Temporary repeater inquiry.
Jared Harvey
I have been participating in an event known as the
NewEngland Forest Rally, up in the Rumford area of
Maine and over into Bethel NH. I volunteer doing
communications as a radio rally person. It's a two
day event, and we have had communications
problems. The terrain is hilly, and the stage
layouts often aren't finalized until the day of
the rally. So planning on where or how many ham's
you need to place along the stage happens at the
last minute.
I did some SPLAT radio analysis's that predicted
the coverage of several points along some stages
of this particular year. Those pictures can be
found here.
http://jaredharvey.com/radio-writeup/NEFR09/
Attached is one particular one of interest. I seem
to recall I modeled that as a 50 watt 8ft above
ground antenna, other antennas at 8 ft above the
ground. Basically if one can get a radio up there,
they will have full coverage of all the stages in
that area.
So what I want to propose or inquire about, is how
would one go about designing and making a
temporary repeater that could be dragged up there,
then taken down a day or two later. To get there,
one will have to climb some couple hundred feet of
elevation, through mostly rugged forest. So it
shouldn't weigh to much. Also it should have
proper protections, such that it can be rained on,
in the hot sun, or windy conditions.
If folks are interested in designing and building
one, and if it's not to crazy expensive, I'm
tempted to build one, perhaps a good hands on
event for the NERDS group. I should be able to
make the next couple meetings, can we allocate a
time where we can discuss the basic technical
things that would need to happen to make such a
repeater possible?
So is anyone interested?
Best regards.
.. ..-. / -.-- --- ..- / .-. . .- -.. / - .... .. ...
.-.. . - ... / .... .- ...- . / .- / -... . . .-.
Jared Harvey Operator KB1GTT
e-mail ma...@jaredharvey.com
Web page http://jaredharvey.com
Thomas Liebert
with repeater design or implementation (aside from using 2m/440
repeaters) so
I don't have much to offer.
However, I will offer this tidbit: for a temporary installation, you
should consider using a weather balloon to raise a vertical antenna.
There's a
car dealer down here in Portsmouth who always has a couple of weather
balloons aloft over his place, maybe 50-75 feet high. They appear
to be quite durable, and have been floating over his place as long as
I can remember.
-t
--
73 de Tom NV1T
(603) 812-6777 Cell
506 Sherburne Road
Portsmouth, NH 03801
Lat/lon: 43.0652 -70.8059 Maidenhead grid: FN43ob
Thomas Liebert
http://www.hard-core-dx.com/nordicdx/antenna/special/baloon.html
-t
On Thu, Jan 12, 2012 at 5:42 AM, Jared Harvey <ma...@jaredharvey.com> wrote:
--
AI2Q
two of them over the years. Moreover, controllers for small portable
repeaters don't need all the bells and whistles that a full time repeater
might need. In fact, some simple audio routing and a carrier operated relay
can do the trick, and you probably don't even need a microcontroller. What's
more, you probably don't need any expensive duplexers (cans), if you can
erect the RCV and TX antennas at a reasonable distance apart using runs of
coax at the temporary site.
Vy 73, AI2Q, Alex
Member: ARRL, FOC, RSGB, CWops, QRP-L, Antique Wireless Association, Wide
Area Amateur Radio Network, New England Radio Discussion Society (NERDS)
http://home.roadrunner.com/~alexmm
AI2Q
years ago. It was quite windy at our ocean shore site, and as soon as the
balloon was deployed, we were drawing inch-long sparks at the feedline!
We then installed a common 2.5-mHy pi-wound RF choke from the antenna to
ground, and the problem was solved. The choke exhibited very high impedance
at RF, but was a virtual short at DC, thereby grounding the antenna for
static build-up.
Vy 73, AI2Q, Alex
Jared Harvey
A> Jared, putting together a 2M FM repeater isn't
A> very difficult.
Agreed, and KISS is certainly a good idea for a
reliable device.
A battery operated one, could be more difficult.
I'm busy during both days, so it would need to be
setup the day before, then operate until I go get
it 2 days later. Also there would likely be a need
for priority traffic. Perhaps two receivers, one
with a + shift, and the other with a - shift. Such
that most folks use the + shift frequencies, then
the priority folks use the - shift frequency. Yet
everyone uses the same Rx frequency. Or perhaps
X-Banding for the priority traffic, might be a bit
more common practice.
I wonder what kind of batteries would be good, I'm
sure that super caps don't store enough energy. I
also wonder how much Ah it'll need.
APRS probably wouldn't be a bad idea either, I
have a TinyTrak4 that could be used. It also would
be nice if it could predict and announce the
battery levels some how. Basically a notification
that it's going dead.
Are there any radio technologies that might lend
themselves well to low power draw? I have an
Alinco rig that needs some repair, perhaps that
could be the base of the repeater. Or perhaps
something can be made from scratch. I'm not sure
what the best approach is. Perhaps it would be fun
to chat about.
