On Wed, 4 Mar 2015 07:31:14 -0500, "Tom" wrote:

Hi Gents,

Thanks for all the info. Yes, I placed a post in the boating newsgroup but
they haven't the radio tech knowledge as here.

I figured that splicing the connector would affect its abilitly to perform
100%. I do not want to damage the fishfinder head. It is 500 dollars.

Transducer and cable only about 100 dollars but the time to install it is
the kicker. It will take more than a day and I worry I would be installing a
less quality one right beside what looks to be a good quality one.For no
reason.

I was hoping someone here had done a similiar upgrade and knew how to
measure that existing tranducer with about 30 feet of cable.

Thank you all for the information, but obviously the best solution would be
to replace it. I was hoping to use existing one that may work just as
equally.

Thanks again for all the info.

Cheers

73s

Tom, again, if you are worried about performance, which is a perfectly
reasonable thing to consider, I would recommend contacting the manufacturers of
the devices, (transducer you wish to try) and the finder for performance
specifications and potential recommendations for items that would satisfy your
needs. Having been in electronics manufacturing, (but not boating accessories) I
can tell you they should know how different transducers perform with their
finder, and vise-versa. I think this would be you best avenue to pursue. At
least it can't hurt to ask.

On 3/4/2015 7:49 AM, Jeff wrote:

Connector impedance doesn't change with frequency, just as coax
impedance doesn't change with frequency. Loss will increase as
frequency increases, however.

Coax impedance certainly does change with frequency. Below about 500kHz
there is a significant slope with frequency.

At 200kHz a 50ohm cable may well look more like 100ohms and by the time
that you get to 1kHz it could be as high as 1kohm.

200kHz is in what is called the transition region and the impedance is
given by:

SQRT((R+j2pifL)/(C+j2pifC))

as opposed to the high frequency region where it is merely:

sqrt(L/C)

Below about 20kHz it changes again to SQRT(R/(j2pifC)

There are also other variables due to changes in the dielectric with
frequency and other losses.

Can you explain the above equations? In general it doesn't make sense
that the same effect would have different equations for different
frequencies. It does make sense though that the equations involved are
all simplifications of a single, more complex equation, optimized to
discount small effects over a given frequency range.

That said, I'm not sure I can see how these three equations can morph
into each other as f changes. The equation for the middle frequency
range seems to be the more encompassing so starting with that - if
frequency goes up enough the terms j2pifL and j2pifC dominate the R and
C terms and the equation simplifies to sqrt(L/C) appropriately.

But when f goes down enough, both terms shrink compared to R and C and
the equation would seem to simplify to sqrt(R/C) rather than
sqrt(R/j2pifC).

Is there possibly a typo in there somewhere?

--

Rick

On 3/3/2015 5:10 PM, Tom wrote:
Hi

I replaced my Eagle Supra ID fishfinder head with a new Lowrance Elite 5
(came with new transducer). The present transducer is the round style
glued to the bottom hull (through hull).

Is there a way to test the transducer to see if it is 200khz compatible
for the new Elite 5? Can I simply splice it myself or is there a reason
why I shouldn't. I have spliced coax many times.

But I really don't want to replace that cable up to the flybridge
through a lot of fishing and pulling. I am wondering if I can use the
old transducer and cable (extension & old transducer with 10ft wire). I
think the extension is 15 feet or so.

Any ideas? I am hoping I can simply splice the plug of the old
transducer wire to the new head.

Maybe the problem people are having is with your use of the word
"splice". That implies that you are cutting the cable. But on
rereading your post I think you are just asking if the existing
transducer is compatible with the new head. I assume they have
connectors at the head unit and at the transducer, right? Do they use
the same connectors on both the new and the old systems?

I certainly don't know anything about these transducers, but I am sure
there is more to it than just the frequency of the fish finder. There
is also impedance and power level. What do you know about the two
systems? Does the manual tell you much about it?

As others have suggested, you might want to contact Lowrance to find out
what they say about compatibility. It is unlikely they will tell you
much that you can bank on since they won't want to assume any liability.
But asking won't hurt. It may turn out that the transducers are a
common denominator in the industry and there is little incompatibility
like other electronics.

--

Rick

"Jeff" wrote in message
...

Connector impedance doesn't change with frequency, just as coax
impedance doesn't change with frequency. Loss will increase as
frequency increases, however.

Coax impedance certainly does change with frequency. Below about 500kHz
there is a significant slope with frequency.

At 200kHz a 50ohm cable may well look more like 100ohms and by the time
that you get to 1kHz it could be as high as 1kohm.

200kHz is in what is called the transition region and the impedance is
given by:

SQRT((R+j2pifL)/(C+j2pifC))

as opposed to the high frequency region where it is merely:

sqrt(L/C)

Below about 20kHz it changes again to SQRT(R/(j2pifC)

There are also other variables due to changes in the dielectric with
frequency and other losses.


Thanks for this Jeff. That is the first time I have seen anything about the
impedance other than formulars that just compair the diameters of the
conductors and modified by the dielectric. There was never a mention of
frequency affecting the impedance.

