KE5MBX wrote:
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?

I am currently using only 50 watts on a 5/8 wave (2m), 25w on a 1/4
wave (10m), legal 4w on a 1/4 wave (11m)

Thanks,
Nelson KE5MBX

Some years ago I keyed up a 2 meter handi-talkie (maybe 2w out) with the
2 meter rig about a foot away from a Radio Shack 5" portable color tv.
The 2 watts of 2 meter rf caused the TV to self destruct! I think
something in the horizontal output section died. The TV was operating
at the time (it probably would not have happened if the tv was off).
The set was repaired by Radio Shack.

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 12 Feb 2007 15:17:50 -0800, "KE5MBX"
wrote:

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

You aren't going to directly damage any cars around you even with high
power, but you might affect some with a 100 on HF or even 2-meters.

overload to a nearby radio likely? At what power level is damage

Ham or broadcast? Broadcast is generally fairly sensitive to
overload. On-the-road it's likely to be for a very short duration so
I'd not worry about it.

likely, and to what componets?

With today's cars it's unlikely you are going to damage any components
unless you have a grounding problem and then the computer is the most
susceptible.


I am currently using only 50 watts on a 5/8 wave (2m), 25w on a 1/4
wave (10m), legal 4w on a 1/4 wave (11m)

I've run 160 watts on 144 which will *typically* desense another
2-meter rig for up to a 100 feet or so, but it depends on the rig.
I've also stopped the car next to another mobile with no *apparent*
problem although here certainly had to be some desense. I've also
"desensed" a mobile 50 feet away with a 5 watt HT (It did have a
clean signal) I also shut down the cable TV system for an entire town
with a 5 Watt HT at a demonstration, but that's another story other
than to say two days after the demonstration you couldn't find a cable
leak in the whole town. :-))

Some mobiles are running up to 600 watts on HF without problems while
others can't get a 100. Most of the car manufacturers are saying you
shouldn't go beyond a 100. I'd have no qualms about going to 500 or
600. If it works, fine. If it didn't I guess I'd have to pay for what
ever broke.

When I purchased my 4-Runner the Toyota mechanics ran the wiring for
my VHF/UHF rigs and that was about 6 years ago. My wife runs a 50
watt (Kenwood TM-V7A) in a Toyota Prius (Hybrid). I'm thinking of
leasing one while they still have good prices and a surplus of cars
available which will disappear sooner with the price of gas going back
up. Only problem with leasing the Prius is how to run an HF rig in
there. Their 12 volt system is very light duty and that 500 volt
batter might be a bit steep for my mobile rig. :-))


Thanks,
Nelson KE5MBX
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On 13 Feb 2007 16:02:34 -0800, wrote:

On Feb 12, 6:17 pm, "KE5MBX" wrote:
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?

I am currently using only 50 watts on a 5/8 wave (2m), 25w on a 1/4
wave (10m), legal 4w on a 1/4 wave (11m)

Thanks,
Nelson KE5MBX

There are many times when "high" power has disrupted other devices.
The early car computers have been know to shut down with 100 watts of
VHF. Worked on a police car that the engine would shut off when over
80 mph and key the radio.
A friend would be taking on his 1KW mobile as he pulled into his
driveway. He would find his base radio receiver front end blown. Took

Some thing wrong there. I'm running two stations here and both are
capable of the legal limit. The one in the shop is a bit more modest
with a 2K4 instead of an Alpha, but both are *old*. OTH there is the
whole Hallicrafters station in the shop as well. The antennas are
fairly close and there has never been a problem. Those antennas
http://www.rogerhalstead.com/ham_files/Tower30.htm (the wire antennas
are difficult to see) are much larger than what your friend would have
had on the mobile. Unless the mobile antenna was almost touching the
other rig's antenna and I do mean almost touching it shouldn't have
created a problem. The antenna over the driveway would have had to be
*low* and very close to the mobile antenna.

three times to think it through and as he should have been doing,
switch his base antenna (dipole over the driveway) to ground, when not
in use.

I don't ground or disconnect any cables even during thunderstorms.
Basically I can't easily get to the cables and any thunderstorm would
be past by the time I could get them disconnected.

The tower, with a large antenna system
http://www.rogerhalstead.com/ham_files/Tower29.htmtakes an average of
3 visually verified direct hits a year although it took 5 by the
beginning of August last summer. OTOH I have a good single point
ground with 32 or 33 (lost count) 8' ground rods CadWelded (TM) to
over 600 feet of bare #2 wire that ties the whole antenna system and
house electrical ground together.

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

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

hallo

It seem to be a issue
to the famous TV serie mythe busters
Seen the amount of respons it seems to be a hot item
i like discusions to learn things and broading my range of vision
also to know people of other backgrounds

can amateurradio blow up cars and/or its equipments ??

the today cars are crammed by electronics,sensors boardcomputers etc
is this equipment BCI free a simple case of BCI may casue a serious accident
by blocking a aboardcomputrer.
who is responsible the cars industry by ignoring the bci problem
or is the transmitting ham

Nelson's question does bci in cars exist ? Yes it does many examples
even trafficligths included

It seems to me that manufactories know the bci problem.often pcb's have
already holes for the needed components who is responsible

The bci problem has a profit too!! I live opposited a snackbar yougsters in
their cars equiped with stereo amp's loadbawlers and their 130dba
bonky bonk music
A 100watts carrier stops that ( not always)

nelson asked what 's the fieldstrongth of RF that effects carequipments
I have heard that a resaerch institute somewhere in SM or OZ has discovered
a strange effect into a TV set sensibillity to bci and tvi was tuned to the
amateurbands by manufactor !!
So the radioamateur had to solve the problem and not the manufactor !
I hope to see your response
73 de Ruud PA0RAB


"KE5MBX" schreef in bericht
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?

I am currently using only 50 watts on a 5/8 wave (2m), 25w on a 1/4
wave (10m), legal 4w on a 1/4 wave (11m)

Thanks,
Nelson KE5MBX