Barry Feierman, K3EUI
There is an interesting article in this month’s QST about the difficulty of linking multiple mobile / portable stations for a car race in Maine. Repeaters on 2-meters is one way to go, if you have propagation. But in mountain passes, you might be in a valley and 2-meter FM won’t cut it.
What about EMCOMM over an entire state the size of Pennsylvania? One thought was to link multiple (dozens) of 2-meter repeaters – good luck. Even if you could do that, not all operators would be able to hear a 2-meter repeater from a valley. Most repeater owners would not buy into the policy tying up “their” repeaters for one event.
So, why not consider HF 80-meters / 40-meters for NVIS (high-angle skywave) propagation? You need a decent HF SSB radio, a sound card, about 50 feet of wire antenna, and of course, a General class license. There are multiple NBEMS weekend nets on 80-meters (3583 KHz is the PANBEMS frequency on Sunday morning at 0730 local). At this time of day, QRP 5 Watt SSB stations can copy each other using sensitive digi modes like THOR22 and a 65-foot wire antenna. But, the 80-meter band closes down by 1100 local time due to absorption of 4 MHz RF in the D layer of the ionosphere. So, 80-meter daytime EMCOMMS are out.
Fickle 40-meters (7 MHz band) is superb for NVIS paths of 10-500 miles from 1000 to 1400 local. 7 MHz RF gets through the D-layer with little absorption, and is a frequency that will get reflected by the E and F layers. One way to test 40-meters is to listen to the W1AW CW bulletins from 0900-1000 local on 7047.5 KHz. Yesterday, W1AW was S9 plus 10 dB with a simple 40-meter dipole mounted 20 feet above ground. The digital portion of the 7 MHz band (7000-7110 KHz) consists of CW, PSK, lots of FT8, some RTTY and a lot of VARA Winlink. Listen to 7074 KHz (USB) and you will hear dozens of FT8 stations using the WSJT-X software. Yesterday, I used an Icom 705 (10W) and worked stations in Ohio and North Carolina.
I am proposing a new “40-Meter EMCOMM Training Net” on weekends around 1000 local for the Mid-Atlantic region. This would be a net to test EMCOMM propagation paths for a few hundred miles around the Philadelphia area. We will need a purpose, a day / time slot and net leadership. If any digital operators are interested in planning this net, please contact me ; k3euibarry@gmail.com.
A possible name might be “Mid-Atlantic EMCOMM Digital Training Net.” We might use an FLDIGI mode like THOR of MFSK (30-80 wpm and 500 Hz bandwidth) or VARA HF 500 Hz (Winlink or VAR AC). We will have a “net control” to take check-ins and pass simulated EMCOMM traffic like severe weather forms, ICS forms, spreadsheets and even small images,
I checked with ARRL EPA leadership and Section Manager Bob Wilson-W3BIG is ready to support a new EMCOMM net like this. The best time to test seems to be Saturday or Sunday mornings around 1000-1100 local, after 80-meters shuts down. A frequency around 7080 to 7085 KHz (VFO) with a maximum of 500 Hz bandwidth looks promising, Any SSB transceiver and a simple sound card and laptop with a 60-foot wire antenna should work well. Dipoles mounted close to the ground are very popular as NVIS 40-meter antennas.
I hope to have a planning committee by July and start this net by August.
Note from SM/SEC Bob Wilson-W3BIG: I have known Barry for more than 20 years when we both conducted intensive NVIS experimentation between field stations in Chester and Delaware Counties using HF frequencies. Our purpose was an attempt to improve EMCOMM operations in our region. This is still a critical need. Providing VHF / UHF comms over a region as expansive as the 34 counties of the EPA is a challenge that continues to be a pipedream. A viable solution to the challenge may very well lie in digital modes on HF using NVIS techniques. Barry has been a force in the EPA – training scores of new operators in digital techniques. If you are interested in digital modes as well as EMCOMM, please volunteer your time and experience assisting Barry to establish this new net.
