Longwave Listening Great Last Night

[Tom WA3KLR]

I tuned into the European broadcast stations at 153, 162, and 171 kHz. last night around midnight.  I haven't listened for them in a long time. 

The French signal on 162 kHz. was by far the best I have ever heard it.

On the 153 kHz. channel, I may have been hearing 2 stations.

Later the 162 kHz. station faded some, and the French station on 171 kHz. was coming in better.

I was using my 75 meter dipole and Drake R-7 receiver.

[k4kyv]

Last time I was in Europe was about 5 years ago.  Riding around with my brother-in-law in England, we listened to the car radio.  He always kept it on FM.  I asked him to try the LW AM broadcast band.  Of course, the stations came in perfectly, but he remarked "No-one here listens to longwave or AM anymore."  Looks like their AM BC service is going the same way as it is over here.

If that's true, I wonder how much longer the LW services in Europe will continue to operate.  Those antenna arrays have to be expensive to maintain.

I recall reading a story about a huge diamond shaped Blaw-knox longwave tower located on the northwest coast of France before WW2.  Unfortunately, it was considered of strategic significance and destroyed by allied bombing during the war.

[Warren]

Tom, Don,

   Conditions have been very good the past few weeks on LW. I've also heard BBC Radio 4 on 198kHz, also the station from Ireland on 252 has been very strong (also the only English language station beside the BBC). Bill Hepburn maintains a good list of LW BC stations:
http://home.cogeco.ca/~dxinfo/lw.htm

LW BC is not dead, a new station from the Isle of Man is due to come online this  June, and existing stations are upgrading to compatible digital (IBOC) broadcasting.

For a good LW bulletin board check out the LWCA site:
http://www.lwca.org/mb/index.htm

Also, Alan Melia G3NYK, maintains a LW propoagation site (mainly to do with the 2200 m ham band, but it applies to the LW BC band as well:
http://www.alan.melia.btinternet.co.uk/latest.htm

73 K2ORS/WD2XGJ
Transmitting on 137 kHz since October 2004

[ve6pg]

...hey tom....no problems with harmonics,or dimmer switches,etc?...i've tried,i'm in toronto,and have a bunch of antennas,but i think i'm too far inland..all i hear is beacons....tim....sk..

[Warren]

...hey tom....no problems with harmonics,or dimmer switches,etc?...i've tried,i'm in toronto,and have a bunch of antennas,but i think i'm too far inland..all i hear is beacons....tim....sk..

Hi Tim,
   You are definitely NOT too far inland, listeners much further away from the coast regularly hear LW BC stations. I just saw a posting on the LWCA board from a guy in Iowa who was listening to the BBC on 198 kHz booming in (and the BBC on 198  is not one of the strongest stations!)  It is probably your receiver, most riceboxes perform poorly below the broadcast band. What you would need would be a pre-selector, something with gain and selectivity (if you just used a pre-amp you would probably be overloaded by AM BC stations). It sounds like your receiver may be overloading already if you are reporting 'harmonics'.  Another route might be a converter such as made by Palomar that converts LF to HF.  If you have a lot of local noise a tuned loop antenna would be very useful in rejecting light dimmers etc. E-mail or send me a message through this board dirrect if you are interested in specific suggestions. It's a whole new world down below the BC band and unfortunately most hams have never experienced it.

73 Warren K2ORS/WD2XGJ

[ve6pg]

ok warren...well,receiver is a ts950sd,and i have a telephone line voltmeter,which is acting up...i bought fer the purpose of listening there...i've done reading on this stuff,and starting to put a lowfer beacon together,but with all the other things going on,i've left that project fer a time...i really would like to explore this stuff,and first thing should be building a receiving loop...in this area,there are alot of mw broadcast stations,but the '950 does appear a good receiver...i hear tons of beacons,with just a wire,so i dont think the deal is the receiver,but more likely a "tuner" to act as a filter for the  qwarm.....tim...sk..

