Some people on this board have complained of mediocre signal strength on KCMD. Today, while driving westward, into downtown Portland, I noted that at times there was quite a bit of interference from traffic signals, despite the towers being visible. At my home location in Hillsboro, about 11 miles from the 970 transmitter site, its signal seems about as strong as that of KPDQ-AM, which is 10 miles away. Unfortunately, I do not have any really accurate way to compare the signal strengths of the two stations. Where is the 970 signal going?

I tried looking at the nighttime patterns of both stations. KCMD should be putting a noticeably stronger signal than KPDQ-AM into the Hillsboro area:

KPDQ Night Signal
KCMD Night Signal

KCMD has always had a weak signal, even back in the days of KOIN. I remember as a kid, watching the S meter at 10 bd droping to 5 db then back up at various times during the day. I thought there must be a problem at that time.
It does seem to be worse in recent times though. You used to be able to hear 970 fairly decent when traveling to Salem, now it gets lost before Woodburn. There are dead spots in Beaverton as well where you can see the towers but the signal gets lost. 160th & TV Highway is one spot.
a 5kW station on 970 should have a stronger signal.

There ant.ground system may be getting tired and old. It could also be the phasor or Ant. system, needs a tune-up. Last I heard the last new transmitter they had was in the mid-70's. And who knows how old the phasor is.

I don't get it. My user name tells you where I live,and both 800 and 970 are absolute blowtorches out my way

Last I noted (about a month ago) their transmitter was running around 3500 watts on the forward power meter. The common point impedance was about 45 ohms. Something in the antenna system is not right, but I would imagine the FM master panel is taking priority right now.

97 country used to blaze into Salem. We actually got stronger in the valley with the night pattern. This was in the early eighties. Too bad it has been neglected.

This station used to have about a 40 share! The signal must have been OK then.

The 970 transmitter, phasor, transmission lines, sampling lines, and antenna tuning units got replaced in 1997. Also, all the ground radials got reattached to copper strap around the base of the towers, and the ground screen got replaced.

The guys who put up the new digital TV tower hosed the ground system between and to the north of the towers, but it mostly got repaired.

Lately, they have been at low power during the day because of the tower work that Chris mentioned above.

970 is non-directional during the day, and has one null to the east, right down Interstate 84, pointed at Fargo, ND at night.

INS.F. KYA-1260 had/has(?) tower on a hill near candelstick park!KFRC-big610 tower was in Bezerkly near the bay.People I talked to thought Kfrc had better signal in outlying areas!!!where I was at they were about the same!!??

I am not familiar with San Francisco topography: Which of the two facilities (1260 or 610) had the towers at a higher elevation? What was your location, relative to the transmitter sites? Where were the other people that you talked to, relative to the transmitter sites?

That's the first time I ever heard anyone compare the signals of KFRC and KYA. 610 goes nearly to the Nevada line and is rock solid in Sacramento! 1260 barely makes it out of the bay!

OK--I see now. 1260 is on a hill; 610 is not. Both stations use 5 kW from a single tower.

610 contours
1260 contours

As expected, the 610 kHz has better groundwave coverage. By the way, 610 is now KEAR, and 1260 is now KSFB.

in 60's and 70's both were the great big top-40 competitors there.!I think 610 was top in Sacramento also!!or as Dr. Don Rose would say:Sacra-tomato!

does KXL-750 coulnt as a hilltop site??

I always wondered why he didn't call it, "Sacra-pimento"! (The spell-check took it!)

Hilltop AM's performance is often skewed by ground conductivity close in which often varies from the conductivity in the surrounding area once you are off the slopes of the hill. Erosional forces and composition of the "rocks" (iron ore vs. basalt, e.g.)over time can leave hilltops with a different conductivity resulting in RF propagation anomalies.

Having said that, DA's do drift for many reasons, some of which is caused by man made changes in the close in areas and some of which is capacitive changes in tower tuning caused by aging components.

In the local example, the amount of and location of the tall towers in the West Hills has changed a lot in the last few years.
Full proof of performance studies are expensive but it's the only way to know how a pattern is truly performing. Large re radiating structures get built after proofs and don't get detuned resulting in skewing of the pattern.

"does KXL-750 coulnt as a hilltop site?"
Your kidding, aren't you? What hill are they on? Are they 20 feet above the farm down the road?

