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Improving AM reception with Inductive coupling
#photo-notice
I found some of these AM antennas by chance, but I want to more about how to construct one.? From all of these?
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videos, its like all these guys found how to make these antennas by accident.? None of the videos provides?
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plans or calculations on how to reproduce the entire project.
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Example of coupling:
https://youtu.be/d1jaojiA1Oo
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This guy has some of the best explanation, but no calculations and no real explanation on how to inductively?
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couple it back to your am radio.
https://youtu.be/_PqEcgJRUkg
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This guy actually gave some dimensions, but no coupling:
https://youtu.be/Wnkf_gQQwwg
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I was hoping I could find someway to build one of these antennas w/o having to have it physically around the?
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radio ?
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Here is another, this guy uses his big toe ?
https://youtu.be/YL4SboK6FTw
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Any help is appreciated
Thanks
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
On Thu, Feb 10, 2022 at 11:34 PM, vbifyz wrote:
If you need both wide bandwidth and nulls, then log periodic would be the antenna to use. The 105-1300 MHz version is about the size of an FM Broadcast receive antenna, but the 50-1300 MHz is much bigger. I have had both, but the 105-1300 MHz version was the most useful. Another alternative would be the Vivaldi, which may be easier to make yourself, but could be very big. Either way you would also need a rotator. Regards, Martin |
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
If you need both wide bandwidth and nulls, then log periodic would be the antenna to use.
An old TV antenna can work just fine. Newer ones don't have the low VHF capability. Unfortunately, its size for the low VHF band is not exactly tabletop. 73, Mike AF7KR |
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
Hi All. A simple loop works fine for FM. Needs to be a bit elevated above ground level, of course. The null is along the plane of the loop, as opposed to the 'normal' loop. Also, as I recall, the feed point location determines whether polarisation is vertical or horizontal.? Used one successfully for a couple of years for Es FM DX.
Have a look at the site below. Regards, JohnS. http://www.users.on.net/~michaelpeck/articles/Simple_FM_Loop_Antenna.pdf |
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
While a discone or double discone can have quite wide band width, it has no ability to null noise or direction find like a loop. There is no reason a smaller loop can't be used on VHF. In fact these were often used as UHF TV antennas. It will need a wideband and low noise preamplifier. A dipole or 2 element yagi might do the job too and still provide some nulls of the side. Of course it won't be as small and portable as a loop.
73 Tom |
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
The problem with traditional discone antennas is that they don't perform well on frequencies lower than their 1/4 wave lower cut off frequency, and the radiation pattern gradually tilts upward with frequency, reducing their effective gain for terrestrial reception.
The bicone (sold as a double discone) is much better in this respect. Alternatively if you wish to build your own antenna, I'd make an inverted discone, which is basically three or four angled elements connected to the coax inner, mounted above a decent sized metal ground plane which is connected to the coax outer. Something like this. Personally, the best antenna I've found is something like an amateur radio dual band VHF / UHF 'white stick' such as the Diamond X-30, which provides some gain on the UHF bands (including UHF air), is decent on the High VHF bands and works as a near 1/4 wave on the Low VHF bands. It's less obvious than a discone and you can paint it with grey car spray undercoat to make it even less conspicuous. Don't be tempted to buy the longer white sticks which offer more gain, as they incorporate a more complicated matching network, which degrades their performance outside of the amateur bands they are designed for. It's also worth investing in some decent coax, so that already weak signals don't become further degraded by cable loss and noise ingress. Regards, Martin |
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Re: OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
For broadband 30-1000 MHz use, I've always used a discone antenna, such as the below link.
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For portable use, the elements can be easily removed and reinstalled. Note the antenna pictured in the link has hex nuts on each element. These are used to tighten the element, and if an element is broken off, allow the broken stub to be removed for the ant body. the Radio Shack discones I've bought didn't have this feature and I had to add them myself. A discone antenna can be easily made. Note the design equations for a discone indicate for a antenna with a lower frequency limit of 50 MHz, the disk diameter should be 41 inches. the diameter of my Radio Shack "30-1000" is only 22.5 inches. John KK6IL On 2/9/2022 7:15 AM, h. garcia wrote:
Hello everyone. Hope you are doing great. |
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Re: Rg6 and rg6
On Wed, Feb 9, 2022 at 03:34 PM, Simon wrote:
But ct or wf100?WF has a foam dielectric, but CT is cellular air spaced, as a result it kinks more easily and if water ever does get in it's like using a hosepipe. Don't use anything with cellular air spaced insulation unless you take additional precautions when installing and using it. If you want a reasonable quantity on a drum, then you may be able to buy direct from Webro. They do other thicker 75 Ohm cables too, but at a price. You may also have to convert between suitable connectors to whatever you wish to use. Regards, Martin |
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Re: Rg6 and rg6
Hi Dave
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Ok wf it is.. Thanks .. On 9 Feb 2022, at 15:34, Simon <ohhellnotagain@...> wrote: |
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Re: A video of a tuned BCB loop using PVC and 3D printed parts
I printed similar parts to make a fat loop (turns connected in parallel rather than in series) for an HF loop.
