On Mon, 2 Nov 2009, bullmus wrote: > APRS on 144.39, and FM Voice repeater at 147.24/147.84. Antennas are > identical Telewave 4-bay stacked dipole. Both antennas are horizontal > to each other, and roughly two wavelengths from each other center loop > to center loop.
> We discovered the problem when we began noticing APRS wasn't getting > out. Troubleshooting identified that the single band-pass can we had > on the APRS was reflecting 100% of the transmit power. We do not know > the history or condition of this can in the first place. It is very > possible it has been faulty for years, and only recently began to > degrade to worthless. We have temporarily bypassed the can, and > expected possibly a little noise on the voice repeater because of it, > but we didn't expect the weird things we're getting now like the noise > continuing even when APRS isn't transmitting, and the level of desense > it creates. APRS is transmitting 5 watts. The Voice repeater is I > believe 25 watts. Because of channel utilization, it is no longer recommended to use a high-power, or high-gain digipeater site. APRS has now gone into micro-cellularization. As such, it is necessary to severely limit the transmit power to limit the effective range of the digipeater. http://www.aprs.org/fix14439.html http://www.aprs.org/newN/ProportionalPathing.txt http://www.aprs.org/APRS-tactical.html http://www.aprs.org/txt/operationsStationRate.txt http://www.aprs.org/txt/fundamental-issues.txt In short, someone probably "fixed" a problem when they were in the site by de-tuning the duplexer. -- Kris Kirby, KE4AHR Disinformation Analyst