I guess that it is like many other electrical/electronic formulars. They
leave out some of the 'small change' . Sort of like what I always referr to
as putting one extra brick on a truck load . Just too small to worry about
in most cases, but it is still there.

On 3/5/2015 4:35 AM, Jeff wrote:
On 05/03/2015 01:50, rickman wrote:
On 3/4/2015 7:49 AM, Jeff wrote:

Connector impedance doesn't change with frequency, just as coax
impedance doesn't change with frequency. Loss will increase as
frequency increases, however.

Coax impedance certainly does change with frequency. Below about 500kHz
there is a significant slope with frequency.

At 200kHz a 50ohm cable may well look more like 100ohms and by the time
that you get to 1kHz it could be as high as 1kohm.

200kHz is in what is called the transition region and the impedance is
given by:

SQRT((R+j2pifL)/(C+j2pifC))

as opposed to the high frequency region where it is merely:

sqrt(L/C)

Below about 20kHz it changes again to SQRT(R/(j2pifC)

There are also other variables due to changes in the dielectric with
frequency and other losses.

Can you explain the above equations? In general it doesn't make sense
that the same effect would have different equations for different
frequencies. It does make sense though that the equations involved are
all simplifications of a single, more complex equation, optimized to
discount small effects over a given frequency range.

That said, I'm not sure I can see how these three equations can morph
into each other as f changes. The equation for the middle frequency
range seems to be the more encompassing so starting with that - if
frequency goes up enough the terms j2pifL and j2pifC dominate the R and
C terms and the equation simplifies to sqrt(L/C) appropriately.

But when f goes down enough, both terms shrink compared to R and C and
the equation would seem to simplify to sqrt(R/C) rather than
sqrt(R/j2pifC).

Is there possibly a typo in there somewhere?


Sorry there is indeed a typo: the general equation should read:

SQRT((R+j2pifL)/(G+j2pifC)) G being conductance.

The reasons that the equations are presented differently in different
frequency ranges are because; at higher frequencies when f becomes
large enough, the terms containing f become so large that R and G can be
neglected; and at low frequencies (2 pi f L) is so small compared with R
that it can be neglected.

Hi - SQRT(L/C)

Mid - SQRT((R+j2pifL)/(G+j2pifC))

Lo - SQRT((R)/(G)) = R vs SQRT(R/(j2pifC)?

You seem to be making some distinction between fL and fC at low
frequencies. Why would fL shrink relative to R while fC does not shrink
relative to G? Are you saying that the L term goes away faster than the
C term in most cases? What is the recondition for that assumption, just
most transmission lines?

Actually, it would be SQRT(R/(G+j2pifC), no?

--

Rick

On 3/5/2015 4:35 AM, Jeff wrote:
On 05/03/2015 01:50, rickman wrote:
On 3/4/2015 7:49 AM, Jeff wrote:

Connector impedance doesn't change with frequency, just as coax
impedance doesn't change with frequency. Loss will increase as
frequency increases, however.

Coax impedance certainly does change with frequency. Below about 500kHz
there is a significant slope with frequency.

At 200kHz a 50ohm cable may well look more like 100ohms and by the time
that you get to 1kHz it could be as high as 1kohm.

200kHz is in what is called the transition region and the impedance is
given by:

SQRT((R+j2pifL)/(C+j2pifC))

as opposed to the high frequency region where it is merely:

sqrt(L/C)

Below about 20kHz it changes again to SQRT(R/(j2pifC)

There are also other variables due to changes in the dielectric with
frequency and other losses.

Can you explain the above equations? In general it doesn't make sense
that the same effect would have different equations for different
frequencies. It does make sense though that the equations involved are
all simplifications of a single, more complex equation, optimized to
discount small effects over a given frequency range.

That said, I'm not sure I can see how these three equations can morph
into each other as f changes. The equation for the middle frequency
range seems to be the more encompassing so starting with that - if
frequency goes up enough the terms j2pifL and j2pifC dominate the R and
C terms and the equation simplifies to sqrt(L/C) appropriately.

But when f goes down enough, both terms shrink compared to R and C and
the equation would seem to simplify to sqrt(R/C) rather than
sqrt(R/j2pifC).

Is there possibly a typo in there somewhere?


Sorry there is indeed a typo: the general equation should read:

SQRT((R+j2pifL)/(G+j2pifC)) G being conductance.

The reasons that the equations are presented differently in different
frequency ranges are because; at higher frequencies when f becomes
large enough, the terms containing f become so large that R and G can be
neglected; and at low frequencies (2 pi f L) is so small compared with R
that it can be neglected.

I just had a brain cramp about the modified formula,

SQRT((R+j2pifL)/(G+j2pifC)) G being conductance.

As resistance goes to zero, G will go to infinity! This makes the
result of the equation go to zero no matter what values of L, C or f are
used. This would imply that wires made with superconductors have zero
impedance?

I read the wikipedia page and they say, "For a lossless line, R and G
are both zero". How dem do dat? Isn't R = 1/G?

