Ask ten amateur radio operators about digital modes, and you’ll get 11 different answers. Digital evokes some strong opinions from hams, good and bad. That’s okay! Hams are a diverse bunch, and we don’t have to like all the same things.
JCAR is soon going to send a digital data transmission as part of its weekly ARES Training Net. In an actual emergency, we will still have to pass data back and forth, and digital modes have significant advantages over phone modes for data transfer.
We’ll be using a mode called MT63-2000L, which works well on noisy repeaters and doesn’t require any special equipment to decode and send. If you’re interested in setting up a computer to decode our digital transmissions, see our guide here: https://jcar.us/digital-mode-decode-setup/.
The 146.90 repeater has been plagued with problems for quite some time. Recently thanks to a grant the club received we were able to replace several key components and alleviate almost all of the old problems that have been around for years.
The original Kenwood TKR-750 VHF repeater was found to be damaged and was only able to output around 20 watts on high instead of the 50 watts it should be capable of. This problem combined with a duplexer that was physically damaged, possibly by lightning, we were only seeing a mere 8-12 watts out of the duplexer. Inside one of the cavities the adjustment rod had become unattached from the tuning rod. We attempted to repair this but later found that the beryllium material inside the tuning shaft had also been damaged as well.
The repeater has since been replaced with a Yaesu DR1-X that is operating in both analog FM and C4FM digital modes. The duplexer was replaced with a brand new Telewave 4 cavity model since the old duplexer could not be repaired or tuned. The feed line and antenna were also checked. After the upgrade the repeater’s coverage expanded greatly and is now covering the majority of Jackson County and being used and heard in two other states and at least 9 other counties. Below are the before and after simulations of the repeater’s coverage. The current simulation is very much on par with real-world tests and reports.
Before Upgrades (pre-2016)
After Upgrades (2016)
After Upgrades Satellite View (2016)
Shortly after completing the new hardware replacement JCAR has installed internet at the site to facilitate the return of Echolink, IRLP, and other internet linking capabilities. Along with the internet Jackson County now has an APRS Digipeater and iGate once again running under the JCAR callsign K4SCO. Currently work is underway to add an Arcom RC210 controller to the repeater which will allow the addition of the internet and VoIP services along with RF linking to other sites and a remote base radio.
I finally had a chance to open up the 147.36 repeater’s power supply that failed a couple of weeks ago and didn’t have to look far for the reason of the failure. The cause is still undetermined but the damage is easy to spot. The power supply was still functioning and could support the repeater however when the link radio and UHF amp were brought up it couldn’t handle it. ~K4NHA
Saturday we attempted to tune the duplexer that was currently installed on the 146.90 repeater. For a long time now there was an apparent issue that was severely limiting the amount of power the repeater could run. Ben, K4QF, began tuning and quickly found that one can was completely unresponsive. The issue became apparent once we removed the bottom of the can. The tuning rod had broken loose from the bottom of the tuning tube:
A quick repair was attempted with 2-part epoxy but because of the coating on all the metal inside the can the epoxy wouldn’t hold at all. The duplexer will need to be sent to Telewave for repairs. Not all was lost however and the repeater is now operating on separate transmit and receive antennas running at full power, a 9.5dB gain over the previous power level. Coverage has been drastically improved at this time however coverage may have changed due to the positioning of the receive antenna on the tower. More repairs and tuning will occur in the coming weeks.
Thanks to Brad Ivey (KK4UWF) and Richard Arnold (KB4RMA) repairs have been made to the building at the 146.90 repeater site. The door was in bad shape and the A/C unit was no longer cooling. Saturday they repaired the door by replacing the damaged wood, re-hung the door to ensure the locks worked correctly, and sealed the opening to prevent and water from getting in. KB4RMA also cleaned the A/C unit which is now cooling the building properly and keeping all of the radio equipment nice and cool.
JCAR would also like to thank the Jackson County Sheriff’s Office for graciously allowing us to use this building for our equipment alongside theirs, it is very much appreciated!
The 147.36 repeater has been relocated back to the Section area in preparation for the severe weather season. This new location will be it’s home for up to a year while work continues on finding a permanent home and tower site in the area. Below are pictures taken from both days showing the tower construction and installation. Click an image to see the full-size version.
