The closing down of am transmitters

[radionortheast]

Greatest hits closing down their am transmitters, it was not long after Absolute announced they were closing down, it is something that has happened quite quickly. I’ve noticed it on the greatest hits 1530 transmitter over the past day they are relaying a short message saying that it is nolonger avaible, absolute have also started, which is a much stronger transmitter on 1215, the message was alot longer more crytic, “there are a number of reasons why were making the changes” they didn’t say why. The 1530 went off, there was a kind of atmospheric noise on the frequency, it is quite sad it wasn’t something I listened to, there was one I found on 1278, it went quiet too, i’m guessing they must be near the Leeds area, they were telling people to retune to 96.3. 1305 and 990 which are to the south are still playing gta, I think it might be staying around there for a little longer. I think this is the last migatation from am to fm, most am stations moved from am years ago.

Its sort of weird the 1530 signal listening to on car radio a mile away, the fact it would tune to it in 1khz steps sound clear was something I admired, was something that made me interested made me go out and get my own am transmitter. I started with 0.1w transmitter, I found it didn’t go far at all, then I got 4w with the wire aerial I found I could get a signal now and again weakly, I ran at 12v because of the annoying fan so it would be more like 3w. I was able to improve it abit hear abit farer away by n loading using the mains as the aerial, I was never alble to get the same clarity. Now the 1530 signal has gone i’ve considered moving it further up the band I don’t think it will make a difference, it would funny to have in on the same frequency, I don’t suppose anyone would have their radio still tuned to it, it is nice to hear something. Last night I heard something coming throught on the frequency, which sounded english from another part of the country it had the judders, dosen’t seem like anything interesting will come throught. I suppose most of these signals come in at night are intemient in nature, when I started testing with the little 4w I thought I had a clear frequency, then other stations seemed to jump on the frequency, I thought it might bounce off the skywave at night but then I realized the powers other stations are using!. I’ve also considered having the am/fm going at the same time, trying to listen to the am signal on a pocket radio a mile away might be asking a lot, my fm 1w I can hear clearly, I may have to move for a ramadan station.

I think Absolute and greatest hits are owned by the same company, its quite interesting, gta has got lots of transmitters going on fm which are the old local radio transmitters, with it been a kind of national network by the back door, here 3 transmitters come in at the same strenght, heart and capital come from Emley are much stronger, I suppose its too late to go rejiging the band. I think greatest hits don’t have as many transmitters to the south, I don’t think there was any local radio station in Sheffield, there maybe a problem with fm coverage there, maybe why the mw transmitters are been kept on, they have a anorak quailtiy here, it is again interesting they seem to be interested in fm coverage when other stations are not. There are afew commercial stations around viking, pulse, they seem to get a bad rep, I don’t know how long they’ll beable to keep going. The frequencies aren’t there to have absolute as national station on fm, they converted the absolute fm transmitter in London to greatest hits, to bring inline with the rest of the transmitters, like with the individual local radio stations having one fm transmitter going is not viable.

Virgin/absolute are not on fm anywhere, I read virgin wanted to close the am transmitters afew years ago when it was still virgin on mw, virgin are quoted as been the most sucessful, maybe themselfs saying that, they don’t broadcast an anlogue signal, it is food for thought. It is sad even thought they weren’t too my taste, its the idea signals you thought would be around forever won’t be there anymore, like after the bildsdale fire i’m nothing hearing any interesting on the old frequencies.

[Barnabas]

High powered AM transmitters are very power hungry, so Bauer (the group who own Absolute and Greatest Hits) presumably made a commercial decision to pull the plug probably driven by stupidly high electricity prices and the relatively tiny number of people still listening on AM. It surprises me that commercial radio on AM has lasted as long as it has, to be honest. When I was a student in the late 90s I got involved with the university radio station which had a very low powered AM licence - there was an induction loop system that transmitted to some of the older halls of residence, and later a freely radiating transmitter with a whole massive 1 watt of power! It was a battle to get anyone to bother listening on medium wave even back 25 years ago due to the crappy audio quality and night time interference from European stations coming in.

It would be nice if they just let community groups and radio nerds play with medium wave now it's dying off. Apparently ofcom aren't allowing any new AM licences now as it's seen as a relic.

