Coaxial cable
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Hi to the group, Could you help me to make a choice between those 2 coaxial cables for a distance up to 50m from the LNB to the NOVRA? RG 6/U or 17VTAC? Many thanks in advance. Laurent
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geojohnt@...
Hello Laurant,
Quick reply.
The satellite TV 'industry standard' cable in the UK is CT100 - or other manufacturers XX100 such as WF100.
The shielding should be copper foil and copper braid - not aluminium.
Some use foam inner insulation - others solid insulation
What you need to know when comparing different cables is the attenuation per 100 metres at the LNB output frequencies from their technical specification.
Regards,
John.
+++++++++++++++++++++.
-----Original Message-----
From: LaurentD <l.deblangy@...> To: MSG-1@groups.io Sent: Tue, 8 Sep 2020 18:48 Subject: [MSG-1] Coaxial cable Hi to the group,
Could you help me to make a choice between those 2 coaxial cables for a distance up to 50m from the LNB to the NOVRA?
(to minimize the losses due to the distance). RG 6/U or 17VTAC?
Many thanks in advance.
Laurent
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Robert Baleja
Hi
toggle quoted messageShow quoted text
I bought this: https://www.televes.com/en/catalog/product/view/id/1088/s/215101-T100plus%2016VRtC%20coaxial%20cable/category/439/ Robert Callsign SP7RB QTH JO91QS67RM www.rbalejameteo.pl SP7RB@... Wysłane z iPhone'a
Wiadomość napisana przez geojohnt via groups.io <geojohnt@...> w dniu 10.09.2020, o godz. 11:13:
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Prem
Hi Laurant,
John is right about the different cables and as he says. If you can find out the attenuation per 100 m and the velocity factor of the cable. If you go onto the website of m5bxp.com you will find an Excel calculator to download. You will need to enter the frequency, the loss per 100 m, the velocity factor and the length of cable by using multiple half wavelengths to as near as to your 50 m. You will then need to add a small amount for the type of dish. This I can't help you with because I do not know whether I dish is considered as 1/4 wave, a half wave or a full wave. If it is a 1/4 wave then add three quarters of a wave to your total length. If it is a half wave then add one quarter wave to your total length and if it is a full wave then just make sure you have odd multiples of half wave.
The problem with the calculator is that it was originally intended for radio amateurs and we never considered satellite dishes or any dishes for that matter.
Hopefully you will find it useful.
Prem Holdaway (G0DCP) Phold29@...
From: MSG-1@groups.io [mailto:MSG-1@groups.io] On Behalf Of geojohnt via groups.io
Sent: 10 September 2020 10:13 To: MSG-1@groups.io Subject: Re: [MSG-1] Coaxial cable
Hello Laurant,
Quick reply. The satellite TV 'industry standard' cable in the UK is CT100 - or other manufacturers XX100 such as WF100.
The shielding should be copper foil and copper braid - not aluminium. Some use foam inner insulation - others solid insulation
What you need to know when comparing different cables is the attenuation per 100 metres at the LNB output frequencies from their technical specification.
Regards, John.
+++++++++++++++++++++.
-----Original Message----- Hi to the group, Could you help me to make a choice between those 2 coaxial cables for a distance up to 50m from the LNB to the NOVRA? RG 6/U or 17VTAC? Many thanks in advance. Laurent
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Hi John! Many thanks for your response and advice. You are correct. I have to check carefully the attenuation per 100 metres and then compare the cables.
On Thu, Sep 10, 2020 at 11:13 AM, <geojohnt@...> wrote: Some use foam inner insulation - others solid insulation
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Hi Prem, I tried but in vain to find the m5bxp.com website. Would it be possible to confirm the correct URL please? Many thanks in advance.
On Thu, Sep 10, 2020 at 12:54 PM, Prem wrote:
m5bxp.com
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Hi Robert,
Thanks for the info. It sounds very good quality cable! Best regards, Laurent
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Hi to the group,
Could you help me to make a choice between those 2 coaxial cables for a distance up to 50m from the LNB to the NOVRA? (to minimize the losses due to the distance). RG 6/U or 17VTAC? Many thanks in advance. Laurent ================================= The table here: http://www.caledonian-cables.co.uk/Coaxia_Cable/CT_Series/CT100.html suggests that a 50m run of standard CT100 would have an attenuation of ~15 dB around the frequencies used by TelliCast Europe (1.5 - 1.6 GHz). Whilst that should be OK, I would suggest considering making provision for adding a "Satellite TV amplifier" in the middle of the cable run if that's possible. Here the signal from a 20m cable run is fine, but I would be reluctant to run 50m without the possibility of an amplifier. The signal level also depends on the LNB itself - there are LNBs which have a higher output, reducing the need for a mid-cable amplifier. I am thinking that mid-cable would be best, as an amplifier immediately after the LNB may be overloaded. Try to get foam insulated CT100 (or equivalent) if possible, and it reduces the chance of water ingress affecting the whole cable run. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-taylor@blueyonder.co.uk Twitter: @gm8arv
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Prem
Hi Laurent,
Strange that you could find in the five the experience website. I had no problem collecting myself but never mind try my website: www.g0dcp.co.uk and on the front page you will find a direct link to the Excel spreadsheet.
Hope you succeed this time.
Prem Holdaway (G0DCP) Phold29@...
From: MSG-1@groups.io [mailto:MSG-1@groups.io] On Behalf Of LaurentD
Sent: 10 September 2020 21:55 To: MSG-1@groups.io Subject: Re: [MSG-1] Coaxial cable
Hi Prem, I tried but in vain to find the m5bxp.com website. Would it be possible to confirm the correct URL please? Many thanks in advance. On Thu, Sep 10, 2020 at 12:54 PM, Prem wrote:
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Hi David, I've always considered until now that an amplifier was absolutely to ban as it has the effect to amplify any noise.
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Hi Prem,
Yes, very strange! It's also a good way to discover your website! Thanks for that. I can use now the Excel spreadsheet. Best regards, Laurent
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Hi David,
Many thanks for those technical information and advice regarding the cable feature. I've always considered until now that an amplifier was absolutely to ban as it has the effect to amplify any noise. Adding an amplifier at mid-cable should be a good compromise. Best regards, Laurent =================================== Laurent, The satellite TV system is a little different to a conventional RF system in that the LNB has a lot of gain, meaning that it is the prime component in determining the signal to noise ratio. Yes, and amplifier will amplify the noise as well as the signal, but the output of the LNB is always quite large, so that you will have much more signal, and much more noise from the LNB that cable loss of perhaps 20 dB will ensure that the signal and noise are sufficiently high at the [PC end] receiver input that the noise from the LNB is greatly in excess of the receiver. I'd love to quote some actual figures but I don't have them in my head, so I wouldn't want to guess. Perhaps someone can point to a suitable Web page? In a conventional VHF or UHF TV system, there is no LNB so the signal from the antenna is much less, and minimising cable loss can be important, as the unamplified signal from the antenna may be much less than that from the LNB which includes amplification. In that case having an amplifier right at the antenna would be a sensible move if the signal was weak. I hope that helps! Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-taylor@blueyonder.co.uk Twitter: @gm8arv
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Sorry to be long in replying. I really appreciate your explanations. Really clear and helpful. LNB makes the difference for sure!
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