[BC] Closest-frequency AM diplexes

[Dan Strassberg]

Rene's comment about 870 and 1090 in Kingsport-Johnson City being real close
in frequency (and using Kahn Powersides to increase the fequency separation
by an additional ~10 kHz) brought up this great AM-techno-Geek trivia
question: What are the closest-frequency diplexed AMs that you know of? For
the uninitiated, "closest" is determined not just by the frequency
difference but by the ratio of the frequency difference to the higher of the
two frequencies. So a hypothetical 1460/1600 (8.75%) would beat a
hypothetical 550/620 (11.29%). I have a feeling that the winner will be in
the Honolulu area, where triplexes are commonplace, quadriplexes are not
unusual, and there may even be a quintaplex. OTOH, nearly all stations in
Hawaii are ND. Answers should include not just the calls, frequences, and
CoLs, but also powers and number of diplexed towers.

I'll start the ball rolling with Wilmington DE, WTMC 1380 519W-D/15W-N ND
and WILM 1450 1 kW-U ND, 1 tower, 4.82% (smallest frequency separation I am
aware of)

and San Jose CA, KSJX 1500, 10 kW-D/5 kW-N DA-2 (three towers in each
array--two shared by D and N arrays, four towers at site) and KZSF 1370, 5
kW-U DA-1 (uses all four towers at the site), 8.67% (smallest frequency
separation I am aware of for moderately high-power stations and more than
three towers)

Locally in the Boston area, we have (among others) WBIX 1060 Natick (days)
40 kW/22 kW-CH DA-2/D two towers at site, both used in both WBIX day
patterns, plus WKOX 1200 Framingham 10 kW-D/1 kW-N DA-N (same two towers as
WBIX) 11.67%, and WSRO 650 Ashland 250W-D/9W-N ND-U 38.68% (with respect to
1060) Grady Moates is CE of WBIX.

And WBIX (nights) 2.5 kW five towers and WAMG 890 Dedham 25 kW-D/3.4 kW-N
(five towers D and N, five towers at site) 16.04%. Note that Craig Healy is
CE of WAMG.

Seattle has KGNW 820 50 kW-D/5 kW-N DA-2 (three towers; three towers at
site) and KJR 950 50 kW-U DA-2 (uses all KGNW towers day and night)
13.68%.(smallest frequency separation I am aware of for two 50 kW stations,

although KJR was previously 50 kW DA-1 five towers and was diplexed with
KHHO 850 Tacoma, 10 kW-D/1 kW-N DA-2 (two towers D/three towers N/four
towers total; two towers shared with KJR by day, three by night--IIRC). This
was a separation of 10.53%.

If anyone can relate any war stories involved in getting close-frequency AM
diplexes to work, that would just add to the fun.

--
Dan Strassberg, dan.strassberg at att.net
eFax 707-215-6367