Bob, I have a solar-powered commercial UHF repeater on a mountain ridge, for which I must have knockdown capability. I satisfied that requirement with an NHRC-Remote+ controller: <www.nhrc.net/nhrc-remote-plus/>
The repeater is a Motorola R1225, which has a built-in knockdown capability on one of its accessory connector pins. I simply feed audio and 13.8 VDC to the NHRC-Remote+, and connect one of its outputs to the knockdown pin. Since the R1225 is always listening on its input frequency- whether transmitting at the time or not- I always can send the knockdown code from my handheld radio. The repeater site has no telephone lines and no commercial power, yet the repeater is always under my control. I'm pretty sure this device is adaptable to other repeaters. I, too, adhere to the KISS principle! 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bob M. Sent: Tuesday, January 13, 2009 10:47 AM To: [email protected] Subject: Re: [Repeater-Builder] Re: Repeater controller to be used with MSF5000 I believe the Motorola DTMF decoder resides in an expansion chassis. I've never encountered a SAM so I don't know where it plugs in. As you said, both are rare and none of the stations I need to control have an expansion chassis. The other suggestions, while innovative, don't seem to decode DTMF, which is what I want to use to control the repeaters. It can be over-the-air on the input frequency, or using another receiver, however that does tend to complicate things one more level. There's already a decent receiver built into the MSF, so I'd rather use that, then I can shut down the repeater using a portable or mobile radio with a DTMF mike. Bob M. ====== --- On Tue, 1/13/09, nj902 <[email protected] <mailto:wb0emu%40arrl.net> > wrote: > From: nj902 <[email protected] <mailto:wb0emu%40arrl.net> > > Subject: [Repeater-Builder] Re: Repeater controller to be used with MSF5000 > To: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> > Date: Tuesday, January 13, 2009, 1:26 PM > Motorola had two factory options that would allow control of > the > MSF5000 station, the DTMF decoder and the SAM [Station > Access > Module]. > > The SAM card can respond to DTMF, MDC, and other signaling > formats > and is the most versatile. It was also referred to as the > Smart > Wildcard. Unfortunately, they are pretty rare, although > they > sometimes show up surplus since they were used in certain > 800 MHz > RDLAP mobile data base stations that are at end of Motorola > support > life. > > Lacking one of those decoders, a simple solution is to use > a > Maxtrac. You can do that two ways. For either case, you > need a way > to get the control function into the station. For CXB > stations > there is one programmable input line available unless > it's already > in use. If so, or for CLB stations, an expansion tray with > a > wildcard is the best way to put signals onto the > station's MUXBUS. > For example, to control a repeater, you configure an input > for 'repeater knockdown'. > > The first way to use the Maxtrac as your decoder would be > to simply > connect a decode output from the Maxtrac to your configured > MSF > repeater knockdown input. That Maxtrac can be configured > as a > receive only radio on a different frequency than the > repeater > input. The use of a different frequency is a common sense > approach > to supervisory control. That radio could also be > configured to > transmit back an acknowledgement if desired. > > In order to have the Maxtrac decode DTMF you need a small > option > board or you need to duplicate that circuit on a perf > board. Using > MDC, however, doesn't require anything extra. > > A second solution is to use just the Maxtrac logic board > and install > it in the same expansion plastic tray where the wildcard > board is. > Over the air control on the repeater input is acceptable > for some > applications, for example, enabling one of several mutual > aid > repeaters that have overlapping coverage or for other > functions like > enabling or disabling PL operation, changing RF output > power level, > etc. > > In this case, you simply feed the raw MSF receive audio to > the > Maxtrac logic board. It really has no way to know that it > doe not > have its own RF board. > > One more trick and an easy way to have several over the air > > functions from the Maxtrac decoder, is to use the Maxtrac > display > driver chip to provide your decode outputs. If the > Maxtrac, either > a complete radio or just a logic board that thinks it's > a radio, is > programmed for only one channel, its display will normally > show the > digit "1" at all times. The Maxtrac high tier > signaling model has > the ability to decode unit ID's and to 'alias' > them, in other words > to display a number corresponding to the ID received. > > For example MDC ID 1234 could show in the radio's > display as "41". > When the radio decodes that ID, it will activate the > display > segments to show that number. The extra segments, other > than the > ones that were active for the current channel display > digit, are > available as outputs to drive your wildcard inputs to set > station > states. > > The radio can have up to 99 different ID's in its list. > There > aren't that many unambiguous display segments available > as outputs, > but the segment lines could be configured to address a PROM > or other > simple circuitry to expand the decode capability. > > In other words, this idea is based on using something > that's cheap > and readily available - the Maxtrac logic board - to do the > hard > work of decoding. You could even configure one of these to > use MDC > ID's for a group of users to enable repeater access > only for users > that are in your decoder's list. > > You can even do this with a five pin logic board, one you > have left > in the parts pile after upgrading radios to use 16 pin > boards. The > TLN5172 trunking models of the five pin board will run the > conventional firmware and initialize fine as conventional > high tier > signaling. After you initialize the radio, go to the > option > connector configuration and set everything to > "NULL". > > You can make a pretty clean install if you put the display > driver > chip onto the wildcard's prototyping area. You can > either salvage a > chip from a Maxtrac front panel or, if all you have as a 2 > mode > front you can order a new chip . The chip is Motorola P.N. > 51- > 844373N25 which is actually a National MM5484N or > equivalent. > > Bob, I can send you some pictures of a completed MSF > project using > this technique. It's sort of a "poor man's SAM > card" > > ---------------------------------------------------------- > > --- In [email protected] <mailto:Repeater-Builder%40yahoogroups.com> , "Bob M." > <msf5kg...@...> > wrote: > > " I'm looking for a low-cost, simple, multi-digit > DTMF controller to > shut an MSF5000 repeater down for legal purposes. ..."
