At 07:22 PM 05/06/06, you wrote: >Good Afternoon Gentlemen, >I am looking to build a hi-fi quality audio repeater to feed audio for >remote broadcasts of a non-commercial radio station which has been >greatly annoying, as I need a specific IF filter for a motorola >receiver a tu-540w and I have been unable to find the filter.
Not surprising, the filter hasn't been made in over 40, maybe 50 years. And when the commercial 2-way service converted from wideband (that's what the W in the TU540W stands for) 30 KHz channel spacing to narrowband (15khz channel spacing) in the late 1950s / early 60s all of the TU540W filters were replaced with TU540S or TSN6000 filters and the W filters were tossed in the trash. >In addition, the chief engineer for the station has been completely un- >helpful. While I am not an amateur radio operator, I am building this >repeater for amateur radio use on the 144-148 mc band You plan on running remote pickup audio in the ham band? That's VERY illegal. There are frequencies assigned for it, and they aren't in the 144-148MHz range... Companies like Marti that make stuff just for that use, on the assigned RPU frequencies. Does your station have an RPU license? If so, use the frequencies on the license and stay legal. If not, make a smart decision and get an RPU license and be legal. See this web page: <http://www.sbe.org/freq/index.html> >and the engineer of the station claims he has an amateur radio license, Which he probably does not want to risk by doing something that he knows is illegal. >but i am beginning to have my doubts and the engineer has not >been supportive of building a hi-fi audio repeater. If he's a ham, and understands that you plan on running an RPU in the ham band, then I would expect him to discourage you. Do you really want to have the FCC bust you, him and the station owner for running remote pickup program audio on illegal frequencies? Maybe you should thank him for keeping you out of trouble. Part 74 is the broadcast rules. Part 97 is the amateur rules. Read them here: <http://www.access.gpo.gov/nara/cfr/waisidx_03/47cfr97_03.html> >how can i confirm if the engineer has a amateur radio license? >is there a listing of engineers and what licenses they have? Go to this web page: <http://www.qrz.com/i/names.html> and plug his first name, middle initial (if you know it) and last name and click on search. Then match the address. >i went through a lot of trouble to find the older tube type equipment Why? There is better stuff out there. Look at the Marti product line (but Marti isn't the only one out there). You probably figured out that your radio was narrowbanded back in the late 1950s to mid 1960s and you get to undo all that work. You will need the radio original manual as a reference plus the narrowband kit manual to make up a list of steps to "undo" the narrowbanding as the IF filter is just one little part of your project. You still have to modify the rest of the receiver, then you get to modify the transmitter. Then you get to replace every coupling or bypass electrolytic capacitor in the radio as they dry out and change value in 30 years. Then you get to use modern test equipment to verify that it is technically legal to use and at that point you will discover that the communications grade radio has unacceptable distortion for broadcast use (translation: the audio is so bad that you won't want to put it on the air). The you will discover that the gear that you spent so much time and effort on is no longer type accepted and therefore is illegal to use anyway. >to build >this hi-fi quality audio repeater and want to make it work to serve the >non-commercial fm station. Then use the frequency bands assigned for RPU use. There is NO part in the 144-148 MHz 2m band that is legal for this. FYI a quick google search on "RPU frequencies" shows this list: <http://allenk.home.infionline.net/rpufcyls.html> and this one: <http://www.sbe74.org/freq_data_rpu.htm> Use the above pages as an example of what frequencies are legal to use in RPU service, NOT as suggested frequencies for you to use. And you will discover that RPUs don't use repeaters. Every one I have seen is a simplex link. The RPU receiver is on the station antenna tower and listens to the RPU mobile - one RF hop - no repeater. A repeater would just add a second distortion generating audio link (the one from the repeater to the broadcast station location) to the audio path. >what suppliers carry older motorola radio parts? If you actually end up widebanding an old Moto radio your only hope is to find some old time ham that used to work in commercial 2-way with a garage full of 50 year old stuff. Lastly, your efforts may be wasted anyway. RPUs are going to narrowerband. From <http://www.sbe15.com/nycmafcc/ET_01-75_Sig_article.html> >On November 13, 2002, the FCC issued the long-awaited Report & Order >("R&O") to ET Docket 01-75. This rulemaking is intended to revise and >update the Part 74 Broadcast Auxiliary Services ("BAS") rules. It is >the most fundamental restructuring of the BAS rules in at least the >last 30 years, (big chunk deleted) >Configures 160 MHz and 450 MHz Remote Pickup ("RPU") channel >bandwidths to match Part 90 Land Mobile Radio Services channel >bandwidths (i.e., stackable 7.5-kHz segments at 160 MHz and stackable >6.25-kHz segments at 450 MHz). A three-year transition period is >allowed to adopt the new channel bandwidths. After the transition >period any RPU operations on "old" channel width/bandplan center >frequencies would still be allowed, but on a secondary basis to >narrowband, co-channel and adjacent-channel facilities. > >RPUs on 166.25 MHz and 170.15 MHz, shared with the federal government, >would have until January 1, 2005, to reduce their channel bandwidth to >no greater than 12.5 kHz, and thus harmonize such operations with >already reduced bandwidth operations of the federal government. (rest deleted) Yahoo! 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