(1) While driving past KOAC's Granger transmitter site I noticed a shortwave antenna at the side of the building - any ideas? An old WWV receive antenna or perhaps ham radio setup?

(2) A few years ago there were rumors that OPB wanted to unload AM550 - why ? It's a killer signal. It blankets the Willamette Valley and at night does wonders on the Oregon Coast. It would be shortsighted. (As you know KOAC is closing down its Corvallis studios if it has not done so already.)

I seriously doubt they would want to get rid of the signal. I can get it up here in Northern Oregon over 130 miles away which makes me wonder why the signal is so bad going south since they have so much trouble picking it up in Eugene. The point is, if they don't have those two AM signals, they have NO coverage in the valley. Maybe they thought about selling it but thought better.

It could be the mineral deposits around Eugene.

KOAC's signal isn't "bad" to the south, but is just a little short of "city grade" in Eugene. Given all the new sources of AM interference like LED traffic lights, various computer devices, etc., a top notch signal is a must for full-market coverage. After all, Eugene-Springfield is Oregon's second largest radio market, therefore OPB has wanted a stronger presence here for years.

I have been able to pick it up all over Vancouver, day and night. It usually isn't very loud (static in the background; also fades in and out occasionally) but it is still listenable.

Oddly enough, on the Superadio, I sometimes can hear Navtex data splattering over onto 550 if I listen really, *really* late at night and the K-Index is low enough! This is when its bandwidth is switched into "Narrow" mode, by the way. (I think its MW tuner needs to be realigned.....haven't gotten around to doing that yet.......)

What is Navtex data?

Dan, from the web:
What is Navtex?

"Navtex" is an informational data broadcast system for shipping; anything from weather warnings, missing or overdue boats, ice warnings, and anything which may be considered a hazard to shipping.

The transmissions are from fairly powerful stations dotted around the coastline, with largely overlapping coverage. The main transmission frequency is 518kHz, just off the end of the AM broadcast band, with a secondary LF frequency of 490kHz less used and for 'local language' or secondary messages; Canadian stations for example use 490kHz for French. Additionally, there is an HF channel at 4209.5kHz. The signals themselves are 170Hz Frequency Shift Keying (FSK) centered on the nominal frequency (i.e. one carrier is 85Hz below, the other 85Hz above) and at a rate of 100 bps. Data is sent 'Forward Error Corrected' (FEC), which means the same characters are sent twice, one a few characters before its repeat, interleaved with subsequent data. Tuned in with a receiver set to SSB, it sounds like a high-speed 'burbling'.
Tom

Sure sounds like it.

I am using a Superadio III (....I know, I know.....) that I got last Spring at Goodwill. Even when it is switched into "Narrow" mode the MW tuner in that box is still really
W I D E . . . .

Dan--also see http://frisnit.com/navtex/index.php

(And one of these weekends I'm gonna pack up the laptop and the Grundig, fill up the gas tank, and high-tail it to Astoria. Maybe I'll be able to log more, being *that close* to the coast...prime Navtex territory. ;o)

Thanks Tom & Moto! Interesting. The low frequency, I guess, to carry across the sea better. I'll have to check out the buzz next time at the beach. Thanks!

I have heard signals on shortwave that sounded like high speed RTTY; perhaps what I was hearing was the HF broadcast of Navtex. I will have to listen for 518 kHz tonight. I think that I have heard this signal in the past, but I didn't know what it was. I have also heard some beacons between 510 and 520 kHz.

Nice schedule of Navtex transmissions here:

http://www.dxinfocentre.com/navtex.htm#XII-A

The transmission from Astoria is booming in ( S-4 to S-5 ) right now.

Though limited to about 200 miles by day, at night a hundred watts would travel a thousand miles or more on 500kHz. Coast stations could be heard across oceans.

MF is the most reliable band in some situations, like up in Alaska where the MUF for under-500 mile hops could fall below 2mHz in winter at night.

The marine MF CW band goes back a century (to the Titanic and spark-gap), and I guess NAVTEX is all that's left of it today, with CW watches having almost completely ended over the past decade.

>

Are we transmitting a little bit of dead air?

........



--ot necessarily *along* the coast as much as somewhat *inland*! But then again, I have been able to recei--









--s far as I can in the PDX area. (I live in Vancouver.) But on the other hand, Frisnit put an "invert" function into his software, so if i *do* end up tuning into the wrong sideba--






--ensibly, it works decently to that effect. At least I think so, anyways. (Y. R. M. V.!!)