[Tom WA3KLR]

Hi Tim, Warren and all,

I'm lucky to be living out in the country with at least 150 yards spacing to the nearest neighbors.  No broadcast transmitter sites nearby either.  So the only lamp dimmer I would hear is my own, under my control.  There is a LOT of plc carriers on the band though.

My Drake R-7 that I do the serious low frequency listening with, is a wide dynamic range receiver.  It was engineered to receive down to 10 kHz. also.  The original Vari-L 1st mixer shorted out last summer when I had a near lightning strike.  I found a pin-for-pin replacement in a Mini-Circuits Labs SRA-3MH.  I believe that it's LF and especially VLF performance is much better than the original Vari-L part (less loss and in particular much more LO-IF output isolation).  This is very important for a LF superhet because the l.o. frequency converges on the 1st i.f. frequency as you tune to 0 kHz., injecting l.o. phase noise into the 1st i.f. 

Warren, are you on 137.000 kHz. exactly?

I have been thinking about if I could come up with a LF matching network to add to my 10-15-20 meter trap vertical to form a passive e-field probe antenna.

[ve6pg]

Hmmmm...ok,so what stations appear to be the best to hear?...qth,freq.,time,(gmt/utc)...considering i've never heard anything on lw,except beacons,what station would be best to look for,most reliable,highest power,etc first time,etc..tim....sk..

[Warren]

Hi Tim, Warren and all,

Warren, are you on 137.000 kHz. exactly?

I have been thinking about if I could come up with a LF matching network to add to my 10-15-20 meter trap vertical to form a passive e-field probe antenna.

   Hi Tom,
     I'm generally on 137.78 (actually 137.7797) sending QRSS (slow cw) you will need to pipe the audio into your pc soundcard and run ARGO or SPECTRAN - free downloads at:
www.weaksignals.com
    I make it into Steve Dove's online receiver in Hershey PA day and night even when running low power.
On high power (1.2kW) I have been copied every night in the U.K. and Europe - usually reported as being the strongest North American station in Europe. Check out Steve's online receiver:
www.w3eee.com - click on "Live Part 5" in the left hand column. You will see my signal displayed on the waterfall near the 137.780 line on the frequency axis on the rhs of the waterfall.

    I don't think your idea of using the trap vertical as an e-probe will work. The capacitance in the coax will load down the signal considerably. The e-probe preamp needs to be physically attached to the antenna, even a short run of coax will kill it. (The e-probe preamp has an input impedance of 10s-100s of megaohms). I have a couple of simple e-probe circuits I could mail you.

73 Warren K2ORS/WD2XGJ

[Warren]

Hmmmm...ok,so what stations appear to be the best to hear?...qth,freq.,time,(gmt/utc)...considering i've never heard anything on lw,except beacons,what station would be best to look for,most reliable,highest power,etc first time,etc..tim....sk..

Hi Tim,
    It varies with propagation but the strongest LW BC stations tend to be the ones on 162, 183, 207, 234 and 252 kHz. When conditions are good (as they have been almost every night for the past month), stations will really bomb in and its as good as listening to a local AM station. Some nights I've put the RX in the 6 or even 16kHz bandwidth and cranked up the audio to hear full quieting signals and generally very good audio quality.
     You will hear tons of NDB beacons even if you are using a deaf receiver. The NDB's are all over the place and some run high power. I don't have 950 but I'll do some research on it. Most  high end $2000-$3000 HF transceivers will tune down there but are as deaf as a post!

73 Warren K2ORS/WD2xGJ

[WA1GFZ]

You guys can check your receiver performance with an audio signal generator that goes to 100 KHz. Just set the output to a set level around -10 dBM and use a step attenuator to reduce the signal. I use a HP3325A that goes to -56 dBM then add an external step attenuator to check the radio MDS.
gfz

[Warren]

Hi Tim, Warren and all,

I'm lucky to be living out in the country with at least 150 yards spacing to the nearest neighbors.  No broadcast transmitter sites nearby either.  So the only lamp dimmer I would hear is my own, under my control.  There is a LOT of plc carriers on the band though.

