Radar vs GPS/Sounder
 

I was curious about this issue, so I sent a query to RayMarine a couple of years
ago. Here's what I asked, with reference to a SL72 radar:

I am curious as to the lifetime of the magnetron, or any other related
components. I often leave the radar in Standby Mode to save power and magnetron
wear, but have been advised that the magnetron is heated in standby and thus can
wear out. How many hours use might I expect, and will standby reduce wear?

Here's the response I received:

The magnetron is being heated anytime the radar is in standby. This will not,
however, significantly impact the life of the magnetron. Actual transmit time
is what really wears out the magnetron. If you are really concerned about it,
you can turn off the radar scanner by holding the CLEAR key in for about 10
seconds. this leaves the display energized, and available for the display of
chart or data. You can turn the scanner back on at anytime by tapping the POWER
key while on the radar mode. You will have to wait 70 seconds for the warmup
sequence to complete. In an EMERGENCY you can always bypass the magnetron
warm-up by holding in the ENTER key for 5 seconds.

For systems installed on recreational vessels, we usually see upwards of 12,000
hours of magnetron operation. That averages out to about 4 years of heavy use.
In many cases, however, we see magnetrons last 10 years or more.

Jim McGowan
Senior Product Support Engineer

Raymarine Inc.
http://www.raymarine.com




By the way, the spec for my SL70 dome says that the power usage is 28 Watts
transmitting, 9 Watts standby. That's a pretty significant difference.

-jeff


"Bruce in Alaska" wrote
"Jeff Morris" wrote:
I often keep it in standby to save power and
magnetron time (they do wear out)

Just a point of note here. Leaving the radar in standby on most
civilian consumer radars does not save anything on Magnitron
Time. What wears out is the Filiment (heater) and that is
always ON whenever the Powersupply is on, even in Standby Mode.
To convise yourself of this, do this simple test. When you first
"Fire up" your radar, there is a timer that allows the Magnitron
to "Heat up and Stabalize", usually for three (3) minutes or so.
After that initial "Warm up Period", when going from "Standby"
to "Operate" does your radar require another "Warm up Period"?
If so, then you are correct on your Magnitron time statement.(Not very
likely to be this way) If not, then then "Standby" only save you
Transmit Power, and that's not really very much in most cases.
Most modern Magnitrons have between 2000 and 4000 hours of Service
Life and that is Filiment Life, really.

Bruce in alaska
--
add a 2 before @

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 06:51:32 -0800, "Lloyd Sumpter"
wrote:


Final question: if the fog was thick (vis. maybe 100 ft) and you had radar (and
GPS, etc) would you go out?


Absolutely. I have done so many times, when I wanted to be somewhere
else for subsequent cruising. Fog doesn't necessarily last all day,
and it may roll in during the day.





Rodney Myrvaagnes NYC J36 Gjo/a


"Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 06:51:32 -0800, "Lloyd Sumpter"
wrote:


Final question: if the fog was thick (vis. maybe 100 ft) and you had radar (and
GPS, etc) would you go out?


Absolutely. I have done so many times, when I wanted to be somewhere
else for subsequent cruising. Fog doesn't necessarily last all day,
and it may roll in during the day.





Rodney Myrvaagnes NYC J36 Gjo/a


"Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 16:01:11 -0500, "Jeff Morris"
wrote:

I was curious about this issue, so I sent a query to RayMarine a couple of years
ago. Here's what I asked, with reference to a SL72 radar:
//
The magnetron is being heated anytime the radar is in standby. This will not,
however, significantly impact the life of the magnetron. Actual transmit time
is what really wears out the magnetron. ///
Jim McGowan
Senior Product Support Engineer

Raymarine Inc.
http://www.raymarine.com

-jeff

In case you're wondering....
the cathode coating 'wears out' by electron emission
from the 'dull emitter' surface so that its emissivity drops.

Brian W

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 16:01:11 -0500, "Jeff Morris"
wrote:

I was curious about this issue, so I sent a query to RayMarine a couple of years
ago. Here's what I asked, with reference to a SL72 radar:
//
The magnetron is being heated anytime the radar is in standby. This will not,
however, significantly impact the life of the magnetron. Actual transmit time
is what really wears out the magnetron. ///
Jim McGowan
Senior Product Support Engineer

Raymarine Inc.
http://www.raymarine.com

-jeff

In case you're wondering....
the cathode coating 'wears out' by electron emission
from the 'dull emitter' surface so that its emissivity drops.

Brian W

Radar vs GPS/Sounder
 

I bought radar before this past season for the first time. Real "eye
opener". Found it very useful, even in clear weather -- we only get
fog 4 day/month in the Northumbeland Strait. If I was venturing out
on a longer range trip I would not be without GPS, sounder and radar.

