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Longwave nighttime propagation questions

J

jim-satx

While staying up way too late chasing distant NDBs, I've been wondering why nighttime skip on the longwave band is so short-lived. It doesn't seem to get really good until a few hours before midnight and then only lasts for a few hours after midnight. Unlike the AM band - at least in my location - there doesn't seem to be much, if any, sunset or sunrise enhancement. Do the E and F layers need to be more deeply ionized for skip to happen at those lower frequencies?

On a related note, what are the odds of me receiving one of the remaining European longwave broadcasters on a portable like a Sony 7600 from my location in San Antonio? Do I really need to be a lot further northeast or on the eastern seaboard?

Thanks.
 
Your best shots would be on the channels below the NDB band which begins just above 190 KHz.
Europe and Africa from your sunset to their sunrise and Asia between their sunset and your sunrise.
Russians are all or mostly off the air, and Mongolians are all 2KHz above the standard channels.
All the longwave broadcasters are dropping like flies.
The ionosphere becomes progressively less reflective at night as one goes below the MUF at about ten megahertz, however fading becomes slow to nonexistent. When I heard France a few times on 162, they would fade in shortly after our sunset, remain constant, and fade out at sunrise in France.
 
Hello,
Your best chances in my experience would be Medi-1 in
Tangiers on 171 khz and maybe France on 162 khz.
Try for them at or just after sunset,taking advantage of
greyline propagation.
You will find fading (qsb) to be extremely slow compared
to MW.
Stay portable to find the best "hottest" low noise place
you can...run with the bfo on to listen for the carrier
(exalted mode).
If you wish to get serious then consider running a Palomar
vlf up-converter ahead of your 7600,it will output on 4 mhz
where your radio is more sensitive.
Avoid the Heathkit converters,they're not as sensitive.
Also-if you want to really get serious-look on Youtube
for the Hula Hoop Longwave Loop antenna video and
fabricate one...loops let you null out the Infernal Noise
and work well ahead of the Palomar.
Unlike HF,LW takes a bit more effort...good luck.
 
If you would prefer to buy rather than build,here is an
excellent choice:http://amradioantennas.com/longwave_antennas.htm
I have bought from Paul and can vouch both for him and
his product.
Expect it to be some less than $100 delivered but you will
never need another one.
Be sure to specify-at no extra cost-the 150-500 khz
version.
This is a passive,loose coupled loop for receivers with a
built in ferrite bar antenna.
 
rtc said:
If you would prefer to buy rather than build,here is an
excellent choice:http://amradioantennas.com/longwave_antennas.htm
I have bought from Paul and can vouch both for him and
his product.
Expect it to be some less than $100 delivered but you will
never need another one.
Be sure to specify-at no extra cost-the 150-500 khz
version.
This is a passive,loose coupled loop for receivers with a
built in ferrite bar antenna.
Click to expand...

Thanks, RTC. I really appreciate all of the info. I would prefer to buy rather than build, so the PK's Loop LW antenna looks like something I really want to get. I've always wished that my Terk loop could go down below 530 kHz, and here is something that does just that.

Are you aware of any portables still made today besides the Sony 7600 that are decent for LW DXing without modification? The closest I've found is a Tecsun PL-660, but it can't really touch the Sony.
 
I use several receivers including a Sony 7600g but like the Kaito 1103.
If you decide for an 1103 get the "old model" with "dual conversion" under the speaker;
the "new model" with "digital" under the speaker is definitely not recommended:

http://swling.com/blog/2015/11/the-new-degen-de1103-dsp-first-impressions-review/

Was talking to Paul at PK Loops yesterday about a LW version of his 20 inch loop.
He said "There's not sufficient difference (signal gain) in upgrading from 16" to 20" with
the HDLTAM, and freight to USA makes it $$$" (total cost delivered would be $207 us).
Also,"In regards to performance of the larger (20 inch) LW loops, the main difference is the
tuning Q, it is substantially higher making the tuning (peak) very sharp.

As you can see Paul is quite honest,not just trying to sell loops.

If you decide to build a hula-loop or try a converter etc please email me,will be happy
to send winding data,pix,etc.
 
To further clarify re the 1103:
I use it with great success behind the VLF converter.
On LW it suffers from MW overload (i.e. AM feedthru) because the
1103 is such a hot receiver,very sensitive,as is your PL-660.
So your 7600 is probably the best choice for LW listening
with, say, a PK Loop.
 
One final note...somehow I got the notion that the
"standard" PK Loop was 16 inches in diameter.
Measured mine,it's 14 inches,about what your Terk
is.
Nevertheless tested it on NDB HUA 286 (my test
beacon) today and could copy it,93 miles and 25
watts away at Redstone Arsenel in Huntsville.
 
Let me know if any of you hear a super strong NDB from Bimini, Bahamas, South Island.
ZBB on 396 KHz is sooo much stronger than anything in Miami,
and I understand that they cover a large chunk of the Caribbean.

BTW...in case you are unaware, all NDBs have a common audio tone of 1020 Hz.
It was chosen because no two, or maybe three, musical notes will mix and create that frequency.
 
I think a piano or other stringed instrument, either by being out of tune or because of inharmonicity, could create that frequency under the right circumstances.
 
pianoplayer88key said:
I think a piano or other stringed instrument, either by being out of tune or because of inharmonicity, could create that frequency under the right circumstances.
Click to expand...
A trombone can theoretically produce an infinite number of pitches,
but 1020 is not normally produced in western music.

rtc...
I no longer have any equipment to check for ZBB,
but I could not find their antenna on Google Maps,
so they might just be..."Only On The History Channel".
 
Last edited:
ai4i said:
Let me know if any of you hear a super strong NDB from Bimini, Bahamas, South Island.
ZBB on 396 KHz is sooo much stronger than anything in Miami,
and I understand that they cover a large chunk of the Caribbean.

BTW...in case you are unaware, all NDBs have a common audio tone of 1020 Hz.
It was chosen because no two, or maybe three, musical notes will mix and create that frequency.
Click to expand...

try DDP 389 from Puerto Rico or CBC 415 from Brac Cayman
 
I haven't purchased a PK loop antenna or up-converter yet, but I did pick up a Sony ICF-2010 on eBay the other day. It's turning out to be even more sensitive on LW than my Sony 7600GR. So far I've logged five new Texas NDBs that the 7600 can't hear.

The 2010 couples very well with a Terk loop on AM, so I imagine it will do great with a PK LW loop antenna.
 
Used to have a 2010 but never used it with a loop...but if it does well with the Terk
that's a good indicator.

Your 7600 may run with the 2010 if you use a 14 inch PK with it.

Paul makes a more expensive 20 inch version,the HDXLTAM.

I have found it furnishes about one third more gain than the
standard 14 inch version and compares favorably with the homebrew
36 inch hula-loop.

Due to fabrication differences the 20 inch covers 160-500 khz (be sure to
specify 160-500) but since there are no LW b/c stations on 153 khz
anymore that's not a problem.

As for costs,the 20 inch is around $212 delivered,depending on your
choice of shipping...this was by Priority Mail.

The standard 14 inch is about $100 delivered,again depending on your
shipping choice...be sure to specify 150-500 khz for the 14 inch version btw.

Here is a link for your convenience:
http://amradioantennas.com/catalogue.htm
GL and 73...
 
Last edited:
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