(I think my @#$%ing Powerside must be going out. Looks like I shall ring Leonard sometime soon and express my "wrath"..... ;o)

I think KOAC 550 should raise their power to 50kw Day and Night so I can hear them very good in the Portland area. Also, I think they should break away from their FM station and create an all news station (BBC World Service) similar to NWPR or Jefferson Public Radio.

550 is a good ststion to test out a radio with!good sensitive radios can pick up koac550 well in portlaand daytime.poor radios can't!!!!
any other good test signals??

"any other good test signals?"

Try:
570-Seattle, 590-Eugene, 660-Junction City, 710-Seattle, 720-Sweet Home, 770-Seattle, 940-Woodburn, 1220-Salem, 1260-McMinnville*, 1280-Eugene, 1390-Salem, 1430-Keizer, 1590-Seattle.

In the Portland Area, during the daytime hours in a fairly quiet location, a decent radio *should* receive these stations.

Update, Next tier (somewhat weaker/more difficult):
840-Eugene, 920-Lebanon, 950-Seattle, 1000-Seattle, 1090-Seattle, 1120-Eugene*, 1240-Corvallis.

*may be weaker on the East side of town.

With regards to the Navtex discussion above, I have been trying to listen for the Navtex signals at 490, 518, and 4209.5 kHz with no success. I only hear a weak signal around 517 kHz that sounds like a beacon.

I Have heard plenty of them on 518, It looks like no nearby transmissions are scheduled for this hour (0600 UT), however. A BFO is necessary to hear them.

Ooops! I didn't realize that these transmitters send out a message and then drop the carrier; I had thought that they transmit the messages over and over. I had been using a BFO, and I expected to hear the "burbling" sound described above. Typically, how long does a Navtex transmission last?

Another good test signal is the PDX Airport TIS at 530 KHz--that is,if you're not in North or Northeast Portland

"how long does a Navtex transmission last?"

Usually about 10-20 minutes. this leaves a little "dead air" between scheduled transmissions. I heard a very weak one last night that started at midnight and continued for about 20 minutes. I have no idea where the signal was coming from. Try about 6:30 in the evening, Astoria *should* be very solid.

About how many watts do Navtex transmitters generally put out?

(I assume it would be somewhere in the order of "a lot"--especially since I logged Alaska here a couple weeks back.....)

Edit add: Okay, it took me a while (had to dig out my other hard drive and set it up) but I posted my Navtex logs; they can be perused at ../2186/371727.html"#f7f7f7" align=left> Author: Alfredo_t
Monday, August 04, 2008 - 3:21 pm

I have been able to pull in the 530 kHz Portland Airport TIS station from Hillsboro at all times of the day. On some nights when the propagation is really good, other TIS stations dominate the 530 kHz frequency. I can also get a very weak signal on 1610 kHz from the TIS transmitter on Timber Rd.; this is the station that runs an announcement about the Tilamook Burn.

Both of these loggings were made using a homebuilt outdoor loop antenna and a heavily modified Technics SA-929.

Occasionally on 530, when rotating the radio somewhat to the northeast, I can receive a TIS from the Washington State DOT; a computer-generated female voice on about a highway construction project along I5. I can't really make out the entire station's call announcement, but I have heard the computer-generated male voice saying "SIX-NINETY" in there.

That's pretty much all I know about it.

Of course, rotating the radio directly south I can get WPHD710 (the TIS station from PDX) loud and clear at the apartment. (At home near EHS it's not very loud and clear, but it's there.)

I haven't been able to pick up anything TIS-like on 1610, via DX.

Ok...I'm hearing "morse code spirts" on KPAM 860 AM noonish today...around 2 seconds every 10-15 minutes or so...what gives?

The Morse Code is from ABC Radio Network...

They have been trying to transition their affilites over to a new satellite receiver... one with better audio fidelity etc...

to alert those station who have not converted they decided to transmit the morse code for X D S,,, (the name of the new Sat Receiver) under the audio of the Hannity show today to show affiliates that they are past the 7/15/08 deadline to switch over to the new system.

Thus ABCRN could weed out those who had not switched by identifying those who called up when they heard the Morse Code.

