmitter. Thank God my Dad was generous with the precious space in his small workshop!

Well, well, well. When I was a member of the Bristol CT Civil Defense we operated a 6 meter AM net and I operated from the car. I used a Halo antenna mounted on the bumper of my prestigious 1967 Rambler American. I actually commuted to college and was seen in public with this car.

Here's the workbench around 1978 along with my first dog, Brownie. You can see the Motorola signal generator on the top shelf and the Motorola service monitor on the bottom. By this time in my life I became rather proficient in servicing commercial two-way radio products.