Welcome to the new DXer based in Breckland!

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John Faulkner, Skegness
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Re: Welcome to the new DXer based in Breckland!

Post by John Faulkner, Skegness » 03 Jan 2015 18:55

Yes, that's correct. It's all about interpretation of figures in a way, between linear and logarithmic. Not wishing to have an argument, but it would be nice if somebody in the know can clarify this. What I am hoping to avoid is people trying slant, assuming it will receive both planes without too much loss. In my own experience, the loss is too great to be of use.

It's a case of suck it and see as the practice of sometimes different from the theory. But don't worry, as I am sure you have read, I am the original Bodgitt & Scarper man, and we usually have to make some kind of compromise along the way.

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a2c39a
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Re: Welcome to the new DXer based in Breckland!

Post by a2c39a » 03 Jan 2015 20:01

I am a bit lost John.

Your -13dB is a reduction of signal power by 20 times (one twentieth of the signal power).

How is your yagi mounted (metal pole or fibreglass)?
How do you change from horizontal to vertical?
What/who do you define as 'someone in the know'?

Best wishes, John.

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a2c39a
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Re: Welcome to the new DXer based in Breckland!

Post by a2c39a » 03 Jan 2015 21:07

John,

I have just thought of the major snag with slant polarised receiving antennas!

If all transmitters used plane polarisation, either vertical or horizontal then a 45° slant polarised receiving antenna would indeed be -3dB relative to an equivalent plane antenna.

However, the above is not the case. Many transmitters employ 'mixed' polarisation. This is just another name for 'slant' polarisation. If the transmitter slant is in the opposite direction from the receiver slant then great (theoretically infinite) attenuation of the signal will result.

This will be the reason why a slant polarised yagi is not suitable for 3m DXing.

Best wishes, John.

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Re: Welcome to the new DXer based in Breckland!

Post by Jim (Bournemouth) » 04 Jan 2015 10:26

I agree with the 3db loss for slant polarisation. I remember a discussion we had during my RAE class years and years back on the subject.

Think about your sines/cosines - find a scientific calculator and put in SIN 45 (or COS 45) comes out at 0.7 approx. Suggests slightly less than 3db difference but it's close enough.

There is a table here: http://www.tscm.com/polariza.pdf
Jim, Bournemouth, Dorset. IO90BR.

Elad FDM-S2, Perseus/FM+ and Funcube Dongle SDR Recievers 8-element OP-DES for Band 2, 12-ele ZL Special for 2m, plus wideband vertical
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a2c39a
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Re: Welcome to the new DXer based in Breckland!

Post by a2c39a » 04 Jan 2015 12:15

Thanks Jim,

for confirmation of the theory.

What I was then trying to find was the reason for the much greater signal loss that John F and others were experiencing when using 45° slant polarisation for 3m FM reception.

I now feel fairly sure that mixed polarisation transmitters are the main cause of the problem.
When they use slant 135° to a receiving slant of 45°, it is the same as using vertical-horizontal cross polarisation and there is a large signal loss.

John F is correct in saying that slant polarisation is not suitable for 3m FM reception. Not because there is anything wrong with slant polarised receiving aerials but because slant polarised transmitting aerials spoil it.

Thanks again for your help.

Best wishes, John.

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Re: Welcome to the new DXer based in Breckland!

Post by Jim (Bournemouth) » 04 Jan 2015 12:20

Just a thought - if mixed polarisation is being used, then if you go to 45 degrees, could the V and H transmissions be cancelling themselves out to an extent?
Jim, Bournemouth, Dorset. IO90BR.

Elad FDM-S2, Perseus/FM+ and Funcube Dongle SDR Recievers 8-element OP-DES for Band 2, 12-ele ZL Special for 2m, plus wideband vertical
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Re: Welcome to the new DXer based in Breckland!

Post by a2c39a » 04 Jan 2015 13:38

Yes, that's exactly it Jim.

However, if you switch the receiving antenna over to slope 45° the other way, everything would be in phase.

Best to stick to true Horizontal or Vertical for 3m FM reception.

Best wishes, John.