Here's a listing from Recnet:

530 - WPHG710 - PORTLAND OR
530 - WPVS690 - Ridgefield WA
530 - WPXM791 - Rainier OR
530 - WPXY406 - Rainier OR
540 - WQBQ728 - Castle Rock WA
1610 - KNFG751 - TOUTLE WA
1610 - WPED431 - FOREST GROVE OR
1610 - WPWK548 - Forest Grove OR
1610 - WPZB638 - Camas WA
1610 - WPZY782 - Camas WA
1610 - WQAD504 - Beaverton OR
1610 - WQBZ700 - Gresham OR
1610 - WQCA312 - Gresham OR
1610 - WQCI718 - Beaverton OR
1629 - KNFA718 - PORTLAND OR
1670 - WQAS782 - Camas WA
1670 - WQDG929 - Camas WA

>>The Morse Code is from ABC Radio Network

you'd think they would have a better off air system/notification than that...annoying...possible tune out factor.

Navtex
Motozak2 said "Enjoy......"

Yesterday I downloaded the little decoder program from the frisnit link above, and plugged the audio from my ICOM (tuned to 518 KHz, CW Mode) into a windows XP computer. I let it run overnight, and found messages from the following stations this morning:

W....Astoria
O....Honolulu
C....S.F.
J....Kodiak
X....Kodiak (perhaps used because Adak is out of service)
Q....Long Beach
D....Prince Rupert.
G....New Orleans

Fun stuff, DX while you sleep!

maybe it would be a good idea to change the title of this thread since it no longer has anything to do with 550 KOAC.

Happens very easy here on pdxradio when you get a few radio geeks yakking...if KOAC where to go 25 or 50 kw they could have the best AM coverage in the NW.

What is interesting about the KOAC pattern is that it looks as if the entire pattern is just flipped around to switch from daytime to nighttime operation. Compare--
Day: http://www.radio-locator.com/cgi-bin/pat?call=KOAC&service=AM&status=L&hours=D
Night: http://www.radio-locator.com/cgi-bin/pat?call=KOAC&service=AM&status=L&hours=N

I can understand that at night, they might want to protect some inland stations on 550 and that is why they throw the signal toward the coast. But, why are they directional during the day? The only other 550 stations within 500 miles are KARI in Blaine, WA and CFJC in Kamloops, BC. If they threw a null to the north to protect these stations, maybe they could do 50 kW during the day.

There could be some protection to the Canadian clear on 540.

Navtex...

Jr_tech, here is a tip: if you can hear a really weak signal coming through and you can't get any readable text (i.e. garbage) disable the "Strict FEC decoding" function. It helps. I don't recommend doing this for stronger signals, but leaving it enabled all the time *could* prevent you from getting some really good, far-away DX if the conditions are just right.

I just took the "JR" groundwave DX challenge. My location is in Hillsboro, so some stations that might be moderately difficult to hear in Gresham are easy to hear from here. I did it on a modified Technics SA-929 with an outdoor loop antenna. Two different bandwidths were tried: narrow is achieved with a ceramic ladder filter (not stock for the SA-929) that yields roughly a 3kHz audio response and sharp skirts. The wide bandwidth is achieved with an IF strip board that I built with IF transformers; this yields a response close to the AMAX standard.

Here are the results for the "tier 1" signals--

570 (Seattle) receivable with wide or narrow with a slight bit of impulse noise

590 (Eugene) receivable in wide or narrow, with little interference

660 (Eugene) receivable in wide or narrow

710 (Seattle) receivable in narrow only

720 (Sweet Home) receivable in wide or narrow

770 (Seattle) receivable in wide or narrow

940 (Woodburn) receivable in wide or narrow; I wouldn't call this DX

1220 (Salem) receivable in wide or narrow; this signal is also reasonably strong

1260 (McMinnville) receivable in wide or narrow; this one is pretty easy

1280 (Eugene) receivable in narrow only with strong electrical interference from a switching power supply

1390 (Salem) receivable in narrow only; loop must be tuned carefully to minimize receiver front-end overload from KUIK

1430 (Keizer) receivable in wide or narrow

1590 (Seattle) No! Nulling out KMBD leaves some electrical noise and KOHI sideband splash.


Here are the results for the "tier 2" signals --

840 (Eugene) receivable in narrow only. On this frequency, I can hear two stations, depending on which way I turn the loop. N-S brings in KKNX, with some co-channel interference; E-W brings in KSWB. KSWB has a stronger signal here.

