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Author Topic: Ham Radio science project ideas needed for 12 yr.  (Read 2270 times)
AG6WT
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Posts: 463




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« Reply #15 on: December 15, 2009, 02:32:17 PM »

To continue with Gerrit's idea, having your son sit by the radio recording stations he can hear might be difficult if his time on the radio is limited or if he can't do repeated sessions under similar conditions.

One thing that might help is to collect data on contacts that are posted on the internet and used that to support or refute his hypothesis.

One website that might help is http://pskreporter.info. There you'll find digital mode contacts around the world broken down by band and time block. The data is plotted on google maps that might make a nice display if your son is making a poster.

73
Ray
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NI3S
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Posts: 67




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« Reply #16 on: December 15, 2009, 03:46:46 PM »

Coax Cable test would be cheap and easy to setup.  Basic instruments and borrowed samples for testing.
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N0SOY
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Posts: 72




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« Reply #17 on: December 16, 2009, 09:21:10 PM »

Google Crystal radio and you will be amazed the detail and complexity that shows up.  Those can provide hours of experimentation.  

Just don't plug them in.  Bad things happen.  I know.
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WA4CUA
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Posts: 23




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« Reply #18 on: December 17, 2009, 09:40:30 AM »

Here is an idea:

01). First, convert an old AM radio to a transmitter (actually it is already, with the local oscillator). The local oscillator is 455 Khz above the radio station frequency, so if it is tuned to 600 Khz, for example, it is "transmitting" at 1055 Khz, and can be picked up using a nearby AM receiver. Adding a small antenna to the local oscillator circuit will help the transmitting distance.

02). Place the radio on a metal plate. Now comes the experiment:

03). Make several covers for the radio (cardboard, perforated screen (metal colander) full metal jacket (soup pan), ceramic dish, etc. that will fit over the radio. The experiment can be to analyze the various radio wave attenuation properties of the various coverings.

It would help if the radio receiver outside the "transmitter" had an "S" meter that could be used to show the relative attenuation percentages (and also show how LOG scales are used, since, I believe, the typical "S" meter is calibrated in LOGbase10).

Alternately, if the signal is strong enough, you might be able to build a sensitive signal-strength meter with a diode and a very sensitive meter (or perhaps use a sensitive voltmeter; some can be purchased on sale for as cheap as $1.95 at Harbor Freight Tools). Then the display should be linear, which is easier to track than LOGbase10 values.

If you really wanted to make a stronger transmitter from the AM radio, you could retune the local oscillator down to the IF frequency of 455 Khz, and would have a much stronger signal at the end of the IF stages for transmitting.

Have Fun!

John
WA4CUA
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