[ARDF] Fwd: [Melb-ARDF] The Case of Missing SI box 101

[Matthew Robbins]

Dale Hunt sent me this reply, below.

Matthew
Cincinnati

---------- Forwarded message ----------
From: Dale Hunt <wb6byu at arrl.net>
Date: Tue, Sep 4, 2012 at 1:53 PM
Subject: Re: [ARDF] Fwd: [Melb-ARDF] Fwd: The Case of Missing SI box 101
To: Matthew Robbins <cedarcreek at gmail.com>


I nearly had to DF the 4 MHz signal from the controller in one of my foxes
when
it was put out but not turned on.  (The PICCONs with colorburst crystals
would be
easier.)

But 125kHz shouldn't be too difficult.  I think my VR-500 tunes down that
low.  DF
may not be easy with a short burst, but just listening for signal strength
should tell
you when you are in the right area.  That's probably the fastest method:
calibrate the
receive range using another box, then beat the bush until you can detect
the pulsed
RF from the missing one.  The range likely will be pretty short (<50m?) so
once you
can hear it and maximize the signal strength by trial and error you should
be able to find it.


If you needed to DF it, an external loop on a suitable ferrite rod would
get you started.

For a dedicated unit (if this happens too often) I could take one of my
direct conversion
sets and replace the VFO coil with a 455kHz IF transformer, then add enough
fixed
capacitance to get it on frequency.  (Varactor tuning isn't going to give
much range,
however.)  Probably easier to convert a superhet receiver, so the LO runs
around 600kHz
using standard AM BC coils.  I'd have to work out the loop details, but an
AM BC
loop antenna with added shunt capacitance might do the job.

     - Dale




 On Tue, Sep 4, 2012 at 10:32 AM, Matthew Robbins <cedarcreek at gmail.com>wrote:

> Forwarding this from the Melbourne ARDF reflector. Has anyone ever tried
> DFing a SportIdent box?  The new ones (BSF7 and BSF8 models) should have a
> short burst of RF every 1-2 seconds. Some details below.
>
> It might be possible to transmit something (???) that would wake it up and
> make it have a continuous signal for the programmed time (usually about 2
> hours).
>
> Matthew
> Cincinnati
>
> ---------- Forwarded message ----------
> From: Bruce <abruceperson at gmail.com>
> Date: Tue, Sep 4, 2012 at 1:14 PM
> Subject: [Melb-ARDF] Fwd: The Case of Missing SI box 101
> To: Melb ARDF <melb-ardf at lists.id.oz.au>
>
>
>  Any one have a loop that low ?
>
> Cheers,
> Bruce
>
> Begin forwarded message:
>
>  *From:* "Don Fell" <don.fell at bigpond.com>
> *Date:* 4 September 2012 3:12:32 AM GMT+02:00
> *To:* "Bruce Paterson" <secretary at ardf.org.au>, "Geoff Hudson <
> geoff.hudson at gmail.com> \(\)"
> *Cc:* "Rex Niven" <fortytroutelectronics at optusnet.com.au>
> *Subject:* *FW: The  Case of Missing SI box 101*
>
>
>   We think there is an SI control box out in the bush at Hepburn. Any
> comments on Rex’s radio tracking suggestion?****
>
> ** **
>
> Don****
>
> ** **
>
> *From:* Rex Niven [mailto:fortytroutelectronics at optusnet.com.au]
> *Sent:* Tuesday, 4 September 2012 7:48 AM
> *To:* Don Fell; 'Phil Giddings'; 'Laurie Niven'; kliley at netspace.net.au
> *Cc:* 'Rex Niven'; 'Ron Frederick'; 'Rob Edmonds'
> *Subject:* The Case of Missing SI box 101****
>
> ** **
>
>
> The snippet of data from Don seems critical - the box never got back to
> base camp.  ****
>
>  ****
>
>
> I dropped a box in the bush once myself, and even though I knew where
> within 100 metres, it still took two hours to find (the setting sun finally
> glinted off its shiny back). ****
>
>
> Here there is  over 1 km to cover.  I suppose the control sites and Phil's
> car park place are the most likely spots.****
>
>  ****
>
>
> You can't call it on your phone, but do any of the ARDF crowd think you can
> detect it with an antenna?  It should send out bursts of 125kHz
> occasionally. An old Long Wave transistor receiver might do it.****
>
>  ****
>
>
> Rex Niven
> Secretary Nillumbik Emus Orienteering Club
> 15 Rockliffe St Eltham Vic 3095
> Australia
> phone    (61  3) 9444 1803
> cell         0417 34 94 27
> FAX       (61 3) 9444 1807 ****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
>
>   ****
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