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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 07 Jan 2015 20:41

a2c39a wrote: I find that when I visit my friends in Oulton Broad or Lowestoft, under flattish conditions, I hear less than at home! My friend Carl says it is because of the extra height at my home location.
Wow, cannot believe that, as Lowestoft is a DX hotspot! Do any of your friends live in valleys? I used to live in Rose Valley, Norwich, until my family moved out into East Harling, as that house, despite having lots of refurbishment, still needed more to be done. It was falling apart. Using a coax cable as an antenna, I hardly got anything from anywhere other than Stoke Holy Cross and Tacolneston. Even Kiss and Heart from Stoke Holy Cross, struggled. Kiss (Ipswich/Mendlesham, 106.4), was there too, but very weak. Once, I did get it, with RDS (maybe tropo), but it got muted into mono in less than a minute. I did once get one DX station, very weak, but audible, Sky Radio from Goes/Alticom Toren, on 101.9 MHz. The Beach, from Lowestoft/Oulton, on 103.4, could never be heard on this setup. The receiver was not any hot DX machine, just a Sony DHC-MD313 mini hi-fi component system, with its built in tuner, that can remind some of the much better Sony ST-SB920 (which I own), ST-S311 and ST-SA3ES tuners, although with a much more simple interface, and no RDS apart from PS names, and worse sensitivity, and no switchable IF filters. High Hunsley (I only knew about Capital 105.8) was a regular via tropo here in Norwich, and the garbage setup I used never grabbed High Hunsley. As obvious, even though at later times I have grabbed Viking on 96.9, in addition to Capital, BBC Humberside on 95.9 would be knocked out by BBC Suffolk in Aldeburgh, on the same frequency, on the car radio in Norwich. At my present house in East Harling, I did get more interesting stuff on the same setup, including High Hunsley on 105.8, even though I did upgrade to a Philex ribbon wire antenna with the same Sony MD313. The tuner was sensitive for a tuner built into a hi-fi system, but it got some annoying blank carriers, one of which blocked out BBC Norfolk and NPO Radio 1 on 104.4, and another was on 105.3 so blocked out Zack FM and France Info. France Culture was a slight tropo regular, by the way, on 98.0. The blank carriers were even there without an antenna. I then did not wanna put that thing upstairs, so I got an Technics SU-810 amp with KEF Coda speakers, to use with a Sony ST-SB920 tuner, that improved my DXing by somehow a lot!
Quite a few of my friends from school live closer to the continent than me, with a lot in Norwich, and one in Lowestoft even! That's because I attend a boarding school, even though I go home every day, as a day pupil. Even some live abroad.
I will move house to a higher up house, also in East Harling, where reception could beat your friend in Lowestoft. Only thing my new house may have more British activity, even than my current house, due to the elevation. Q-music has been possible over Heart Cambridge (both 103.0) a few times recently, and very frequently Heart Peterborough (102.7) has been knocked out by Radio 538 from Rotterdam, but both may be harder at my new place, due to the extra height. John Faulkner frequently takes a DX trip to Kenwick Top, near Louth, Lincolnshire, and so do I sometimes, and John Faulkner said, because of the elevation, that Dutch signals were really good, but, also due to the elevation, there was more inland UK activity than at his home in Skegness. Same with my old and new houses, both in East Harling. I dunno where my friend from Lowestoft lives, as she's new to my school. Better talk more to her then. I may ask here if she ever is aware of Dutch stations on the car radio.

UPDATE: I thought she wouldn't know what I'm talking about, as DXing is something rare. Some of my close friends know I like listening to distant radio, some teachers as well, but a handful of classmates and teachers don't know my hobbies, particularly new ones. Although my friend Finn (from Norwich) does know I'm a DXer!
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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 07 Jan 2015 20:46

Alex Cator wrote: I may ask here if she ever is aware of Dutch stations on the car radio.
I meant, I may ask HER, just my typing error! I obviously wouldn't ask HERE, as you don't know this girl I'm talking about.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
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John Faulkner, Skegness
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Re: Welcome to the new DXer based in Breckland!

Post by John Faulkner, Skegness » 07 Jan 2015 21:35

You know you can edit and delete your own posts in this forum. No time limits on editing either. There aren't many forums which give you that. Just in case you need to make an edit.

Regarding slant, it might be the best compromise for receiving both planes, but I am wondering if you are confusing slant with mixed and circular. As I understand it, circular will give you the optimum reception no matter which plane you are in. "Mixed" will usually mean employing both horizontal and vertical. Slant doesn't come into it. Anyway, just a random thought.

The 3dB is indeed a logarithmic way of saying "half" or "double". But I still remember the difference between the signal variation from fully vertical to fully horizontal is about 20dB. 20dB is also a figure often quoted as the typical loss suffered when the antenna is in a loft, compared to the same antenna outside the loft at the same height. I remember the red brick tiles were supposed to be the worst.

