wa8dbwret

The "new" WA8DBW Repeater
The Micor

The OLD REPEATER has been RIP for the time being. I wish to thank the following persons for their help in the move: Dale N8NVO, Dan KC8HLB, Dave AL7OP, Jim N8SGP, Joe N8MUM, Mike WB8CXO, and Tom KA8YKP and my wife CHARMAINE for putting up with me spending too much time on this yet to be completed project.

Looking South towards the equipment room
Visible are some of the antennas at the site. They range from 10 meters to 1.2 GHz.
The repeater antenna is the one at the top of the tower. It is a PD-455 Super Stationmaster.

LOOKING N.E. TOWARDS DOWNTOWN AKRON

Here are some pictures of the repeater installed!

Joe N8MUM, Dave AL7OP, and Mike WB8CXO
It survived the trip through the roof hatch!

Joe N8MUM and Dave AL7OP
Joe N8MUM and DAN KC8HLB
Another flight?

DAN KC8HLB
DAN W8DBR ~~(KC8HLB)~~
Discovers it is in and it WORKS!

The construction!

Another view

This is a view of the rear of the exciter - power amplifier assembly.

At the top is the amplifier heat sink. The amplifier is designed for continuous duty at 75 watts minimum output with no forced air-cooling. Because I dislike trips to the repeater site, I have improved on the design with the addition of two 3 3/4 inch 12 volt DC fans mounted to the heat sink. A third fan is mounted at the top of the cabinet to exhaust the hot air out of the cabinet.

Two sensors on the PA heat sink thermostatically control them. One sensor is mounted in the amplifier between the four PA transistors. The second sensor is mounted between the fins of the heat sink. It can be seen in the photograph above the top left corner of the first fan. This second sensor acts as a backup in the event the internal sensor should fail. Both are set to turn the fans on at 120 degrees.

A test was made transmitting into a dummy load for 12 hours at 100 watts out. The fans kicked on after 20 minutes. The fans turned off 12 minutes after transmission was stopped. This was done with the room temperature being 68 degrees at the start of the test. At the end of the test the temperature in the shack had increased to 74 degrees. The internal cabinet temperature was 107 degrees. This was up from 77 degrees at the start of the test.

Richard Reese, WA8DBW

March 12, 1999

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