On Sun, 12 Jan 2014 11:31:23 -0500, Jerry Stuckle
wrote:

On 1/11/2014 11:51 PM, Jeff Liebermann wrote:
On Sat, 11 Jan 2014 19:41:20 -0500, Jerry Stuckle
wrote:

I didn't say they were unknown. Just that professional integrators
(including us) use better quality connectors.

Could I trouble you for a photo or part number for the crimp type F
connectors that you are using? I want to see what I'm missing.

I can't post an image to the list, and distributors websites require
logins. It won't do you any good anyway - you won't find them on ebay
and the link. Sale is restricted by the manufacturers to professionals.

Ah, secret sauce. A secret connector manufacturer and model number
obtainable only from a secret distributor. No doubt made exclusively
for professionals. The secret manufacturer probably made you sign an
NDA before he would sell you the connectors. He can't have
unprofessional hams using his secret connectors. The unobtainium
plating probably makes it difficult for you to take a photograph and
post it.

We know what is good and what is not. You don't need to tell us our job.

That's the problem. You haven't said anything about what you do, what
type of systems you work on, how you do it, what connectors you use,
what tools you use, where you obtain them, and the relative merits of
your system to those in use by Comcast and Charter. You offer nothing
that can be used, except that everything that I've been doing is
wrong, that every connector that I use is junk, and that everyone in
your area uses secret connectors and has magic cutters that last
nearly forever.

You might know what is good for "professionals", but I have no clue
what that might be. For me, questioning authority, trying something
different, and testing assumptions is a learning experience. I'm
doing a 10 year running experiment on the effectiveness of using 1"
PTFE wrap over commodity RF connectors for waterproofing. I'm testing
75 ohm coax where 50 ohms is standard. I use F connectors in a ham
radio environment for which they were never intended. I've designed
and build some rather odd antennas. I question and verify
conventional wisdom, claims, standards, test results, and
specifications. I've made both big and small mistakes, irritated the
experts, and occasionally inspired vendors into modifying their data
sheets and claims. I look for new ideas that I can use (or steal) and
had hoped that perhpas your secret F connector was in some way better
than the common Snap-n-Seal connector. I'm disappointed.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 1/12/2014 12:00 PM, Jeff wrote:


I go by my textbooks and professors. I don't believe someone who read
an article about a specific installation and tried to apply that to the
entire world.

And I didn't say their article was wrong. I said YOUR APPLICATION of
what the article said is wrong.

Two entirely different things.


The point that are missing is that the graphs in that article are
independent of application. They represent the true picture for
correctly terminated coax. You also seem not to understand how those
graphs are derived.

Jeff

OK, I give up. From reading one chart, you know more than all of the
physicists, professors and engineers in the world. And you can write
the book that contradicts every physics textbook out there.

You're THE MAN! I bow to your expertise.

NOT!


--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

On 1/12/2014 11:14 AM, Jeff wrote:


Try again. I had it back in college in the early 70's (as an EE major),
and I don't think the laws of physics have changed.

And the best impedance for a coax is that which matches the input and
output impedance of the system, or if the input and output are of
different impedances, acts as a matching stub between the two.

And yes, I read the article. But you obviously don't understand it. The
30 ohms they are talking about was for ONE SPECIFIC REQUIREMENT. That
does NOT mean it is true in different situations.

I suggest you learn what you're talking about before you make yourself
look even sillier.

Jerry, let me put you out of your misery.

The peak power capability of coax is not set by the ohmic losses but by
the breakdown voltage, that is where the ~30 ohms for best max power
handling comes from.


Which has absolutely nothing to do with what we were discussing. And
breakdown voltage of the coax is dependent on the dielectric only
(material and thickness). While these will affect impedance, saying 30
ohm impedance is the "best" impedance is not true.

The max *average* power capability is governed by heating of the cable
due to the losses per until length (both resistive and reactive). The
losses being proportional not the the cross sectional area of the
conductors but to *surface* area (due to skin depth considerations).


Which is directly related to the square of the current through the coax.
The lower the impedance of the coax, the higher the current for the
same power.

