Art, the main point your missing here is the type and quality of the RX front end of the equipment
that is being used. There is a huge difference in the receiver that has a narrow front RX system with
tuned cavities over the cheap radio that has nothing but a front end that goes from DC to white light.
I have seen the front end of commercial two way equipment blown from overload.
In the case of my own equipment, I have had the RX front end blown by a UHF radar system that
I use to drive by each day. the solution was to add a couple of hot carrier diodes from the gate
of the FET to ground. This limited the max peak to peak voltage to the FET.
As for the ham stations running all sorts of power for field day and the likes, given the placement
of the antennas, yes they will blow the front ends up. have seen it happen on a number of
occasions. With some careful placement of the antennas and maybe some mods to the
receivers, this won't happen the next time. I am talking about some serious contest people
that spend months getting ready for the weekend. Even they bring extra radios just in case
they wipe out one of their receivers.
Don't down play this issue. It is real and people need to be aware of the damage that can
happen. Bottom line is to try and space antennas as far apart as possible. In the size of
the roof on vehicles today, that is not easy. If you look on the roof of any of the public
safety mobile command vehicles, you will see that there is little space left open. Normally
the radio geek that had a hand in laying out the antennas on the roof will interleave the
different band antennas in between the VHF ones. Like a VHF then a UHF then an 800
and start all over again. It can be done, but takes some care in the original layout to do it.
Jim
Hi, I am calling "that it is not fairly common."
Besides being in the industry,I have GPS, CBs, vhf-uhf ham, and 120 watt hi-power HF ham radio in my truck cab; all next to each other for a decade and no problem. I have all the same and more in my trailer.
I have very sensitive GPS receivers that survive at 100K feet altitude, 900mz hi-power Telemetry transmitters, s-band hi power video transmitters all in a rocket payload section; and the GPS does not blow.
I know how things can get damaged, but some of this speculation is going way too far.
I would ask that folks do not toss out rare issues and get the majority of folks worries about issues that will not effect them; rather then talk about normal issues and those rare issues.