[RFI] RFI Digest, Vol 220, Issue 7
David Eckhardt
davearea51a at gmail.com
Sun May 9 13:46:59 EDT 2021
Just my 2 cents: blue, not white, 1/2-inch long or greater, and about the
diameter of your little finger or larger.
Dave - WØLEV
On Sun, May 9, 2021 at 5:01 PM Joe Locascio via RFI <rfi at contesting.com>
wrote:
> WHAT is a 'strong arc'???
>
>
>
> Joe
>
> On Sunday, May 9, 2021, 09:00:37 AM PDT, rfi-request at contesting.com <
> rfi-request at contesting.com> wrote:
>
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> Today's Topics:
>
> 1. Re: Next step visually sighting arc's (David Eckhardt)
> 2. Re: Next step visually sighting arc's (Charles Plunk)
> 3. Radar Engineers Model 251 Parabolic dimensions? (Charlie Delta)
> 4. Re: Radar Engineers Model 251 Parabolic dimensions?
> (n0tt1 at juno.com)
> 5. Fwd: RE250 Sighting? (Charles Plunk)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 8 May 2021 16:48:19 +0000
> From: David Eckhardt <davearea51a at gmail.com>
> To: Charles Plunk <af4o at twc.com>
> Cc: "rfi at contesting.com" <rfi at contesting.com>
> Subject: Re: [RFI] Next step visually sighting arc's
> Message-ID:
> <CAODdWWE0tJP1pRHH_6-2KVuukKroZyQxM0adkB==asj045DfWg at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Instead of the 'rifle' scope, I'd suggest something a bit more capable with
> a larger aperture. I have the Celestron Ultima 65 used for this purpose
> and many others. The 65 mm objective is excellent, it can be either
> hand-held or tripod mounted, and costs a bit less than twice your 'rifle'
> scope (in the $100 to $150 range, store dependent).
>
> Dave - W?LEV
>
> On Sat, May 8, 2021 at 3:13 PM Charles Plunk <af4o at twc.com> wrote:
>
> > As you may remember, I sighted my first strong arc with binoculars after
> > triangulation, ultrasonic, etc. Its been fixed by the util for over a
> > month and still gone gone :-)
> >
> > A not near as strong arc is on the same pole but on the opposite side.
> > This pole is in the corner of my backyard so makes it convenient to
> > experiment with. Playing with the success of the first, I tried
> > binoculars and thought, with some imagination that I could see this arc
> > too. Its tiny.
> >
> > So, I bought a stronger spotting scope, like you sight in rifles with.
> > And mounted it on a tripod. Last night the source was active and still
> > think I see it in the same spot. A crusty old ground lug wired to the
> > bottom of a fused disconnect. Connects to the wire stapled to the pole.
> >
> > One has to be careful as reflections off the ceramics from distant
> > street lights (~200' away) can look like arc's. But a crusty ground lug
> > should not reflect. This area is also where I hear it with ultrasonic.
> > Its a very narrow place to stand on the ground to hear it with
> > ultrasonic. Another issue is its so dark its hard to make out the
> > outlines of the pole in the dark to tell where you are seeing. But I
> > could see enough. The bigger the lens on the front of the
> > scope/binoculars the better to capture more light to see the pole I
> > suppose.
> >
> > My experiments so far with digital cameras, one with the IR/UV filters
> > removed, have resulted in failure. Cannot even see the pole in the dark.
> > Nothing but a grainy picture. Even trying to capture a picture through
> > the scope. The scope came with a phone mount for capture.
> >
> > I am going to look at the same spot when the source is inactive. If the
> > suspected tiny arc is absent then going to request the util replace that
> > connector unless anyone has any further suggestions.
> >
> > The spotting scope I bought was ~$60 so another low cost tool maybe for
> > your rfi toolbox.
> >
> > Underneath this one, at night I am hearing a repetitive noise. One
> > minute on ~0.5 - 4 seconds off. But thats another story, lol and does
> > not sound like power line arc.
