Sparc

I had created a channel on my Meshtastic node for SPARC and at the Elmer night, we signed people up to use it.

Name: SPARC
PSK: WVaaYi2B/GJWGJwgbyXH7+na142aLwend1+UA2W2CPo=

W3IHM, Sam, presented the 900MHz band at the SPARC member meeting.

History

• 1926 - first regulation of amateur radio
  • before 1926, ban on anything belowe 200m
    • amateurs could do anything they want above 1.5MHz
• First regulations defined bands
  • harmonically related
• Amateurs imposed legislation for technical reasons
• 900MHz has been available to hams since 1926
• People wanted broadcast interference from ham radio gone in mid 1920s
• 1930s - allow anything above 110MHz
• 1935 - people were getting up to 3200MHz with magnetrons (spinning electron)
• Commercial broadcastsers pushed hams into bands and out of lower bands in 1920s when we started figuring out propagation in the ionosphere, and they wanted to broadcast around the world.
• war-1940 - we’re allowed above 300MHz
• 1941 - all ham radio is shutdown for war
• 1947 - military is reluctant to give back bands
  • bands shifted around a little
  • allowed up to 300GHz
• 1952 - added 15M
• 1979 - added WARC bands (12, 17, 30)
• 1986 - 33cm
• 2002 - 60M
• 2016 - 2200M, 630M
• Will we get 8M, 5M, and 4M like other parts of the world?

Characteristics

• 900MHz-928MHz
• Feed line loss is double that of 440MHz
• Antenna loss
• Atmospheric loss
• Simplex is pretty dismal
• Bounces well, like off airplanes
  • Once got Harrisburg to Philly bouncing off an airplane
  • Hit repeaters with Yagis and bounces
• It’s a shared band with some other services.

Possibilities

• Commercial radios with other software and surgery
• Harris radio - expensive software
• EF Johnson - free software, but needs surgery
• Alinco had something, but not available
• Kenwood TK981/481
• Retevis RT10 - 1W $80
• Listen with Quansheng, but filters won’t transmit.
• Baofeng with dirty harmonics might TX on 900MHz
• Baby monitors?
• SDR dongle
• Transverters

Shared Bands

• Power meters are everywhere in the middle of the band, and the noise causes the FM squelch to stay closed.
• Everyone’s trying to use the slivers on the end to avoid interference.
• Amplifiers can overcome the noisy power meters.
• Surplus amplifiers and antennas can be cheap.
• K3LV has a repeater in the area.
• Use it or lose it (already to the power meters).
• Power meters may go away after a while to move up to 2.4GHz
• Lots of competition for 900MHz - 2GHz - goes through the atmosphere easily.

I took along the old slim jim antenna I bought at my first ham fest. I understand now better how to tune it: I need to make it a little longer, not just slide the feed point up and down the batch.

The antenna was a little short by measurement with the NanoVNA. I hung it from a fan in the middle of the room to measure it without interference. I lengthened it at the far bend by soldering some extra house wire in the bend.

Now it looks perfect for 2m and 70cm.

There were only 3 of us at the SPARC elmer night, but we were on the same page. I compared notes on packet/APRS and WoAD with KC3QEH, JJ. We both had these new Btech-based radios. Even on the hill, our HTs with small antennas didn’t pick up much inside the building. I tried an external antenna from another club radio and I started receiving lots of packets. Sending APRS messages worked under the Signal menu: KC3QEH-7:TEST MSG

Club Business

• Elections
• Ideas
  • Looking for help with fox hunt
    • have the transmitters
    • can get help from other clubs

Presentation: DMR with Jason

• originally designed for professional radio installations.
  • lots of motorola gear
• developed in europe first
• digital voice
• data
• components
  • radios
  • repeaters
  • controllers (for routing traffic)
  • network infrastructure
• lots of networking and linking over large areas.
• types
  • tier 1 - consumer
  • tier 2 - professional, trunked
  • tier 3 - trunked, large-scale
• TDMA (time-division multiple access) - 2 channels / slots
• narrow bandwidth 12.5khz band
• modes
  • private
  • group
  • broadcast
  • data: text, gps, telemetry
• radio id is assigned by radioid.net to you and your call sign
• talkgroup = collecting a bunch of radio ids into a single contact
• popular public networks:
  • tgif
  • brandmeister
• can also be a private network
• hotspots access dmr network via the internet
• delmarvadmr.com
• 3 building blockse
  • talk groups
  • channels
  • zones

At the previous week’s meeting, many people built EFHW kits and untangled some wire to use with them. No one finished the build and brought them back, so I offered a quick demo of tuning such an antenna.

I connected my 49:1 unun that I’ve been using to a new wire we had hanging. We connected a handful of different analyzers to see how they operated.

Joined the Club

My membership was approved, so SPARC now has 146 members. Mark asked if I’m a climber. It sounds like lots of people chicken out about half way up when climbing the tower. When studying for my license, I didn’t commit a lot of the tower stuff to memory, since I didn’t expect to be involved in that sort of thing.

Ham Fest in York

SPARC will be at the Ham Fest in York with some “ham junk” for sale. Ralph, from Radio Shack, bought Souders’ small hardware business, so he’ll have all those small accessories there. Testing will be available at the Ham Fest on a walk-in basis.

Other Programs and Notes

• Breakfast in Manheim, every 2nd Saturday, at City Star Diner.
• Mike is building fox hunt transmitter. Someone else is building a battery for it.
• Tech classes will start again, Maybe on Mondays. Someone suggested conducting a mock net for training.
• UHF repeater is working. Full-time tied to VHF.
• Field day is coming up soon at the club house.
• There may be room for me to help with website maintenance.
• Some people are going to Dayton Ham Fest.
• Trying to use Ham Club Online again to manage membership. It’s a database for ham clubs. Ares is on it.
• Balun Designs is a good source for durable hardware.
• HFQso runs nets for testing propagation.
• There’s an Appalachian Trail APRS Golden Packet event to pass an APRS packet the entire length of the trail.
• Podcast: Ham Radio Workbench
  • An old episode (1 year ago?) had Vance, N3VEM, doing rocket stuff.
  • I’m never going to finish my podcast list.
• I chatted with JJ, KC3QEH. I need to look into his POTA activations.

Club Net

I checked into the club net for the first time tonight.

I visited the K3IR tower site for their Elmer Night. People were configuring cameras and testing an ultra-portable FT8 setup:

• truSDX radio
• ft8cn on a phone
• very lightweight wire antenna and transformer kit
• an inexpensive, but super-long, fishing pole as a mast

(Now I need one of those fishing poles.)

I borrowed a soldering iron and started on my own project: assembling a couple common mode chokes from a short piece of RG174. It got dark quick, so I finished the chokes at home. It was my first time trying to crimp those SMA connectors.

I got a quick tour of all the repeater hardware. There are a lot more services running on these towers than I realized.

I attended the SPARC member meeting tonight and heard about lots of interesting plans. They have some fun events coming up, like a fox hunt, some antenna building to prepare for the fox hunt, and even some POTA outings. They’ll also start planning for field day.

The main presentation was about the recent Dry Tortugas DXpedition.

I went home and sent my member application right away.