Meeting Minutes - July 2012
Larry Stokes (N7IBC) and Ray Montagne (W7CIA) travelled to Brundage Mountain to look into the intermittent behavior of the 2-meter repeater with respect to coverage going up and down on both transmit and receive. The coax was replaced with LDF4-50 Hardline. A high SWR was evident but there was no time to return to the roof to investigate root cause. A second trip to the mountain will be made to place a dummy load on the end of the hardline to verify the hardline, then migrate the dummy load to the end of the diplexer that is located at the base of the antenna and then verify the antenna. Since the antenna system is not functioning properly, a mobile mag mount antenna is in use temporarily, with the transmitter power amplifier disabled to avoid receiver de-sense (with the antenna attached to the repeater cabinet and in very close proximity to the receiver). As a result, coverage will be greatly diminished until the antenna system is repaired.
Reports of spurious emissions received on a Radio Shack Realistic Scanner appear to be an issue with the scanner. The report indicated spurious emissions at 168 MHz. The transmitter output was verified to be clean from the primary frequency of 147.020 MHz up through 180 MHz. No emissions could be correlated to the repeater transmitter. It should be noted that scanners are not selective by design. As such, it is possible that the scanner has an image appearing at the local oscillator frequency + the IF frequency or the local oscillator - the IF frequency.
Harmonic content from the 2-meter transmitter at 294.04 MHz and 588.08 MHz appears to be acceptable.
The deviation of the encode tone on the 2-meter transmitter was reduced from 1.5 KHz to 750 Hz. This is the proper level for encode and should greatly reduce the buzz heard on the 2-meter transmitter.
The 900 MHz link radios were installed but since the antenna system problem also impacts 900 MHz, the 900 MHz transmitter was left disabled. The 900 MHz receiver is active but is attached to the non-resonant temporary 2-meter mobile antenna. The audio levels were not adjusted for the 900 MHz radios due to a lack of time and will be addressed during the next trip to the hilltop.
The 2-meter transmitter output was verified to be stable with 31 watts coming out of the cabinet.
In summary, the performance issues appear to be isolated to the antenna system.
Final resolution requires working from the roof of the building. For safety reasons, at least two individuals are needed to complete the antenna system repair.
|McCall Trail Running Classic - Station Designators|
|1||W7CIA||Ray||0600||Net||Jug Mt. Ranch|
|2||N7IBC||Larry||0700||Aid 2||Jug Meadows Saddle|
|3||KE7TQV||Peter||0800||Aid 3||Boulder / Louie Lake Trailhead|
|4||W7LCC||Dave||0830||Aid 4||Shaw Twin Lakes Ridge|
|5||KF7JPJ||Bob||0900||Aid 5||Lake Fork Trailhead|