Now whilst it is true that 75ohm cable will have marginally lower loss
than 50 ohm cable, this is only true when the inner conductor diameter
is kept constant and the 75 ohm cable hase a larger shield diameter. For
cables with the same outside diameter the losses for 75ohm are greater
due to the smaller diameter (and hence lower surface area) of the inner.

So in practical terms for the same size cable 50 ohm has lower loss,
greater average power capability, and greater peak power capability.

If you don't believe me these figures can be easily verified by looking
at the specs of 50 & 75 ohm cable of the same shield diameter.

Jeff

But as I said - you're the man. You are able to interpret this chart
and contradict every physics textbook, engineer and professor in the
world. You are the expert!

NOT!

--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

On 1/12/2014 12:40 PM, Jeff Liebermann wrote:
On Sun, 12 Jan 2014 11:31:23 -0500, Jerry Stuckle
wrote:

On 1/11/2014 11:51 PM, Jeff Liebermann wrote:
On Sat, 11 Jan 2014 19:41:20 -0500, Jerry Stuckle
wrote:

I didn't say they were unknown. Just that professional integrators
(including us) use better quality connectors.

Could I trouble you for a photo or part number for the crimp type F
connectors that you are using? I want to see what I'm missing.

I can't post an image to the list, and distributors websites require
logins. It won't do you any good anyway - you won't find them on ebay
and the link. Sale is restricted by the manufacturers to professionals.

Ah, secret sauce. A secret connector manufacturer and model number
obtainable only from a secret distributor. No doubt made exclusively
for professionals. The secret manufacturer probably made you sign an
NDA before he would sell you the connectors. He can't have
unprofessional hams using his secret connectors. The unobtainium
plating probably makes it difficult for you to take a photograph and
post it.


Nope, professional grade connectors which are only available to
professionals. But you obviously know more than the professionals about
our business and our product.

We know what is good and what is not. You don't need to tell us our job.

That's the problem. You haven't said anything about what you do, what
type of systems you work on, how you do it, what connectors you use,
what tools you use, where you obtain them, and the relative merits of
your system to those in use by Comcast and Charter. You offer nothing
that can be used, except that everything that I've been doing is
wrong, that every connector that I use is junk, and that everyone in
your area uses secret connectors and has magic cutters that last
nearly forever.


No, and it doesn't matter. But even though you don't know, you know
better then I what I do, and what components I should be using.

Sorry. I don't use the cheap stuff available to you. No, they're not
"secret sauce". But they aren't available on Ebay (or at Radio Shack).

And unlike what you have told me, I haven't said ANYTHING you do is
wrong. Neither did I say anything you use is junk. I just said
PROFESSIONALS don't use it.

You might know what is good for "professionals", but I have no clue
what that might be. For me, questioning authority, trying something
different, and testing assumptions is a learning experience. I'm
doing a 10 year running experiment on the effectiveness of using 1"
PTFE wrap over commodity RF connectors for waterproofing. I'm testing
75 ohm coax where 50 ohms is standard. I use F connectors in a ham
radio environment for which they were never intended. I've designed
and build some rather odd antennas. I question and verify
conventional wisdom, claims, standards, test results, and
specifications. I've made both big and small mistakes, irritated the
experts, and occasionally inspired vendors into modifying their data
sheets and claims. I look for new ideas that I can use (or steal) and
had hoped that perhpas your secret F connector was in some way better
than the common Snap-n-Seal connector. I'm disappointed.



But you seem to be telling me left and right what I should and should
not be using.

You want to learn? Go to school. Learn what professionals use.

I'm not about to waste my time here on usenet trying to educate someone
who argues with everything I say.

I'm outta here.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On Sun, 12 Jan 2014 16:32:40 -0500, Jerry Stuckle
wrote:

Nope, professional grade connectors which are only available to
professionals.

Please advise when you are able to identify or photograph your secret
connectors. I would also be interested in the name of your
distributor that has a private stock of professional only connectors,
but since I don't intend to buy from them, that's optional.

But you obviously know more than the professionals about
our business and our product.

