I found it strange that these stations appear to use the same towers. Maybe it's just an error on the FCC site for the tower locations, but that seems doubtful. Any engineer out there that can explain how this is possible? Thanks, Mike

The KPAM and KKAD transmitters are able to share the same towers by by using a system of filters called a diplexer. Some sites have three transmitters on one or more antennas with a triplexer.

Now, question to the readers: Which stations in Portland are diplexed?

They do use the same towers. Other tower sharing arrangements exist in Portland:

KXPD (1040) and KBNP (1410) share a tower in Oaks Park.
KPOJ (620) and KEX (1190) share towers in Clackamas.
KKPZ (1330) and KDZR (1640) share towers on Mt. Scott. 1640 uses just one of the three towers in the KKPZ directional antenna system.
KKSL (1290) and KGDD (1520) used to share towers in Clackamas. KKSL is now off the air.

I will let an engineer who has worked on an AM antenna diplexer explain how it works.

One more, think hard.

Bonus question: which stations are about to diplex?

Now I'm curious, what happened to KKSL? Was the license moved to another area, or did it just go dark?

KKSL 1290 moved to 1640 and sold it to Disney.

the fan 1080 and 910??

Disney owned KKSL at 1290 and KPBC at 1640. They bought them from Crawford which was a religious broadcaster. Anyone know the history of KKSL?

the old KLIQ.owned by dave jack.

The other pair of Portland stations that currently share a tower are:

KOOR (1010) and KSZN (1230). I had forgotten about those!

"Disney owned KKSL at 1290 and KPBC at 1640. They bought them from Crawford which was a religious broadcaster. Anyone know the history of KKSL?"

KKSL was formerly KLVS. Crawford got it in 1994 or early 95, I don't remember exactly. I started there in 95. Crawford won the lottery for expanded band 1640 and had to retire the 1290 signal after a certain time period. KKSL was "the Salt and Light". It was the original KPraise though before Crawford bought KUPL-AM 1330.

Yes. I understand 910 is moving to the 1080 site.

Also 1010 and 1230 out in Gresham.

Won the lottery? That's a new one on me. The expanded band is to reduce interference on the rest of the AM dial. The idea was to move stations that created the most interference. After careful study, the FCC printed a list and stations on the list were allowed to move to whatever frequency was listed.

1290 was also KVIX & KLVS and in an earlier era KBKO.

I'm looking forward to all the AM's moving to channels 5 and 6!
Hey...theres talk of it possible in the future as an option.

"Won the lottery?"

That's what we were told at the time. PD at the time told me that x amount of people applied for an expanded band frequency and that Crawford was picked in a lottery style fashion. Being based on interference makes more sense though.

I remember seeing that KOHI had applied for a move to the expanded band in the late 1990s. I was surprised that they didn't move, as the ability to have 1 kW nighttime power instead of 12 W nighttime power would have been a significant benefit of moving. Perhaps, the cost of making the change was prohibitive? In other words, did the FCC require that expanded band stations operate with 10 kW daytime power, or would they have allowed KOHI to apply for 1 kW operation 24 hours a day?