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SAFE Ark Two Newsletter
January 15th, 2013
Radio Progress
This newsletter is late because of the intensity of the weekend.
Radio engineers, Adam and Bob, made great progress on Friday. Adam came
on Thursday and stayed overnight so that they could spend a full eight
hours together on the radio on Friday. Below, I will go into detail with
a picture about what they accomplished.
Amer came on Sunday for eight hours and shot footage on how to build a
radiation detector. It was supposed to be YouTube #18 but I didn't have
it ready for Victoria so she worked on #19 Expedient Shelters for this
week. Held her up on that also because I couldn't get to the voice-overs
until Monday, which I then spent the full day on. As full a day as I
can do with the wood stove and so forth. However, didn't have to shovel
snow. The rain took care of that for me. Unfortunately, just now that
the #19 YouTube upload failed this morning so I will send the newsletter
without it.
Lady in her 90's that I thought they might be moving to a nursing home -
passed on. Lived three doors up from the shelter. Asking 160K for her
place, but it may be gone already because I don't see a sign any longer.
The other place three doors from us has never had a sign and I think
they are asking 144K. Has five rental rooms. I do wish people
sympathetic to our cause would move in. It has only been about every two
years that some reasonable house has become available.
By virtue of Jean's age, I guess we are now the oldest residents of the
village. Jean was born in the next house south from us and her mother
here also - now two centuries ago. Time is taking its toll with us. It
would be great if some energetic lady wanted to move up here and live
with us, because Jean really needs a hand. She still drives, and doesn't
use a cane - but has really slowed down.
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The New Prototype Board
Bench Prototype Version 1 consisted of three boards and for Bench
Prototype Version 2 we have gotten down to one board. I am hoping that
for Bench Prototype Version 3 we may be able to reduce the size down to
fit into a metal case that is 6.0 inches x 4.0 inches x 2 inches which
would would in turn fit into a one gallon metal bucket for shipping -
that would also act as a Faraday cage. This goal may be overly
ambitious. The problem is that closeness of the components might cause
RF interference and it would also increase the heat problem.
Since my writing the above - I have an email from Adam saying he doesn't
think that 6x4 is possible - so the 8 inches by 6 inches size you see,
is probably about the size you will get, or maybe maybe a little smaller
down to around 7x5. The cabinets we have at the moment are actually 4
inches tall - so we may be able to find something a little lower
profile. But still, by not getting down to the smaller size, we are
going to have to use a two gallon bucket as the Faraday cage. The one
gallon buckets that I wanted to use are more standard, so two gallon
will cost considerably more and add to the packaging and shipping costs.
The new prototype is not yet performing up to the spec that we obtained
with the first bench prototype - but Adam and Bob plan to get together
again on January 25th for another session. In the interim, both are
working on a number of tasks to identify/isolate/remedy the problem. I
will now go through a full description of the board so that you can know
what you are looking at in the picture. This will probably be only of
interest to technical types but here goes:
To follow all this it is probably easier if you open the picture of the board in a separate window - and here is a link if you wish to do so:
1.
Starting at the top right hand corner and off the board - is a butterfly
switch that moves between transmit and receive. It will be mounted on
the same panel face as the large red light below it.
2.
The large red light is the transmit light. I wanted this to be very
prominent because I don't want anyone to accidently leave the
transceiver in transmit mode. The switch could have been a momentary PTT
(Push To Talk) switch but because our concept is to send somewhat
longer digital messages we are designing it to stay on until turned off.
3.
Working on down the board - the tiny black component above the
yellow LED is the transmit enabling device. Because it is illegal in
peacetime for anyone except advanced hams to use this transceiver to
transmit PSK31 it will be delivered with the transmitting capability
disabled. The unit, right out of the package, will be fully operational
as a receiver, which is legal for anyone to use, but to use it to
transmit one will have to take a screwdriver and open the unit and
insert the key (which we will also send to everyone) into the enabling
device. It is only legal for advanced hams to enable the device in
peacetime - but in case of a catastrophy, such as nuclear WW3, anyone
can do so. All users can practice receiving with the unit and it is very
easy to then proceed to transmitting when the necessity arises. The use
of PSK31 is not restricted to advanced hams because it is difficult,
(our system is actually the simplest and most reliable system we could
design) but PSK31 is restricted by law so as to be a 'reward' for people
getting their advanced ham license.
4.
