wrote in message
ups.com...
And I suspect I would make the problem worse if I let the kids
telegraph in their own language.

(Cough cough)....... yap!!!!!!!

I couldn't really think of a way to avoid a cataclysm that is why I ditched
the idea of using the ham band, and especially the color burst frequency,
without second thought.

The 3.579545Mc (Got a color burst crystal in my hand right now.) frequency
is popular because the crystal is so readily available. So it's used in a
lot of homebrew equipment. The crystal may be pulled up or down a bit in
frequency, but within a few KC of that frequency.

You would basically be dropping them into a hornets nest of activity.

Any other alternative would be highly suggestible, even running relatively
high power on the AM broadcast band would have less of a chance of stirring
up trouble.


Another idea.
Going with off the shelf CB's would also be an idea. You could use a code
practice oscillator held close to the mike, or even wired into the mike
circuit, to send code practice. You could even implement digital
transmission systems via a computer, program, and sound card (RTTY, PSK31,
MFSK) if you wired the soundcard output into the mike. It would work
perfectly fine on Stock AM. Only one person could use the frequency at a
time. It wouldn't exactly match the designed method of operation, but it
would work. It would get them familiarized with the modes of operation.

If you spent the money on SSB CB's then you could fully implement the
intended method of operation for soundcard/computer based programs. And it
would allow multiple people to carry on a PSK31/RTTY/BPSK/MFSK.....
conversation on the same channel without bothering each other. Basically
the same as you would have on the Lowfer band. And you wouldn't really have
to build a thing except for a few audio interface cables.

Just get a bunch of SSB radios, the cheapest ones you can get. Wire up a
bunch of interface cables to hook the mike, and speaker connections to the
sound card, and you are done.

You could also set up a packet network with CB's. Other people have done it.

You could even implement the newest DRM transmission systems that are
hitting the ham band if you had SSB CB's.

And the CB band is relatively dead right now, so you have plenty of open
channels to work with.

And you can use off the shelf antennas, that are a lot smaller. It would
also open up the realm of mobile operation.


There is plenty of options, besides putting them in a situation that is just
asking for trouble.

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A little note to add to that, in case someone thinks that no one will hear a
station at a distance that is running real low of power.

A few weeks ago, I was playing with an oscillator design. I had just used a
random inductor that i had laying around for the LC network. The frequency
that it landed on was totally at random.

That happened to be around 8.199Mc

All that i had hooked to the proto board was the power supply, and the
frequency counter, (and sometimes the O scope). The oscillator was
developing about a 8V P to P signal across the 1Kohm loading resistor on the
proto board.

I wanted to have an audio representation of the oscillator drift, so I went
to my normal HF receiver and tuned it in on the SSB setting so i could hear
the drift in real time.

The oscillator was being pulled by the frequency counter a bit. When the
gate of the counter would open, the oscillator would shift down a hundred
cycles or so. The audio signal I was hearing was along the lines of ...
drrrrrrrrrrrr duuuuuuuuuuuuu drrrrrrrrrrrrr duuuuuuuuuu...........

I had a reason to turn it off for a minute, and then when i turned it back
on, i heard a Burlblbublbublbub ..... for a few seconds, then it went away,
for a few seconds, then it went Burlblbublbublbub ..... again, and then
went away........ I thought that it was totally by coincidence. There was no
way anyone could be hearing it.

So, to settle my mind, that I wasn't going crazy, I shut off the oscillator
again, for a few minutes. I never heard the unknown signal in that time. But
when I turned the oscillator back on..... About two seconds after i turned
it on.......... Burlblbublbublbub........ then a few seconds later......
Burlblbublbublbub....

After subsequent test cycles I had pretty much figured out that it was some
kind of frequency hopping signal that I was hearing. The signal from my
oscillator must of correlated closely with the type of contact initiation
signal that the outside station was looking for. When it heard that warbling
tone, it would try to interrogate the calling station (my oscillator) to set
up a two way contact. It would try two times, then give up until the signal
disappeared for a certain amount of time. When the signal would come back,
then it would try to set up a two way contact again

I looked up what band the 8.199Mc signal fell in, and my old reference book
said it was a maritime mobile band. The data in the book may be out of date,
but if it isn't, then the receiving station may have been a long ways away.
Probably some automated ship to shore station along the great lakes. The
propagation was just right for my signal to hit their receiver.

Stuff like that is why direct antenna coupled regenerative receivers that
are operated in the oscillation region for CW/SSB detection are frowned
upon. If they are hooked to a good antenna, then your "receiver" can be
heard quite a distance away.

That is why most regenerative kits sold today, have an RF amp stage on the
input, to stop the regenerative section from back feeding the antenna.

I have even heard of a few people using a regenerative receiver as a
transceiver by keying the tube with the regeneration control turned way up.
They only made contact to people on the other side of the island, but it
worked. Now try to beat that, a one tube or transistor transceiver!