[BC] Intermod or blanketing?

[Cowboy]

On Friday 14 October 2005 10:50 am, Steve Michaels N4AY wrote:
>Third order intermod products on 95.1mHz, for one.....

 OK, that we can deal with.

 IF that product is above -80 below any of the stations on-site,
 then all are required to find it.
 ( I'd have to run the formula on the AM, since it's below
 5kw, but it's likely some 70db below carrier, but is not likely
 caused by the AM, though it could be the source of the non-linear
 rectification )

 Part of the reason the proof rules are the way they are, is to
 put responsibility on the broadcaster ( now, THIS is an unfunded
 mandate ) for finding and correcting ( or getting corrected ) mix
 products not emanating from the transmitter, but caused by
 non-linear rectification on power lines, fence posts, and such.
 Since the commission could not regulate fence posts and such,
 they put the onus on the only ones they could.

 That's why you have that requirement to do the legal proof
 some distance from the site, to theoreticly find spurious products
 not emanating from the site itself.

 The one, or ones, in whos transmitter the product above -80
 is being created by the 2nd of the 100.1 mixed with the 105.1
 is required to take whatever steps are necessary to eliminate it.

 It could be any of the transmitters at the site, OR yes, it could
 be generated in the receiver front end.
 If it's in the receiver(s), and all of the stations have been operating
 more than a year, then the solution is being a "nice guy" and helping
 out that listener.
 If any station has been there less than a year, AND the problem is
 within their blanketing contour, AND it can be shown that they are
 in any way a contributor causing that product ( easily shown by turning
 off that transmitter momentarily ) then that station bears full responsibility
 for eliminating the problem.

 If the problem is caused by off-site rectification ( like the fence post ) then
 the rules are quite ambiguous as to who is responsible ( in a financial and
 legal sense ) for correcting it, but the rules put the responsibility for
 *getting* it corrected on the broadcaster(s).
 Except within the blanketing contour of a new station, in which case it's
 that station that also bears financial responsibility for getting it corrected.

 Yes, one of the stations could say "MY transmitter is clean, so screw you."
 but I can gaurantee the commission will not see it that way.

 Renting a spectrum analyzer would not be a bad investment for the
 broadcasters at that site.
 ( and maybe hiring someone with the expertise to find the source
 of the offending spur, if it becomes problematic ) 

-- 
Cowboy

http://cowboys.homeip.net

My theology, briefly, is that the universe was dictated but not
signed.
		-- Christopher Morley