Hi guys,
Just to address a few important points you brought up and to clear up a misconception;
"I know that DOD is after >100 ham repeaters in the 420-440Mhz range that are "interfering" with the new radar on both coasts."
You may consider this a long delayed echo (LDE). The radars have been active since the 70s and all but two have been dismantled, only now they decide to complain. This alone makes me suspicious of their motives as just about everything the government does.
"In your experience, are the new federal systems popping up after re-farming landing
in a narrow range of frequencies in the low 400's ??"
There is no re-farming going on, however there's a whole slew of military trunked systems and various federal interoperability systems cropping up. None of them have anything to do with the 70cM radars or Amateur bands.
FYI, the most powerful 70cM radar on the planet is at Arecebo PR, the big dish is a lot more than a radio telescope. With ERP in the terawatt range it's used for planetary mapping. At one point the transmitter was throttled back to the 1500W Amateur limit by a couple of hams who work there, hearing signals from Uranus became a reality all jokes aside. I forget the gain of the antenna but in any case the ERP was still in the megawatt range, quite legal since the limit is on transmitter output only, you can use as much antenna gain as you can muster.
"I'm very active on 70cm. Radar is frequently heard in Southern Calif, although I don't know if it's PAVE PAWS."
It's the only 70cM radar in North America, the other site is on Cape Cod Massachusetts.
"The interference seems to be involving a single radar site up north."
You've got it pegged.
"The radar is a mixed blessing. ... Otherwise there would be no 70 cm ham band at all."
Probably so, seventy cems is the most sought after band worldwide and has already fallen victim to spectrum snatching in ITU Regions 1 and 3. Military allocation being primary hams in Region 2 operate under their umbrella of protection, nobody messes with a guy with a gun.
"I hear radar on everything from 420 to 470 at times. I can be listening to Fresno County's EMS dispatch on 462.975, and I'll hear the radar pulses coming through."
Probably front-end overload, you're getting hit with what starts out as pulses in the hundreds of kilowatts range diminished by the square of the distance. In Fresno you're right in the thick of it. I used to get clobbered close by the rotating dish at Newark (NJ) International Airport when I worked there and that radar operates nowhere near the VHF/UHF bands. That zzzZZZzzz sweep was only scatter, I really wouldn't want to be in the beam. You don't see why because you don't understand the workings of the system.
"As for the bandwidth, it's a function of pulse width and pulse repetition rates."
That's basically it, think "broadband Internet" and you've got a grip on it.
"12 volt radios are for wimps. Real radios can kill you."
I just LOVE high voltage!
