I Have a LPB FMS 2000 synthesized FM Modulator. it cranks out 50dbmV into an F connector at 75 ohms. that is 1.3mW into 75 ohms the specimen is in excellent electronic and cosmetic condition. it is rack mountable uses standard pcb mount discrete components available from mouser or digikey. the stereo generator (which is made of dsicrete components and not a black box ic) can be switched between stereo or mono.
i have a 3 meter 75 ohm cable and a 1/4 wave whip and have verified using a grundig reciever and a certified part 15 that this approximates (it seems to fall slightly short of) the range of a typical high end certifed part 15 transmitter.
I am asking $275.00 shipped conus for everything. rack mount FM modulator, 1/4 wave whip with L mount and 75 ohm 3m coaxial cable
this piece of equipment is built like a professional full power FM exciter all the RF sections are shielded it has peak modulation leds to let you know when you have reached 100% modulation. it has input gain adjustments, frequency pll adjustments with chart, RF power adjustment to tailor the RF to your specific situation. has 600 ohm RCA inputs and the whole system is in a 1ru rack mount package. think of this as a rack mountable decade cm10 on steroids.
i will get detailed pic's of this equipment soon. this uses NO unobtainium parts. everything is available from mouser or digikey to affect user service should you ever need to.
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kc8gpd posted "I Have a LPB FMS 2000 synthesized FM Modulator. it cranks out 50dbmV into an F connector at 75 ohms. that is 1.3mW into 75 ohms ... i have a 3 meter 75 ohm cable and a 1/4 wave whip and have verified using a grundig reciever and a certified part 15 [sic] that this approximates (it seems to fall slightly short of) the range of a typical high end certifed part 15 transmitter."
Parties with a possible interest in making an offer in response to the quote above might want to verify the assertions made in that quote.
If an unlicensed FM broadcast band transmitter and antenna system really "cranks out" and radiates ~1.3 mW (or even 1/10th of that power) from a 1/4-wave whip antenna system, then the field intensity generated 3 meters from that transmit antenna would FAR exceed what is permitted legally by FCC §15.239.
The fact that this is a "modulator" very likely indicates it is intended to be used on a cable system, not radiated in the air from an antenna.
If it contains an FCC Certified Sticker, that would only apply to the modulators use on a cable system.
Making it compliant with 15.239 would take special engineering design to hold back most of that signal output strength, using a very short stub antenna and perhaps an attenuator, for example.
this is real world not free space paper world. you have coax loss, connector loss and other system losses.
i verified these with a real world engineer. no offense rich/carl
the whole point of this hobby to experiment outside of the little box. there is nothing wrong or against the rules with using a cable modulator for 15.239.
Point taken, kc8gpd. I agree that an FM modulator could legally be used for 15.239.
My station call letter was originally registered for use as a cable FM station, in the 1970s when cable systems were first being strung on the poles, but unlike some cities which had cable FM services, this town's cable system never developed the FM as a subscriber service, so I was left holding the call-letters until Part 15 came to mind.
If I'd been able to go ahead with cable FM, I guess I'd have a dedicated FM modulator in the cable company's racks on some frequency for FM cable customers.
Maybe I ought to have a list of cities with cable FM, we could arrange to have our streams put on those systems! A whole new avenue would open up!
Robert's modulator might be the right tool at the right time!
i sold my RS but didn't get what i need to replace my 15.239 certified fm. i will sell this modulator cheap. $200 obo shipped conus. i need to make a few more dollars to get my certified fm. this can be adjusted and the power/antenna tailored to cover your private property with nice mono or stereo sound.
pic's of transmitter
http://s537.photobucket.com/user/kc8gpd/library/fms2000
this is a re-branded dx antenna DHM-332 modulator and these still even today cost close to $1000.00
spec's
http://www.amt.com/images/products/DHM-332_AMT.pdf
and here is a dbmv to mw conversion chart
http://www.maximintegrated.com/app-n...dex.mvp/id/808