[Casual]

To be totally honest I don't know how anyone has the patience to listen to AM in this day & age. The sound quality is bloody awful! No offence to anybody, just my opinion.....

[Albert H]

Casual - if it's done right, AM can sound very good. Back in the early 80s, we used "Tower Block Sloper" aerials - you got a ¼-wave of wire, and hung it over the side of a block, then tied off the lower end to a lamp post or tree, so the wire came away from the block at about 15°, using something insulating like fishing line or nylon string. At the top, we used to use the plastic rings that held beer cans together to provide the upper insulator, usually attached to a railing. The rig aerial output went to the wire, and the earth went to the block's lightning strap (which usually ran down the side of the block to an earth at the ground level). Effectively we had a ¼-wave "inverted-V" aerial. The match was (usually) very close to 50Ω, and just a few Watts would cover much of London in the daytime.

The little rigs we used were (usually) FET-output, running around 10 - 15 Watts carrier and 4 times that on mod peaks. With some good compression and a bit of "top-boost", the quality could be excellent. A rig that was quite frequently built used a 9MHz crystal divided by 8 for 1125kHz, which was a good frequency at the time - a couple of channels away from LBC one way and some pop station a couple of channels the other way - and it didn't have too much European stuff jamming it at night. It used to get quite a big audience!

We discovered in the summer that through the sunrise and sunset periods 1125kHz could be heard in the Benelux! The rigs only cost about £12 to build in those days and the link receivers cost around the same, so getting raided wasn't too expensive!

[Barnabas]

To be totally honest I don't know how anyone has the patience to listen to AM in this day & age. The sound quality is bloody awful! No offence to anybody, just my opinion.....

It's not too bad for speech and the last two national stations left are speech stations, 5 Live and Talksport, I guess if you have an old car or van without a DAB radio and you're into sport then you might still listen on the move. But yeah, for music, the quality is piss poor.

[RingwayManchester]

Hear Absolute Radio's 200KW Transmitter Switch Off Forever

[RingwayManchester]

These Transmitters Should Not Have Been Switched Off

[Albert H]

All the more room for us!

C'mon - get your soldering iron hot and get building some MW AM rigs. They're MUCH easier than FM rigs - the technology isn't as layout-critical. The only "fly in the ointment" is that they aerials are bigger, but you can get city-wide coverage for cheap! With some good compression and frequency response tweaking, AM can be made to sound pretty good for music. Over in Europe, there are plenty of EDM stations with big audiences on AM!

Modern FETs are great for AM output stages, and you can get 100 Watts peak / 25 Watts carrier from a FET that costs about £1.50. Compare that with a VHF FET! Getting good frequency stability is easily achieved with a simple, cheap CMOS synthesiser, and you can use almost any standard crystal as a reference (though 4608kHz (baud rate generator crystal) is convenient since it divides to 9kHz easily). My most recent AM rigs are PWM-based, and their efficiency is pretty good - they don't get hot! I've been using the TL494 PWM Power Supply controller chip for my modulator, but there are other, simpler approaches for beginners.

Time to get building for AM!

[Persona Non Grata]

RTE in Ireland have announced the (several times postponed) closure of its 252 KHz transmitter (despite it being the only for listeners in parts of NI to receive it terrestrially since the Northern half of Co. Antrim can't get them on FM)

They say there's no need for longwave now because It's all digital nowadays despite them axing the DAB service as well (although when it was on the coverage was even poorer than FM) theyre also trying to dress it us as environmental.

[Albert H]

I was in the Netherlands over the last few days. Where I was - in the South-East of the country - I could hear about thirty of the little Medium Wave stations that proliferate over there. Some of them are pretty good, and are certainly not seen as a "waste of electricity".

Building MW AM rigs is as easy as building audio gear, and the parts cost next to nothing. The modern FETs available for <£2 make quite high power cheaply possible.

One rig I saw recently had a mains dropper capacitor feeding a zener regulator for the low voltage part of the circuit, with rectified mains (around 380V) for the PA. It did close to a kilowatt carrier, and didn't even have a mains transformer in it! The only expensive components were the Class X capacitors in the power supply, and the high voltage electrolytics for smoothing the PA supply - all the rest were parts scrounged from scrapped computer power supplies and some cheap logic. On the air, it gives a cracking signal......