50KW at 540 vs. 1600

[rfry]

I just installed A TIS here on Vashon Island. We tested both 540Khz and 1650Khz. We didn't have a field strength meter because all the field sets on Vashon (Home of seven am transmitters) were not able to go up to 1650Khz.

Just wondering then how you can be sure that the TIS rule about having no more than 2 mV/m at 1.5 km is being met?
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[xmtrland]

The people that sold us the TIS system, Information Station Specialists (Bill Baker), came out with their feild set when they were in the area and measured it for us. We had no problem making the 2 mV/m at 1.5 km. After taking several readings at various location it was determined that the TIS was operating within the 2 Mv/m 1.5km limit.

 

[menotti1]

how much is the xmtr and antenna? are there different companies doing TIS xmtr's?

 

[xmtrland]

We bought our equipment from Information Station Specialist http://www.theradiosource.com/ Bill Baker was great in helping set it up. The basic transmitter and antenna can be purchased for under around $5,000. They can even provide various ground planes for your project.

The only real issue I have with the transmitter they provide is the audio quality is very very voice grade. The audio front end has a clipper that just destroys the audio if not set up right using some EQ to chop everything below 600Hz and anything above 5khz. I find the unit seems to drift modulation wise with wide temperature swings. The transmitter is mounted outdoors on the pole that suports the antenna in a metal cabinet. So I find my self adjusting the audio once or twice a month as the temperature varies.

There are no tuning controls except for the tuning of the antenna. Once you have the Antenna on a 30’ pole you need a bucket truck to fine tune it, which is a pain in the ass.
It would be great if they could provide a simple way to fine tune the transmitter to antenna match without using a bucket truck. I’m sure it would slightly help the modulation characteristics with a perfect match.