Yes, I am very aware of that after standing on the deck fishing. Forgot
about the radar, and got a headace. It got away when I switched it off.
thanks

"SB" skrev i melding
e.rogers.com...
I work on weather radars that have up to 250kiloWatts out.
this is a peak value.
with the pulse widths we use it's actually only an average of 120Watts or
so
out.

Now, don't think that since you have 200W speakers and are safe standing
in
front of them, that you are safe sitting in front of your 20W (average)
radar. Just a note for safety...exposure times and all.....


"Aron Tvedt" wrote in message
...
There is something I dont understand about radars. I have a JRC 1500
radar
(16 miles), in according to the manual, the antenna is supposed to send
out
a radarbeam of 2000 watt. My engines (yanmar 4lha htp) generator
produses
12v 80A (1120watt).

I dont use the radar all the time, but if I did, would the engine be
able
to
produse enough power to my batteries?

Some experienced sailors say my radar cannot have an effect of 2000watt.
It
is the same effect of an electical owen.

Do these little guys use magnetrons??

not much for power....would this use some sort of tube??

"Larry W4CSC" wrote in message
...
The 2KW is PEAK power, only during the very short radar pulse. The
average power is very low because the time in between pulses is very
long, in comparison to the pulse. If you measure the DC power applied
to the radar, you'll only get a few amps of DC power because of this.
Power is stored in what is called a "pulse forming network" so the
magnetron has a charged source of power to pull the big pulse of
current from. This is why there are no big DC cables going up the
mast to power it. The electronics fires the stored power through the
magnetron, very quickly, producing a very narrow pulse time, which is
why you can see that bouy so close to the boat.

You'll have no problem powering even the 8KW radar from any
alternator......


On Sun, 29 Feb 2004 10:44:53 +0100, "Aron Tvedt"
wrote:

There is something I dont understand about radars. I have a JRC 1500
radar
(16 miles), in according to the manual, the antenna is supposed to send
out
a radarbeam of 2000 watt. My engines (yanmar 4lha htp) generator produses
12v 80A (1120watt).

I dont use the radar all the time, but if I did, would the engine be able
to
produse enough power to my batteries?

Some experienced sailors say my radar cannot have an effect of 2000watt.
It
is the same effect of an electical owen.




Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

They use magnetrons in 1 KW to 10 KW range, depending on unit design.
Doug K7ABX


"SB" wrote in message
le.rogers.com...
Do these little guys use magnetrons??

not much for power....would this use some sort of tube??

On Mon, 01 Mar 2004 23:01:21 GMT, "SB" wrote:

Do these little guys use magnetrons??

not much for power....would this use some sort of tube??

Yes, they do. Magnetrons are both oscillator and amplifier and
frequency controller. They are extremely efficient at putting out a
very narrow pulse of very high powered RF energy. Any FAA long-range
radar site has another similar device on S-Band, the amplitron. It
takes the powerful pulse of the magentron and amplifies it into the
megawatt range!

The magnetron in our 2KW Raymarine is a tiny little thing with a tiny
little filament to hold down the power drain. Every microwave oven in
the world has a magnetron firing 50 to 60 times per second into its
cooking cavity. They are also dirt cheap, which is why the marine
industry loves them....(c;



Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

What 'primes' the magnetron on these systems?

A maggie will do the work at ampin up the input and all, but I thought there
was a certain threshold you had to achieve before it could to it's work
properly.
In some of our old systems we used thyrtrons to bring up the power a bit
(volts/current?? not sure) and then the maggie would jack it up and kick it
out.

The cavity of our maggies can be adjusted for the frequency you are putting
out, but we also have some external compnents that assist with that and with
the firing rate.
We've gone completely solid state in a black box...so that's a s much as I
know about it!! haha

Fun stuff though! I used to have to shave my head....might be age...or
exposure...but if I keep working on these I won't have to anymore. OH, and
my tan as gotten a lot better! j/k


"Larry W4CSC" wrote in message
...
On Mon, 01 Mar 2004 23:01:21 GMT, "SB" wrote:

Do these little guys use magnetrons??

not much for power....would this use some sort of tube??

Yes, they do. Magnetrons are both oscillator and amplifier and
frequency controller. They are extremely efficient at putting out a
very narrow pulse of very high powered RF energy. Any FAA long-range
radar site has another similar device on S-Band, the amplitron. It
takes the powerful pulse of the magentron and amplifies it into the
megawatt range!

The magnetron in our 2KW Raymarine is a tiny little thing with a tiny
little filament to hold down the power drain. Every microwave oven in
the world has a magnetron firing 50 to 60 times per second into its
cooking cavity. They are also dirt cheap, which is why the marine
industry loves them....(c;



Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

In article
ogers.com,
"SB" wrote:

Do these little guys use magnetrons??

not much for power....would this use some sort of tube??



ALL small boat Radars use Magnitrons.
Yes, they are a Vacumn tube.

Bruce in alaska
--
add a 2 before @

In article gers.com,
"SB" wrote:

The cavity of our maggies can be adjusted for the frequency you are putting
out, but we also have some external compnents that assist with that and with
the firing rate.

