Radio Blackbeard 1512KHz Medium Wave

[Albert H]

he must have a place to put a long wire, like a tower block

The wavelength of 1512 kHz is 198.3 metres, so a quarter wavelength will be ~49.5 metres.

If he got 50 metres of wire and put it over the side of a high building, and tied off the lower end to the top of a lamp post (or anything else well above head height) with an insulating string (we used to use nylon fishing line) so that the aerial was about 15° out from the building, and then earthed the rig to the building's lightning conductor, he'd have a big "Inverted V" aerial, with a match at about 50Ω!

You'd be surprised at how far you can get on AM with a relatively low power. At one time we ran just 8 Watts carrier and ~30 Watts peak, and got daytime coverage of much of London and surrounding areas!

My current experimental rig runs around 1 kW PEP (250 W carrier), and I've found a site that will allow a big enough aerial for operation towards the lower end of the band..... A brief test into a non-ideal "Marconi" aerial resulted in signals audible throughout the Benelux in the daytime (though not "entertainment quality"). With the big aerial rigged, and a quiet frequency (now that most of the Medium Wave stations have disappeared), I should be able to get quite spectacular coverage.....

[radionortheast]

Medium wave is really interesting, I read in a blog he used to broadcast were the dutch broadcast above the am band, he upgraded his aerial, thought I was more interested in the story of the husband and wife team, who were heard all over Europe, before been raided by the dutch authorities. There a story in a video about someone setting up a transmitter in derelict building, he connected the earth while the transmitter was live got blown across a room.

[surefm]

Think this might the same station that did buzz fm nottingham back in the 80S, Dave Norris partfree radio network east midlands
https://buzzfm-nottingham.com/

[Planet266]

Most of the (not very many) medium wave pirates of recent years have been rock or oldie stations so Blackbeard is unusual in that respect. But there are plenty of AM dx-ers out there and this was quickly picked up by the logging sites. I think they've had reports from Belgium and further afield. I seem to remember one of the London stations in the late 80's trying it out on about 1404 kHz if my memory serves me correctly, just to avoid the clogged up FM band. It didn't last very long. I'd have to dig out my old Anoraks UK weekly report sheets to find out.

The signal did not get out well because they came from a tower block too high for that frequency. Plus they didn't like the bass response.
The calculation for a 45 degree sloper wire from a block was simple pythagoras, where the hypoteneuse was the aerial wire itself and the right angle was where the block met the ground.

The Edge on 819, and Argus used this several times, on 783, 819, 837, 1125, 1494 and 1503, and it always got out very well. The best was on 783 kHz from the [now gone] Green Man tower block at Leytonstone. It was heard from Worthing to Cambridge and Orfordness to Bristol with only about 5 watts! However, you needed the earth to be properly attached to the lightning conductor; one station was installed on 1260, and when someone went up the block to change the tapes, he disconnected a lot of the earthing, causing the rig to 'take off' so all you heard was a farting noise on 1260!

[Planet266]

he must have a place to put a long wire, like a tower block

The wavelength of 1512 kHz is 198.3 metres, so a quarter wavelength will be ~49.5 metres.

If he got 50 metres of wire and put it over the side of a high building, and tied off the lower end to the top of a lamp post (or anything else well above head height) with an insulating string (we used to use nylon fishing line) so that the aerial was about 15° out from the building, and then earthed the rig to the building's lightning conductor, he'd have a big "Inverted V" aerial, with a match at about 50Ω!

You'd be surprised at how far you can get on AM with a relatively low power. At one time we ran just 8 Watts carrier and ~30 Watts peak, and got daytime coverage of much of London and surrounding areas!

My current experimental rig runs around 1 kW PEP (250 W carrier), and I've found a site that will allow a big enough aerial for operation towards the lower end of the band..... A brief test into a non-ideal "Marconi" aerial resulted in signals audible throughout the Benelux in the daytime (though not "entertainment quality"). With the big aerial rigged, and a quiet frequency (now that most of the Medium Wave stations have disappeared), I should be able to get quite spectacular coverage.....

The lower the frequency the less the resistance to earth and the further the signal goes, but you are then limited using tower blocks by the maximum possible height. However, we discovered that they can be made directional by coming from a block really too low for the frequency as long as the first 1/8th wave is in free space, you can run the last along a hedge or top of a fence, and it will be directional in that direction. We once put 1125 kHz off a block in Peckham that was lower than usual, and found that it was getting to Gatwick Airport some 28 miles away to the south but wasn't even reaching the Thames 3 miles away to the north!

As for using a sloper aerial with 250watts, make sure the end is way above head height, the voltage at the end is not going to be kind if someone touches it.

[tokingmenace]

It's been off for a while. I think mainly down to issues with Dutch Pirates also using the frequency.

Sounds like 1512khz will be making a return with a new format, so worth seeing if anyone can receive it in the evenings

[Albert H]

The calculation for a 45 degree sloper wire from a block was simple pythagoras, where the hypoteneuse was the aerial wire itself and the right angle was where the block met the ground.

We really experimented with the slopers back in the 80s. We found that the ideal angle away from the block was around 15° to 17°, and you'd get damned close to a 50Ω match!

A lot of the rigs we used were little 8 Watt carrier / ~30 Watt peak, with a couple of VN66AF FETs in parallel for the final, modulated by a TDA2030 or an LM1875 - a simple little circuit that I came up with. Those little rigs used the 3-chip CMOS synthesiser, and four of the inverters in a 4049 for the gate drive to the finals. They were physically tiny, had a little 80VA toroid transformer for the PSU, and were built in folded aluminium boxes, with homebrew heatsinks. The last few of them had built-in Band I receivers, and were made on a single PCB that I designed. Frequency setting was done beneath the board, with solder blobs selecting the pins on the 40103 divider chip! The link receivers used my little stash of ~49 MHz crystals (+10.7 MHz, of course) for receive frequencies around 60 MHz. They had carrier-and-tone-access, and the VCO in the 4046 would be inhibited until the link carrier came up, and a sub-audio tone was detected (using an NE567).

I think that I might still have one of the prototypes here somewhere! Those little rigs into those slopers really worked well, and could get remarkable daytime coverage despite their low power.

[Planet266]

it recently moved to 1494 kHz to get away from infrequent high powered Dutch stations. It has also been noted relaying Radio Argus (which seems to be making a comeback) and WMR

[radionortheast]

it recently moved to 1494 kHz to get away from infrequent high powered Dutch stations. It has also been noted relaying Radio Argus (which seems to be making a comeback) and WMR

That explains why i’ve not heard it in a while, think there are two french transmitters on 1404 and 1593, i've heard them relaying dance it was on a weekend, so there is some dance on mw.