After the Columbus Day storm knocked down the 3 towers for 1330 at the top of Mt. Scott, they wanted to move down off the hill to a vacant piece of land at the bottom of the hill on Foster Rd. They weren't allowed to because they still had to protect the monitoring station site north of there....even though it wasn't used anymore. So they had to put up new ones in the same location. They had trouble to tune the pattern correctly and keep it there. The big consultant came in from Texas and set it up, said it was correct, and left. They had trouble maintaining it and it never was very good at the time. Don't know how it is now.
I was told, but haven't verified, that the same person who set up the KOIN hilltop setup also did the same for 1330. He liked hilltops. Maybe even had something to do with 1410.

I believe KXL is on a plateau, overlooking Damascus.

Well, if you're looking at Royer Road south from Hwy 212, THAT goes up a hill! (Been a LONG time since I was in that neighborhood...)

How is KKPZ 1330 coverage since they are on the top of Mt. Scott?

Also, you have to realize 610 KEAR is located on a marsh (landfilled) right next to I-80 Freeway and the bay. The 1260 tower is located on top of Candlestick point right off US 101 freeway and adjacent to Candlestick Park, home of the SF 49ers.

They used to have a pretty decent signal from north of Longview to about Salem, where it ran into KLOO 1340.

the KYA1260 tower had a signsaying KYA about half way up,so it was kind of obvious what it waseven to non-technical people!very obvious from freeway 101 southbound when going to Candelstick park or to the COW Palace.nothing like that on Kzzfrc tower in Berzerkleythere wasa sign "KRE" on nearby buildding!!!???

Anything attached to a broadcast tower has to be licensed. So its a hassle to put signs on your towers or anything else non relevant for that matter.

Installing AM tower sites , directional or not, on hills is extremely 'Old School ". It has been considered automatically ' Very Lossy " for many many years now, for at least 50 I believe ! You dont find engineers recommending installations like this anymore.

As Andy indicated above, the ground conductivity which is related to the antenna ground plane itself can change radically in soil located in hilly areas from season to season or year to year depending upon rainfall or erosion characteristics, which is much more variable in sharply hilly areas, like Sylvan or Mt Scott. Perhaps not so critical where the KXL towers are located. You can have the best components , the best engineering and have a drifty antenna due to forces completly out of your control. Especially if you are operating a directional system !

That is why the 'wizards from Texas" came in and laid their hand on the Mt Scott and Sylvan sites and declared it 'healed', went back to the Lone Star state and sent them a bill for their services. They tuned it and beyond that couldnt do anything else about it.

Andy's answer indirectly confirmed something that I suspected: when an AM antenna system is built on a hilltop, extra variables are thrown in that compromise the accuracy of groundwave signal contour predictions from modeling algorithms, like that used by radio-locator. The hilltop AM site (as Andy points out) has ground conductivity "discontinuities" around it, and the antenna ground system is elevated above the rest of the earth's surface by some amount that may be significant compared to the wavelength.

Consistent ground conductivity and of course a marshy salty geology would be the most advantages environment for an AM vertical tower buried ground plane type antenna placement. I am not certain that the elevation above sea level or average terrain has much to do with the groundwave efficiency itself.

High ground conductivity places , like marshy and salty land, are not usually located on hilly mountain tops ! Maybe on hilly plateau tops.

One of the old timers I knew once, now long dead , told me once that the notion of hilltop vertical towers for Broadcast stations started back in the 20s and 30s when much of the engineering was being done on other ' Short Wave ' broadcast and or governement service stations. Such vertical tower installations built to operate on a frequency of say 3.0 to 9.0 MHZ had an advantage being on hilltops because of the groundwave/skywave ratio. You could cover local terrain fairly respectably by groundwave and then with the higher elevation you had a hotter chance at DXing your signal better with the skywave characteristics at those frequencies.

Those engineering practises and that specific notion followed to the long wave/ medium wave broadcast bands for some years after.

KFRC had a big signal advantage being on 610, and being right next to the bay. Plus, KYA had to drop to 1 kW at night.

About 1990, KYA's tower blew over the same night that one of KCBS's blew over. At the 98.5 transmitter site in Sacramento that night, the wind was strong enough for me to lean on it. Hadn't been able to do that since I was a little kid. You can see a picture of KYA's original tower at http://www.sfradiomuseum.com/schneider/kya_site.shtml .

Good pictures of the KFRC transmitter site at http://earl.cc/jim/kfrc/kfrc/index.htm .

You can hang pretty much anything you want on the tower of a non-directional AM station as long as it doesn't change the strength of the signal.

Remember "Fred Rated?" He said that from the toes of Sacred Men came Sacramento.

Kent,
Image 280 on the KFRC site states:
"Outside view. KEX is near the parking lot, KFRC is in the back near the open side door."

That would be a good trick, would it not???

sometimes it wasSasSacraPimento!sometimes it was Sacrato(mah)/(may)to!!!works either way!!!