Scott, I think you hit the nail on the head! Many of the suggestions received so far call for the purchase and installation of new radios and/or microphones. Other suggestions call for reprogramming of every radio in the fleet. Such solutions can hardly qualify as "simple" or "inexpensive."
Let's get back to the original premise, which must be simple and inexpensive. That rules out any reprogramming of the existing fleet radios, any additional radios, and any additional microphones. That doesn't leave us much, especially if there is no electrically-operated gate at the site now. How will the technicians get into the site, if the power has failed? the typical mountaintop radio site usually has one power line feeding it, and when that dies, the generator- if indeed there is one- probably feeds only the critical radios. Once you thoroughly understand the up-front and continuing maintenance costs of an electrically-operated vehicle gate, and the complexity of its positive control, the plain old padlock looks pretty darn good! 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Zimmerman Sent: Wednesday, May 30, 2007 7:57 AM To: [email protected] Subject: Re: [Repeater-Builder] Re: OT: Need to find a product to develop goodwill at a tower site(s) Are we missing the obvious here?? Are all of the mobile radios capable of sending 1+1 or MDC type signaling?? I would think MDC especially would be more secure than either DTMF or PL type stuff. Even if you had to buy a small cheap voice recorder and play it back though the microphone manually... (Similar to the old pocket phone dialers) I know maxtracs can be had for little money that when paged with activate the horn/light relay output on the back. I would think that could be used to help keep things more secure. I think they can also be programmed so that they must have the correct PL/DPL code along with the 1+1 to make it trip. Just an idea. YMMV Scott Scott Zimmerman Amateur Radio Call N3XCC 612 Barnett Rd Boswell, PA 15531 ----- Original Message ----- From: "Mike Morris WA6ILQ" <[EMAIL PROTECTED] <mailto:wa6ilq%40pacbell.net> > To: <[email protected] <mailto:Repeater-Builder%40yahoogroups.com> > Sent: Saturday, May 26, 2007 7:25 PM Subject: Re: [Repeater-Builder] Re: OT: Need to find a product to develop goodwill at a tower site(s) > At 04:19 PM 05/26/07, you wrote: >>One other thought... >> >>If they don't already have dtmf mics on their radio gear then I >>would not consider adding them for cost and reliability reasons. >> >>I'd probably buy some of the low cost key-chain remote control >>units and the master decoder receiver. >> >>It's probably easier to buy a $10 to $25 key-chain remote vs. having >>to place new dtmf mics on radios. >> >>skipp > > And one more bonus - if someone loses the key-chain remote or > if someone gets fired and keeps theirs it can be "dropped" from > the master a lot easier than reprogramming a DTMF decoder and > informing everyone of the new code. There's always someone that > doesn't get the message... > > And one comment on using a garage door opener... as I remember > the starting message to this thread, it's a tower site company. > This means high altitude... and the garage door opener receiver will > be able to "see" a lot of residential area... what;s to say that some > consumer down in the valley won't have the same RF frequency > and digital code on their opener? > There are openers that have a "rolling code" feature, but I don't > know if those units can handle multiple remotes controlling a > receiver at each of multiple sites. > > And all of the above assumes that the garage door opener receiver > even survives at a tower site that has lots of RF in the air... > (and I'm not kidding - I've seen a Genie brand receiver in a metal box > with SuperFlex going to a pass cavity with 3db loops... with a 6db pad > on the cavity output... and a RG-8-sized feedline to a coathanger-style > ground plane. I was not able to get close enough to the feedline to > read the cable type). > > If you do go with DTMF mics on all the mobiles (are they in place now?) > and an appropriate decoder on a commercial receiver on the talkaround > channel I'd suggest a deliberately poor antenna. Maybe a 6 or 10db pad > between the RF connector and a stubby duck. Just to keep the riff-raff > out of the system. No sense in allowing someone thirty miles away who > has a beam antenna and a DC-to-Daylight programmable radio be able to > open the gate. > > But I still question broadcasting a DTMF sequence over an open > radio channel. Anybody can listen, anybody can decode, anybody > can duplicate the signal. > If I remember the original message there are power gate openers... > a good quality key switch accessible from the vehicle door would > seem to scratch their itch. Sometimes low tech is more secure. > Use a Medeco or Abloy if you need key blank control. If not, just > pin the key switch to an existing key on the company vehicle keyring. > I know of one site where the padlock on the gate is a Schlage, and > the keycode is the same as the shop vehicle driveway gate. > > Another trick... pick a community repeater frequency at the site... > put the insensitive commercial radio on that input. Program the > receiver for a DPL code that no existing user currently has. > Have the DPL decoder drive a relay to open the gate. Or if the DTMF > mics already exist have the DPL decoder enable the DTMF decoder. > > Mike WA6ILQ
