Sunday, October 6, 2019

-APRS applications

Overlooking Anchorage, Alaska 3510 ft ASL.  Anytone 878-UV transmitting APRS beacon.
On the way up/down some location beacons were not recorded. APRS tracking is limited to where you can be heard by an igate or repeater.  On VHF this is basically line of sight to town.

Sunday, April 28, 2019

-Install/upgrade external antennas, coax into house, & ground system.

2x galvanized conduit (1 & 1.25" EMT) + hose clamps & exhaust clamp saddle + extended ubolt to connect the two sections.  Arrow OSJ 146/440 Mhz J-pole now @ ~30 ft HAAT.

Safety and compliance inspector Jay collecting fee after approval of a Steller installation.  Always seal exposed UHF connections with rubber splicing and electrical tape.

2x Comet CTC-50M window feed-thru jumper with vinyl sliding windows. Final setup will go through wall.

Ground rod installation.  Easily bore down 10 ft in 2 minutes using EMT conduit & home water pressure.

Sunday, March 24, 2019

-Raspberry Pi 3 and Mobilinkd TNC2 for APRS duty

  • Setup XASTIR on Raspbian to act as an Igate using Mobilinkd KISS TNC.

XASTIR doing RF -> inet gating.  Terminal highlights commands to activate Bluetooth serial link after paired to Mobilinkd.

Update 6/2020 - Have been running an APRS Igate KL3RR-2 for about 1.5 years. Initially had some issues with bluetooth stability on the Raspi3.  The BT link would fail after a few weeks. I found this was a known issue and solved in the Raspi3 B. Indeed it fixed the problem and now has run stable for many months without any intervention.

Current hardware for KL3RR-2 is a Baofeng UV3R, Mobilinkd TNC2, Raspi3 B running Raspbian and XASTIR.  Antenna is an Arrow J-Pole at approx 30' height.

I appreciate the GUI of XASTIR both for visualization (which is a key outcome of the data produced by APRS) as well as being able to interact and use the station for APRS functions such as messaging.  Coupled with connecting to the raspi via VNC this makes for a functional APRS Igate that is remotely accessible and controllable. 

KL3RR-2 APRS Igate interface via remote connection (VNC).

Sunday, March 17, 2019

-12 Vdc power

Current home setup for powering radio equipment:

Electrical hardware mounted on a cutting board.  Samlex SEC-1230UL 30-A charger, Optima Blue Top 55-Ah battery.  Blue Sea Systems (marine) fuse panel and various other components intended for car audio.
  • The SEC-1230UL is a switch mode supply but quiet enough to not interfere with HF reception.  
  • With the SEC-1230UL and a battery, the system behaves as a dc Uninterruptible Power Supply.
  • With 120 Vac available, the system can maintain a <30 A draw indefinitely (limited by the charger).  However, higher amperages can be sustained intermittently (limited by the battery).

Monday, March 11, 2019


New Mobilinkd TNC 2.2 . Working well so far.  Very quick to setup.  
It links to a tablet, phone, or computer (via Bluetooth) and a radio (via cable).  

The Mobilinkd is a KISS TNC.  It MOdulates/DEModulates between the radio audio in/out and a digital signal sent over the Bluetooth-serial link while facilitating switching of the radio PTT.

The end functionality is completely dependent upon software.  One of the most common uses is for APRS:

Mobilinkd TNC 2.2 w/ Baofeng UV-3R and APRSdroid on a tablet.
The high resolution screen is ideal for mapping APRS data.

The radio and TNC are a compact package.
The Bluetooth is nice as the tablet is not constrained by a physical link to the TNC.

Sunday, February 10, 2019

-DMR hotspot operational

TP-Link TL-WR802N (Travel Wifi AP router) and SharkRF openSPOT 1
Local digital radio internet gateway. 20 mW max output (UHF)

(radio) <-> (openSPOT) <-> (worldwide DMR networks via internet)

-APRS troubleshooting. Anytone 878UV

Anytone AT-D878UV as heard by rtl-sdr+gqrx. Garbled coordinate data in APRS position transmission causes it to be ignored by receiving stations.

A second example showing other stations' APRS traffic for comparison

Update 2/27: Found some information here leading me to a solution for the APRS issue.  Below is a screenshot of my 878 APRS settings which have resolved the unintelligible transmission problem:

Take note of the time delay settings (with red dots) as well as the lack of a coma in "APRS signal path".  These changes resulted in my APRS transmissions clearing up and finally showing up on


Update 2020: Updating the CPS and radio firmware to the latest (and matching) versions seems to have eliminated the above issues.  Through the last year I have been using the 878 with to transmit my position in a number of challenging outdoor environments and it has performed and held up well.  Looking forward to APRS messaging capability in the future.

Anytone AT-D878UV DMR & Analog VHF/UHF radio