UHF Northern Hub & VHF Drop Repeater

New UHF Rptr &
Equipment Rack
Move to
New Building
VHF Repeater
2003 Activity
New VHF Repeater


Early 2000 It was time to find a new VHF drop repeater for VE6NHB. The existing GE Master Exec II had provided years of good service, but it was starting to have problems due to old age and having to operate in the high level RF environment at the VE6NHB site.
( >460,000 watts of 77 to 2400 MHz RF from 2 TV transmitters, 1 FM transmitter and 5 Cell & Pager operations.)

Feb 2000 Brian, VE6BCA, located on the internet a used Motorola MSR2000 VHF repeater for sale by Daryl Jones at Telecommunications Engineering Associates (TEA), http://www.tcomeng.com/. After some negotiation and learning that the repeater was for amateur radio use, Daryl offered the repeater for much less than he was advertising or Brian had found elsewhere. A thank you to Daryl & TEA for their generosity and assistance in this project.

The problem of shipping the 100+ lb repeater was solved by Bruce, VE6BRZ, who frequently travels to California on business. Bruce occasionally drives his own vehicle and on April 6 found himself near TEA in San Carlos, California. However Bruce had problems contacting Daryl by phone to give advance notice of his arrive that Daryl required in order to arrange for someone to meet Bruce at TEA's warehouse where the repeater was located, some distance from the TEA office. So Bruce phoned Brian in Edmonton who eventually was able to contact Daryl and pass on Bruce's cell phone number. Daryl then phoned Bruce to make the arrangements for someone to meet Bruce while Brian  sat back in Edmonton and watched Bruce's progress in California on his computer via the internet and APRS.

Click for a larger viewAt the warehouse, Bruce was unable to get into the parking lot as there was no room for his travel trailer. Bruce drove around and found a parking lot with enough room to leave the trailer in as he needed to drop the trailer anyway in order to load the repeater into the back of his truck. Bruce found a spot and left his wife reading a book inside to guard the trailer while he went back and got the repeater. When Bruce returned to the trailer he found not only his wife, but also the police waiting. The police had responded to a call from someone concerned about the abandoned trailer. After hearing Bruce's story they just smiled and left.

      (Click on the map for a Larger Image)

April 14
Bruce, VE6BRZ, delivered the repeater
to the QTH of Barry, VE6SBS.

The Motorola MSR2000 intermittent duty 110W VHF repeater
will be operated at 70 Watts for continuous duty operation.

(4) MSR2000 modules were "customized" for use in the VE6NHB repeater.



R1 Audio & Squelch Module TRN5069A.

- Mic circuitry was modified to allow use of a local mic.
- Squelch circuitry was modified to reduce the squelch threshold when PL tone encoded signals are received. This allows setting the squelch as required to minimize false squelch openings without concern of limiting weak signals access to the repeater.

PL Tone Encoder Decoder Module TRN5075A

Indicator LED's for PL Tone Decode and Encode, Receiver COS, Squelch Indicate, Transmit, PL Disable and Transmit Disable were added to modules for convenience when servicing and monitoring repeater operation.

Normally a PL tone will be encoded whenever the repeater is transmitting. The CD-3 controller, via DTMF control, can switch the repeater to only encode a PL tone while the receiver COS is active. In addition, the CD-3 controller was modified to provide a signal to the VHF repeater to also encode a PL tone when the UHF repeater is linked to the VHF repeater and the UHF repeater receiver COS is active.

Encoding a PL tone only while the receiver COS is active provides an alternate method of linking to the VHF repeater by using a PL tone decoder to eliminate repeater hang-time, courtesy tones and I.D. messages.

An AC Fail and Battery Control home brew circuit was added to switch the repeater over to 12 volt DC battery operation upon loss of AC power. The circuit also adds a low level beep tone to transmissions while operating on battery power to indicate battery operation and the loss of AC power or power supply problems.

The 60 amp diode that
was added to isolate the
repeater power supply
from the backup batteries.

On July 31, 2001 this new MSR2000 VHF repeater replaced the old GE repeater.

Project Documentation

In response to a number of requests, here are PDF files of this projects documentation.
NOTE: Module schematics below are of the MODIFIED MODULES.
Refer to Motorola documentation for unmodified module schematics.

These PDF documents are sized to print on standard 8 x 11 inch paper
except for the receiver schematic which is 8 x 14 inch.

This was never intended to be a "how to" project so modified and unmodified Motorola schematics will have to be compared to determine how each module was modified. Modified schematics do not show un-used circuits and un-used circuit components were often removed and their PCB pads were re-used for the components of added circuitry and existing PCB traces were re-used to provide much of the required interconnecting wiring. It has been some time since this project was completed and I am not sure if all on site 'as built' drawing corrections have been transferred to these drawings so their accuracy can not be guaranteed. E-mail if you have any questions.

Squelch Gate Card
Station Control Card
R1 Audio & Squelch Card
PL Tone Encoder Decoder Card
Hand Mic Schematic
Backplane Drawing
Wiring Schematic
Battery Control Board Schematic
Battery Control Board Layout
Documentation & Setup Notes


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