Variable Frequency Magnitorns are not allowed in the Maritime Mobile
Radio Service in the USA. All of the Type Accepted Radars in the US
use fixed Frequency Magnitrons.

Bruce in alaska
--
add a 2 before @

Question:

In the days of yore, did early marine radars ever use klystrons? We used them
in (very) early microwave communications systems. They were a bear to
keep on frequency, and didn't last long.

Maggies are interesting devices. If you've ever torn one apart, it mostly
looks like a machined hunk of steel, which in fact it is, and surprisingly small.
The magnets account for most of the weight.

As to power, I recall that our airborne radar had a peak power output of
2 megaWatts, but the maggie current was only 18 - 20 milliamps. Of course the
high voltage was 20 kV.

What kind of maggie power supply (voltage & current) is normally found in small
marine radars these days?

Norm

In article ,
engsol wrote:

Question:

In the days of yore, did early marine radars ever use klystrons? We used them
in (very) early microwave communications systems. They were a bear to
keep on frequency, and didn't last long.

Maggies are interesting devices. If you've ever torn one apart, it mostly
looks like a machined hunk of steel, which in fact it is, and surprisingly
small.
The magnets account for most of the weight.

As to power, I recall that our airborne radar had a peak power output of
2 megaWatts, but the maggie current was only 18 - 20 milliamps. Of course
the
high voltage was 20 kV.

What kind of maggie power supply (voltage & current) is normally found in
small
marine radars these days?

Norm

Back before Gunn Diode LO's, all radars used Klystrons as Receiver LO's.
All the early Commercial Radars that came on the market after WWII used
Klystrons as receiver LO's. 2K25 comes to mind but don't hold me to
that.

Now days the radar receivers use LNA/MMIC's for FrontEnds with intergrile
solidstate LO's driving Double Balanced Active Mixers. This is why
Radars these days can see 48 and 72 miles with less than 6Kw Maggies.
Back in the bad old days it took 20 and sometimes 40Kw to see out 72
miles, because the receivers were KLystron feed Crystal Diode Mixers
with Sky High Noise Figures.

Receivers have become orders of Magnitude more sensitive than 2nd and 3rd
generation receivers of the 70's and 80's. Your Tax dollars at work.
(US MIlitary Electronics Development Dollars)

V and A for common Maggies are in the 2Kv- 3Kv range with peak currents
of an amp, and up to 2 amps PEAK. This all compes from the Pulse
Forming Network that is usually feed by a switching powersupply up in
the T/R Pan that runs on 10-40 VDC Ships Mains, or some such variation
of Power supply for the Radar. 9M502 and 9M503 come to mind for common
3-5 Kw maggies, with the old 2J42 for the 9 - 10 Kw versions. Haven't
kept up on the state of the art for the last 7 or so years, but the
basic's haven't changed all that much in the Tx side of the Antenna Pan.

Bruce in alaska
--
add a 2 before @

Newer equipment having to meet tighter European spurious emission
requirements in the past couple years have seen some fightening of
manufacturers tolerance on magnetrons or in some cases, even requiring
equipment manufacturers to upgrade current model with new magnetrons,
circulators, limiters, etc.
Doug K7ABX

"Bruce in Alaska" wrote in message
...
In article ,
engsol wrote:

Question:

In the days of yore, did early marine radars ever use klystrons? We used
them
in (very) early microwave communications systems. They were a bear to
keep on frequency, and didn't last long.

Maggies are interesting devices. If you've ever torn one apart, it
mostly
looks like a machined hunk of steel, which in fact it is, and
surprisingly
small.
The magnets account for most of the weight.

As to power, I recall that our airborne radar had a peak power output
of
2 megaWatts, but the maggie current was only 18 - 20 milliamps. Of
course
the
high voltage was 20 kV.

What kind of maggie power supply (voltage & current) is normally found
in
small
marine radars these days?

Norm

Back before Gunn Diode LO's, all radars used Klystrons as Receiver LO's.
All the early Commercial Radars that came on the market after WWII used
Klystrons as receiver LO's. 2K25 comes to mind but don't hold me to
that.

Now days the radar receivers use LNA/MMIC's for FrontEnds with intergrile
solidstate LO's driving Double Balanced Active Mixers. This is why
Radars these days can see 48 and 72 miles with less than 6Kw Maggies.
Back in the bad old days it took 20 and sometimes 40Kw to see out 72
miles, because the receivers were KLystron feed Crystal Diode Mixers
with Sky High Noise Figures.

Receivers have become orders of Magnitude more sensitive than 2nd and 3rd
generation receivers of the 70's and 80's. Your Tax dollars at work.
(US MIlitary Electronics Development Dollars)

V and A for common Maggies are in the 2Kv- 3Kv range with peak currents
of an amp, and up to 2 amps PEAK. This all compes from the Pulse
Forming Network that is usually feed by a switching powersupply up in
the T/R Pan that runs on 10-40 VDC Ships Mains, or some such variation
of Power supply for the Radar. 9M502 and 9M503 come to mind for common
3-5 Kw maggies, with the old 2J42 for the 9 - 10 Kw versions. Haven't
kept up on the state of the art for the last 7 or so years, but the
basic's haven't changed all that much in the Tx side of the Antenna Pan.

Bruce in alaska
--
add a 2 before @