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STL frequency coordination

G

Groove1670

Guest
Hey gang,

Help. Got two Marti Stl's. (944.375 & 947.50) for stereo class A FM. Gotta apply for STL license. How far/distance from station using same freq. Channel seperation. I know it will be pure luck if both of the freqs listed work in my location. Where do I start. :-\ Thanks.
 
A little background on STL frequencies. You are basically given 500 khz of bandwidth for your STL. If you use a composite STL, it will be centered in the middle of the 500 khz. So, if your STL is licensed for 950.000, you are actually allotted 949.750 to 950.250

If you decide to go with discrete STLs, your 500 khz would be divided into two 250 khz licenses. Your STLs will be centered in the middle of each 250 khz block. Example: Your STL license now becomes 949.875 (the center of 949.750 - 950.00), and 950.125 (the center of 950.000 - 950.250).

So, if you have an STL on 944.375 and one on 947.50, they do not fit into the same 500 khz bandwidth. Someone correct me if I'm wrong, but I don't believe you can get a license for two frequencies that far apart.

The better bet would be to get with a frequency coordination service and have them find you an open channel, then have your Matris re-tuned to those frequencies.
 
1. You can check on open channels by using the Wireless Bureaus search function found at the old FCC.gov May be best to contact other local engineers as this database is not up to date in many cities. You could also get a cheap scanner (Uniden makes one that will go up to the STL band for around $100, try Universal Radio) and see what's out there.

2. To be licensed, you need to use one of the firms who do the pre-coordination notification mailings. This requires sending notices to everyone on and adjacent to the selected channel within several hundred miles and in several different dimensions. :) Gov't requirement to drive business to their buddies. I use Terrestrial RF Licensing in Tulsa, cost is reasonable. http://www.rflicensing.com/

3. The channel you have to use is based on the division of the bandwidth designator by 25--for STL 10's this is (I recall) 180KF9. So this STL is an "odd" instead of an "even", such as the composite STL's that carry a designator like 300KF9 (typical: PCL-606)

Note for the onlookers: If you have a composite STL save yourself some grief and just use 300--even if the manufacturer calls it something different (e.g.--Armstrong). Gettysburg don't do no stinking ITU designators.

So your 944.375 would be 944.3625--and LJ is right, the other then should be 944.8625.
or a channel next to it. See 74.502.

International crystal can cut new crystals for $12.00 each--(Around $50 for two sets)--there is another crystal in the receiver that may need to be changed. Best bet is to contact Rick Neace at http://www.rpu-stl.com/--his prices for changing over your STL-10's are also quite reasonable.

4. I realize this is some unanticipated expense. However, once the system is built it will run for years. The STL-10 Martis, though somewhat long-in tooth, are very reliable and in a well-engineered system, will easily beat most digital systems for reliability. Plus once it's built--you own it. No on-going charges going out to some telco.
 
This subject pops up periodically, might wanna search the archives. I recently had a STL and ICR (inter-city relay) to install. I used Graham-Brock http://www.grahambrock.com/ and they did all the paperwork, notifications, filings, pretty maps, and everything else. Just another suggestion if you want to shop around. (no relationship, just feel that good service needs to he promoted just like the negative things that get posted now and then).
 
You are right on, as far as Graham and Brock are concerned. It is great to deal with the principals of the company, and develop a relationship with them...they will tell you what you are facing on any proposal, and those sky high rates and (hours) are not there. Kudos to them. (No, as a former broadcast consultant, I have no personal financial interest in their company) JBI
 
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