> >
> > Chuck
> > W4NBO
> >
> > _______________________________________________
> > RFI mailing list
> > RFI at contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
> >
>
>
> --
> *Dave - W?LEV*
> *Just Let Darwin Work*
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 8 May 2021 12:46:48 -0500
> From: Charles Plunk <af4o at twc.com>
> To: David Eckhardt <davearea51a at gmail.com>
> Cc: "rfi at contesting.com" <rfi at contesting.com>
> Subject: Re: [RFI] Next step visually sighting arc's
> Message-ID: <5beb9125-e7ac-7ce9-8ce2-d3503fd624a5 at twc.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Thanks Dave. Its a spotting scope. Like the ones you look downrange at
> the target to see where you hit and not the scope mounted on a rifle.
> This is the one I have;
> https://www.amazon.com/dp/B0728C4K7W?psc=1&ref=ppx_yo2_dt_b_product_details
>
> Wish i had not sold my high dollar leupold rifle scope I had years ago.
> It could almost see in the dark. I could see almost nothing in fields in
> the dark but looking through that scope could easily see.
>
> Chuck
>
> W4NBO
>
>
> On 5/8/21 11:48 AM, David Eckhardt wrote:
> > Instead of the 'rifle' scope, I'd suggest something a bit more capable
> > with a larger aperture.? I have the Celestron Ultima 65 used for this
> > purpose and many others.? The 65 mm objective is excellent, it can be
> > either hand-held or tripod mounted, and costs a bit less than twice
> > your 'rifle' scope (in the $100 to $150 range, store dependent).
> >
> > Dave - W?LEV
> >
> > On Sat, May 8, 2021 at 3:13 PM Charles Plunk <af4o at twc.com
> > <mailto:af4o at twc.com>> wrote:
> >
> > As you may remember, I sighted my first strong arc with binoculars
> > after
> > triangulation, ultrasonic, etc. Its been fixed by the util for over a
> > month and still gone gone :-)
> >
> > A not near as strong arc is on the same pole but on the opposite
> > side.
> > This pole is in the corner of my backyard so makes it convenient to
> > experiment with. Playing with the success of the first, I tried
> > binoculars and thought, with some imagination that I could see
> > this arc
> > too. Its tiny.
> >
> > So, I bought a stronger spotting scope, like you sight in rifles
> > with.
> > And mounted it on a tripod. Last night the source was active and
> > still
> > think I see it in the same spot. A crusty old ground lug wired to the
> > bottom of a fused disconnect. Connects to the wire stapled to the
> > pole.
> >
> > One has to be careful as reflections off the ceramics from distant
> > street lights (~200' away) can look like arc's. But a crusty
> > ground lug
> > should not reflect. This area is also where I hear it with
> > ultrasonic.
> > Its a very narrow place to stand on the ground to hear it with
> > ultrasonic. Another issue is its so dark its hard to make out the
> > outlines of the pole in the dark to tell where you are seeing. But I
> > could see enough. The bigger the lens on the front of the
> > scope/binoculars the better to capture more light to see the pole
> > I suppose.
> >
> > My experiments so far with digital cameras, one with the IR/UV
> > filters
> > removed, have resulted in failure. Cannot even see the pole in the
> > dark.
> > Nothing but a grainy picture. Even trying to capture a picture
> > through
> > the scope. The scope came with a phone mount for capture.
> >
> > I am going to look at the same spot when the source is inactive.
> > If the
> > suspected tiny arc is absent then going to request the util
> > replace that
> > connector unless anyone has any further suggestions.
> >
> > The spotting scope I bought was ~$60 so another low cost tool
> > maybe for
> > your rfi toolbox.
> >
> > Underneath this one, at night I am hearing a repetitive noise. One
> > minute on ~0.5 - 4 seconds off. But thats another story, lol and does
> > not sound like power line arc.
> >
> > Chuck
> > W4NBO
> >
> > _______________________________________________
> > RFI mailing list
> > RFI at contesting.com <mailto:RFI at contesting.com>
> > http://lists.contesting.com/mailman/listinfo/rfi
> >
> >
> >
> > --
> > *Dave - W?LEV*
> > /*Just Let Darwin Work*/
> >
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 8 May 2021 23:34:30 +0000 (UTC)
> From: Charlie Delta <vk3od at yahoo.com>
> To: "rfi at contesting.com" <rfi at contesting.com>
> Subject: [RFI] Radar Engineers Model 251 Parabolic dimensions?
> Message-ID: <521177757.304660.1620516870639 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> Thanks to all that replied.
