Mike Powell of Tower Erection and Maintenance, Inc. replaces the antenna for the FWRC 146.91 MHz EchoLink repeater on the campus of IPFW. (WB9SSE photo)
The 20-foot long Cellwave PD-220 antenna atop the tower on Kettler Hall at IPFW was replaced on Wednesday, 22 January. The antenna does its thing launching and absorbing photons for the Fort Wayne Radio Club’s 146.910/.310 MHz EchoLink repeater. The existing antenna had been defective for over a year thus limiting the performance of the EchoLink machine.
It was COLD up there on the roof of Kettler Hall when Mike Powell and his crew of two from Tower Erection and Maintenance, Inc. started work around 10 a.m. They finished at 2:30 p.m. The task had been scheduled on numerous dates starting from right after Christmas until it was finally accomplished on the 22nd. It had to be rescheduled numerous times because of the less than moderate weather we have been experiencing here in Ft. Wayne for the last month or so. The temperature Wednesday morning was around 10 degrees F, but the wind was fairly low and there was no precipitation (at least not until 2 p.m. when we started getting some flurries).
Despite the best laid plans of mice and men (specifically Jim Pliett, K9OMA, and myself), ole Murphy struck. We had planned that the tower climbing task would consist of climbing the tower, removing the existing antenna from the tower leg, lowering it to the ground, removing the PL-259 to type N jumper cable from the base of old antenna, reinstalling it on the replacement antenna, hauling the replacement antenna back up the tower, reinstalling it on the tower leg, reconnecting the jumper to the transmission line at the top of the tower, and then climbing back down the tower. The intent being to minimize the time expended by Tower Erection Maintenance, Inc. since they charge at an hourly rate. Easy-peasy, ehh?
Well it turned out that the jumper cable was damaged on the PL-259 end, and that meant that we (Jim) would have to replace the connector. And that meant that the tower climber had to climb back down the tower to keep from freezing in place while the cable was repaired.
If you have ever installed a PL-259 connector on double-shielded RG-8-style coax, you know if can be a difficult job, especially in the field. But Jim got it done.
Once the jumper was repaired the climber shimmied back up the tower and the new antenna with the repaired jumper was hauled back up to the top of the tower and was installed.
When we measured the forward and reflected power at the output of the duplexer and into the transmission line, we were quite pleased to see 60 watts forward and only 1 watt reflected. While we were at it, Jim checked the receiver sensitivity (measured at about 0.25 micro-volts), and the amount of desensitization (which appeared to be zero).
So the EchoLink machine should be talking and hearing well now. Go have fun with it.