Topics

OT: High Frequency coax?? Copper tubing??

tinkera123
 

Thanks to all who responded ... I now have a better general understanding of this ... and plenty of reference material to ponder.

Reg ... yes, my R&S SMS Signal Generator in the Rubbish Dump was a good find .... it will be better if I can get it working properly. The friend who found it, finds a lot of electronics stuff eg. a BC-348 R (your WW2 radio) which is waiting for me to bring it back to life, other radios, audio amps, a fully working 'entry level' dual trace scope, Heathkit Signal Generators and MiniLab etc etc.. Unfortunately, no Tek Scopes or Plugins as yet ... :)

Many thanks,
Ian

GerryR
 

Dennis,
Thank you again, but just for the record, I was not referring to Leo's design. When I went to his website, I realized that his design was much different than the tunnel diode pulser. It was actually a designer (I don't know his name) that uses tunnel diodes (I believe from a Russian source) in his pulser, so I assumed it was a copy or similar design of the old Tek pulser. These subtleties in the designs, which make all the difference in performance, are rarely explained in detail. I realize that certain aspects of a design must remain proprietary for marketing reasons, but as "they" say, the devil is in the details, and that's what interests me. Thank you for your explanation; it will be added to my file of notes on the Tek pulser.
Best regards,
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
To: <TekScopes@groups.io>
Sent: Sunday, November 03, 2019 7:40 PM
Subject: Re: [TekScopes] OT: High Frequency coax?? Copper tubing??


Hi Gerry,
I'm going to go out on a limb and guessing you are talking about the Leo Bodnar Pulser and the Tektronix 067-0681-01 Calibration Fixture Tunnel Diode Pulser designed by a legendary engineer at Tektronix, John Addis, who spent much of his career understanding and designing high speed vertical amplifiers.

Making a fast rise pulse generator is actually pretty simple. Controlling the aberrations is where the skill comes in. I introduced Leo to John because I thought Leo might benefit from John's experience particularly when it came to reducing aberrations on the leading and trailing edges. They did share many emails discussing circuit changes that would improve the performance of Leo's Pulser. Some were easy to incorporate into the design. Some changes resulted in tradeoffs that would require building many actual prototypes to evaluate which would be very time consuming. Other changes would result in increases in cost that might have an adverse impact on sales.

John's tunnel diode design incorporates some very subtle design features that aren't obvious such as three 1K 1/8W resistors in series (this eliminates the inductance and capacitance that a 3K 1/4W resistor has) which further reduces the aberrations. The BNC output connector is special as well. Nearly all BNC connectors are assumed to be 50 ohms but they are actually 51 to 52 ohms and poorly specified by their manufacturers. Tek made actual BNCs that are 50.0 ohms for their TD Pulser to reduce aberrations caused by the impedance mismatch. Tek placed the TD right between the center pin and the case of the BNC to further reduce aberrations. On several occasions manufacturing actually relaxed John's requirement on keeping the TD leads as short as possible because it was too time consuming. The result was an increase in aberrations that John found out about. He quickly put a stop to it.

Leo took an entire different approach which takes advantage of readily available semiconductor devices made today. If I am not mistaken Leo used extremely fast current mode optical driver ICs. They have their own advantages and have been steadily improving over time. It is entirely possible they will one day outperform the aberration specs of the TD Pulser. The BNCs that are sold today are not capable of more than a few GHz and they are still poorly specified. Today's SMA connectors are routinely capable of
14GHz and they are well specified. The capabilities of sampling scopes have
improved dramatically since John designed the TD Pulser. Leo has the benefit of being able to take advantage of those scopes as well as high speed pulse circuit design software that didn't exist when John designed his TD Pulser.

It is no accident that the fastest Tek sampling heads (S-4 and S-6) have SMA connectors on them. I urged Leo to replace the BNC on his original design with an SMA connector. I was aware it would result in an inconvenience for some people but I felt Leo's goal should always be to create a reasonably priced pulse generator with the fastest possible rise time and the minimum aberrations. Buyers can always attach an inexpensive SMA to BNC adapter to it if convenience is more important than speed.

