PBJ audible in London
Posted by Mitch VE3OT on September 01, 2001 at 09:52:51
Hi Chris:
Audible and good screen capture in Spectrogram here in London, ON this Saturday morning. Jpeg on the way.
73 Mitch VE3OT
"Ultrasound Receiver"
Posted by Frank Carson on September 01, 2001 at 21:21:33
I occasionally get a catalog from a company called "American Science & Surplus" (their website URL is www.sciplus.com). They're a great source for all kinds of stuff from empty glass IV bottles and lab stuff to electronic gizmos and parts. Anyway, in their latest catalog on page 15 they have an "Ultrasonic Receiver Kit" that they say "amplifies incoming 20khz to 90 khz signals and changes them to the audible range". It says you can hear mosquitos, electricity arching, etc. Anyway, it's a solder kit for $18.95. I ordered one today - cause it sounded interesting. Thought I would pass it along. The catalog number is 91851.
Frank Carson N3OCW
Re: Jim Creek VLF station
Posted by Tim Billings on September 02, 2001 at 16:15:53
VLF has been used for many years as an exploration tool in locating conductive ore bodies. Numerous VLF stations around the world are used as signal sources...the station chosen is dependent on the assumed orientation of the ore body being studied. The variation in the phases of the recieved signal as one traverses the surface over the ore body are recorded and the data is "filtered"..mathmatically manipulated... and plotted on a common base map. This map is used in conjunction with other geophysical and geochemical surveys to help understand the ore body in question.
Re: LF Engineering
Posted by Bob Gaye - K2LGJ on September 02, 2001 at 19:24:11
Good info Clint. My 400B is about a year old. Still uses the RG-174 and strain relief. Think I'll try to "unglue" mine too :-) I've been using F connectors and RG-6 on my antennas. There are weatherproof versions and they are easy to work with. Interesting on the higher voltage. Didn't consider that to be a possibility. Wonder if you measured the current drain at the higher voltage? Mine is drawing about 20 Ma in stock condition.
73 - Bob K2LGJ
SAQ On Air Sept 5
Posted by John Davis on September 03, 2001 at 17:06:41
Christer Andersson has passed along word to the LF community that the historic Alexanderson alternator will be on the air from Sweden Wednesday.
Please check the LWCA Longwave Home Page for details.
73,
John
Re: LF Engineering
Posted by Douglas Williams on September 04, 2001 at 10:22:36
"The only complaint that I have had was that mine used RG-174 through a strain-relief coming out of the bottom. When I first got the antenna, I was hauling it all over the place and quickly fatigued the connection. I had to carefully 'unglue' the bottom cap and install a BNC connector."
I completely disassembled my L-400B and rebuilt it in a new PVC tube. I used PVC glue on the top cap and sealed the bottom cap with latex caulk (so I could remove it in the future if repairs needed to be made). I attached an SO239 connector on the bottom cap. This way, I can change out the coax whenever I feel the need. The coax I'm currently using is mil-spec non-contaminating RG-58. I seal the base of the connection with "coax-seal" from Radio Shack (black, silly putty type stuff that comes in a roll...works great).
I dislike the stock design of the L-400B because it is not possible to easily replace the coax. Standard coax only has a life span of about five years when kept outdoors and regularly exposed to UV and the weather. Mil-Spec non contaminating doubles that to ten years or so.
Re: Really low-frequency PLCs
Posted by Tony Levstik on September 04, 2001 at 11:42:23
I was looking over some of the Q/A's on the turtletech web page and one of them stated operating "on or near 60hz switching only at Zero voltage parts of the waveform"??
That sounds a like what the X10 appliance controller moduels use but on a much Lower baud rate.
Tony Levstik
Re: Ham rigs as LF receivers
Posted by Douglas Williams on September 04, 2001 at 12:20:46
Most ham rigs (and general coverage receivers) are pretty deaf at LF. The only recent ham transceiver I can think of that had decent sensitivity at LF was the TS-850. Build or buy a converter. Palomar Engineers sells one.
Re: LF video transmission
Posted by Les Rayburn, N1LF on September 04, 2001 at 12:29:58
Unfortunately, no. Standard NTSC video occupies a bandwidth of 6MHz, while the largest part 15 allocation on LF is only 30khz wide.
For the most part, only the bands you mentioned would allow for this type of operation without a license.
