[FoxHunt] MicroHunt vs Pocket Fox.
Kenneth E. Harker
kenharker at kenharker.com
Mon Nov 7 11:39:30 EST 2005
On Mon, Nov 07, 2005 at 07:58:22AM -0800, R. Simmons wrote:
> This is from Bob Simmons, I make and sell the MicroHunts ( so does Marv
> Johnston ) so consider the source of this info.... ARDF inquiries should be
> directed to Marv, he is VERY big in that sport.
>
> I see no price for the PocketFox, but looking at the PC board it probably
> is about $ 70- $100. ( my best guess ) Looks like a kit, too. I did not look
> a the zipped download.
>
> Genuine international style ARDF hunting involves 3, 4 or 5 transmitters,
> so it could get expensive using these guys...Marv and I both offer a
> discount for multiple purchases, ( more than 1 TX ) so considering that,
> plus the smaller price for a MicroHunt, it makes a difference. I think Marv
> has a fixed discount price for a complete set... ask him : marvin at rain.org
The IARU rules stipulate 5 transmitters, but of course local hunts can
offer variations of those rules.
> Genuine ARDF hunts involve multiple transmitter all operating on the same
> channel, with staggered timing... 30 sec for TX1, then 30 sec for TX2, then
> 30 sec for TX3, etc. All operating in the same area, so their signal
> coverages will "overlap". That requires crystal timing to prevent
> transmitters from "drifting" into each other's time slots, and causing
> interference.... MicroHunts have crystal timing, their timing will only
> drift about 1 second ( max ) after several hours of operation. It is not
> clear what is the timing source for the Byonics TX... if the PIC uses a
> low-precision RC oscillator, genuine ARDF hunts won't really be practical...
The IARU rules specify one-minute transmit sequences, so an entire cycle
of transmitters is five minutes. Also, the ARDF rules specify 1/4 to 1 W
output for 2M transmitters - much more than the 50mW the MicroHunt
puts out. The MicroHunt devices would be good for smaller practice ARDF
sessions rather than a full-size ARDF event.
It's not clear to me, exactly, but the PocketFox trasnmitter certainly is
using a crystal - you can see it in the photo - so maybe the controller
circuitry is also using that for its timing source as well.
Byon also sells a transmitter controller (http://www.byonics.com/piccon/)
that has all the features you need to run an ARDF event with a separate 2M
or 80M transmitter. The older versions of the PicCon (you can see a picture
here: http://www.qsl.net/n6bg/piccon/) use crystal timing. The newer version
(the PC boards I have are rev.2.3) use a ceramic resonator instead. We ran
our first ARDF event in Texas last month (http://www.texasardf.org/) and
discovered that the ceramic resonators do a really, really poor job. Eight
hours after turning them on, some of the transmitters had drifted well over
60 seconds off their nominal cycle, so almost every transmitter was
overlapping. It was really bad. I've bought some crystals and small caps
and intend to mod the PicCons soon to try to fix the problem. Once I figure
it out, I'll document it on the web.
> Other differences / virtues ot the Byonics unit = ? ( invitation to others
> for comment ... )
>
> The MicroHunt is NOT flexible or agile... it was designed with extreme
> economy and simplicity in mind... There is no "major heartbreak" if one is
> destroyed or lost. Very small ( 0.9 x 1.2 inches ) so some extremely
> "artistic" hiding spots are also possible, and ( of course ) ideal for
> airborne beacons.
>
> In contrast, the SquawkBox uses RC timing so it is not really suitable for
> ARDF hunts, ( a crystal timed version is available for $10 more ) but it
> also has a PTT and audio output, so it can drive an external TX if desired.
> ( allows a different freq / band, and / or more TX power )
>
> regards / Bob S.
>
>
> ----- Original Message -----
> From: "KF7GD Art" <kf7gd at yahoo.com>
> To: <foxhunt at mailman.qth.net>
> Sent: Monday, November 07, 2005 1:32 AM
> Subject: [FoxHunt] MicroHunt vs Pocket Fox.
>
>
> > Hi folks does anyone know what the difference is
> > between The MicroHunt (I have one and like it) and
> > the Pocket fox (http://www.byonics.com/pocketfox/)?
> >
> > It looks like the pocket fox is more versital but the
> > MicroHunt is smaller and simpler (a good thing for
> > loanable gear).
> >
> > I am considering buying a set to get some ARDF type
> > hunts going in Seattle.
> >
> > Thanks for your thoughts.
> >
> > Art. kf7gd
> >
>
>
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--
Kenneth E. Harker WM5R
kenharker at kenharker.com
http://www.kenharker.com/
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