Until further notice, the MARC repeater (223.960 MHz, standard load channel 27) is OFFLINE.
A few weeks ago, the repeater failed with a "PA FAIL" indicator. At the time, we were able to bring the repeater back online, but a week later it failed again in the same way. MARC members pulled the repeater from the rack and had it examined by a local repeater tech, who identified a blown cap in the finals. The cap was replaced and the repeater is once again functional... HOWEVER:
When reinstalling the repeater, some additional testing on the feedline and antenna configuration took place. You may recall that when the repeater was initially installed, we had a length of Heliax cable donated to the club, but the cable was not long enough to reach all the way from the antenna to the repeater. The final 70 feet or so was bridged with LMR-400 cable. Analysis of the installation showed that the feedline and antenna is presenting an SWR of 1.6:1. With the repeater pushing 35W of power up the cable, this results in a reflection of about 4W of power back into the repeater's output finals.
While many repeaters would be able to handle this, the Quantar repeater we have appears to be extra sensitive to this type of SWR condition. We need to replace the coax with a continuous length of Heliax cable and retune the antenna in situ (on the tower). We have chosen to make plans to do this BEFORE putting the repeater back online.
We have identified a source for the cable we need, but it is quite expensive. In addition, installation of the new cable will require someone climbing the tower, and Murray City (the owners of the tower) require that this be done by a professional tower crew for insurance purposes. We have brought the requirements and numbers to our contact with the fire department and the city is currently working on providing the funds required. Unfortunately, this may need to wait for the next budget year (which starts in June).
For now, we will continue using the 223.440 simplex frequency (standard load channel 29) for our Sunday evening nets, and we are also exploring other options for temporary use. Stay tuned to this post for more details as they become available.