AirNav Systems Forum
AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: bailey_uk on May 11, 2009, 09:55:55 PM
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Hi folks, recently installed a new SSJ VHF antenna for my Scanner, and well pleased with the reception, but unable to hear any ATC transmission, just aircraft.
I thought this would be the case, as I live a fair distance from any main airport.
If I turn the squelch right up, I can faintly hear some ATC transmissions on certain frequencies but definately not enough to make anything out. Is this a typical case of needing a pre amp?
I am unable to get my antenna any higher, as its already 10ft above the chimney, and used RG213u cable to my scanner. (14m).
Thanks
James
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James,
There is a possibility that a good quality masthead amplifier might help but I would be inclined to replace the feeder with Westflex, Ecoflex or similar low loss feeder if you were going to consider this measure. Don't bother with a preamp at the receive end of the feeder, you would be wasting your money.
hth
Chris
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Ok cheers Chris, I bought the RG213u with the impression it was the best for VHF, and Westflex would be overkill and possibly the same loss, but I take it its not?
By the receive end, do you mean the scanner end? So it best to have the preamp connected to the base of the antenna or near?
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You need your preamp at the top of the mast next to the antenna unfortunately. The loss in your coax will be pulling the valuable signal closer the noise floor and placing an amplifier inside the house near the receiver will just have the effect of amplifying the noise as well as the signal which is already barely audible.
RG213 is ok under normal circumstances in that part of the VHF spectrum but in your case where every db at the antenna socket of your receiver counts the difference between RG213 and a lower loss cable might just be the difference between hearing a readable signal or struggling to hear it.
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James
Your profile indicates you are in the Lake District. How far from Great Dun Fell. Try 125.475 126.6 and 128.675. Also, 121.5 on that transmitter as well as some Mil UHF.
Dudley
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Thanks for the info guys, Yeh I have heard of Great Dun Fell, is it a repeater station?
The 125.475 was the one VHF frequency that I managed to receive the base station last night.
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Not repeaters in the strictest sense of the word but remote transmission/receiver locations. R/T for London, London Mil, Scottish, Shanwick and Manchester ACCs are all remotely operated from various hilltop sites around the UK. Great Dun Fell is closest to you of course. If you're near the coast you may be able to hear the Snaefell site on the IOM, key ones:
130.975 Scottish ACC Talla Low sector
133.050 Manchester ACC
282.125 London Mil
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James
That frequency is also on Sneafell IOM. If you are not getting 126.6 which is Volmet then may be you are getting Sneafell. Try 133.05 for Manchester control. These transmitters are sending from Swanwick, Manchester and Preswick
Dudley
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James,
Just wondering which ground stations you are hearing faintly, do you have the frequencies to hand? Might be worth considering a log periodic fixed in the direction of said station if feasible and you have room on your mast. LPs for VHF/UHF are relatively compact and efficient directional antennae widely used for commercial VHF applications. I've built a couple for 2m/70cm portable operation and they work very well indeed.
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126.6 seems to be there very faint, like you say VOLMET, like a continuous transmission,
Im pretty sure it was the 124.475, that I heard last night and it was Cessna 404 Titan, G-MIND, 400CAD, Requesting to Route via Dean Cross - Pole Hill and then onto Coventry at lowish level.
My house lies directly in the line of DCS and POL so looked out for it and saw it fly overhead.
Added the suggested frequencies and listening out.
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Good
Now let us look at 126.6. As it is transmitted from several sites it cannot be on the same frequency as other sites, as it will cause interference. So try 5khz low and 5khz high to see if there is an improvement. The system is called Climax.
What ever happens you are now able to check radio and antenna system at any time because as you said it is continuous.
Try 118.775. This is Manchester transmitted from Preston. If you get this then there are 12 more.
Dudley
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Sticking with the theme of VHF transmissions a strange thing has happened to me recently. I'm located just to the south of LGW, great reception area with the Reigate, Ventnor & Warlingham transmitters within range. I also have a roof mounted antenna.
For some reason, I cannot now pick up the Swanick controllers for 126.07, 128.425 & 134.9 any longer- these used to be 3 of my strongest signals too. Even at full squelch open I hear no ATC now.
Does anyone know if the transmitter sites for these frequencies has been changed?
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Yep 118.775 is one of my favourites, appears to be the frequency used for slightly lower flights, around FL195 into Manchester from the north, flying over head my house.
(Irritating thing is that the lower flights as mentioned above seem be mainly the 'Jersy' call signs, which are the FlyBe DH8D's with no ADSB!
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Good
Now let us look at 126.6. As it is transmitted from several sites it cannot be on the same frequency as other sites, as it will cause interference. So try 5khz low and 5khz high to see if there is an improvement. The system is called Climax.
Dudley
Wow,. yes your right!
126.595 is coming through considerably stronger, however squelch is still needed!
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Yep 118.775 is one of my favourites, appears to be the frequency used for slightly lower flights, around FL195 into Manchester from the north, flying over head my house.
(Irritating thing is that the lower flights as mentioned above seem be mainly the 'Jersy' call signs, which are the FlyBe DH8D's with no ADSB!
Draw an imaginary box approximately North-South distance Honiley to Dean Cross then East - West DOLAS to LIFFY, that's Manchester ACC up to FL285
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Thats exactly how Id imagined it!