> 1. Midnight sciences have closed down W0xi has retired and no longer sells
> kits or dishes.
> 2. I appreciate all the suggestions for a parabolic dish source. However I
> more interested in spending money on a true parabolic shape with the right
> F/D ratio. Its a fruitless exercise building good electronics on an
> imperfect dish? geometry platform
>
> 3. I have gone down the road of trying, wok lids, Skylight domes, Cake
> display stands, salad bowls, Sony parabolic dish, and all sorts of? odd
> objects that have a half decent parabolic shape. Sure it? works however
> range and sensitivity wont get near a Radar Engineers or even a MFJ5008.
> Even the ARRL review of the MFJ5008 mentioned that the Radar engineers had
> a detection range of in excess of 200 ft whereas the MFJ? units range was
> in the 100 to 150 ft range. Other professional? dishes by companies like
> SDT and Sonaphone in Germany have? stated specifications of 50 to 100ft for
> electrical airborne dischare detection.? Even the Super Fluke ii910? that
> costs 30,000 dollars has a range of 70 meters.
>
> 4. I used a weak signal Sparak source which was an iridium spark plug and
> my Associated Reseach 15KV Hypot to generate a test signal. If the signal
> is strong enough any scrap dish will hear it, even with a funnel as a dish!
> However when you want to hear a weak signal then the whole setup becomes
> important and the dish design becomes critical to the success of detection.
> Sounds a lot like ham radio and having the right antenna!
>
> 5. What is clear is that? anything parabolic in shape works however the
> sensitivity and directivity? varies a lot to the point of causing?
> frustration.
> 6. Symptoms? include weak? signal detection,?? washed out signal detection
> ability? and off axis? sidelobes which make the device usesless for pin
> pointing.
> So with all of the above in mind I wanted a fresh start? by 1st building a
> proper dish. There are a number of parabolic dish sources availableI am
> more interested in experimenting by trying to building something that
> works. After shippings costs and paying the high prices in US dollars its
> really cheaper for me to get something molded locally by a plastic molding
> specialists who do this kind of thing everyday.
> 7. For those wanting? a really good dish thats optimum you can buy one
> from Wildtronics. There webpage has some excellent information on parabolic
> dish design which I used as a reference. http://www.wildtronics.com There
> is another company on Italy called Dodotronic that makes nice ultrasonic
> mic's and also sells optimum parabolic dishes.
>
> 8. I have 2 X Sony Parabolic mics 330 and 400 models which are 33 cm and
> 40cm's in diameter. These have a far from optimum FD? ratio and work no
> better than random junk dishes. Most parabolic mic's on the market ? have
> poor dish designs and only the specialist wildlife people have taken care
> with the design paramters(Telinga and Wildtronics)
>
> 9. If someone does have access to the Model 251 and if they could measure
> the dish depth and focal point since this would give us the optimum
> dimensions for the correct size dish for 40khz frequency and with the
> correct F/D ratio.
> 10. Every time that you drop the dish size by 10 cm in diamter the gain
> drops 6db according to the research. This suggests that the radar engineer
> size of 18 inches? or about 50cm is close to optimum.? A 60cm dish would be
> even better.11. The critical part is the illumination of the Mic or
> transducer and this is where building a proper parabolic dish with the
> right? FD ratio and focal point will reap rewards.
>
> If all else fails I will sell the house and buy a Fluke ii910.
> 73CraigVK3OD
>
>
>
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sun, 9 May 2021 02:02:00 +0000
> From: <n0tt1 at juno.com>
> To: vk3od at yahoo.com,RFI at contesting.com
> Subject: Re: [RFI] Radar Engineers Model 251 Parabolic dimensions?
> Message-ID: <AABSKQSZWAAZ8UJ2 at smtpout03.vgs.untd.com>
> Content-Type: text/plain; charset=utf-8
>
> The RE 250. I have one. The dish dia measures 18" and the depth is
> 4-3/8".
> The transducer opening is just over 4-3/8". The opening of it's housing
> is
> level with the dish when viewed across the dish opening. Hope that
> helps.