I've been very careful to only mention what I do, and what the local
cable companies are doing. My only suggestion to you was to measure
the loss and view the reflections of an "impedance bump" artificially
produced with a squashed coax cable. If you would like me to tell you
how to run your business and manage your product, please email for my
list of services and I will provide an estimate.

No, and it doesn't matter. But even though you don't know, you know
better then I what I do, and what components I should be using.

True. I know nothing about what you are doing, what you are using,
and how you are doing it. Most commonly, you only indicate what you
are NOT doing. That's not very helpful.

But you seem to be telling me left and right what I should and should
not be using.

See above. Except for testing your "impedance bump" theory of
attenuation, I haven't told you what you should be doing or using. I
normally charge for commercial advice.

You want to learn? Go to school. Learn what professionals use.

That probably wouldn't be a bad idea if I had the time. I could use
some more wallpaper. However, if I do go back to skool, it will
probably be to teach. Learning how to use compression connectors does
not require a class. There are YouTube videos and instruction
documents that are more than adequate. Some people learn best from a
formal classroom education. I do better getting my hands dirty.

I'm not about to waste my time here on usenet trying to educate someone
who argues with everything I say.

It's called a discussion, which has been interesting, but not very
informative.

I'm outta here.

Please come back when you are able to identify your secret connectors.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 12 Jan 2014 11:48:13 -0500, Jerry Stuckle
wrote:

I'm not talking about fiber, and I'm not talking about some half-assed
gadget cooked up in your basement. I'm talking about a real,
professional-grade TDR.

Make and model please?

I used to drag around a Tek 1503 but rarely used it. It was most
useful for find broken cables, usually where the rats chewed through
the wires. Also, for measuring the length of cables on a roll that
didn't have ft markers. One day, I needed it, and it was dead,
probably from bouncing around in my truck. Rather than fix it, I sold
it as-is.
http://www.ebay.com/itm/131091152872
I was already carrying a scope, so I saw no reason to buy another
scope just to get a TDR. So, I designed and built a TDR, mostly
checking CAT5 and telco wires, not coax. Something like this:
http://www.epanorama.net/circuits/tdr.html

We use expensive stuff because it gives accurate results.

I use cheap stuff because I know its limitations and can work within
those limitations. Much as I value my money, old test equipment is
good enough for most things.
http://www.learnbydestroying.com/jeffl/pics/home/slides/test-equip-mess.html

You stated that the losses come primarily from the "impedance bump"
presumably produced by the non-50 ohm connector or adapter in the
line. Well, time to put that to the test.

I didn't say anything about a non-50 ohm connector. The connector can
be 50 ohm and still get an impedance bump. With a TDR you can see every
connector on the cable (as long as they are far enough apart - typically
3-4 feet).

If the connectors were a prefect 50 ohms, you wouldn't see any
reflection. Therefore, either the connectors are not quite 50 ohms,
your coax is not quite 50 ohms, you have a high resistance shield
connection, or this is one of your cases where theory fails to
accommodate your reality.

That's theoretical. Reality is much the same.

First of all, we don't crush cables to try to emulate something we can
easily see in real life.

I crush, chop, dissect, and set fire to cable to see how they're
built. Amazing what you find if you look inside of things. However,
since you have an aversion to crushing coax able, you can get the same
effect with a short length of different impedance coax cable and some
adapters. Just insert where I suggested you crush the coax, and you
should see it clearly on the TDR. Then replace it with an identical
length of the correct impedance cable and compare the losses. At
worst, the loss difference will be fractions of a dB. That suggests
that your "impedance bump" isn't really responsible for much loss.

Of course, you have set fire to plenum, non-plenum, and riser CAT5
cables to see how they burn. I think you might be surprised. Learn
by Destroying(tm).

Second of all, you can gimmick up something all you want with signal
generators, spectrum analyzers, crushed cables, all you want.

For those that believe theory, proof by bench testing is possible. For
those who do not believe or understand theory, no amount of test
equipment will ever prove anything. Theory and testing go hand in
hand. If there's a discrepancy, then either one of them is wrong, or
the procedure is flawed.

We SEE the results in real time in real installations with the
appropriate test equipment.

