96.5

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zach_dx
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Re: 96.5

Post by zach_dx » Thu Apr 18, 2019 5:27 pm

4therecord wrote:
Wed Apr 17, 2019 2:21 pm
Albert, that's a ridiculous idea.... makes far too much sense that does!

Interesting that zach_dx is getting a poor signal in Hatfield, we know from your previous posts your a DX'er so I'm guessing it's not just a normal radio / antenna picking it up? - I also have a poor signal at mine but the problem is, I live IN Greenwich!!! - which is the target area / borough - I just feel a bit sorry for them, they waited a long time for their chance and must be thinking, was it worth it... early days though, perhaps it can be improved
I am receiving it indoors with an FM folded dipole antenna (also receivable on my FM loop antenna). I don't have an external antenna.

Edit: here is a proof of my reception.

DX logs at: http://fmdx.info

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teckniqs
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Re: 96.5

Post by teckniqs » Fri May 17, 2019 2:35 pm


Albert H
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Re: 96.5

Post by Albert H » Mon May 20, 2019 2:04 pm

The Lindenblad aerial is entirely inappropriate for that station. It'll do them no favours whatsoever. The pole it's on is too short too - they'll be losing huge amounts of their signal into the roof below. Whoever's engineering that hasn't got a clue (and has ripped the station off for a very expensive and ineffective aerial).
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OldskoolPirate
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Re: 96.5

Post by OldskoolPirate » Mon May 20, 2019 4:58 pm

What would you recommend for that setup then Albert ?

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teckniqs
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Re: 96.5

Post by teckniqs » Tue May 21, 2019 8:52 am

It also looks far too close to the end fed collinear, I'm surprised they don't just have something like that instead...

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Re: 96.5

Post by Albert H » Sat May 25, 2019 3:02 am

OldskoolPirate wrote:
Mon May 20, 2019 4:58 pm
What would you recommend for that setup then Albert ?
It depends on the coverage they're trying to attain. It also is affected by their permitted radiated power. The Lindenblad is supposed to provide "mixed" or "circular" polarisation to the signal, and be omni-directional. Circular polarisation was used by the early commercial FM stations as it was thought to penetrate city buildings better, and be less prone to multipath distortion - at least that was the claim of the manufacturers of these over-priced slightly radiating dummy loads.....

If they are supposed to have coverage that's in one direction from their site, then they can use directional aerials like "H"s which give hemispherical radiation, or three element Yagis if they need a more restricted beam angle. If they want mixed polarisation, they can use an "X-Y" Yagi (constructed for horizontal and vertical operation), and with the use of a phasing harness, they could put spin on the signal and go circular....

If their coverage is to be omnidirectional, then a J-pole or a Slim Jim are good choices. Either gives a marginal gain over a dipole, and are easy to match. A friend of mine in Egypt developed the "MSJ" (Modified Slim Jim) for high sites. The feedpoint is moved up the aerial (to a second resonant point) were the aerial still appears to be 50Ω, but the radiation angle droops - great for a high site that needs very local coverage.

Of course they could try the trick a friend of mine used on his 25W RSL station. When it was inspected, it was running into a J-pole. When the inspector left site, they added the top two sections to the antenna, turning it into a version of the "Super-J" colinear!!! Their ERP quadrupled.
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"Because it doesn't know the words!"
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4therecord
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Re: 96.5

Post by 4therecord » Sat Aug 10, 2019 3:45 pm

To resurrect this thread only as I've been monitoring since the African thing on 964 seems to have been cleared for a while now and boy those photo's are very interesting.... I couldn't agree with Albert anymore when he says "Whoever's engineering that hasn't got a clue" - that's for SURE!!! - anyone who knows the geography there knows that a simple half-wave dipole would achieve better coverage (for Greenwich... which is it's TSA after all) ... what a joke that install is! I hear it's doing OK toward West London.... that's great that is, in Eltham and Blackheath (both IN Greenwich) it's pants!

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