Jim
http://jimthompson.net/boating/ECharting/JRC1500.htm

On Sun, 23 Nov 2003 09:07:50 -0800, "Lloyd Sumpter"
wrote:

Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without radar.
If it's really foggy, I just stay put. If I venture out, I use several nav aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would think
that GPS, sounder and a good chart would be better to find that anchorage than
radar, assuming I could see at least 100 ft or so.

Comments?

Radar vs GPS/Sounder
 

I bought radar before this past season for the first time. Real "eye
opener". Found it very useful, even in clear weather -- we only get
fog 4 day/month in the Northumbeland Strait. If I was venturing out
on a longer range trip I would not be without GPS, sounder and radar.

Jim
http://jimthompson.net/boating/ECharting/JRC1500.htm

On Sun, 23 Nov 2003 09:07:50 -0800, "Lloyd Sumpter"
wrote:

Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without radar.
If it's really foggy, I just stay put. If I venture out, I use several nav aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would think
that GPS, sounder and a good chart would be better to find that anchorage than
radar, assuming I could see at least 100 ft or so.

Comments?

Radar vs GPS/Sounder
 

Jim Thompson wrote:

I bought radar before this past season for the first time. Real "eye
opener". Found it very useful, even in clear weather -- we only get
fog 4 day/month in the Northumbeland Strait. If I was venturing out
on a longer range trip I would not be without GPS, sounder and radar.

We have a radar set on the tugboat. A bit old, and doubtfully installed by DPO, but
it seemed capable of working. The return was very garbled and unclear, it would not
even pick up large buildings on shore from more than 1/2 mile away. I was convinced
that we should buy a new one, but going through the tuning & timing procedure in the
owners manual (at least the DPO saved them) improved the return picture a LOT.

Over the past year I've tweaked the thing a little here and there, as time &
opportunity came along, and after some coaching by a retired Navy OS Master Chief, we
get a great return picture out to about 16 miles. It will pick up a floating soda can
in calm water, show rain squals, outline marshy shore, etc etc.

Our radar has proven to be a really good tool for use in marginal visibility and for
tracking ship traffic. When we first bought the boat I was not convinced of it's
usefulness, especially not that particular set. But now it works great.

BTW thanks Jeff for your comments about magnetron life.

Fresh Breezes- Doug King

Radar vs GPS/Sounder
 

Jim Thompson wrote:

I bought radar before this past season for the first time. Real "eye
opener". Found it very useful, even in clear weather -- we only get
fog 4 day/month in the Northumbeland Strait. If I was venturing out
on a longer range trip I would not be without GPS, sounder and radar.

We have a radar set on the tugboat. A bit old, and doubtfully installed by DPO, but
it seemed capable of working. The return was very garbled and unclear, it would not
even pick up large buildings on shore from more than 1/2 mile away. I was convinced
that we should buy a new one, but going through the tuning & timing procedure in the
owners manual (at least the DPO saved them) improved the return picture a LOT.

Over the past year I've tweaked the thing a little here and there, as time &
opportunity came along, and after some coaching by a retired Navy OS Master Chief, we
get a great return picture out to about 16 miles. It will pick up a floating soda can
in calm water, show rain squals, outline marshy shore, etc etc.

Our radar has proven to be a really good tool for use in marginal visibility and for
tracking ship traffic. When we first bought the boat I was not convinced of it's
usefulness, especially not that particular set. But now it works great.

BTW thanks Jeff for your comments about magnetron life.

Fresh Breezes- Doug King

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 20:30:38 GMT, Bruce in Alaska
wrote (with possible editing):

In article ,
"Jeff Morris" wrote:

I often keep it in standby to save power and
magnetron time (they do wear out)

Just a point of note here. Leaving the radar in standby on most
civilian consumer radars does not save anything on Magnitron
Time. What wears out is the Filiment (heater) and that is
always ON whenever the Powersupply is on, even in Standby Mode.
To convise yourself of this, do this simple test. When you first
"Fire up" your radar, there is a timer that allows the Magnitron
to "Heat up and Stabalize", usually for three (3) minutes or so.
After that initial "Warm up Period", when going from "Standby"
to "Operate" does your radar require another "Warm up Period"?
If so, then you are correct on your Magnitron time statement.(Not very
likely to be this way) If not, then then "Standby" only save you
Transmit Power, and that's not really very much in most cases.
Most modern Magnitrons have between 2000 and 4000 hours of Service
Life and that is Filiment Life, really.

Bruce in alaska

No flame, Bruce, but what normally wears out a magnetron is depletion
of the cathode. The cathode is heated by the filament so that it will
emit electrons. As the tube ages, its ability to emit them decreases.
As radar operates in pulsed service, the tubes should last a good deal
longer. Often, a magnetron which is substantially dead, will still
"light up" just like the final output tubes in transmitters.
--

Larry
Email to rapp at lmr dot com