You see the results, but for some odd reason, I haven't seen your
results or list of appropriate professional test equipment. Why
always so vague and non-specific? FoN (Fear of Numbers)?

So? Dipoles aren't 50 ohm antennas. They're typically closer to 75 ohm.

I guess you missed my point. If you can tolerate the 1.5:1 VSWR, the
reduced attenuation and cost of 75 ohm coax makes the effort
worthwhile.

No, it's worthwhile because your coax will more closely match the
antenna. And you can easily match the coax to the transmitter with a tuner.

Tuners can be lossy. Try this T-tuner Java app on the lower bands.
http://fermi.la.asu.edu/w9cf/tuner/tuner.html
The starting values (hit the AutoTune button) produce a 2dB loss at
160 meters. The losses are much less on the higher bands. Q=100 for
the inductor seems a bit high.

Please re-read the article:
www.belden.com/blog/broadcastav/50-Ohms-The-Forgotten-Impedance.cfm
http://www.microwaves101.com/encyclopedia/why50ohms.cfm

I read the article. Unlike you, I understand what it is saying.

What part of the following do you disagree with and why? (It's all in
the above articles). Please try to be specific:
1. Loss for approximately equal size is less for 75 ohm cable.
2. 50 ohm cable will tolerate a higher power due to a higher voltage
breakdown.
3. Maximum power is with about 30 ohm coax cable.
http://www.microwaves101.com/encyclopedia/coax_power.cfm
4. Mismatch loss from 75 ohm cable in a 50 ohm system is 0.18dB.
5. If the mismatch loss from using 75 ohm cable is less than the
difference in attenuation for a comparable 50 ohm cable, and there are
no high power levels involved, then it is better to use 75 ohm cable
and tolerate the mismatch.

You don't know our installations. We've been in business for several
years, with lots of satisfied customers. Trying to tell a professional
what their job is only makes you look stupid.

I only debate a persons ideas and never attack them personally. If
you are unable to do that, you lack "professionalism" which presumably
goes with your professional title.

No MoCA installations?
http://www.mocalliance.org

Nope. It's used by few professionals. Coax ends up with too many
problems. Category cable for runs under 100M or so and fiber for longer
runs.

Fiber is generally better and much more expensive. I also do fiber
where possible. However, when faced with a large apartment complex,
with no possible way to economically rewire the building, I was forced
to consider what could be done with the existing wiring. The building
had CAT3 going to all the apartments, but CAT3 is useless (no twists).
Even DSL had crosstalk problems. I tried to use the CAT3 as a pull
line to drag in CAT5, but that also failed (no smurf tubes in the
walls). I also tried 2.4/5.7 wireless, which proved erratic because
of aluminum foil backed insulation, untouchable firewalls, and
interference from existing Wi-Fi systems.

So, I tired MoCA and it worked.
http://www.netgear.com/service-providers/products/in-home-connectivity/moca-bridges/
http://www.netgear.com/service-providers/products/in-home-connectivity/moca-bridges/wm2500rp.aspx
They're now bringing in Comcast TV, internet, and phone via coax,
using MoCA to distribute internet around each apartment. Depending on
wiring, Jperf shows about 100-300 Mbits/sec between clients (16
maximum). Speedtest shows whatever was ordered from Comcast from/to
the internet, typically 22/2 Mbit/sec.

To be honest, things did not go smoothly. MoCA is expensive. The
isolation between apartments on the main Comcast splitter was not
enough to prevent leakage between bridges. Using couplers instead of
splitters were a big help. I also needed to select a different
channel, which is not allowed by every MoCA unit. I started with
Actiontek, which was cheaper, but does NOT offer channel selection and
was therefore useless. Some of the apartments had satellite TV, which
had to be accommodated with diplexers. However, the worst problem was
that I rapidly became the single point of contact for any problem with
the system. Fortunately, I was conveniently underbid for the
maintenance contract by another service company, which has taken over
the system. To the best of my knowledge, it's still running nicely
after about 18 months.

Next time you run into a situation that does not economically allow a
retrofit of fiber or CAT5/6, and there's existing coax, think about
MoCA.

