[ARDF] Did you read the ARRL Letter?
Charles E. Scharlau
cscharlau at earthlink.net
Sun Apr 8 09:51:25 PDT 2007
Here's my 2 cents on the ideal ARDF starter set:
1. 80M band only. Beginners don't need confounding factors like reflections
and broad antenna peaks/nulls.
2. Very simple receivers. I suggest something like the simple kits that Dale
Hunt has made available in the past, but I would make them even simpler: no
sense antenna, and no frequency adjustment (crystal controlled). I'd also
suggest using a rod antenna to reduce the size. I imagine a small box with
almost everything inside, an attenuation adjust and earphone connector on
the outside, and some Velcro for attaching a compass directly to the case.
3. The transmitter(s) can be simple CW TXs that identify using international
ARDF standards. Just count the beeps. Low power and just 1 km max distance
to start. One-minute on and several minutes off works nicely when giving
instructions, especially to youngsters, because it provides a quiet period
for question/answer time.
4. Beginners can work in groups, and share information to triangulate.
Everyone should have a receiver, compass, a map, and a good time.
When I've given demonstrations at a local middle school I've found that the
students at that age catch on very quickly. They are still into
hide-and-seek, turning knobs, and secret treasure maps... it is just the
right age to get started. Now the trick is how to get the parents to support
their interest and keep the kids involved!
73,
Charles
NZ0I
> Date: Fri, 23 Mar 2007 23:05:19 -0800
> From: "Dale Hunt, WB6BYU" <wb6byu at arrl.net>
> Subject: [ARDF] Did you read the ARRL Letter?
> To: ardf <ardf at kkn.net>, foxhunt <foxhunt at mailman.qth.net>
> Message-ID: <4604CCC7.781CF4A8 at arrl.net>
> Content-Type: text/plain; charset=us-ascii
>
> I just noticed this in the ARRL letter:
>
> Regarding the ARRL "Big Project", formally called the
> Education and Technology Program (ETP), Coordinator
> Mark Spencer, WA8SME said about the Teacher's Institutes (TI)
> that they offer:
>
> >
> > "This has resulted mainly in changes to the TI content,"
> Spencer explains.
> > "In future TIs, I will increase emphasis on space and on radio
> > direction-finding -- fox hunting."
>
>
> What can we all be doing to support this? Any
> good ideas?
>
> - Dale WB6BYU
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 24 Mar 2007 07:58:19 -0800
> From: "Dale Hunt, WB6BYU" <wb6byu at arrl.net>
> Subject: Re: [ARDF] DF and the "Big Project
> To: ardf <ardf at kkn.net>
> Cc: Homingin at aol.com, wb6byu <wb6byu at arrl.net>, N5ZGT at swcp.COM
> Message-ID: <460549B0.8AFA964F at arrl.net>
> Content-Type: text/plain; charset=us-ascii
>
> While we've used 80m DF with Scouts locally and they
> really enjoyed it, my impression is that for intuitive
> ease of use simply being able to point the antenna for
> maximum signal is the simplest concept to learn. This
> would imply that VHF/UHF may be a better place to start.
>
> The problem, of course, is that conventional equipment
> is more expensive on VHF. (This may be offset by the
> fact that most hams start with a 2m rig that could be
> used with an attenuator.) One of the less expensive
> circuits that we have been using for ELT DF is a
> simple crystal set - the perfect thing for finding a
> strong AM signal, and no battery to worry about.
> The circuit naturally gives an audio indication.
> Range on my 30mW practice beacon is a couple hundred
> feet (which makes it great for sniffing in a hanger)
> but for this application with a 1 watt AM transmitter
> and a stage of audio amplification in the receiver
> I think we can get some reasonable distances. This
> isn't perfect since the receiver bandwidth is pretty
> wide, but may meet the requirements for simplicity
> and cost. To reduce the antenna size we might want
> to try it on 440 (or 220) instead of 2m, in which
> case a PCB with strip-line circuitry or printed
> inductors would make it simple to build. It should
> be able to fit inside the PVC pipe boom of an antenna.
