Low Power MW DX?

[linescan87]

This is a short list of stations received at entertainment quality here today, there are a few missing but it gives an idea of conditions.

Spirit 549Khz
Radio 4 720Khz
BBC Scotland 810Khz
BBC Radio Lancashire 854Khz
BBC Wales 882Khz
Key 2 Manchester 1152Khz
Absolute 1215Khz
BBC Radio ulster 1341Khz
Manx Radio 1368Khz
Gold 1458 Khz (mixing with another unknown station)
BBC Radio Merseyside 1485Khz
Radio city talk 1548Khz

Radio used is a Hitachi marine radio.

I hope this is of interest,

John Joe

[paulsherwin]

Dublin really isn't that far from NW England, with a sea path. W Scotland is a bit further away, but there's still a sea path, and BBC Scotland uses a pretty meaty 100kW transmitter at Westerglen as it has to get up to the Highlands.

[dsergeant]

For us radio amateurs who regularly work all over the place with as little as 5W on 160m it hardly surprises me that many of these 1KW or so MW transmitters with antennas far better than most amateur ones can also be heard at long distances.

[G6Tanuki]

Originally Posted by dsergeant

For us radio amateurs who regularly work all over the place with as little as 5W on 160m it hardly surprises me that many of these 1KW or so MW transmitters with antennas far better than most amateur ones can also be heard at long distances.

Yes, my experience is that the big problem with reliable DX on the lower-bands (broadcast and amateur) is the noise-floor at the receive end. In the 1930s/40s/50s it was set by car ignition-system impulse-noise and sparking from tram/trolleybus power-rails; a good noise-limiter helped. 1960s through the 1990s the TV line-timebase harmonics took over [annoyingly the 405 and 625-line harmonics interleaved so there were no AM-broadcast-reception-friendly gaps in the rasping noise].

Then as analog-TV faded away the noise-of-the-current-millennium became SMPS and CFL-bulb hash!

[Croozer]

Thanks for the confirmation guys. If Simon can pull in Fife and Aberdeen sub 2kW from Bristol then maybe it's not such a freak as I thought. The clear channel argument is one I hadn't considered. WABC on 770kcs at 50KW sets an interesting context. I'd love to think that BBC Scotland on 810kcs at 100kW could be heard stateside.

I usually think of DX in the context of the unconventional aerial arrangements of my youth (a bean-can on a wire hung out a 3rd story window) chasing fading signals like Laser 555 (?) around the dial. What surprised me was that 1116kcs was solid entertainment quality (except the odd bit of powerline hash) all the way down the road. Maybe that's the advantage of no cochannel interference?

John Joe -are those daytime reports? Even given a sea-route, pulling in the lower power stations at the high end of the dial is still impressive if they are use able signals.
MW ain't dead!!

Interesting point about the TX on the M5 Does that mean that Droitwich R4 on 198kcs is horizontally polarised? I've never passed the M5 site, but I know the Westerglen site is a vertical mast with a capacity hat. I 'think' the Burghead site is the same, although it's a while since I passed closeby. Is R4 horizontal in England and Vertical in Scotland? Does it make much difference? As an experiment I rotated the set 90 degrees so that the ferrite rodd was vertical and the signal definitely dropped. ..

[paulsherwin]

You are thinking of Laser 558.

[linescan87]

Hi Croozer,

Yes this was today around 1.30pm just before I posted

[ms660]

Droitwich LW is vertically polarized, a T antenna, the vertical section is less than 1/4 wavelength long, the top horizontal section adds capacitance to the system, the upshot of that extra capacitance along with taking other things into consideration is more radiated power, to save me wearing my fingers out I've included a link that will show the basics of the T antenna including current distribution:

https://en.wikipedia.org/wiki/T-antenna

Lawrence.

[Hybrid tellies]

This morning on the car radio I picked up Pulse 2 from the 0.74Kw transmitter at Vicars Lot near Huddersfield. This uses a vertical mast as the medium wave radiator with the FM transmitting aerial for Pulse 2 mounted on top of the medium wave radiator. The IBA successfully used this arrangement at quite a few sites across the country.
When conditions are really good to the North I have also received the low powered local Scottish commercial stations such as Tay 2, West Sound, North Sound and MFR2 from Inverness all around 1Kw or less and on my car radio whilst parked in my works car park near Bath just before I go into work.
I am making the most of this low powered MW DX before these transmitters are switched off.

[russell_w_b]

Originally Posted by 'LIVEWIRE?'

That article about WABC New York is fascinating, Martin. For one thing, I either didn't know, or had forgotten, that a vertical mast makes a better radiator if it is an (electrical) half-wavelength at the transmitted frequency.

The optimium (electrical) height for a vertical radiator to give maximum ground-wave field-strength is 5/8 wavelength (0.625). Above this, secondary high-angle lobes are produced and the ground-wave falls off dramatically.

[russell_w_b]

Originally Posted by G6Tanuki

In the 1930s the US Blaw-Knox company heavily promoted the 1/2 and 5/8-wave vertical lattice-mast for MW broadcast-stations. Their design was the one which starts off thin at the bottom, gets fatter for the first 1/3 or 1/2 of its height, then tapers to a point again at the top.

Droitwich had a Blaw-Knox mast as a reserve aerial. It must've been taken down around the back-end of '84. Lisnagarvey in N. Ireland had one too.

Didn't Blaw-Knox make bulldozers?