Soooo today there was some strange but not unheard of interference…
First off, I thought my new 49:1 transformer was busted. I re-installed it in my backyard on my deck in the configuration that gave the best SWR on 40 and 20 meters which is basically my transformer is at about 1 meter from the ground sit-ing on 2×6’s on my my decks lower railing next to a pressure treated 6×6 post.
The wire is 63 feet 2 inches (1/2 a 40 meter so about 20 meters long).
From the transformer, it goes vertical to about 4 meters from the ground next to the 2×6 above the pergola. Then horizontally south for about 10 meters into a tree. Then makes a left, eastward horizontally for another 6 or so meters into another tree. So basically a horizontal L plus a short vertical portion. I wanted to keep it high enough so that we don’t walk into it and also so that neighbors don’t easily see the stealth wire.
Anyway. Then I bought my old Kenwood TS-180 downstairs and hooked it up to 50 feet of coax. Connected it to a my 12v LiFePO4 battery and connected that to my 24v solar panel and put it in the window where the Colorado sun was beating down on it.
Barely any stations came in on 20 and 40 along with S4 level noise. I searched both bands. I was bummed. I almost went upstairs to grab my iCom 7100 to see if it could do better when I remembered something.
I walked over to the solar panel, closed it so that it produced no current, and unhooked it from the battery and tuned around again.
The bands were alive! Stupid solar panel!
I then methodically put up my solar panel, listening for a change of reception. Apparently it was putting RF into its power leads which was being transferred into my Kenwood input power. I unhooked the solar power leads to the battery and went on my merry away. There were a lot of rag chews so I couldn’t make any contacts. I might try putting an RF choke around the solar panel leads because its nice to keep the battery juiced-up while I amateur radio.
Then I wanted to test my 49:1 to see how much power it could handle/output and what the true SWR was at the radio.
I hooked up an old SWR/Power meter with a 3 foot patch cable. I set the TS-180 to a blank station in the 40 meter CW band, about 25 watts, and tried to adjust the calibration for SWR. I heard funny beeping coming out of some device. I yelled upstairs to my XYL and asked her what she was doing. Nothing.
Hmm. I noticed the oven (1 year old Bosch gas/electric) was beeping. Weird. I got suspicious. I tried keying up again. The oven went into cleaning mode! Whoa!
I changed frequencies and tried again. It’s warming up for baking! WTF!
At this point my wife was nervous wondering if other things could turn the oven on when we weren’t home.
I changed to SSB and keyed up. Nothing. Added power to about 100 watts and keyed up. Nothing. Whew.
I’ve used the radio at 200 watts SSB on 40 and 20 here before. I suspected the SWR meter and unhooked it and tried the experiments again.
Nope. No issues. Either the 3 foot patch cable and/or the SWR/Power meter is emitting something funky that is lighting up my oven.
This isn’t the first time our Bosch kitchen has acted up. The touch panel on the refrigerator had to be completely replaced because something would make it seem like the temperature button for the freezer was being pressed randomly.
Finally, I wanted to see if adding a counterpoise wire would help SWR/Bandwidth of the 40m band. So I added some random 6 foot wire (which is the about the right length if we’re going for 0.05 lambda which comes out to 2m . No effect really. So then I unrolled the massively rolled up 50 foot coax and guess what? That helped! Since the coax is being used as a counterpoise, it makes sense that if its otherwise overlapping and rolled up, it can’t work as efficiently.
Anyway. So that was fun.
Note to self:
-
- no cw in the kitchen (easy cause I don’t know cw)
- solar = qrm
- coiled coax = not great swr/bandwidth
- “counterpoise” not necessary (didn’t test actually grounding but from what I hear…)
- 49:1 transformer = bueno/stealthy
- there’s a reason there are RFI questions on the technician, general, and extra tests
