Many thanks to all who responded to my query on this topic. Several asked that
I
forward a summary of the replies to the list, so here goes.
There is a quite detailed description of the WWVB 60 kHz transmitter at
Fort Collins, CO at the site below. Their ERP is 50 kW. This power
level is a bit lower than the highest power AM broadcast stations in
the US (50 kW into a near half-wave vertical). I've never heard them in
Chicago (roughly 1,000 mile path and a pretty high noise level), but my
el-cheapo digital clock is able to synchronize to them.
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
All of the WWV HF transmitters run 10 kW into half-wave verticals that are
one half-wave above ground. See
http://www.boulder.nist.gov/timefreq/stations/wwv.html
The WWVH HF transmitters (Hawaii) are comparable, except that most are
directional to the west (two vertical towers phased to produce a
cardioid pattern.
http://www.boulder.nist.gov/timefreq/stations/wwvh.htm
European long wave broadcasters use transmitters ranging from about 200 kW to
3MW. Most antennas are 1/4 wave or less, but some use phased arrays. The BBC
station on 198 kHz, for example, runs 500 kW, at least one French station runs
2
MW, as do some stations in Eastern Europe.
Long wave transmitters are able to cover long distances by ground wave, because
ground losses are much lower. It is well known, for example, that 5 kW on 540
kHz
has much more ground wave field strength at 100 miles than 50 kW on 1590 kHz
over
average soil.
= = = = = =
Norm, W1ITT wrote;
I'm not a member of the Topband group...but I lurk and read. I don't know of
any
databases in particular, but about a year ago I was in Romania upgrading MW
facilities, and was also involved with the 153 khz station in Bod, just down
the
road from Dracula's castle. We were subcontracting for Harris Broadcast out of
Quincy, Illinois. They may have field contour info, but the transmitter is a
400
kw into an interesting array that was two towers, both series fed in phase,
with
a multiwire flattop connecting the tops of the two towers. We supplied a new L-
network matching unit for that particular site.
I'm not sure who you might talk to at Harris, but John Hall was project
manager.
He's not an engineer but he has friends who are, and if they aren't too busy
they
might have access to the info you're looking for.
Longwave is nifty in eastern Europe. I rented a Land Rover and it had a LW,MW
and
FM radio in it. I was able to receive Bod anywhere I went in Romania. The
story
I heard was that the government liked to maintain the LW station so that
Romanian
sailors in the Black Sea could get a taste of home entertainment. Seems to me
there was another 153 khz in Germany that I occasionally heard cochannel when I
was up the Satu Mare area in NW Romania. Others from western Europe were
listenable up around 240 or so.
= = = = =
Peter McGuire of Cadac Electronics, sent these excellent links re: long wave in
the UK:
http://www.bbc.co.uk/reception/transmitters/radio_trans/medium_long_wave.shtml
http://tx.mb21.co.uk/gallery/droitwich/droitwich-lf-data.asp
http://www.subbrit.org.uk/sb-sites/sites/r/rugby_radio/index.shtml
And this one that lists time standard transmitters:
http://www.cl.cam.ac.uk/~mgk25/lf-clocks.html
Any further comments will be appreciated, but because this discussion is pretty
far off topic, please reply directly to me, not to the list.
Thanks again,
Jim Brown K9YC
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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