"KE5MBX" wrote in message
oups.com...
Hi,
What's all this business I hear people talking about blasting people's
car stereos or killing cars altogether with high-power RF? I run 2m,
10m, and 11m in my jeep and I'd like to sort out the fact from the
legend and find out what kind of power I can use without risking
damage to my jeep or cars around me. At what power level is front-end
overload to a nearby radio likely? At what power level is damage
likely, and to what componets?

A couple of years back there were cars that included the caveat that any
transmitter installation would void the warrenty. Now that everyone and
their brother uses their cell phones in the car I guess they don't put that
notice in anymore.

Back in the mid 1970's I was in NROTC in college. There it was mentioned
that an EA6B (the electronics warfare version of an A6) could pulse its
radar and fry the electronics of a plane in the cone if it was close enough
(under 1 mile if I recall correctly). Anecdotal stories like that are the
source of electronic killing rf. That involved a multi megawatt microwave
pulse, not something you would normally see in an amatuer installation.

Living in an apartment, years ago I tried putting a 10 meter dipole across
the ceiling in a stealth installation, I shut down when the residents above
me complained that their tv would scramble while I tried running psk31.

You may not blow out their electronics but can definately interfere with
them if they are close enough.

thanks, John.
KC5DWD

On Feb 18, 8:00�am, "john graesser" wrote:
"KE5MBX" wrote in message

oups.com...

Hi,
What's all this business I hear people talking about blasting people's
car stereos or killing cars altogether with high-power RF? I run 2m,
10m, and 11m in my jeep and I'd like to sort out the fact from the
legend and find out what kind of power I can use without risking
damage to my jeep or cars around me. *At what power level is front-end
overload to a nearby radio likely? At what power level is damage
likely, and to what componets?

Back in the mid 1970's I was in NROTC in college. There it was mentioned
that an EA6B (the electronics warfare version of an A6) could pulse its
radar and fry the electronics of a plane in the cone if it was close enough
(under 1 mile if I recall correctly). Anecdotal stories like that are the
source of electronic killing rf. That involved a multi megawatt microwave
pulse, not something you would normally see in an amatuer installation.

Back in the late 1960s I was a staff engineer at a small
microwave company called Micro Radionics Inc. One of
the projects I worked on was a pre-flight test set for the
E6 Intruder. Battery-powered, it could be used on deck
in front of the radome to confirm that the E6's radar was
still operating properly. No specifications existed warning
of "megawatt" peak pulse powers from Intruder aircraft.

I'm not familiar with the EA6B and doubt it had "megawatt"
output powers. EW designed to interfere with receivers
generally don't need such high RF output powers.


Living in an apartment, years ago I tried putting a 10 meter dipole across
the ceiling in a stealth installation, I shut down when the residents above
me complained that their tv would scramble while I tried running psk31.

In 1960 I was living in a second-story apartment and put
a short base-loaded CB antenna in the attic space about
five feet in front of the stacked TV "vee" antennas for
apartment dwellers, my own apartment included. The
2 W peak output CB had a 60 db minimum (measured)
attenuation (at Channel 2) lowpass filter. No problems
seen or reported. The TV transmitters in Los Angeles
were all grouped on top of Mt. Wilson, about 30 miles
away from the apartment.

A simple thing such as a lowpass filter can solve a lot
of problems before they happen.

In article . com,
" wrote:



I'm not familiar with the EA6B and doubt it had "megawatt"
output powers. EW designed to interfere with receivers
generally don't need such high RF output powers.

Actually Megawatt Output Powers for Pulsed Radars are easily in the
range of most military Radars.......note I say "Pulsed" and not "CW"...

From: You on Sun, 18 Feb 2007 21:54:36 GMT

" wrote:

I'm not familiar with the EA6B and doubt it had "megawatt"
output powers. EW designed to interfere with receivers
generally don't need such high RF output powers.

Actually Megawatt Output Powers for Pulsed Radars are easily in the
range of most military Radars.......

Actually, NO. "Most" are not at over one-megawatt
peak pulse levels.

Do the "radar equation" or just do the two-way free space
loss and then subtract the varying reflections of the
target (way NOT uniform). That gets a reasonable
approximation of power levels involved.

A long-range ship search radar has high power. It must
because it has to "reach" over the radio horizon. [more
loss due to refractive bending and scattering effects]

Intruders and Prowlers (E6 family) operate at altitude.
Their direct radio horizon is much farther due to that
altitude in comparison with a surface ship.

Electronic Warfare suites concentrate on copying the
enemy signal and returning it AS IF it were a target
return, either there or some distance away or on either
side. Only HALF the RF path is involved and the EW-
originated signal is quite low in level. Again, do the
"radar equation" but only the return path.

"Jamming" with over-much RF power went out with WW2.
It is much more subtle now and has been for years.
The circa 1958 MacDonnell Quail missle was a small
unmanned decoy air-breather with lots of automatic
radar futz-up on it. B-52s carried them then. I
worked a little bit on those at Ramo-Woldridge in
El Segundo, CA.

I'm also acquainted with the Association of Old Crows,
a professional one made up of those who work/worked in
Electronic Warfare. Try as I might, I can't remember
anyone there called "You." :-)

OK, let's get back to HOMEBREW things...

On 18 Feb 2007 12:48:50 -0800, "
wrote:

On Feb 18, 8:00?am, "john graesser" wrote:
"KE5MBX" wrote in message

oups.com...

Hi,
What's all this business I hear people talking about blasting people's
car stereos or killing cars altogether with high-power RF? I run 2m,
10m, and 11m in my jeep and I'd like to sort out the fact from the
legend and find out what kind of power I can use without risking
damage to my jeep or cars around me.
t what power level is front-end
overload to a nearby radio likely? At what power level is damage
likely, and to what componets?

Back in the mid 1970's I was in NROTC in college. There it was mentioned
that an EA6B (the electronics warfare version of an A6) could pulse its
radar and fry the electronics of a plane in the cone if it was close enough
(under 1 mile if I recall correctly). Anecdotal stories like that are the
source of electronic killing rf. That involved a multi megawatt microwave
pulse, not something you would normally see in an amatuer installation.

Back in the late 1960s I was a staff engineer at a small
microwave company called Micro Radionics Inc. One of
the projects I worked on was a pre-flight test set for the
E6 Intruder. Battery-powered, it could be used on deck
in front of the radome to confirm that the E6's radar was
still operating properly. No specifications existed warning
of "megawatt" peak pulse powers from Intruder aircraft.

Those were the days when the techs would check the output by putting
their hands up in front of the antenn to see if they'd get "warm".
(always take any rings of first thoughg)

I'm not familiar with the EA6B and doubt it had "megawatt"
output powers. EW designed to interfere with receivers
generally don't need such high RF output powers.


Living in an apartment, years ago I tried putting a 10 meter dipole across
the ceiling in a stealth installation, I shut down when the residents above
me complained that their tv would scramble while I tried running psk31.

In 1960 I was living in a second-story apartment and put
a short base-loaded CB antenna in the attic space about
five feet in front of the stacked TV "vee" antennas for
apartment dwellers, my own apartment included. The
2 W peak output CB had a 60 db minimum (measured)
attenuation (at Channel 2) lowpass filter. No problems
seen or reported. The TV transmitters in Los Angeles
were all grouped on top of Mt. Wilson, about 30 miles
away from the apartment.

A simple thing such as a lowpass filter can solve a lot
of problems before they happen.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com