VHF Update: Repeaters, Earth and Sky

Relais 5R8ZZ
Relais 5R8ZZ

I got an email from Albert, 5R8GV, last week alerting me and other hams in the area that Serge, 5R8GX/FR5GX, had put a repeater into operation: 5R8ZZ.  The repeater is based at his house and puts out 16 watts (after filters) through a quarter-wave ground plane antenna on his roof. The repeater’s input frequency is 145.150 Mhz and the output frequency is 145.750 Mhz (i.e., set your radio to 145.750, with 600 khz negative offset). No PL tones are used; instead send a brief 1750 Hz tone to open the repeater.

With that news, I stuck my mobile mag-mount antenna on the metal roof of my house and verified that I can hear the relay. I think I can open the relay with the tone (which required some reference to the radio manual), but I’m not sure I’m getting in very well on voice, even at relatively high power. My antenna is not in the clear — there lot of surrounding structures, tree, etc.  I’ll need to find a way to elevate and otherwise improve the antenna.

The antenna is a comet SB-224, which covers 2m/1.25m/70cm and the single coax comes down the shack, enters a 2m/70cm duplexer, and then into my B2000, the headless version of the Kenwood TS-2000 that I previously used as a mobile radio in my car. Satellites were on my mind since I had just heard about the launch of Fox-1A (now designated AO-85) last week. I decided to see what I could hear with my simple antenna.  In the past, I had a handful of CW contacts from the car using this radio and antenna combination with VO-52 and FO-29, so I was more confident than most sane people that this might work.

I had Ham Radio Deluxe (the final version before it became a commercial product) installed on a PC, so I used that for rig control and tracking. I have determined that I can hear most active satellites on low elevation passes, particularly to the west, where the view is less obstructed. Taking it a step further, I’ve been able to hear my own cw transmissions on XW-2E and XW-2F; the rig’s power output is high enough that I can hit them even without a directional antenna.

1024px-STS-130_Endeavour_approaches_ISS_3My biggest success so far, though, was with the ISS, which isn’t surprising since it is in such a low orbit and has less worries about power than most satellites. I set my radio to the APRS digipeater frequency (145.825) and listened for packets. On most passes, I hear two or three identification packets even if there is no traffic.

I downloaded UISS, an APRS package written with the ISS in mind, and rather than mess with the B2000’s limited built-in TNC, went with the more flexible UZ7HO sound modem. After some fiddling (I’ll probably make a video about it), I had both the virtual TNC and UISS package installed and working together. I tested the set up using my Yaesu VX-8R to send some APRS status messages and ensured that packets could be received.

That evening, I waited for the ISS to come in range and poked the buttons to send APRS packets with GPS coordinates and a short test message. After a couple attempts, I was rewarded by hearing the ISS relay my packets. I hit the button a couple more times on that pass for good measure. Since there wasn’t any other traffic, I thought it would be okay to send a few times.

Screen capture emailed back to my by FR400
Screen capture emailed back to my by FR400

The next morning, I was surprised to see an email from Paul, FR4OO — he had been monitoring the APRS downlink and recorded some of my packets that must have been relayed when Réunion and Madagascar were both in the satellite footprint. This success has me greatly fired up about doing more with satellites.

I’ve let the B2000 in monitoring mode, tuned to the APRS downlink frequency, which is shared by both the ISS and AO-84. I’m considering setting up an internet gateway for APRS here since I have a good internet connection.

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