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Hey Jim...Jim202 wrote:It is clear that the radio tech that did that installation has never had a a mentor to teach him anything about radio propagation. My guess would also be that he is fairly new to the work.
I would be ashamed to even be associated with an installed antenna in that location. Maybe someone should take the radio tech aside and have a talk about the birds and the electrons about how they behave and propagate through the atmosphere. We all have to learn somehow and it is much easier to have a mentor to lead the way.
Jim
Two Tek screws and the antenna was never cut to the freq used.........FireCpt809 wrote:I see a bill from a body shop in the future for that radio dealer..
Not to mention it doesn't conform to exposure guidelines, unless its a very low power radio.HLA wrote:regardless of how to fix the problem in the future, If that antennae is on a working radio right now i'd put some kind of sleeve over it so it can't ground out on the body of the truck or any of the gear. Plus if anyone touches it while it's transmitting they can get burned from it.
Guess you need to train the truck driver that he needs to make sure the drivers side of the truck always points toward the direction you will use the portables on the vehicle repeater.KG4LHQ wrote:It is for the 2 watt vehicle in band repeater which by the way isnt installed correctly.
That was really easy to do with the tank mounted so close to the floor of the trunk in the raised area above the rear axle. We learned the hard way too on the first one we did. We also learned how to fab a frame system that attached to the seat back mounts. They really left you no place to put any screws in the Crown Vics. For taxis with remote mount radios and AVL systems, we built an aluminum panel that enclosed the driver side trunk fender cavity. That left the rest of the trunk space available for passenger belongings including folding wheelchairs while protecting the comm equipment in a tamper resistant box (emphasis on resistant, not tamper-proof).train_radio_guy wrote:Back in the day, one of the local radio shops had the contract for State Police. When mounting a racking system in the trunk, to accommodate several 100 watt radio decks, the radio tech managed to drill right into the gas tank, of a brand new Ford Crown Vic. Luckily, there was very little gas in the tank, and there was no fire.
The radio shop paid the bill, for the local Ford Dealer, to repair the damage, & replace the gas tank. The radio tech was removed from the service side of the business, and put in sales.
The following year they lost the contract. Can't imagine why?
Don't forget the old B-body Caprices. I learned the old adage "measure twice, drill once" the hard way on my old '96, then a few years later learned the fine art of custom radio shelf fabrication.Bill_G wrote:That was really easy to do with the tank mounted so close to the floor of the trunk in the raised area above the rear axle. We learned the hard way too on the first one we did. We also learned how to fab a frame system that attached to the seat back mounts. They really left you no place to put any screws in the Crown Vics.train_radio_guy wrote:Back in the day, one of the local radio shops had the contract for State Police. When mounting a racking system in the trunk, to accommodate several 100 watt radio decks, the radio tech managed to drill right into the gas tank, of a brand new Ford Crown Vic. Luckily, there was very little gas in the tank, and there was no fire.
The radio shop paid the bill, for the local Ford Dealer, to repair the damage, & replace the gas tank. The radio tech was removed from the service side of the business, and put in sales.
The following year they lost the contract. Can't imagine why?
The same radio shop had their trunking system, on the center (energized) tower of three; primarily used by a Commercial AM Radio Station. One of the iso-couplers was failing, and desperately needed to be replaced. In order to safely remove an iso-couple, from the feed line of a live tower, the broadcast transmitter is typically turned down to a minimum power, or shut off completely. The local radio station wanted $1,000 an hour, in compensation for lost revenue, during the 'down-time' of the transmitter.train_radio_guy wrote:Back in the day, one of the local radio shops had the contract for State Police. When mounting a racking system in the trunk, to accommodate several 100 watt radio decks, the radio tech managed to drill right into the gas tank, of a brand new Ford Crown Vic. Luckily, there was very little gas in the tank, and there was no fire.
The radio shop paid the bill, for the local Ford Dealer, to repair the damage, & replace the gas tank. The radio tech was removed from the service side of the business, and put in sales.
The following year they lost the contract. Can't imagine why?
Suffice to say this is not the OSHA approved method of removing iso-couplers, from a live tower. The tech completed the job, while exposing himself to 50,000 watts of RF, which resulted in swelling of his arm, and 1-2 days of lost work. Stupid doesn't begin describe this type of work, but unfortunately very typical for this particular radio shop. 
Same.com501 wrote:I never asked permission. We showed up at the site, since the site belonged to us, at 2am. When we were ready, we just downed their transmitters and disabled their STL so they couldn't turn it back on remotely. When we were done, we turned it back on.