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 2:22 PM

Thanks Dennis,
After I asked the question I did look up the cable and found out its characteristics. I've spent most of my career (now retired) in industrial electronics / control systems, so some RF stuff still puzzles me.
For instance, recently I inquired about a tunnel diode pulser from a person who makes them. He stated that he offered them with SMA connectors; I wanted BNC connectors. He told me that he couldn't get the response with the BNC's that he can get with the SMA's, yet Tektronix offered (at one
time) a tunnel diode pulser that had a better response than what he offered, with BNC connectors. Why? Thus, my question as to why the semi-rigid cable is so much better at the higher frequencies? Just curious. Thanks, again; I didn't mean for anyone to do my homework for me.
Best regards,
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
To: <TekScopes@groups.io>
Sent: Sunday, November 03, 2019 4:54 PM
Subject: Re: [TekScopes] OT: High Frequency coax?? Copper tubing??

Hi Gerry,
Every general class ham should have a coax chart at your fingertips
somewhere. Personally I prefer the quickly accessible Wikipedia article on
Coaxial Cable at https://en.wikipedia.org/wiki/Coaxial_cable. It contains a
very detailed chart listing a very large number of coax types and all of the
important parameters anyone would need to compare them all.

It says the insulator / dielectric for RG-402 and RG-405 is PTFE (aka
Teflon).

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 11:15 AM

I'm not at all familiar with this type of coax. What is the core material,
and what makes it so good at the higher frequencies?
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
Sent: Sunday, November 03, 2019 1:46 PM

These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used
to. Tools to cut it properly and to bend it properly are expensive. Using
common tools to cut it like a pipe cutter, and to bend it like an
inexpensive bending jig, will almost certainly affect the high frequency
performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is
great stuff provided you don't want to bend it more than once. Though
rebending used cables is OK. The solder filled braid "RG402" has become my
standard cable for anything above 1 GHz. I've made a couple of H field
probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been
documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now
that I have an APC-7 cal kit and adapters.
Have Fun!
Reg




--
Dennis Tillman W7PF
TekScopes Moderator

 

Hi Gerry,
I'm going to go out on a limb and guessing you are talking about the Leo Bodnar Pulser and the Tektronix 067-0681-01 Calibration Fixture Tunnel Diode Pulser designed by a legendary engineer at Tektronix, John Addis, who spent much of his career understanding and designing high speed vertical amplifiers.

Making a fast rise pulse generator is actually pretty simple. Controlling the aberrations is where the skill comes in. I introduced Leo to John because I thought Leo might benefit from John's experience particularly when it came to reducing aberrations on the leading and trailing edges. They did share many emails discussing circuit changes that would improve the performance of Leo's Pulser. Some were easy to incorporate into the design. Some changes resulted in tradeoffs that would require building many actual prototypes to evaluate which would be very time consuming. Other changes would result in increases in cost that might have an adverse impact on sales.

John's tunnel diode design incorporates some very subtle design features that aren't obvious such as three 1K 1/8W resistors in series (this eliminates the inductance and capacitance that a 3K 1/4W resistor has) which further reduces the aberrations. The BNC output connector is special as well. Nearly all BNC connectors are assumed to be 50 ohms but they are actually 51 to 52 ohms and poorly specified by their manufacturers. Tek made actual BNCs that are 50.0 ohms for their TD Pulser to reduce aberrations caused by the impedance mismatch. Tek placed the TD right between the center pin and the case of the BNC to further reduce aberrations. On several occasions manufacturing actually relaxed John's requirement on keeping the TD leads as short as possible because it was too time consuming. The result was an increase in aberrations that John found out about. He quickly put a stop to it.

Leo took an entire different approach which takes advantage of readily available semiconductor devices made today. If I am not mistaken Leo used extremely fast current mode optical driver ICs. They have their own advantages and have been steadily improving over time. It is entirely possible they will one day outperform the aberration specs of the TD Pulser. The BNCs that are sold today are not capable of more than a few GHz and they are still poorly specified. Today's SMA connectors are routinely capable of >14GHz and they are well specified. The capabilities of sampling scopes have improved dramatically since John designed the TD Pulser. Leo has the benefit of being able to take advantage of those scopes as well as high speed pulse circuit design software that didn't exist when John designed his TD Pulser.

It is no accident that the fastest Tek sampling heads (S-4 and S-6) have SMA connectors on them. I urged Leo to replace the BNC on his original design with an SMA connector. I was aware it would result in an inconvenience for some people but I felt Leo's goal should always be to create a reasonably priced pulse generator with the fastest possible rise time and the minimum aberrations. Buyers can always attach an inexpensive SMA to BNC adapter to it if convenience is more important than speed.