Tom, Tim & the gang...

    Tom - you're lucky to live in a quiet location, but I started listening to LW broadcasts from Europe while living in a 6 story apartment building just off Commonwealth Ave in Boston - back in 1980. I used a large (2') ferrite loop w/ preamp into my Kenwood R-1000. The loop had deep nulls and I was able to null out all the noise from dimmers, flourescent lights etc and copy the LW staions quite clearly. The loop was very high-Q and that helped in rejecting overlaod caused by nearby AM BC transmitters. With the right combination of antenna and receiver you should hear them just as well in Toronto.

73 Warren K2ORS/WD2XGJ

[Warren]

Hello the board,


   I highly recommend the RSGB book "The Low Frequency Experimenter’s Handbook"  by my good friend Peter Dodd, G3LDO for tons of practical details on LF work. It's available from the ARRL (probably from RAC as well). Also on the web, Dave Pick's page:
                           www.wireless.org.uk
                            is very good.
73 Warren K2ORS/WD2XGJ

[Warren]

ok warren...well,receiver is a ts950sd,

  Tim,
      Eureka! After some digging and a post to the LF reflectors, I came up with the following from no less than the estimable Alberto Di Bene I2PHD:
"And it was then that I had a great disillusion... while the 950 performed flawlessly under any other aspect, its sensitivity on the LF band was nothing to be compared with that of the 850. Plainly said, it was deaf as a doorknob on this frequency..."
     Alberto has posted a mod to improve the LF performance of the 950 on the mods.dk site:
http://mods.dk/index.php?ModelId=542&RadioRec=kenwood
(this site requires free registration OR you can Google "TD 950 LF mod" and look at the cached article from the mods.dk site. If you have trouble with the site, I can get it off the web and send it to you.)

Alberto's mod is  entitled "New ears to the TS-950sdx". It involves replacing a transformer labeled "L3" in the TS950sd with a MiniCircuits transformer.

  After changing the transformer Alberto reports:
"But, SUCCESS ! This time the 950 was alive and sensitive as a young girl in springtime ! I checked both in the 10-meter band and at LF, and in both bands the radio performed well. On the 28 MHz I compared it using an A/B switch with another transceiver I have, and on LF I was able again to listen to the 77.5 kHz time signal from DCF77 and to hear the RTTY-like signal around 43 kHz. From a purely subjective point of view, the increase in sensitivity on the LF band can be deemed not less than at least 10 dB."

   So you need to do some work on the 950 (or else use an external pre-amp) to get good sensitivity on LF.
 73 Warren K2ORS/WD2XGJ

 
   

[Tom WA3KLR]

Warren, the passive matching I was referring to would be put at the base of the antenna.  I have 2 e-field probe amplifiers here that I used to use portable for listening to lowfer beacons.  They can only tolerate a 3 foot maximum of antenna.

Frank, I did use a function generator (line powered) to test receiver sensitivity after replacing the 1st mixer.  I found that I had to isolate the R-7 receiver by running it on a 12 Volt gel-cell so that the stick attenuator did not have a ground leakage path.  I could hear 0.2 uV at 10 kHz.

[Warren]

Tom,

  O.K. on the passive matching at the antenna, it's usually very worthwhile to match the antenna to the rx on LF.

  For Tim VE6PG,
    The TS950sd mods are on Alberto's web page:
http://www.qsl.net/i2phd/TS950/change.html

73 Warren K2ORS/WD2XGJ

[WA1GFZ]

I have found low frequency EMI receivers like to operate off an isolation transformer to reduce ambient noise.
Tom, .2 uv is very good at 10 khz. Do you have the IF and RF ports swapped to get that kind of performance?

[Warren]

I have found low frequency EMI receivers like to operate off an isolation transformer to reduce ambient noise.
Tom, .2 uv is very good at 10 khz. Do you have the IF and RF ports swapped to get that kind of performance?