I would also point out that these equations assume a non-ideal conductor
by accounting for R, but they assume the dielectric *is* ideal and
ignore dielectric losses which become dominant at high enough frequencies.

--

Rick

In article , rickman wrote:

I read the wikipedia page and they say, "For a lossless line, R and G
are both zero". How dem do dat? Isn't R = 1/G?

I think they're referring to series R (that is, resistive loss in the
conductors) and shunt G (perfect dielectric, infinitely high shunt
resistance between the conductors).

With those being posited, all of the current flow is into or through
reactances (non-dissipative impedances) , and there's no current flow
through anything with resistive loss (dissipative impedance).

On 3/5/2015 6:18 PM, Dave Platt wrote:
In article , rickman wrote:

I read the wikipedia page and they say, "For a lossless line, R and G
are both zero". How dem do dat? Isn't R = 1/G?

I think they're referring to series R (that is, resistive loss in the
conductors) and shunt G (perfect dielectric, infinitely high shunt
resistance between the conductors).

With those being posited, all of the current flow is into or through
reactances (non-dissipative impedances) , and there's no current flow
through anything with resistive loss (dissipative impedance).

Ah, that makes perfect sense now.

I skipped over the diagram on the wiki page. They actually make this
very clear.

--

Rick

On 3/4/2015 6:31 AM, Tom wrote:
Hi Gents,

Thanks for all the info. Yes, I placed a post in the boating newsgroup
but they haven't the radio tech knowledge as here.

I figured that splicing the connector would affect its abilitly to
perform 100%. I do not want to damage the fishfinder head. It is 500
dollars.

Transducer and cable only about 100 dollars but the time to install it
is the kicker. It will take more than a day and I worry I would be
installing a less quality one right beside what looks to be a good
quality one.For no reason.

I was hoping someone here had done a similiar upgrade and knew how to
measure that existing tranducer with about 30 feet of cable.

Thank you all for the information, but obviously the best solution would
be to replace it. I was hoping to use existing one that may work just as
equally.

Thanks again for all the info.

Cheers

73s



I have a lot of experience with this from a long time ago. Just use the
transducer you have. Almost all are 200khz. If you really want to test
it, just put a signal generator on it and a scope. When you swish past
the frequency the amplitude will jump up. Very simple. There were some
125 khz transducers made and some 50 khz transducers, but they were far
more expensive and of course more rare.








"Flash" wrote in message
...
On Tue, 3 Mar 2015 17:10:29 -0500, "Tom" wrote:


Is there a way to test the transducer to see if it is 200khz
compatible for
the new Elite 5?

It is quite a simple procedure actually that can be discovered in one
of a few
different means.

1st - Consult the product information for the required information. or
2nd - Call a local supplier/authorized service provider. Many Marinas and
boating accessory sales locations will be happy to provide you with some
examples.
3rd - Call the manufacturer.

Can I simply splice it myself or is there a reason why I
shouldn't. I have spliced coax many times.

Many people can splice coax. Very few will do it right or not at all when
inadvisable. being able to pass a signal is no indication that the
splice was
done properly. Given your past posts covering a wide variety of
subjects and
technologies, hardly any having to do with the actual purpose of this
group, my
advice is to contact the manufacturer for advice and the proper parts
for your
ideal installation.

On 3/4/2015 6:31 AM, Tom wrote:
Hi Gents,

Thanks for all the info. Yes, I placed a post in the boating newsgroup
but they haven't the radio tech knowledge as here.

I figured that splicing the connector would affect its abilitly to
perform 100%. I do not want to damage the fishfinder head. It is 500
dollars.

Transducer and cable only about 100 dollars but the time to install it
is the kicker. It will take more than a day and I worry I would be
installing a less quality one right beside what looks to be a good
quality one.For no reason.

I was hoping someone here had done a similiar upgrade and knew how to
measure that existing tranducer with about 30 feet of cable.

Thank you all for the information, but obviously the best solution would
be to replace it. I was hoping to use existing one that may work just as
equally.

Thanks again for all the info.

Cheers

73s




BTW, you can splice that cable all you want. It's 200Khz for God's sake.






"Flash" wrote in message
...
On Tue, 3 Mar 2015 17:10:29 -0500, "Tom" wrote:


Is there a way to test the transducer to see if it is 200khz
compatible for
the new Elite 5?

It is quite a simple procedure actually that can be discovered in one
of a few
different means.

1st - Consult the product information for the required information. or
2nd - Call a local supplier/authorized service provider. Many Marinas and
boating accessory sales locations will be happy to provide you with some
examples.
3rd - Call the manufacturer.

Can I simply splice it myself or is there a reason why I
shouldn't. I have spliced coax many times.

Many people can splice coax. Very few will do it right or not at all when
inadvisable. being able to pass a signal is no indication that the
splice was
done properly. Given your past posts covering a wide variety of
subjects and
technologies, hardly any having to do with the actual purpose of this
group, my
advice is to contact the manufacturer for advice and the proper parts
for your
ideal installation.