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Diplex Question

There's a AM/Fm tx station for sale with Tower land. There's another AM tower basically across the street. I'm thinking I can buy the station, sell the land and diplex across the street. Does this make sense? Anyone have an idea how much it would cost me to diplex, I really have no idea. I'm assuming there are one time engineering costs and then a monthly tower rent. We are talking small market in the 150-200 range. Sorry can't be more specific, confidentiality and all that.
 
There's a AM/Fm tx station for sale with Tower land. There's another AM tower basically across the street. I'm thinking I can buy the station, sell the land and diplex across the street. Does this make sense? Anyone have an idea how much it would cost me to diplex, I really have no idea. I'm assuming there are one time engineering costs and then a monthly tower rent. We are talking small market in the 150-200 range. Sorry can't be more specific, confidentiality and all that.
Depends on the frequencies between the station you're buying, and the station you want to diplex with. If the new cohabitated tower is not close to 5/8, 1/2, or 1/4 wavelength of the station being purchased, the difficulty (aka cost) increases. Another factor is frequency separation. The closer the two stations are in frequency, the more difficult it is (aka expensive) to keep the one station out of the other and attenuate any possible out of bounds harmonics created by the two stations.
Assuming you clear these hurdles, and depending on power involved; I'd plan on somewhere between $50,000 to $250,000 in capex.
 
Assuming you clear these hurdles, and depending on power involved; I'd plan on somewhere between $50,000 to $250,000 in capex.
I don't think you can do the engineering plus the new ATU for the second station and the rejection network for both for less than $100,000. And there will be legal fees for filings, too.

And if the shared tower was built for a much higher on the dial frequency, the lower frequency "new" tower partner will be very low impedance with a huge j to be overcome.
 
I don't think you can do the engineering plus the new ATU for the second station and the rejection network for both for less than $100,000. And there will be legal fees for filings, too.

And if the shared tower was built for a much higher on the dial frequency, the lower frequency "new" tower partner will be very low impedance with a huge j to be overcome.
Sure there are a lot of variables, but assuming best case; let's say both stations are 1kW daytimers and not too close in frequency, you could probably find some local engineer install a Kintronics diplexing gear (filters) and tune it up. But again, that's a perfect low-budget scenario.
 
Sure there are a lot of variables, but assuming best case; let's say both stations are 1kW daytimers and not too close in frequency, you could probably find some local engineer install a Kintronics diplexing gear (filters) and tune it up. But again, that's a perfect low-budget scenario.
One of the issues is finding a local engineer who has an OIB and can do the proper measurements for the tower at both frequencies once the diplexing gear is delivered. For Kintronics to build, someone will have to use an RF generator and a low power impedance bridge to get the measurement on the tower that will be used by the second station.

There are so few engineers now that can do that kind of AM antenna work that it would be important to find someone who can do it properly with the right gear.
 
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