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What happened to KNBR yesterday?

A

awj223

Guest
Yesterday, KNBR 680 dropped off the air during the Giants pregame show. KNBR tweeted http://twitter.com/#!/knbr that they were "currently experiencing technical difficulties". I don't think it was a case of the feed from the studio being interrupted; I don't think the transmitter was even sending out a carrier, because I heard two stations apparently on 680 fighting for dominance for about 2 minutes of the total 30-40 minute outage (very surprising, as I would think that nobody would be allowed on that frequency anywhere near the Bay Area).

Today, while driving along N 1st Street in San Jose, I noticed that the nearby light rail line appeared to be interfering with 50,000 watt KNBR. Normally, KNBR is strong enough in that area that the light rail interference can't be heard. What's going on?
 
awj223 said:
Yesterday, KNBR 680 dropped off the air during the Giants pregame show. KNBR tweeted http://twitter.com/#!/knbr that they were "currently experiencing technical difficulties". I don't think it was a case of the feed from the studio being interrupted; I don't think the transmitter was even sending out a carrier, because I heard two stations apparently on 680 fighting for dominance for about 2 minutes of the total 30-40 minute outage (very surprising, as I would think that nobody would be allowed on that frequency anywhere near the Bay Area).

Today, while driving along N 1st Street in San Jose, I noticed that the nearby light rail line appeared to be interfering with 50,000 watt KNBR. Normally, KNBR is strong enough in that area that the light rail interference can't be heard. What's going on?
Click to expand...
At one time I worked at KNBR, and from time to time the Engineering staff would switch to the backup (less powerful) transmitter for maintenance. It could be the signal is diminished on the backup transmitter. As far as the LRV noise is concerned, the fact you are sitting beneath the electric lines relative to the location of the KNBR transmitter, it is nearly expected that the signal would be overwhelmed by the much closer source. I'm sure one of our Bay Area broadcast engineers could provide a more concise response though.

Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
 
sloux said:
At one time I worked at KNBR, and from time to time the Engineering staff would switch to the backup (less powerful) transmitter for maintenance. It could be the signal is diminished on the backup transmitter. As far as the LRV noise is concerned, the fact you are sitting beneath the electric lines relative to the location of the KNBR transmitter, it is nearly expected that the signal would be overwhelmed by the much closer source. I'm sure one of our Bay Area broadcast engineers could provide a more concise response though.

Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
Click to expand...

Except that I drive this route several times a week, often listening to Giants games on 680, and have NEVER once heard the interference in this location except for today. It's not a case of the interference source being much closer, it's just comparing my experience during all of the past times I've driven through that location with today. And I doubt Engineering would take the station off the air for 30-40 minutes during the Giants pregame to switch to the backup. If KNBR's running with reduced power from the backup transmitter, I suspect that something in the primary transmitter blew up yesterday.
 
sloux said:
Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
Click to expand...

680 was a 1-B clear before reclassification. There are oodles of stations on 680

KNBR San Francisco
WCNN North Atlanta
WRKO Boston
KBRD Lacey
WGES St. Petersburg
WCBM Baltimore
WISR Butler
KKYX San Antonio
WAPA San Juan
WPTF Raleigh
WMFS Memphis
WHBE Newburg
WKAZ Charleston
WINR Binghamton
WOGO Hallie
KOMW Omak
KKGR East Helena
WDBC Escanaba
KFEQ St. Joseph
WCTT Corbin
KBRW Barrow
KWKA Clovis
 
awj223 said:
Today, while driving along N 1st Street in San Jose, I noticed that the nearby light rail line appeared to be interfering with 50,000 watt KNBR. Normally, KNBR is strong enough in that area that the light rail interference can't be heard. What's going on?
Click to expand...

Today they were probably running at lower power and thus the light rail noise was strong enough to be heard on your radio over KNBR.
 
DavidEduardo said:
sloux said:
Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
Click to expand...

680 was a 1-B clear before reclassification. There are oodles of stations on 680

KNBR San Francisco
WCNN North Atlanta
WRKO Boston
KBRD Lacey
WGES St. Petersburg
WCBM Baltimore
WISR Butler
KKYX San Antonio
WAPA San Juan
WPTF Raleigh
WMFS Memphis
WHBE Newburg
WKAZ Charleston
WINR Binghamton
WOGO Hallie
KOMW Omak
KKGR East Helena
WDBC Escanaba
KFEQ St. Joseph
WCTT Corbin
KBRW Barrow
KWKA Clovis
Click to expand...
The strange thing is I heard TWO of these stations at nearly MIDDAY (about 12:20pm-1pm local time in the Bay Area). Is it possible to get an opening for skip signal in the middle of the day for 1-2 minutes like that?
 
Stranger yet is that, during the outage on Sunday, they never switched the 680 programming over to 1050, which was running generic ESPN network stuff.

I'm sure there was a very sound decision behind not doing it, but it seemed like the smart thing to do.
 
If you're hearing other stations on 680 when KNBR is off the air in the daytime in the city, my bet is it's spillover harmonics or whatever from other local AMs that you're catching off-frequency, either due to the type of radio in your car, or to factors such as electrical lines picking up some other strong AM signal in the area and splattering it onto 680, where you wouldn't have otherwise heard it with 50kw KNBR occupying that space.
 
Goldilocks94941 said:
If you're hearing other stations on 680 when KNBR is off the air in the daytime in the city, my bet is it's spillover harmonics or whatever from other local AMs that you're catching off-frequency, either due to the type of radio in your car, or to factors such as electrical lines picking up some other strong AM signal in the area and splattering it onto 680, where you wouldn't have otherwise heard it with 50kw KNBR occupying that space.
Click to expand...

To me it sounds like a poor antenna connection acting like a semiconductor and detecting (that's a technical word) the AM signal. This happens on my car radio when I'm near any AM transmitter. In fact the other day as I was listening to the Giants game in English I passed KIQI and heard the plays called in Spanish at the same time! There is no harmonic relationship between 680 and 1010, so it was likely a corroded antenna connection that detected the KIQI signal.

When KNBR is off the air there shouldn't be anything listenable in or around the Bay Area on 680, and a car radio should be selective enough to not pull in 670 (Boise) or 690 (Tijuana).
 
sloux said:
Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
Click to expand...

As has already been pointed out, there are plenty of stations on 680 in North America. Moreover, a significant percentage of the stations on 680 that were listed are 50 kW--at least during daylight hours. One that wasn't listed and is 50 kW-U is CFTR, which uses an eight-tower directional array day and night. Regardless, ALL AMs on 680 in North America protect KNBR day and night. AFAIK, KNBR is the only Class A station on 680 in North America.
 
DanStrassberg said:
sloux said:
Your musing about 680 KHZ being clear channel (now Class A) is correct. There are no other stations on that frequency in North America (excepting KBRW Barrow. Alaskan stations are treated separately).
Click to expand...

As has already been pointed out, there are plenty of stations on 680 in North America. Moreover, a significant percentage of the stations on 680 that were listed are 50 kW--at least during daylight hours. One that wasn't listed and is 50 kW-U is CFTR, which uses an eight-tower directional array day and night. Regardless, ALL AMs on 680 in North America protect KNBR day and night. AFAIK, KNBR is the only Class A station on 680 in North America.
Click to expand...

And, of course, there are a half-dozen stations in Mexico on 680, too. All, in theory, protect KNBR... generally by dropping power at night, something that careful observation proves to be infrequently done.
 
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