It's very helpful to isolate the utility ground and your antennas ground system as the utility brings in a lot of noise and trash. A simple toroidal transformer can be used. See the following reference on the LWCA web page:
http://www.lwca.org/library/articles/wa4ghk/gnd_isol.htm

73 Warren K2ORS/WD2XGJ

[Tom WA3KLR]

Frank,

Yes, in the Drake design of the Up-Converter board, the mixer's port assignments for the IF and RF have been swapped, yielding more LO-IF isolation.  The Mini-Circuits part appears to have much better overall performance than the old Vari-L part did.

Many years ago, in the late 1970's when I bought the new receiver, I did some mod. work on the PLL - loop filter, fine tune varactor bias point, added shielded cables to 500 kHz. reference clock routing, etc.  My LO spectrum may be a little cleaner than stock R-7's.  My goal at the time was to greatly reduce the bird heard when tuned to the marine frequency of 500 kHz.  My goal was achieved and the reference sideband spurs at LO +/- 500 kHz. were greatly reduced also.

[Tom WA3KLR]

What I consider to be amazing is the strength of the FSK signal on 24 kHz.  It is about S-8 1/2 on my R-7 which is about 170 microvolts at this frequency.  With the efficiency of my 75 meter 1/2 wave dipole at this frequency and the receiver mismatch, imagine the field strength the military is radiating!

[Warren]

What I consider to be amazing is the strength of the FSK signal on 24 kHz.  It is about S-8 1/2 on my R-7 which is about 170 microvolts at this frequency.  With the efficiency of my 75 meter 1/2 wave dipole at this frequency and the receiver mismatch, imagine the field strength the military is radiating!

Tom,
     That is NAA in Cutler, Maine. Running 2 Megawatts into a top loaded vertical supported by 27 1000' towers. The antenna array is clearly visible on satellite photos! I will dig up some links and send them to you when I get my laptop fixed.

73 Warren K2ORS/WD2XGJ

[ve6pg]

..the only decent receiver i have,is acting up...telephone line voltmeter...sk..

[AB3L]

I went to the Google main site and clicked on "More" then "Maps", did a search for Cutler, Maine with a "satellite" view. Is the location you are talking about the bright green finger of land jutting out into the water? Everything else shows in dark green.

If so, it is a huge chunk of ground!


After a closer look that must be it. I see pronounced black dots in the picture and then a trailing long thin shadow above each dot.(building and tower) Looks like the satellite took the picture in the morning by the angle of the shadows. The light green color of the land might mean that they have been using a de-foliant?? Or the RF is killing everything?........ouch

[Warren]

I went to the Google main site and clicked on "More" then "Maps", did a search for Cutler, Maine with a "satellite" view. Is the location you are talking about the bright green finger of land jutting out into the water? Everything else shows in dark green.

If so, it is a huge chunk of ground!


After a closer look that must be it. I see pronounced black dots in the picture and then a trailing long thin shadow above each dot.(building and tower) Looks like the satellite took the picture in the morning by the angle of the shadows. The light green color of the land might mean that they have been using a de-foliant?? Or the RF is killing everything?........ouch

    I believe you've found it! I think the light green color is grass as opposed to the darker green (forest) further inland.
Check out the following web page for ground based photo of NAA and other vlf installations:
http://members.aol.com/trekkspill/VLF.html
73 Warren K2ORS/WD2XGJ

[Warren]

..the only decent receiver i have,is acting up...telephone line voltmeter...sk..

Hi Tim,
   Hope you get the selective level meter going soon I also have a couple of HP-3586C selective level meters that I use as vlf-lf receivers (and also for measuring levels and as a freq. counter).
   Your TS-950 only needs one rf transformer to be changed out to make it a hot LF receiver, shouldn't be a big deal to do.

73 & GL
Warren K2ORS/WD2XGJ