Finally, just to throw something else into the mix, it's sometimes weird when you know a location is good, but you don't seem able to receive anything in a particular spot in that general location. I am referring to Sweet Spots and Dead Zones. It's amazing what moving an antenna a foot or two can do. Something always worth considering when erecting a new antenna. Nothing is ever perfect.

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Re: Welcome to the new DXer based in Breckland!

Post by a2c39a » 08 Jan 2015 04:35

Hello John,

I have agreed with you elsewhere in the thread:

Slant polarised antennas are best avoided for FM DXing.

All houses have Sweet Spots. Find and use them, especially when using a portable radio for DXing.

Lofts are not ideal places for antennas.

Best wishes, John.

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Re: Welcome to the new DXer based in Breckland!

Post by John Faulkner, Skegness » 08 Jan 2015 10:50

Hello John

My apologies if I have said anything to offend. I am not looking for an argument. I am not that good with technical matters and have always been open about that. The only thing I am trying to do is make sure people are aware of the pros and cons of aerial mounting so they can get the best out of the hobby.

Andrew Webster,Wigan
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Re: Welcome to the new DXer based in Breckland!

Post by Andrew Webster,Wigan » 08 Jan 2015 14:09

2 years ago I built a replica of my Antiference FM 3 and used half inch tubing as that's all I had and I have mounted that just above the gutters pointing S/E which is 6 ft below the FM 5 height.
That is my sweet spot as I strategically placed it there so I could reduce the signals from the West and some of the locals.

http://i593.photobucket.com/albums/tt15 ... 4cd736.jpg

This is what I refer as the homebrew it has worked much better than I thought it would do as it receives a lot of DX that is not present on the FM 5 or not as good as the FM 5 picks up more stations than the homebrew.
My location overload alley is 126 m ASL and I bombarded with many 75 db + signals from all directions and the band is chocker so it's like looking for a needle in a haystack.

DXing here is not easy if the UK stuff is enhanced then basically I am stuffed but the hombrew does help and also when there's a lift the band changes locals sink into the noise and some stronger stations loose RDS it's weird at times.
I don't do too bad though considering the situation here I have been to Johns a few times and can't believe the quietness of the band there absolutely superb.

It's always good to experiment with aerials in different places to help reduce locals.
I did the same thing with TV aerials had some at the side of the house as well as on the roof because of a similar situation.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 08 Jan 2015 18:06

If your band is chocker, Andy, it must be very difficult to DX! :(
I do consider some stuff from the UK DXing, particularly if not from England. What I want to avoid is the locals and semi-locals. I know you erected a Korner 9.2 antenna for John Faulkner, would you like to make or buy one yourself? Not so much from the UK, unless it's easterly to you.
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Re: Welcome to the new DXer based in Breckland!

Post by Andrew Webster,Wigan » 09 Jan 2015 20:19

Yes it's challenging but it's not all doom and gloom though I have had some superb FM DX here the past 3 years I have been band 2 DXing.
On 08/07/13 there was a good opening to Germany during the day the signals were mediocre but many I had not received before but early evening I could not believe it the signals just got stronger so much the band was more German than English loads of locals just weren't there just wiped out.
Later that night Holland came in at good strengths.

Then the Spanish opening 22/10/14 that was another brilliant opening and I had not long put the vertical FM 3 on the top of the mast as most of the Spanish stations came in on vertical on this occasion UK stuff was not enhanced that much so that helped.
You can see videos of these events on my youtube channel.

https://www.youtube.com/user/radioredcat/videos

Regarding the Korner I might build one but I do intend to build a crossed FM 5 so I can have both horizontal and vertical on one boom also my rotator needs attention as it's going out of sync .
As it's been up on the roof for 30 years I think it needs a service so that will be my next job .