>
> Not everyone still has a Gonset Communicator or
> Benton Harbor Lunchbox around to transmit AM, of
> course. But we already have available 1 watt
> amplifiers designed to be amplitude modulated, and
> we can build one that would take, say, 100mW from
> an HT (for frequency agility) and put out 1 watt
> of AM. (The Hamtronics synthisized transmitters
> can be amplitude modulated fairly easily, though
> they are expensive compared to the price of a used
> IC-2AT.)
>
> But perhaps where we should start first is to consider
> the typcial needs of a school program and develop our
> recommended design goals, then consider what equipment
> would meet them. Clearly we start with:
>
> (1) afforable cost for transmitter + several receivers
> Shifting expense from the receivers to the
> the transmitter probably reduces overall cost.
>
> (2) ease of use - simple and intuitive to learn
>
> (3) suitable for the distances typical for schools.
> This is a tough one - what is a good range?
> At a minimum a couple hundred yards - enough
> to cover a typical schoolyard. For beginners
> a half mile is probably enough - that provides
> plenty of places to hide without getting too
> far away. (Would students be allowed to leave
> the school grounds to find it?) The transmitter
> power can be adjusted to limit the coverage,
> but we have to consider the effect of other
> strong local signals.
>
> (4) rugged, easy to fix, little maintenance required.
>
> Any others that we should add?
>
> One thing that I have found with local T-hunts is that
> even two synchronized transmitters get too confusing
> for beginners who are still trying to learn all the
> skills. We will want the ability to use more than one
> once the students get more advanced, but we should
> start with one on continuously.
>
> A good method for ID would be one of the voice recorder
> chips - that would let the teacher (or the students)
> record whatever message they want and make it easy to
> store any callsign without special programming steps -
> just push the button and record.
>
> Hmmm... perhaps I should add another criteria:
>
> (5) easy to upgrade to standard ARDF and/or T-hunt
> equipment.
>
>
> But whatever we do, we need to get some kids of the
> target age group involved in the planning to see what
> works best for THEM. Most of us are, umm, somewhat
> past that age by now. It is critical that we have
> good feedback about what kids of this age feel is
> too simple, too complex or appropriately challenging,
> and make sure that our recommendations fall in the
> third grouping.
>
> Might be good also to look at DF from the point of
> view of what educational objectives it can accomplish.
> At UHF in particular we can demonstrate signal blockage
> and reflections in a standard classroom. Triangulation
> can help teach geometry. Any other thoughts from this
> perspective?
>
> My ha'pennyworth,
>
> - Dale WB6BYU
>
>
> Gerald Boyd wrote:
> >
> > Dale, All
> >
> > I am also copying Brian N5ZGT who is one of our local ARRL officials on
> > this.
> >
> > I think that some type of quick starter kit should be made
> available from
> > the ARRL that would list resources and contacts that would let
> instructors
> > put on a DFing program. The kit should have the step by step
> instructions
> > for putting on a DF program.
> >
> > However, Key things to making this work are cheep transmitters,
> receivers
> > and a licensed ham (from a local club or school instructor) to be the
> > control operator of the transmitters.
> >
> > A possible solution is something like my new micro-80
> transmitters. They are
> > low power and run on a 9V battery all day. They also do the ARDF cycle.
> >
> > Your kit 80 meter receiver is a good possibility for the receiver.
> >
> > A resource (quick start) KIT that ARRL could produce and
> handout to a school
> > or local ham club would be a way of having a standard program
> that everyone
> > can use. The kit could have a video DVD showing how to DF (could also
> > include the 2006 USA ARDF DVD). Brian I need to show it to you
> some time.
> >
> > If this were to occur I think Joe would be the person to work
> with the ARRL
> > to organize and coordinate the development efforts and program content.
> >
> > If us (the DF'ers develop the kit for the ARRL) so that the
> upfront cost to
> > the ARRL is low, then the ARRL could produce the kit. That
> Makes ARRL look
> > good (also gets ARDF on there radar scope) and helps us by getting more
> > ARDF'ers. A win win for all.
> >
> > My two cents worth.
> >
> > Jerry
>
>
> ------------------------------
>
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