The yellow LED is the 'power-on' LED. It is actually redundant because
when the power is on either the red TRANSMIT light is on - or the green
receive light.
5.
Next is the green receive light. If the power is on, either the green
receive light or the RED transmit light is on. Both won't turn on
simultaneously. Which one is on is determined by the switch described in
#1.
6.
Next on the edge of the board is the color coded receptor where you will
receive the radio signal. You will plug a cord into this and run it to
your microphone input on your sound card. On the back of your computer
you should have easy access to the sound card jacks.
7.
There is an identical receptor of a different color next to the above
one. Into this one you will plug a connector that plugs into the speaker
outlet on your computer sound board, again on the back of your
computer. This is how the signal gets from your computer to be
transmitted over the radio.
8.
The long black component on the edge of the board and in the bottom
corner is the power level indicator. It consists of 5 LEDs and we may
replace it with 5 separate LEDs. The power level is indicated by the
number of LEDs that are lit. You will control it through your computer
User Interface, the SAFE Emergency Messaging System program that will
come with the package.
9.
Turning the corner of the board and going to the far left end you will see the connector that goes to the antenna.
10.
Turning that corner and going to the remaining corner of the board there
is the blue connector with two wires (you have to look closely to see
more than the red one) which is the power connector -
11.
and adjacent to the power connector is a red device which is an
automobile fuse - because those would be the simplest to find if you had
to replace one.
12.
Now for a tour of the major items/components on the board. You can see
many ICs, resistors, capacitors, etc., but I won't get into that detail.
There are two types of major components that I will mention.
13.
The power transistors. There are two larger ones and two smaller
ones. Towards the far left of the board you will see a black finned
object. This a heat sink with the transistor mounted on it. In actuality
the heat sink is much smaller than will be used in production because
in production the heat sink will be mounted on the OUTSIDE of the
cabinet on top.
14.
There is another identical transistor and heat sink just below and to
the right of the first - but because of the camera angle the fins of the
heat sink appear even less well.
15.
And to the right of the previous heat sink you will see two more smaller
transistors with their heatsinks. These sort of look like devices with
bolts going through them.
16.
The other major devices are the Ferrite Torroids (rings with wires
wrapped around them). To the right of the big one -
and looking down the board you will see three - (the one at the edge is
standing vertical and is a little harder to see) and then to its left is
another - and on the far edge of the board going up in a row are three
more - for a total of seven of these small cores. These are mostly a
part of the amplifier and how the radio is tuned. It is tuned to a
single crystal so that the user doesn't do any tuning but can through
through the software interface on their computer instantly select any
one of many frequencies in the PSK31 range on the 80m band that we use.
Now, for a little general discussion. We could use different size cores
but Dave has suggested that by using the same core for the seven
locations - and varying the windings we will be able to buy in greater
volume and reduce the cost.
In the the bench proto-type we have found four areas where the circuit
is generating RF that is interfering with adjacent parts of the circuit
so that in the next prototype pass the layout will be somewhat changed
to eliminate those conflicts.
We are trying to provide a dual component mounting scheme of
plated-through holes for easy repair and pad mounting for mass
production. We are also planning on a thicker PC board than is customary
these days - for extra durability.
In our bench test this past weekend - we were able to get the signal all
the way through and generate twenty watts - but we only did so briefly
because of the heat generation and a frequency anomaly that we were
experiencing. Still, this was more than we could have optimistically
hoped to accomplish in this single session.
Once Bob is able to isolate and correct the frequency anomaly, and we
receive additional cores to wind - we hope to complete the other three
boards and send one to Dave and another to Adam's professor, for their
critique/evaluation/recommendations.
Lots more to tell you about the software, the antennas, the
documentation, and other aspects - but you can see that we are still
working on and making progress. The further along that we get I am
astounded how much better the capabilities and suitability of the system
are turning out to be over even the original vision.
At this point I am probably giving you more detail than you want to
know. I have lots of work to do this week on the radio manuals. If I do
get a newsletter out next Sunday, it will be a short gap and it may take
a week or two to get the #18 YouTube up because to my chagrin, Jean
mailed the camera memory card to Victoria - by regular mail! It is
involved video, so it may take Victoria a week or so to edit it anyway.
Back to snow this morning. Called our generator guy to say we missed the
window of opportunity to get into the shelter - but I was way too busy
anyway. Snow allows me to stay in and work - so that will be good for
the manuals - and I hope the books.
Peace and love,
Bruce
DawnSayer@webpal.org
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