Getting Back On HF

8 07 2011

I’m an extra class amateur radio operator, but haven’t touched an HF radio other than Field Day in several years. As ham radio always provides a plethora of little projects to work on, I decided to try and round up enough stuff to get back on the radio at my apartment by the end of the summer.

It’s turning out to be a decent amount of work (and I’ve barely started…). Since moving out from my parent’s place, my tool box and pile of junk parts shrunk to almost nothing, either since I left stuff behind or it was my parent’s to begin with. It’s the little things that kill you… audio cables, coax, connectors, adapters, drills, power poles… Basic plan is as follows.

Step 1: get a working HF radio going. I’ve got an Elecraft K2 that’s been collecting dust since Field Day about 5 years ago when, at around 3:00am, the receiver seemed to be experiencing deaf spots on 40 meters (or was it 20…). We swapped it out for another radio and I never got around to figuring out what happened to it. It’s possible that the front end got damaged from the other Field Day transmitter on a nearby frequency overloading it. It’s also possible the coils on the torroids just got jostled around on the trip and during setup, meaning it may just need to be retuned. There’s also a slight possibility nothing’s wrong with it at all and I just thought there was, so let it collect dust for half a decade not wanting to figure out how to fix it.

Step 1.1: build an HF white noise generator in order to test the receiver sensitivity across the band and to retune the filters. Couple of trips to Radio Shack and a few hours soldering, I managed to get this little gadget together. It sucks at high frequencies (anything above 40 meters), probably because I’m using a Zener diode with a little lower voltage than they said. I tried fiddling with the value of R1, but it didn’t seem to help enough to make it worth trying to unsolder the 1.8k I had on there.


I decided since I was going to all the effort of building it, I might as well stick it in an enclosure so it doesn’t get destroyed like most of my tiny perf board projects inevitably do if they get thrown in a box somewhere. I ran into a dead end when I was trying to figure out how to mount the PL259 connector when I don’t own a drill, a saw, or much of anything to cut through the plastic enclosure in the shape of a 9/16″ circle. Finishing it up will have to wait for a Tuesday when I can borrow some tools from someone to drill out the holes for the case.

I’m also retrieving the K2 from my parent’s house Tuesday (or sooner if I get antsy on Sunday). I’m really hoping that it’ll just work, or perhaps it just needs to have a hard reset and the filters retuned. Otherwise I’ll have to dig out some more junk and try to inject some signals that I can do signal tracing on and hopefully identify the cause of failure… that could quickly turn into putting a dead end to this plan and sticking the K2 back in a closet for another half a decade if it’s going to cost a lot to fix.

Backup plan, I’ve got a Yaesu 767gx also collecting dust. The thing is massive and I have no idea where I’d put it, the K2 is certainly easier to stick somewhere and use. Maybe I’ll drag both of them from my parent’s house to my apartment so I have a backup radio and something I can use to test the other with.

Step 2: Shopping for the odds and ends…

There’s a hamfest coming up in a little over a week, I’m hoping I can gather together all the little things I seem to be missing.

  • Coax (25 foot section, some short sections)
  • Red/Black heavy gauge wire
  • Power Pole power connectors
  • A dipole balun (or entire dipole, or other antenna I could hide near my apartment)
  • Alligator clips (always need them, never have them)
  • An SWR/Power meter
  • A decent pair of headphones (optional)
Step 3: Once I’ve got a working radio, plus all the odds and ends, I need to somehow get an antenna up. Luckily, this apartment is in a fairly decent spot for doing such a thing.
The bedroom window faces north, and happens to have a nice 8 foot block wall 15 feet behind the window (thick black line). Even better, there’s a large tree (green dot) right in front of the window, which will be great for concealing coax. The current plan is to throw either a 40 or 20 meter dipole up along the fence to at least get started again. Alternative/future plan includes trying to run an east/west dipole along the roof (no idea how I’d get up there, need a ladder), maybe a 20 meter east/west and a 40 meter in the back going north/south. I’ve got a few hundred feet of rope and copper wire, the only thing stopping me is the lack of coax and not having a balun, hopefully two things that will be remedied at the hamfest.



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