920 (Lebanon) receivable in narrow only; there is a lot of sideband splash from KTRO and some local heterodynes

950 (Seattle) receivable in narrow only; there is a lot of sideband splash from KWBY and some local heterodynes

1000 (Seattle) receivable in narrow only; there is background hiss due to this being a weak signal, but otherwise, it is clear

1090 (Seattle) receivable in narrow only; there is a lot of sideband splash from KFXX

1120 (Eugene) receivable in wide or narrow; there is strong interference from a power supply or similar device

1240 (Corvallis) receivable in wide or narrow; there is a little bit of co-channel interference

Summary: I can receive all of the stations except for 1590 from Seattle. I could improve the reception slightly if I were to find the source of the ground loop that is picking up the locally-generated power supply interference. At the moment, I don't know where this power supply is located.

OMG! how could I forget KMBD, of course that is what the daytime signal on 1590 is! Sorry about that.

My favorite difficult daytime DX is KBRD (680), 250 Watts in Lacey WA. This station plays "really oldies" some sound as if they may be from wax cylinders. Very weak signal and co-channel interference from KNBR.

I just tried 680. I hear what sounds like two very weak signals with one playing music. The signal is too noisy for me to be able to make out anything, and the co-channel interference is pretty strong.

The other might be
KOMW OMAK, WA 5000 watts Daytime ONLY

Possibly it may be in there too, but I hear mostly KBRD and KNBR. Both KNBR and KGO can be heard (very weak) during the daytime from my location.

Daytime DXing...I love it.

>>1220 (Salem) receivable in wide or narrow; this signal is also reasonably strong

my old stomping grounds...keeping their facilities strong...just a 1kw 1990 vintage Gates One on a 140ft stick built in 2001 in NE Salem.

Without getting too far off topic, I have a physics nerd question about skywave propagation that is not often discussed in the radio books: When skywave propagation is very good, can the signal received via skywave be stronger than if one could get a clear line-of-sight path, of the same distance, to the transmitter? If so, is the phenomenon at work analogous to what one would experience if one were speaking in a very large room or a tunnel with walls that reflect the sound, compared to speaking in an open field, where there is nothing other than the ground to reflect the sound?

Example: last night, I was getting a monster signal from KGO. At times, it was stronger than that of KPDQ-AM, per the signal strength indicator on my DX-390. I found a signal strength calculator online ( http://www.daycounter.com/Calculators/Maximum-Field-Strength-Calculator.phtml ) that tells you the field strength that can be expected for a given transmitter power, antenna gain, and distance from the transmitting antenna. I entered the distance from Hillsboro to San Francisco (862 km), left the antenna gain at the default value of 2.15 dBi, and guessed that KGO is sending about 120 kW ERP in our direction, due to its directional antenna system. The field strength value that comes back is 2.8 mV/meter, which seems kind of weak. If I do the same calculation on KPDQ-AM, which is 16 km from my location, the predicted field strength is 9.8 mV/meter.

I just checked tonight, and measure about the same level for each (about 25-30 over S-9 on my ICOM) with my outside loop rotated and tuned for each signal.

If this post is irrelevant, just yank it.

To Broadway: In 1979, I relocated from Portland to Salem. When I was commuting during the transitional month, KCCS am-1220 would drown out KEX am-1190 as I got near to Salem. It should be remembered that my 1976 Chevette had the antenna embedded in the windshield glass. Perhaps that was an antidote to disco?

The antenna on the side of the building is probably leftover from some kind of early communications link from the Grainger transmitter site to the studios in Covell Hall at the OSU-OSC-OAC campus. The station was not remote controlled under the regulations of the 50s and 60s and required a first phone at Grainger on duty any time the station was on the air, so it was probably set up to talk back and forth to campus...or maybe to a mobile unit out doing field strength measurements. A couple of my friends with first phones babysat the place on a work-study arrangement...this was in the late 60's and early 70's. One told me of the great broadcast DXing he was able to do by putting an AM radio near one of the RF chokes that they ran the tower light power through.

The wire attached to the side of the tower is the RF feed wire. They are shunt fed antennas. Not very popular anymore and not allowed on new builds and very rare on directional arrays. KBPS is also shunt fed.

Photos and a description of the KOAC antenna system can be found here: http://www.fybush.com/sites/2007/site-070223.html Scroll about half way down the page, and you will see the towers with the shunt feed system.