There have been some video tests on LF...but these use a system called Narrow Band TV...which yields pretty awful, grainy, B&W pictures of interest really only to experimenters. Certainly not suited for your applications.
Les
Re: SAQ On Air Sept 5
Posted by Bill Ashlock on September 05, 2001 at 18:16:12
Hi John,
I copied the SAQ transmission at 11:15 EDT today. The signal was at least 6db over the background noise level (not counting the random noise bursts remaining from yesterday's electrical storm) with no fading at all - probably the best of 4 previous captures. I used my 4ft/side loop this time but also compared the signal to that produced from my 3ft diameter ribbon cable loop I used on the last two transmissions. The signal quality was identical although I had to increase the receiver's RF gain by >20db for the 3ft loop.
Based on the constant and predictable reception of five different SAQ transmissions at different hours of the day, I conclude this is likely to be surface wave propagation. If I use attenuation values for salt water, at this frequency, from my propagation textbook, the signal level for this distance calculates to be strong enough to be heard above the atmospheric noise. I'm interested to see if you have looked into this as well. Comments from others are welcome, too.
Bill WA
Re: SAQ On Air Sept 5
Posted by John Davis on September 06, 2001 at 00:14:02
>>> If I use attenuation values for salt water, at this frequency, from my propagation textbook, the signal level for this distance calculates to be strong enough to be heard above the atmospheric noise. I'm interested to see if you have looked into this as well. Comments from others are welcome, too. >>>
When I was a youngster...way longer ago now than I care to contemplate...our local library had a book that was long out of print even then (published in the late Twenties), with a chapter on the subject of transatlantic telegraphy. There were some calculations confirming that stations built on the same pattern as SAQ should be capable of nearly full-time commercial service, including groundwave, even taking atmospheric and man-made noise (such as it was at the time) into account.
Of course, use of true multi-wavelength Beverage antennas back then didn't hurt anything, either. The accompanying photograph showed wires on stubby, short-spaced telephone poles, stretching out for miles of relatively open countryside from the RCA receiving station. Not much chance of doing that on Long Island today, I don't suppose. :-)
Sure wish I had known when the library planned to discard that old volume!
73,
John
FWD: TransPac tests
Posted by John Davis on September 14, 2001 at 16:30:47
---------- Forwarded message ---------- Date: Fri, 14 Sep 2001 17:55:49 +1200 From: Vernall
TRANSPACIFIC TESTING 21/22 SEPTEMBER
ZL and VK LF stations will be transmitting on September 21/22. Separate frequencies are allocated to each participating station, as summarised in the following table:
FREQUENCY SCHEDULE FOR TRANSPAC TESTING ---------------------------------------
FREQUENCY MOD & ID CALLSIGN LOCATION kHz 176.515 QRSS AX2TAR AX2TAR Hobart, VK7 177.0148 QRSS ZL3FJ ZL3FJ Christchurch 182.68 QRSS ZL3PN ZL3PN Timaru 183.50 QRSS ZL3JE ZL3JE Pareora 184.00 QRSS ZL4MD ZL4MD Cromwell 183.3999 DFCW Q ZL6QH Wellington 183.3999 QRSS L ZL4OL Dunedin
Note: Signals from ZL6QH and ZL4OL are deliberately "co-channel" so they can fit on a single Argo screen with 120 second dot setting. Frequencies of ZL6QH and ZL4OL should be maintained within 0.1 Hz.
ZL6QH will send QQQQQ... with dual frequency CW, 0.4 Hz shift. Q will be encoded as 184.4001, 184.4001, 183.3997 & 184.4001 kHz, with no spacing between elements and a 120 second gap before starting the next cycle. The ten minute sequences will be nominally synchronised with the hour (there is some minor slippage in the control software). ZL6QH will beacon from before sunset to after sunrise.
ZL4OL will send LLLLL... with single frequency CW on 183.3999 kHz, taking 18 minutes to send di dah di dit with Morse character spacing. Sequences will nominally commence on the hour and half hour.
Both ZL6QH and ZL4OL intend to insert 12 wpm CW ID twice an hour. ZL4OL intends to insert CW ID between 18 and 20 minutes, as well as between 48 and 50 minutes into each hour. ZL6QH intends to insert CW ID between 28 and 30 minutes, and 58 and 60 minutes into each hour, and use a frequency of 184.4020 kHz so as to be offset from Argo captures correctly set for 183.3999 kHz centre frequency.