AI2Q
The Alinco could be used for the receiver or the transmitter section, but
not both---at least not at the same time, which is what's needed for a
repeater; the RX and TX must operate at the same time. So, the Alinco could
be used for part of the system, but you'd need another RF strip as well.
For starters I wouldn't complicate it with high band inputs, high/low
splits, etc. Just KISS and have it work on one pair on 2M, like an ordinary
garden variety repeater.
For battery power I don't think you can beat a standard off the shelf 12V
lead-acid car battery or a glass mat AGM type. They're easily recharged and
relatively cheap, and have tremendous reserve power. Forget about
super-caps, at least for now. Maybe gel cells, or even a solar charger (I
have a 12V 1-A panel I could loan to you)..
The Ah calculation will be based on the predicted repeater duty cycle as
well as the RX standby power and the TX demand, depending on RF output power
and the antenna and height of same.
I have a 450 MHz NBFM xtal-controlled commercial Motorola rig here which
you're welcome to borrow, if that will assist in the project.
I also have some 9600 bit/s packet rigs (with TNCs) on 2M that run about a
watt or two each (they're based on commercial HTs). These might be useful if
you wanted to set up a data network instead of voice. That would give you
simplex single-channel operation, assuming folks along the route were
equipped with notebook PCs or the like. I am sure the NiCds are dead by
now, as I haven't used them in years, but they are another possibility.
These MFJ-1270 TNCs that I have modified with G3RUH fir filter boards can
likely be pushed to 19.2 kbits/s, too, although I have not tested that. They
do work nicely at 9600 though, and I've tested them over a 20-mile path.
By the way, if you had a voice repeater set up, you could route slower speed
(1200 bit/s) AFSK packets through it, and put the CD into the CSMA equation
(CSMA/CD). The repeater would repeat packets, and there would be NO hidden
transmitters to cause contention and backoff time-outs. I have run a packet
repeater this way, using TCP/IP, and the throughput went up like a
skyrocket.
Vy 73, AI2Q, Alex
----- Original Message -----
From: "Jared Harvey" <ma...@jaredharvey.com>
AI2Q
The next bimonthly Tech Talk of the New England Radio Discussion Society
will be held Tuesday night, 21 February at 7-PM. For this session we'll
focus on the world of CW---and look at three separate, but related, aspects
of the art.
Although the ol' Friendly Candy Company no longer requires demonstrable
Amateur Radio proficiency in radiotelegraphy, more hams than ever are using
Morse code. Just listen to the CW segments of the bands if you need proof.
At our next Tech Talk we'll start by (1) looking at Morse from the vantage
point of modern communication theory (after all, this is a technical
discussion!) We'll briefly examine the Huffman entropy-encoding computer
communications algorithm, and see how it compares with Mister Morse's code
that was invented 175 years ago.
We'll follow that with a discussion of ways and means to learn Morse and be
really good at it. We'll examine this from both practical and philosophical
points of view.
If you'd like to look at two great books that are available on the Web,
check out "The Art and Skill of Radiotelegraphy" by N�ｿｽHFF. William G.
Pierpont emphasizes his book is for "those interested in telegraphy, for
those who would like to learn it, for those who love it, and for those who
want to improve their skills in it."
You can download a copy of Pierpont's book on-line, or I'd be happy to send
you the 94�ｿｽ-kbyte .PDF file upon receipt of an e-mail.
Looking at CW from both a philosophical point of view as well as a highly
practical vantage point, my FOC pal IK�ｿｽYGJ offers his on-line book entitled
"Zen and The Art of Radiotelegraphy." Carlo Consoli melds psychology with
practicality, and his very entertaining treatise is worth spending some time
with.
Like N�ｿｽHFF's book, you can download a copy of IK�ｿｽYGJ's book on-line, or I'd
be happy to send you the 824-kbyte .PDF file upon receipt of your e-mail.
Next week's NERDS Tech Talk will conclude with a roundtable focus on (3)
keys, keys, keys! W3NA and AI2Q will show representative examples of
straight keys, semiautomatic keys, and electronic paddles and keyers, and
we'll fire these up and look at how they play and feel. I'm certain many of
you own and/or use Morse keys, so bring your favorites for show-and-tell or
swap and sell.
Save the date---and invite a friend. There are no membership requirements,
dues, etc.
As always, many thanks to AA1LO and his friends at the firehouse for
providing a first-rate meeting place. We will convene at 7-PM sharp at the
High Pine Fire Station in Wells, Maine, off Rte. 1�ｿｽ9. The firehouse is just
off the Maine Turnpike on High Pine Loop Road.
CU on the 21st. All WAARN members are welcome.
Vy 73, AI2Q, Alex
Member: ARRL, FOC, RSGB, CWops, QRP-L, Antique Wireless Association, New