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it may be worth you checking my website - www.jonjorobb.netne.net/e107/ for information on the Preston transmitter, and which offsets its best heard on. Please note this is a new site, not yet complete.
Thanks,
Jonjo
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Wow, that site is exactly what Ive been looking for, after 10 years of making my own assumptions of what sectors are where and corrosponding frequncies.
Will be checking back regularly! Good work!
Quote from the site 'Ever wondered where FIWUD is?'
Hehe I was the same when I first started Airband scanning, wondering where Margo was, after hearing it so many times with northbound traffic heading over the borders!
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Thanks! - will put some more maps up, but the Waypoints are gonna take a while, updating them all!
Thanks,
Jonjo
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Does anyone here have any info on UHF freqs used by mil traffic overflying the SW of England (Cornwall Deven etc)?
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Great website Jonjo.
Will you be adding to the transmitter page to include the southern ones?
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Hi
These are mainly Mil for Daventry Chedburgh Grantham Greenford Swingfield Warlingham Ventnor Clee Hill Sneafell Winstone Davidstow Moor. Rothwell are trimingham are very similar.
125.275 Anglia Radar Anglia Radar Trimingham 1
125.95 Manchester N Upper Pres Kel 1
127.45 London Mil Clee Hill 1
127.45 Manchester Centre Pres Kel 1
128.05 Manchester Centre West Pres Kel 1
128.25 London Mil Greenford Clee Hill 1
128.7 London Mil Chedburgh Clee Hill 1
131.125 Manchester Centre Preston 1
131.225 London Mil Trimingham 1
133.05 Manchester Centre Preston 1
133.3 London Mil Dav 1
133.325 London Mil Chedburgh 1
133.4 Manchester Centre Trent Pres Kel 1
133.9 London Mil Clee hill 1
134.425 Manchester Centre Preston 1
134.475 Scottish Preston 1
135.075 London Mil Trimingham 1
135.15 London Mil Clee Hill DSM 1
135.275 London Mil Trimingham 1
135.575 London Preston 1
135.575 London l Wirral Sector Preston Kel 1
135.625 London Mil Trimingham 1
135.925 London Mil Trimingham 1
231.825 London Mil London Mil Green Vent DSM Win 1
232.875 London Mil ICF W (S) Clee Hill DSM 3340 Dk 34 1
233.225 London Mil East Trim 1
233.725 London Mil East Trim Roth Wash. Navpi 1
251.425 London Mil East Trim 1
251.475 Scottish Mil Scottish Mil 1
252.875 London Mil Central Clee Hill Greenford AARA 6. 1
252.975 London Mil Chedburgh 1
256.575 London Mil Clee Hill Litchfield 133.90 1
259.6 London Mil East Trim 6130 Desk 13 1
261.35 London Mil East Trimingham ARA8 1
269.475 London Mil East Trimingham 6120 Desk 12 1
270.05 London Mil East Trimingham 6110 Desk 11 1
275.5 London Mil East Grantham 1
275.625 London Mil Southeast Ched Warl Ven. CC 371.55 1
275.65 London Mil East Trimingham 1
277.625 Lon Mil Preston 1
277.775 London Mil ICF Trimingham 1
278.6 London Mil ICF SW Warl Clee Hill DSM 1
280.825 Lon Mil Preston 1
282.125 London Mil Snaefell GDF Grantham 1
282.5 London Mil Clee Hill 1
283.475 Anglia Rader Anglia Rader Trimingham 1
284.675 London Mil East Trimingham 6140 Desk 14 1
284.7 London Mil S Warl Swing 1
292.525 London Mil Central Clee Hill 1
293.475 London Mil South Greenford DSM Win 1
341.675 London Mil ICF Cen (Sec) Greenford Daventry Win 1
342.075 London mil Rothwell Only 1
370.625 London Mil East Wash Rothwell Only 1
371.55 London Mil ICF Sec Ched Warl 275.625 1
371.8 London Mil East Trimingham 1
372.675 London Mil West Clee Hill DSM 1
397.175 London Mil East Rothwell Only 1
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Be aware, some of these Freq's are no Longer in use, and also some of the Sectors.
@ DCA - When I can, Yes
Jonjo
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Does anyone here have any info on UHF freqs used by mil traffic overflying the SW of England (Cornwall Deven etc)?
Inital Contact Freq is 278.600
This is the map I made http://jonjorobb.netne.net/jonjo/MMARS.png
Thanks,
Jonjo
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wow ...just looked at your website
I doff my cap in your direction !
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it may be worth you checking my website - www.jonjorobb.netne.net/e107/ for information on the Preston transmitter, and which offsets its best heard on. Please note this is a new site, not yet complete.
Thanks,
Jonjo
Hi Jonjo
How long does it take to be approved to login to your site after signing up for an account?
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Sorry to hear your having problems.
Ive had a lot of problems with the Member access, so im considering just making it a page open to all and scrapp the Idea of members.
Will be done be tonight, I promise
Jonjo
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Sorry to hear your having problems.
Ive had a lot of problems with the Member access, so im considering just making it a page open to all and scrapp the Idea of members.
Will be done be tonight, I promise
Jonjo
Thanks, I have tried a couple of times including today, I get the message confirmation email sent but nothing arrives :-(
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Its done now :)
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Excellent, thanks for providing such an informative site.
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No Problem, I enjoy doing it. :)
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Good site Jonjo