SUNRISE AND SUNSET TIMES (UTC) ------------------------------ DX stations can decide on their best times for monitoring. The Americas will already be dark when sunset occurs in ZL (at approx 0613 UTC), and VK7 is two hours following for sunset (at approx 0803 UTC).
Sunrise in the Americas occurs while it is still a dark path to ZL and VK. Around local sunrise may give best LF DX propagation for reception in the Americas. Sunrise eventually gets round to ZL (approx 1813 UTC) and VK7 (approx 2003 UTC).
Reception reports can be emailed to vernall xtra.co.nz
Good luck to all prospective listeners.
73, Bob ZL2CA
Addition to info
Posted by BobVernall on September 14, 2001 at 23:20:14
Date: 9/14/01 9:05:42 PM Eastern Daylight Time
John,
Regarding my drafting of the "TransPac" schedule, I should have made it clearer that the time of the tests is from late Friday night to around Saturday dawn your local time local.
Good luck,
Bob ZL2CA (I'll be at the ZL6QH station)
Re: FWD: TransPac tests
Posted by Bill Ashlock on September 14, 2001 at 23:42:08
John,
Thank you for posting this info. I shall be watching for them on the ARGO screen. Do you know what powers levels are being used?
Bill WA
RY off for the season
Posted by John Andrews on September 17, 2001 at 09:44:33
I have taken Hifer beacon RY off the air until next spring. Thanks to all who reported hearing it!
John Andrews, W1TAG
Re: LF Engineering
Posted by Robert Bicking, W9RB on September 21, 2001 at 17:56:33
I have a LF-111 and L-400 which I purchased in 1995. It works good on LF, including NDB's, however, considering that the antenna is about 1 yard long it is not suprising that a 600' Beverage works better. I continue to use the LF-111 converter as it seems to be slightly more sensitive than my Yaesu FT-1000 which is a great radio and very good on LF. Now that I have put up several Beverage antennas from 300' to 600' in length, I don't use the L-400 antenna but rather, feed the Beverage into the LF-111. The combo of LF-111 and L-400 is great to take on vacations and I have used it to log NDB's while in Fla. and Aruba.
ndb database
Posted by Richard Allen, W5SXD on September 28, 2001 at 14:14:46
Does anyone know where on the internet I can obtain an up to date list of all of the LF NDBs? I found one from 1997 but lots have been born/killed since then. I need call sign, frequency, lat/lon and hopefully power info and city/state. The FAA used to have this but I cannot find it on their website any more.
Thanks ...
Re: ndb database
Posted by John Davis on September 28, 2001 at 18:44:08
Interesting question, Richard. One answer came recently from LWCA member Kriss Larson, who sent me a source of information on "all the NDB, TACAN and VOR's of the world kept up and downloadable from the NIMA website. I don't know whether this file is common knowledge to beacon dx'ers or not, but it appears to include everything and is supposed to be up to date. It's tab delimited so it's easy to import into Excel and make a sortable spreadsheet out of it."
Actually, the National Imagery and Mapping Agency cautions in a roundabout way that it doesn't necessarily contain all navaids. It's an unclassified version of the database, described by NIMA as "incorporating U.S. Military-selected aeronautical data similar to that published in the DoD Flight Information Publications," but it does appear to be pretty thorough with regard to civil aviation.
Kriss goes on to say: "The instructions of how to get the file off of the NIMA website are:
1) go to www.nima.mil
2) choose "Safety of Navigation"
3) choose "Aeronautical Information homepage"
4) choose "DAFIF"
5) choose Ed. 6 FTP
6) choose DAFIFT.ZIP this is a large file--I used our T1 connection at work to download it. When you unzip it, there will a number of folders of various aero info. The radionav file is in the Nav folder."
I hope that helps answer your question. The raw data is not particularly convenient to print out in usable form without importing it into some other spreadsheet or database program, but I'm investigating some possible ways for us to make it available in a more user-friendly form through this website at a later date.
John
Re: ndb database
Posted by Richard Allen, W5SXD on September 29, 2001 at 12:50:55
Thanks, John. I think that I can use the NAV.txt and APT.txt files to get what I want.
www.lwca.org
potrzebie