Having fun with amateur radio
On About.Com, Mary L. writes about her experience with “haunted ham radio.” She writes,
The next day, sometime in the early evening, I plugged the radio into the wall and began tinkering with it. Then, the most terrifying thing happened. The static faded completely. The silence came back on as did the sound of breathing. Suddenly, the creepy voice of a man came on and said, “Hello, little girl.”
Yipes! :)
On the IC-746PRO mailing list, a fellow asked, “On the 2m band, why doesn’t the S-meter reading on my IC-746PRO match the S-meter reading on my 2m mobile radio?” My answer was that while there is a standard (it’s actually a recommendation), it’s rarely followed, so it’s not a surprise that the two readings don’t agree.
Mark, K5LXP, corrected me, noting that the recommendation specifies one value for an S9 reading below 144 MHz, and a different value above 144 MHz. The recommendation reads:
STANDARDISATION OF S-METER READINGS
- One S-unit corresponds to a signal level difference of 6 dB.
- On the bands below 30 MHz a meter deviation of S-9 corresponds to an available power of -73 dBm from a continuous wave signal generator connected to the receiver input terminals.
- On the bands above 144 MHz this available power shall be -93 dBm.
- The metering system shall be based on quasi-peak detection with an attack time of 10 msec ± 2 msec and a decay time constant of at least 500 msec.
This corresponds to a voltage of about 50 microvolts below 144 MHz and a voltage of 5 microvolts about 144 MHz.
It would be interesting to know how the software of the IC-746PRO handles this. I say software because the S-meter on the IC-746PRO is a digital meter whose readings are controlled by the rig’s microcontroller. Theoretically, the software could calculate the S-meter readings differently based on the band that the rig is set to, but I don’t know that the programmers would go so far as to do that.
On the AMRAD mailing list, Andre, N4ICK, posted a link to the YouTube video, “12AU7 regenerative radio on a tin bake plate” (see photo at right) It’s a very cool regenerative radio made with a single 12AU7 vacuum tube. The only problem is that there are no links to the schematic for the radio.
So, I Googled a bit, and came up with this circuit. The cool thing about this circuit is that it uses a 12V power supply, not the high voltage power supply normally required for a tube circuit.
Over the weekend, I went to a big rummage sale sponsored by the local Kiwanis club. They had quite a few aluminum baking pans there for very little money. I should have picked up a couple of them. :)
Simliar Radios
VK3YE has also posted a YouTube video of his experiments with a similar circuit. Unfortunately, he also doesn’t include a link to a schematic.
Another related YouTube video is for a one-transistor radio. This is actually a very well-done video. It shows you step-by-step how to build the radio. This is something that we may actually be able to do down at the museum with some kids.
At the very least, watching the videos is amusing. At best, maybe they’ll inspire you to do a little experimenting.
As the title implies, here are a few more interesting items I’ve gleaned from all the mailling lists I’m on:
I believe I’ve written about the second, but the first is a new one on me. Both are interesting reading.
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