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 2:22 PM

Thanks Dennis,
After I asked the question I did look up the cable and found out its characteristics. I've spent most of my career (now retired) in industrial electronics / control systems, so some RF stuff still puzzles me.
For instance, recently I inquired about a tunnel diode pulser from a person who makes them. He stated that he offered them with SMA connectors; I wanted BNC connectors. He told me that he couldn't get the response with the BNC's that he can get with the SMA's, yet Tektronix offered (at one
time) a tunnel diode pulser that had a better response than what he offered, with BNC connectors. Why? Thus, my question as to why the semi-rigid cable is so much better at the higher frequencies? Just curious. Thanks, again; I didn't mean for anyone to do my homework for me.
Best regards,
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
To: <TekScopes@groups.io>
Sent: Sunday, November 03, 2019 4:54 PM
Subject: Re: [TekScopes] OT: High Frequency coax?? Copper tubing??

Hi Gerry,
Every general class ham should have a coax chart at your fingertips
somewhere. Personally I prefer the quickly accessible Wikipedia article on
Coaxial Cable at https://en.wikipedia.org/wiki/Coaxial_cable. It contains a
very detailed chart listing a very large number of coax types and all of the
important parameters anyone would need to compare them all.

It says the insulator / dielectric for RG-402 and RG-405 is PTFE (aka
Teflon).

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 11:15 AM

I'm not at all familiar with this type of coax. What is the core material,
and what makes it so good at the higher frequencies?
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
Sent: Sunday, November 03, 2019 1:46 PM

These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used
to. Tools to cut it properly and to bend it properly are expensive. Using
common tools to cut it like a pipe cutter, and to bend it like an
inexpensive bending jig, will almost certainly affect the high frequency
performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is
great stuff provided you don't want to bend it more than once. Though
rebending used cables is OK. The solder filled braid "RG402" has become my
standard cable for anything above 1 GHz. I've made a couple of H field
probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been
documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now
that I have an APC-7 cal kit and adapters.
Have Fun!
Reg




--
Dennis Tillman W7PF
TekScopes Moderator

Reginald Beardsley
 

On Sun, Nov 3, 2019 at 12:46 PM, Dennis Tillman W7PF wrote:


These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used to.
Tools to cut it properly and to bend it properly are expensive. Using common
tools to cut it like a pipe cutter, and to bend it like an inexpensive bending
jig, will almost certainly affect the high frequency performance of whatever
you make.

Dennis Tillman W7PF
I've not made up any cables yet, but I have bent it by hand. I've been using TDR, so I don't have the dynamic range of a VNA, but I've never seen a reflection from a bend which was even within an order of magnitude of the connectors.

The UCB EE department uses soldered braid RG402 for cables for student use. They do point out that the cables are not phase stable and to tape the cable down before doing a cal and inserting the DUT. There is a very good document about making up RG402 SMA cables from UCB, but google is unable to find it at the moment.

Properly ending the solid tube cable only requires a suitable equivalent of a copper tubing bender. It *does* require bending dies of the proper diameter and radius. They need not be expensive, but they often are because the buyer is not spending their own money. Also, bear in mind that it *only* gets difficult if you are working with very wide BW.

Cutting it is a bit more fiddly as tubing cutters deform the outer shield, but there is nothing about it that requires expensive tools. An Exacto or jeweler's saw works fine. However,you *do* need to understand what you are doing and the constraints imposed by Maxwell's laws.

Reg

GerryR
 

Thanks Dennis,
After I asked the question I did look up the cable and found out its characteristics. I've spent most of my career (now retired) in industrial electronics / control systems, so some RF stuff still puzzles me. For instance, recently I inquired about a tunnel diode pulser from a person who makes them. He stated that he offered them with SMA connectors; I wanted BNC connectors. He told me that he couldn't get the response with the BNC's that he can get with the SMA's, yet Tektronix offered (at one time) a tunnel diode pulser that had a better response than what he offered, with BNC connectors. Why? Thus, my question as to why the semi-rigid cable is so much better at the higher frequencies? Just curious. Thanks, again; I didn't mean for anyone to do my homework for me.
Best regards,
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
To: <TekScopes@groups.io>
Sent: Sunday, November 03, 2019 4:54 PM
Subject: Re: [TekScopes] OT: High Frequency coax?? Copper tubing??


Hi Gerry,

Every general class ham should have a coax chart at your fingertips somewhere. Personally I prefer the quickly accessible Wikipedia article on Coaxial Cable at https://en.wikipedia.org/wiki/Coaxial_cable. It contains a very detailed chart listing a very large number of coax types and all of the important parameters anyone would need to compare them all.

It says the insulator / dielectric for RG-402 and RG-405 is PTFE (aka Teflon).

