sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) (09/20/87)
I am trying to build a circuit I found in an old Lafayette Electronics Book (from before it became Lafayette Department Stores), but I am not sure it is legal now. It uses 'i-f transformers' to transmit an audio signal over an AC line at 400KHz. The Radio Shack salesman near me said that the FCC now allows only 46-49Mega Hz for this type of stuff. Is this true? Does anyone know where I can get so-called if transformers? If the above-mentioned circuit is not legal, is there a circuit around that is? Thanks Seth Rothenberg sr16@andrew.cmu.edu rochester!pt!andrew.cmu.edu!sr16 sbrst@cisunx sbrst@pittvms.bitnet
parnass@ihuxz.ATT.COM (Bob Parnass, AJ9S) (09/23/87)
In article <IVImuXy00Uo5Q7c0jH@andrew.cmu.edu>, sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) writes: > I am trying to build a circuit ..., but > I am not sure it is legal now. It uses 'i-f transformers' to transmit > an audio signal over an AC line at 400KHz. The Radio Shack > salesman near me said that the FCC now allows only 46-49Mega Hz > for this type of stuff. Is this true? Carrier current transmission, if done in compliance with FCC regulations is still legal. Here is a partial list of wireless intercoms and their transmission frequencies (in MHz). Several of these models are in production now: intercom, wireless, Allied Knight-Kit [KG-225]____________ 0.1360____- " " 0.2150____- intercom, wireless, Heathkit, fm [GD-1114]___________ 0.2820____- intercom, wireless, Lafayette, fm [FM-50]_____________ 0.1600____ch C " " 0.2000____ch B " " 0.2400____ch A intercom, wireless, Radio Shack, power 50 mw, fm [43-212A]___________ 0.1600____ch B " " 0.2000____ch A " " 0.2300____ch C " [43-214]____________ 0.1600____ch B " " 0.2000____ch A " [43-218]____________ 0.1600____ch B " " 0.2000____ch A " " 0.2300____ch C intercom, wireless, Tele-Tender, power 50 mw, fm [Comm-Call 300]_____ 0.2000____ch A " " 0.2300____ch B " " 0.2600____ch C -- ===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-=== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihuxz!parnass - (312)979-5414
georgep@vice.TEK.COM (George Pell) (09/24/87)
In article <IVImuXy00Uo5Q7c0jH@andrew.cmu.edu>, sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) writes: > I am trying to build a circuit I found in an old Lafayette Electronics > Book (from before it became Lafayette Department Stores), but > I am not sure it is legal now. It uses 'i-f transformers' to transmit > an audio signal over an AC line at 400KHz. The Radio Shack > salesman near me said that the FCC now allows only 46-49Mega Hz > for this type of stuff. Is this true? Does anyone know where I > can get so-called if transformers? If the above-mentioned > circuit is not legal, is there a circuit around that is? Your first mistake was to believe the Radio Shack salesman. He doesn't know what he is talking about. Radio Shack even sells devices (wireless intercoms, BSR remote controllers, etc) which operate over the AC line. These do not operate at 46-49 Mhz, but at the Khz frequency range. You should be able to find a replacement IF transformer, used for AM superhet radios, hanging on the parts rack at Radio Shack. Find yourself a more knowledgeable salesman. geo