Fitting into a PVC pipe cross, holes for 4 wires. One problem with PLA plastic is that it doesn't keep its shape in Arizona sun :) 73, Mike AF7KR |
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Re: Rg6 and rg6
Simon - WF100 is the one to go for (lower loss than RG6, and copper throughout).? CT100 is? the cheaper alternative (alu foil), but it's intended for internal use only, whereas WF100 is rated for exernal use.? Look for Webro WF100 on Amazon or Farnell etc..
Regards, Dave |
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OT: would it be a well-balanced, pronounced nulls, wide-band antenna for VHF?
Hello everyone. Hope you are doing great. I'm a fan of broadband small magnetic receive antennas for their portability vs performance relation. One can grab aloop and a receiver, hit the road, assemble a small RX station on a pic-nic table and the loop at some distance away and you're in busine with fairly good results. The loops balanced and nulling helps mitigating noise loop and a quality pre-amp enables frequency agility. I was wondering which antenna would offer the same features at VHF High between, say, 50-80 or -80-120MHz. Is there any favorite design (specially for field days) at this segment? Cheers, pu3hag huelbe |
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Re: Rg6 and rg6
Ok
Anyone using cft100? ( beldon i think) 75r copper clad foil plus copper clad ali braid.solid copper inner.. Attenuation at 5mhz 1.6db per 100m Can get 100m for ?19.. similar price to rg6 Simon |
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Re: Rg6 and rg6
On Tue, Feb 8, 2022 at 07:59 PM, Simon wrote:
any thing to look out for when buying rg6??Personally I'd avoid RG6 completely. I bought some branded stuff recently to use with a CCTV system, and it was very variable regarding loss on the LF bands when I measured it prior to installation, even between reels bought from the same supplier. The Aluminium foil is probably too thin (skin depth) on the lower frequencies, and the aluminium has a tendency to oxidise and turn to white powder over time. RG11 Quad is advertised as being suitable for direct burial, and it has 4 aluminium screen layers, but it's not that common in the UK. I now tend to use WF100, which has proven to be the most reliable and cost effective over time, but I'm always on the look out for better alternatives. Regards, Martin |
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Re: Rg6 and rg6
开云体育Simon, Finally building my new loop next week. Just bought 50m of WF100 from Farnell for under 30 sovs (I can talk londonish!) 250m is <?140.00. See Recommended by Martin, G8JNJ Its 6.5mm diameter but I found some good BNCs on eBay. 73 Tom G6PZZ From: [email protected] <[email protected]>
On Behalf Of Simon
Sent: 08 February 2022 20:00 To: [email protected] Subject: [loopantennas] Rg6 and rg6 ? When move this year putting up a vertical rx array.. ( along side loop array)? |
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Re: Rg6 and rg6
Hi all, I would use RG11/quad shielded cable. the 11 has less loss than the 6. You can also get rated for burial applications. Its also easy to get; my local Home Depot has tons of it. hope this helps.
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Cheers? Bob.
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Re: Rg6 and rg6
开云体育Are you sure it was solid copper?? A 1000 foot roll of that would be so heavy you couldn't even pick it up. ---
Rick Karlquist
N6RK On 2022-02-08 12:32, W0LEV wrote:
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Re: Rg6 and rg6
开云体育Where are you getting SOLID COPPER inner conductor RG-6???? It has been very hard to actually get it.? Yes, you may see it advertised for sale, but it will turn on NOT to be solid after all.? A "tell" is that the shipping weight of solid copper is MUCH more than CCA.? A low price is another "tell".? True solid copper will be MUCH more expensive.?? ---
Rick Karlquist
N6RK On 2022-02-08 11:59, Simon wrote:
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