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 11:15 AM

I'm not at all familiar with this type of coax. What is the core material, and what makes it so good at the higher frequencies?
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
Sent: Sunday, November 03, 2019 1:46 PM

These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used
to. Tools to cut it properly and to bend it properly are expensive. Using
common tools to cut it like a pipe cutter, and to bend it like an
inexpensive bending jig, will almost certainly affect the high frequency
performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is
great stuff provided you don't want to bend it more than once. Though
rebending used cables is OK. The solder filled braid "RG402" has become my
standard cable for anything above 1 GHz. I've made a couple of H field
probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been
documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now
that I have an APC-7 cal kit and adapters.
Have Fun!
Reg
--
Dennis Tillman W7PF
TekScopes Moderator




--
Dennis Tillman W7PF
TekScopes Moderator

 

Hi Gerry,

Every general class ham should have a coax chart at your fingertips somewhere. Personally I prefer the quickly accessible Wikipedia article on Coaxial Cable at https://en.wikipedia.org/wiki/Coaxial_cable. It contains a very detailed chart listing a very large number of coax types and all of the important parameters anyone would need to compare them all.

It says the insulator / dielectric for RG-402 and RG-405 is PTFE (aka Teflon).

Dennis Tillman W7PF

-----Original Message-----
From: GerryR
Sent: Sunday, November 03, 2019 11:15 AM

I'm not at all familiar with this type of coax. What is the core material, and what makes it so good at the higher frequencies?
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
Sent: Sunday, November 03, 2019 1:46 PM

These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used
to. Tools to cut it properly and to bend it properly are expensive. Using
common tools to cut it like a pipe cutter, and to bend it like an
inexpensive bending jig, will almost certainly affect the high frequency
performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is
great stuff provided you don't want to bend it more than once. Though
rebending used cables is OK. The solder filled braid "RG402" has become my
standard cable for anything above 1 GHz. I've made a couple of H field
probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been
documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now
that I have an APC-7 cal kit and adapters.
Have Fun!
Reg
--
Dennis Tillman W7PF
TekScopes Moderator




--
Dennis Tillman W7PF
TekScopes Moderator

GerryR
 

I'm not at all familiar with this type of coax. What is the core material, and what makes it so good at the higher frequencies?
GerryR
KK4GER

----- Original Message -----
From: "Dennis Tillman W7PF" <@Dennis_Tillman_W7PF>
To: <TekScopes@groups.io>
Sent: Sunday, November 03, 2019 1:46 PM
Subject: Re: [TekScopes] OT: High Frequency coax?? Copper tubing??


These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used to. Tools to cut it properly and to bend it properly are expensive. Using common tools to cut it like a pipe cutter, and to bend it like an inexpensive bending jig, will almost certainly affect the high frequency performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is great stuff provided you don't want to bend it more than once. Though rebending used cables is OK. The solder filled braid "RG402" has become my standard cable for anything above 1 GHz. I've made a couple of H field probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now that I have an APC-7 cal kit and adapters.
Have Fun!
Reg




--
Dennis Tillman W7PF
TekScopes Moderator

 

These two sizes of Semi-Rigid Copper Coax cable are very common:
RG-402 which is 3.58mm OD (0.141" OD)
RG-405 which is 2.20mm OD (0.0865" OD)

Working with it is very different compared to typical coax we are all used to. Tools to cut it properly and to bend it properly are expensive. Using common tools to cut it like a pipe cutter, and to bend it like an inexpensive bending jig, will almost certainly affect the high frequency performance of whatever you make.

Dennis Tillman W7PF

-----Original Message-----
From: Reginald Beardsley
Sent: Sunday, November 03, 2019 9:01 AM

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is great stuff provided you don't want to bend it more than once. Though rebending used cables is OK. The solder filled braid "RG402" has become my standard cable for anything above 1 GHz. I've made a couple of H field probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been documenting my efforts in this thread:
https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now that I have an APC-7 cal kit and adapters.
Have Fun!
Reg




--
Dennis Tillman W7PF
TekScopes Moderator

Reginald Beardsley
 

Ian,

I put together some quick examples for you as I have everything sitting next to me. Have a look at this:

https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2768098/#msg2768098

The Tek 11801/SD-24/SD-26 setup I used has a frequency response to 20 GHz. In the top photo you're seeing the reflection responses for the 3 open cables. The SD-24 produces a <19 ps rise time 100 kHz square wave. The low frequency of the square wave allows testing very long cables. The fast rise time allows testing to 20 GHz.