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 11 Jan 2015 11:48

I tried my Tecsun PL-390 in another part of my house, with its standard telescopic antenna. It gets daily signals of Lille/Bouvigny Le Mont (I guess general scatter, which means either aircraft or tropospheric scatter) while in the landing of my house, which is obstructed by lots of walls as it's in the centre of my house, and it can get nothing when by a window. All of them are there, even though France Musique on 88.7 gets swamped a little by Belmont, but the DSP reduces Belmont's QRM. Yesterday, via what was guessed to be aircraft scatter, it got Dudelange, Luxembourg, on 100.7 (Radio Hondert Komma Sieben) and 88.9 (RTL Radio Lëtzebuerg), when there was a local power cut in East Harling, so I couldn't use the mains-powered Sony ST-SB920 tuner. The Tecsun often gets more than the SB920, even though the SB920 gets Viking FM from High Hunsley (96.9) under flat conditions (sometimes unlistenable due to second-adjacent semi-local KL.FM 96.7), when the Tecsun gets Heart Bedfordshire from Sandy Heath (very weak). That is because I am using a rubbish antenna (Philex ribbon wire antenna), along with a TV antenna pointing towards Tacolneston, which struggles with stuff like Wales, Normandy and London. Compare that to my setup in a year's time (Korner 9.2 with Yaesu G-450A rotator and HS Publications phasing unit).
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Re: Welcome to the new DXer based in Breckland!

Post by Andrew Webster,Wigan » 11 Jan 2015 16:10

I take it the Sony 920 is unmodified if so then narrower filter's will make huge difference to it's selectivity so it's worth thinking about.

Hmm the mention of powercuts make me shiver as here is dubbed powercut alley we had 6 long ones last year fortunately no DX lost yet.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 11 Jan 2015 17:48

Andrew Webster,Wigan wrote:I take it the Sony 920 is unmodified if so then narrower filter's will make huge difference to it's selectivity so it's worth thinking about.
You are right, Andy. My Sony ST-SB920 is unmodified, but I am planning to modify it with an 80 kHz Murata SFE10.7MT filter (narrow position) and three 110 kHz Murata SFE10.7MHY filters (wide positions). I'm getting constantly sick of my semi-local KL.FM 96.7 (from Great Massingham, near King's Lynn) swamping Viking FM, which is transmitted on 96.9 from High Hunsley, near Kingston upon Hull. Viking FM, despite big distance, and the obstruction of the Lincolnshire Wolds, is a daily catch on my DX setup, and it constantly fades in and out. It is unlistenable at its weakest strength due to KL.FM. The mono mute also bugs me, which is when it mutes weak stereo stations into mono, without the TUNED light. Without the TUNED light, RDS is impossible. I, therefore, in addition to the new filters, would like to increase the RF gain and the stereo sensitivity. My narrow filters (80 kHz) will have difficulty getting RDS, particularly on stations with low RDS levels, such as BBC Radio Lincolnshire and BBC Radio Cymru, even though the wide filters (110) will be fine with RDS. I will also get a Kenwood KT-6040 tuner, which I will use mainly for meteor scatter and general scatter (aircraft and tropospheric scatter) reception, with both 110 and 80 kHz filters fitted. I also need a way to get an external RDS decoder to work with the Kenwood, which is not an RDS tuner. I am keeping my SB920, but I will modify it. I'm keeping it because it's my only tuner that decodes PI codes.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
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Re: Welcome to the new DXer based in Breckland!

Post by Nick Gilly » 11 Jan 2015 18:06

You could buy a Kenwood KT-6050 Alex which apparently has similar performance to the 6040 but with RDS included. Alas, it doesn't display PI codes, but there aren't many tuners that do.
Good DX.

Nick, Whitchurch, Hampshire.

BW Broadcast RBRX Encore, Kenwood L-1000T, Yamaha T-2, Denon TU-800L, Kenwood KT-1100SD (modified), Yamaha T-85, Sony XDR-F1HD tuners, horizontal Körner 9.2 beam (Antennenland version), Yaesu G-450C rotator

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Re: Welcome to the new DXer based in Breckland!

Post by Alex Cator » 11 Jan 2015 18:58

Nick Gilly wrote:You could buy a Kenwood KT-6050 Alex which apparently has similar performance to the 6040 but with RDS included. Alas, it doesn't display PI codes, but there aren't many tuners that do.
In fact, I think the KT-6050 doesn't have as good performance as the KT-6040. The 6040 is guessed by me that it has outstanding performance on airplane scatter, troposcatter and meteor scatter stations, up to its own standard of sensitivity performance that is unbeaten, even by the Onkyo T-9090 II, and the Sony XDR series (even though the XDR series have better stock selectivity than the 6040, and the audio quality is better than a 6040 modified for similar selectivity). I don't know much about the 6050's performance, but I would guess it's more to the Sony ST-SB920 level of performance.
Thanks Nick, for your help, but I do think that I would do better with a 6040 and an external RDS decoder. I would like John Faulkner to help me with this, as he used a Conrad RDS Manager (one example of one, that can be linked with RDS Spy) with his 6040.

Cheers,
Alex Cator.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

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