>
> I'll repeat the gist of my previous post on the squirrel guard. It works
> VERY well
> as a US dish. It has pin point accuracy! It's easy to check the focus
> of
> any dish that has even a somewhat reflective surface. Clear plastic
> dishes
> are in that group. Set the dish up on a tripod in a darkened room. Set
> up
> a light source, such as a flashlight (AKA a "torch") say, 50 ft away and
> aimed
> toward the dish. View the concentrated light "falling" on your detector.
> It
> should fully illuminate it without blowing by the detector. It should
> NOT be
> a single point of light, but instead, illuminate the entire surface of
> the detector.
> Don't have a detector yet? Just use a piece of white paper and do
> whatever physical measurements
> you want. You can even do this at your local store to check the focal
> length, etc.
> I've done that. The dish, of course, must be pointed directly at a light
> source.
> Will this work outside, pointing at the sun? Yes, but it may set the
> paper on fire!
>
> Now a few words on the detector electronics. First off, don't bother
> setting
> up a dish to bench test. Whatever detector circuit you use should be
> sensitive enough to hear (loudly!)
> your fingers rubbing together at a distance of at least 10 feet. That's
> with NO dish
> attached. No kidding. You should hear virtually no "rushing" noise when
> the
> transducer/circuit is NOT receiving a US signal. IOW, the circuit should
> have very good S/N ratio.
> Do all of that and you'll have the most sensitive US detector you could
> buy.
>
> 73,
> Charlie, N0TT
>
> On Sat, 8 May 2021 08:08:44 +0000 (UTC) Charlie Delta via RFI
> <rfi at contesting.com> writes:
> > Hi
> > Can someone who owns a Radar Engineers model 250 or model 251
> > Ultrasonic RFI receiver kindly tell me the dimensions of the dish?
> > I am particularly interesting in the dish depth and the focal
> > distance point. I understand that dish is 18 inches in diameter.
> > The plan is to get a suitable parabolic dish molded by a local
> > Dome skylight maker who thinks that he can mold a suitably
> > accurate true parabolic dish.
> > I am curious to know if the Radar engineers dish falls within the
> > 0.5 to 0.6 F/D ratio? Since it works so well I thought I might as
> > well start off with a set of dish dimensions that is proven to work
> > around the 40khz Ultrasonic frequency.
> > Since the beam-width is so sharp , I presume that the dish
> > dimensions and the illumination from the dish of the ultrasonic mic
> > will be critical. I have already played around with the W1TRC
> > detector and various odd ball dishes and the results have not been
> > that great since these dishes have a far from optimum F/D ratio.
> > From playing around it seems that a deep dish with the focal point
> > deep within the dish produces a very poor result and may even
> > produce minor sidelobes that causes confusion. Depending on the
> > strength of the signal, an ultrasonic signal can disappear because
> > of the poor illumination of the microphone sensor. So it does
> > appear that an optimum f/d ratio dish would produce a better result.
> > Any input or comments would be welcome from anyone who has tried to
> > build a similar project.
> > (pick your mould VS mold spelling)
> > 73CraigVK3OD
> > _______________________________________________
> > RFI mailing list
> > RFI at contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
> >
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sat, 8 May 2021 22:29:33 -0500
> From: Charles Plunk <af4o at twc.com>
> To: Rfi List <rfi at contesting.com>
> Subject: [RFI] Fwd: RE250 Sighting?
> Message-ID: <a07cb58f-19d1-8850-b7c3-3a123fd445e7 at twc.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> My dish, from the W1TRC QST article, is exactly those dimensions. Great
> info on the electronics Charlie. I'm sure I have room for improvement
> there. How does the RE250 sight with pinpoint? Crosshairs? rifle type
> sights? The W1TRC you simply are looking through a hole in the back with
> the transducer in the middle. Not much of a accurate sight.
>
> Chuck
> W4NBO
>
> On 5/8/21 9:02 PM, n0tt1 at juno.com wrote:
> > The RE 250. I have one. The dish dia measures 18" and the depth is
> > 4-3/8".
> > The transducer opening is just over 4-3/8". The opening of it's housing
> > is
> > level with the dish when viewed across the dish opening. Hope that
> > helps.
> >
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> RFI mailing list
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> http://lists.contesting.com/mailman/listinfo/rfi
>
>
> ------------------------------
>
> End of RFI Digest, Vol 220, Issue 7
> ***********************************
>
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>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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