The lower scope photo shows both the reflection and the thru. Reflection is the shorter step delay and thru the longer step delay.

My first encounter with SMA connectors was an HP 8601A. Because they are small, cheap and have lots of BW they have become the default choice for lots of Chinese modules on ebay.

If you look through the thread you'll see various adapter and connector combinations. The wider the reflection bumps, the lower the frequency that unit can pass. The SMA-F/N-F connector comparisons shows that my ebay Chinese versions are only good up to 1 GHz. But both my rigs only go up to the 70 cm ham band at 430 MHz, so they will do just fine for antenna switching using Radiall ST6P SMA relays.

A bump downwards is capacitive reactance and a bump upwards is inductive reactance. The width of the bump shows the approximate cutoff frequency. At best BNC is usable to 3-4 GHz, but only if they are very good quality and are fairly new. The marvelous thing about TDR, is that every discontinuity appears in sequence from left to right. So you can tell if it's the cable to connector or the connector to connector interface.

Cycle limit on SMA connectors is typically 500 connections. Pretty much all test gear has used SMA internally for connections to the exterior bulkhead connectors for many years. It makes replacing worn bulkhead connectors easy. The exception would be things that go too high to use SMA. At which point the connectors get *very* expensive.

Certainly in my view the question is appropriate here. It's a really fine group of people most of whom also follow the HPAK list. I just wish I could fish an R&S SMS out of the trash. :-)

BTW There is an R&S group in the process of moving from yahoo to groups.io.

Have Fun!
Reg

Reginald Beardsley
 

Here's a representative link for the information you're looking for:

http://www.sumlocable.com/sub_product/rg401-rg402rg405-semi-rigid-43.html

There's lots more. This was simply the first one google tossed up. It is great stuff provided you don't want to bend it more than once. Though rebending used cables is OK. The solder filled braid "RG402" has become my standard cable for anything above 1 GHz. I've made a couple of H field probes from a used piece of high grade stuff.

Connector quality on Chinese ebay jumpers is rather variable. I've been documenting my efforts in this thread:

https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/

I will be supplementing the TDR results with 8753B/85046A testing soon now that I have an APC-7 cal kit and adapters.

Have Fun!
Reg

Jeff Kruth
 

Called "Semi-rigid coax" usually 50 ohm, diameters of .250,.141,.085 &.047 inch are fairly common and have connector families available. There are other sizes and impedances, of course. Very common in microwave-UHF gear. Made by Uniform Tube (UT-141 is very common) and others. Now a re-bendable style has become common, called "reformable" basically began as solder filling coax braid. 

Jeff Kruth
Hope this helps.

In a message dated 11/2/2019 8:02:34 PM Eastern Standard Time, @tinkera123 writes:
Hi,This question is related to my Rohde and Schwarz SMS Signal Generator (rescued from a Rubbish Dump).  There is some type of coax or copper tubing in this Signal Generator which I am unsure about.  There are several photos in the following Album ...  https://groups.io/g/TekScopes/album?id=130642 ....  specifically photo "Rohde and Schwarz.... 1007"  Although this is not related to my current problem with its PSU, I would like to understand what this tubing is. My Google searching has led to discussions about limitations of coax and BNC's, and waveguides at GHz frequencies etc, but I do not understand this in the context of a 520MHz Signal Gen and that the the lower tubing in photo "1009" terminates on the rear panel at a BNC.Any explanations or 'pointing me in the right direction' would be appreciated.My apologies if this is too far off-topic, but this is one Forum I trust where the appropriate expertise resides..-- Cheers,Ian,Melbourne, Australia

tinkera123
 

Hi,
This question is related to my Rohde and Schwarz SMS Signal Generator (rescued from a Rubbish Dump). There is some type of coax or copper tubing in this Signal Generator which I am unsure about. There are several photos in the following Album ... https://groups.io/g/TekScopes/album?id=130642 .... specifically photo "Rohde and Schwarz.... 1007" Although this is not related to my current problem with its PSU, I would like to understand what this tubing is.
My Google searching has led to discussions about limitations of coax and BNC's, and waveguides at GHz frequencies etc, but I do not understand this in the context of a 520MHz Signal Gen and that the the lower tubing in photo "1009" terminates on the rear panel at a BNC.
Any explanations or 'pointing me in the right direction' would be appreciated.
My apologies if this is too far off-topic, but this is one Forum I trust where the appropriate expertise resides..
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Cheers,
Ian,
Melbourne, Australia