Find a different distributor or ask for it by part number.
Thomas and Betts SNS1P6U.

We use several distributors - both U.S. and international companies.

Did you any of them if they specifically carry T&B or stock T&B
SNS1P6U connectors? Where we left off, you were having difficulties
finding a stocking distributor. Are either of your unspecified
distributors on the T&T distributor search page?
http://www.tnb.com/ps/dls/dls?ca=corp
Within 25 miles of your location, it shows 5 stocking distributors
with 13 locations.

Quick check: Stocked by Allied, Newark, Tessco, Farnel(UK), MCM.
Not stocked by Digikey, Mouser, Arrow.

T&B distributor search:
http://www.tnb.com/ps/dls/dls?ca=corp

These are consumer (retail) outlets. They are not used by most
professionals.

None of those listed above have a retail (brick and mortar) store.
Many do sell online and from catalogs, but even the largest
distributors do that. Legally, if they charge sales tax, they are a
"retail" operation. Offhand, I can't think of a single large
distributor that does not accept taxable sales or requires a resale
permit in order to process an order. There used to be those as B2B
(business to business) operations, but not any more, because the
growth of internet commerce has made retail processing a necessity.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 1/12/2014 7:24 PM, Jeff Liebermann wrote:
On Sun, 12 Jan 2014 11:48:13 -0500, Jerry Stuckle
wrote:

I'm not talking about fiber, and I'm not talking about some half-assed
gadget cooked up in your basement. I'm talking about a real,
professional-grade TDR.

Make and model please?


It's in my office, and not my lap. And quite frankly, I'm not about to
go out of my way to follow up because it's none of your business.

You're trolling now, and I don't respond to trolls.

rest of garbage snipped because it just proves you have no idea what
you're talking about.

One other comment. No, you won't go back to school not because you
don't need another piece of paper on the wall. You already think you
know everything. And it just might ruin your day to find out how wrong
you are.

--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

On Sun, 12 Jan 2014 21:10:17 -0500, Jerry Stuckle
wrote:

On 1/12/2014 7:24 PM, Jeff Liebermann wrote:
On Sun, 12 Jan 2014 11:48:13 -0500, Jerry Stuckle
wrote:

I'm not talking about fiber, and I'm not talking about some half-assed
gadget cooked up in your basement. I'm talking about a real,
professional-grade TDR.

Make and model please?

It's in my office, and not my lap. And quite frankly, I'm not about to
go out of my way to follow up because it's none of your business.

No doubt a private label TDR made especially for professionals and
considered a trade secret by it owners. Gosh, I want one of those.

You're trolling now, and I don't respond to trolls.

Not exactly trolling but close. I'm asking you to substantiate your
claims and to supply specific makers and model numbers.

rest of garbage snipped because it just proves you have no idea what
you're talking about.

One other comment. No, you won't go back to school not because you
don't need another piece of paper on the wall. You already think you
know everything.

I'm not sure I can decode your comment with it's 3 negations. I said
that I *DO* need another piece of paper for my wall. My 2013 calendar
expired last week, and I need something to fill the wall space.
Obtaining a new 2014 calendar is both costly and time consuming. It's
easier to just fill the space with another diploma.
www.ebay.com/sch/i.html?_nkw=fake+university+diploma

And it just might ruin your day to find out how wrong
you are.

You first, then you can cross examine me. You stated that I don't
understand the two articles on 50 versus 75 ohms. You also stated
that you do understand the articles. Then please explain them to me.
The following are my claims, all derived from the articles. Where in
the following am I wrong and why?

1. Loss for approximately equal size is less for 75 ohm cable.
2. 50 ohm cable will tolerate a higher power due to a higher voltage
breakdown.
3. Maximum power is with about 30 ohm coax cable.
http://www.microwaves101.com/encyclopedia/coax_power.cfm
4. Mismatch loss from 75 ohm cable in a 50 ohm system is 0.18dB.
5. If the mismatch loss from using 75 ohm cable is less than the
difference in attenuation for a comparable 50 ohm cable, and there are
no high power levels involved, then it is better to use 75 ohm cable
and tolerate the mismatch.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558