Calls poured in the next day. Huh? Maybe it was a power glitch or something, we weren't up there.....
KitN1MCC wrote: use a heavy duty 1/4 wave
Take a heavy-duty mirror mount, remove the backing bracket, and use it as a L-bracket. You'll tear the rack off the roof of the truck before you break the mount (caution: this might actually occur if the obstruction is low enough and/or stout enough.)jhooten wrote:KitN1MCC wrote: use a heavy duty 1/4 wave
Because they bend or break the mount. The cheapie whips are soft enough they bend first and are easily straightened out several times before the work harden and snap. I got tired of replacing the 5/8th, even with a spring the drivers would find a low enough branch to rip them off, and Larsen NMOQs on our brush trucks after every fire and went back to the silver nut SS wire quarterwaves like the one in the pic and only had to replace them every year or so.
I agree, but the owner of the radio shop was cheap, the radio tech was unfortunately, not terribly safety conscious, and the current chief engineer for the radio station didn't much care for either of them. This particular radio station's studios & broadcast transmitter(s) were at the same location, so it would have been hard to 'hide' our presence. They had door alarms on the radio huts, at the base of the tower, and there were only 2-3 individuals, that had access to the tower.com501 wrote:I never asked permission. We showed up at the site, since the site belonged to us, at 2am. When we were ready, we just downed their transmitters and disabled their STL so they couldn't turn it back on remotely. When we were done, we turned it back on.
Calls poured in the next day. Huh? Maybe it was a power glitch or something, we weren't up there.....
My friend says now International on the buses offers a pre-installed NMO mount at the factory which makes things easier. Though he says of he has his way, he would put a locomotive type antenna on the roof!AEC wrote:Busses are a PITA to mount antennas, due to the usually thick roof structure.
Radios are a hassle, bur never a real concern. Kids need to be kept away from the control head, and at times, I have had to mount a sheet of aluminum behind the driver to keep the kiddie's hands away from the radio.
The better area to mount anten as appears to be the front section on the bus, the skin is normally one sheet and not two with insulation barriers. You just get stcuk drilling a few more holes to route around the roofline, and into the driver's compartment. Of course, who builds the bus makes a difference as well.
I am speaking of Blue Bird here, with an International drivetrain/chassis.
Look out for those hidden cameras that are popping up in the overhead comparments!
KE7JFF wrote:
My friend says now International on the buses offers a pre-installed NMO mount at the factory which makes things easier. Though he says of he has his way, he would put a locomotive type antenna on the roof!
Tree limbs are definitely one of the problems with buses around here with all our oaks, maples, ash, and alders. The low cost plastic radome transit antennas (formerly by ASP), besides having squirrley patterns, rarely survive the first limb strike. But, few agencies / companies want to spend the money for the cast aluminum Excaliber series. They'll go for it if they can get the cost built into the initial purchase of a new coach. Buying them after market for a used / transferred vehicle ain't gonna happen. Keep it cheap cheap cheap, and off the tippy top of the roof in the haircut zone. Standard NMO mount VHF and UHF quarter waves usually end up over the driver in the down slope of the roof curve. They don't look too horrible. Then we just have to figure out how to get the line out of the captive space in the overhead down to the radio someplace.Jim202 wrote:KE7JFF wrote:
My friend says now International on the buses offers a pre-installed NMO mount at the factory which makes things easier. Though he says of he has his way, he would put a locomotive type antenna on the roof!
Depending on where the buses are used, it may be a better idea to go as suggested with the rail type antenna. If they are using the buses out in the rural area where you have low tree branches, normal antennas won't last long. I had one customer that would get the antenna ripped of all the time. Went to the transit or rail type antennas and that was the end to antenna replacements.
Jim
Speaking as someone who's day job is in Broadcast radio... unless that AM station was located in a top 10 market (New York, LA, SF, etc) the station owner was trying to fleece the shop. In a top 30 market, the rates for spots in the middle of the night are so low, that if the station goes off the air at midnight and comes back at 5am, it loses 30 bucks. Tops... usually less. On average, it COSTS the owner money to run an AM station (especially if it's running that IBOC crap) at night.train_radio_guy wrote: The same radio shop had their trunking system, on the center (energized) tower of three; primarily used by a Commercial AM Radio Station. One of the iso-couplers was failing, and desperately needed to be replaced. In order to safely remove an iso-couple, from the feed line of a live tower, the broadcast transmitter is typically turned down to a minimum power, or shut off completely. The local radio station wanted $1,000 an hour, in compensation for lost revenue, during the 'down-time' of the transmitter.
