Re: Topband: RG-6 Delay cables
"Solid" in this context means not braided, and that is what the inner bonded foil shield is in my RG-6 (actually F-6, for CATV). I left out "foil", sorry. 73 Mike W0BTU On Thu, Apr 9, 2020, 12:19 PM K9FD wrote: > Ever see RG6 with a solid aluminum shield? > > > One thing that hasn't been mentioned here is how the aluminum shield, > > jacket, and dielectric behaves. I'm pretty sure that the CoE/°F of > > aluminum is *more than twice* that of copper and steel. > > > > I am speaking specifically about a solid aluminum shield bonded to the > > dielectric. > > > > Braided shields would of course expand and contract with the rest of the > > coax. > > > > Also, many cables also have the center conductor bonded to the > dielectric. > > > > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Ever see RG6 with a solid aluminum shield? One thing that hasn't been mentioned here is how the aluminum shield, jacket, and dielectric behaves. I'm pretty sure that the CoE/°F of aluminum is *more than twice* that of copper and steel. I am speaking specifically about a solid aluminum shield bonded to the dielectric. Braided shields would of course expand and contract with the rest of the coax. Also, many cables also have the center conductor bonded to the dielectric. I am not disagreeing with anyone; I just thought that I ought to throw that into this discussion in case it matters. 73 Mike W0BTU _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
One thing that hasn't been mentioned here is how the aluminum shield, jacket, and dielectric behaves. I'm pretty sure that the CoE/°F of aluminum is *more than twice* that of copper and steel. I am speaking specifically about a solid aluminum shield bonded to the dielectric. Braided shields would of course expand and contract with the rest of the coax. Also, many cables also have the center conductor bonded to the dielectric. I am not disagreeing with anyone; I just thought that I ought to throw that into this discussion in case it matters. 73 Mike W0BTU _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
More on the cable testing, Thinking along the lines Rick was I decided to retest the same cable to see if the results were repeatable. The original phase shift for both room temperatures was 59 deg. F and 23 deg. F Results were -74.6 degrees and -0.61 dB to -74.6 deg and -0.58 dB loss warm to cold. VNA calibration was used at the start of each test again. Several hours after that test the room and cable were up to 61 deg. F . The second round of tests began. The first test of phase delay matched the early tests with -74.59 to -74.60 degrees again with loss at -0.617 dB. Very close to the original tests. I decided to add 4 inches of cable to verify small changes in the readings. The reading then was -74.89 deg with loss of -0.618 db. After freezing the cable for another couple hours the temp of it was again average 23 deg. F . Verified with a thermocouple meter and non-contact device. The cable phase delay was -74.62 deg. with a loss of -0.517 db . This leaves some question on the loss number. Perhaps some cable tightening issue or misreading. I added the same 4 inch cable to the cold cable. The result was -74.97 deg and -0.582 db loss. Loss matches the original tests. All this very respectable data with all the connector connecting and disconnecting and just finger tightening the connectors. I probably should have torqued them for the best result. As I mentioned before I think I am going to not worry about significant cable phase delay and loss changes with temperature. Regards all and thanks for the tips and the bandwidth, 73 Lee K7TJR OR On 4/8/2020 1:28 PM, Lee STRAHAN wrote: > Even if the copper center conductor expands, the way the cable connectors > are made allows the copper to simply push in the connector past the > connection point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Great job Lee 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 4/8/20 4:11 PM, Lee STRAHAN wrote: Robin WA6CDR mentioned this to me in an earlier exchange this AM. It was not me. Should have mentioned that before. Sorry Robin, You the Man! Lee K7TJR -Original Message- From: Richard (Rick) Karlquist Sent: Wednesday, April 8, 2020 2:00 PM To: Lee STRAHAN ; topband@contesting.com Subject: Re: Topband: RG-6 Delay cables On 4/8/2020 1:28 PM, Lee STRAHAN wrote: Even if the copper center conductor expands, the way the cable connectors are made allows the copper to simply push in the connector past the connection point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
RG-17 has the same problem, but the Type LC connector (a giant F connector) solved the migration problem the same way the F connector does. 73 Frank W3LPL - Original Message - From: "Richard (Rick) Karlquist" To: "Lee STRAHAN" , topband@contesting.com Sent: Wednesday, April 8, 2020 8:59:58 PM Subject: Re: Topband: RG-6 Delay cables On 4/8/2020 1:28 PM, Lee STRAHAN wrote: > Even if the copper center conductor expands, the way the cable connectors are > made allows the copper to simply push in the connector past the connection > point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
To obtain 40 dB cancellation, the maximum amplitude difference between the signals is 1% and the maximum phase difference is 8 degrees. Verzonden vanuit Mail voor Windows 10 Van: Richard (Rick) Karlquist Verzonden: woensdag 8 april 2020 23:00 Aan: Lee STRAHAN; topband@contesting.com Onderwerp: Re: Topband: RG-6 Delay cables On 4/8/2020 1:28 PM, Lee STRAHAN wrote: > Even if the copper center conductor expands, the way the cable connectors > are made allows the copper to simply push in the connector past the > connection point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Robin WA6CDR mentioned this to me in an earlier exchange this AM. It was not me. Should have mentioned that before. Sorry Robin, You the Man! Lee K7TJR -Original Message- From: Richard (Rick) Karlquist Sent: Wednesday, April 8, 2020 2:00 PM To: Lee STRAHAN ; topband@contesting.com Subject: Re: Topband: RG-6 Delay cables On 4/8/2020 1:28 PM, Lee STRAHAN wrote: > Even if the copper center conductor expands, the way the cable connectors > are made allows the copper to simply push in the connector past the > connection point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
On 4/8/2020 1:28 PM, Lee STRAHAN wrote: Even if the copper center conductor expands, the way the cable connectors are made allows the copper to simply push in the connector past the connection point maintaining its physical length. Very astute. You may have explained this paradox. I didn't think of this type F effect. Some type N connectors also work this way. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Hi Rick, Agreed, the numbers surely seemed too good to be true. I also researched cable delays versus temperature at various manufacturers. I found no data at the low bands we use. I found just enough information to make me do the test. I am confident the answers I recorded are correct. I did not look at higher frequencies with the VNA. Teflon cable is the only one I found that had a nonlinear curve so rejected that idea as I don’t use Teflon for this. There are way too many things going on with the cable construction to estimate in my mind. That’s why I did the test. I also reaffirmed that after the cold test the cable loss returned to the starting point. Perhaps someone else would care to look at the cable. Even if the copper center conductor expands, the way the cable connectors are made allows the copper to simply push in the connector past the connection point maintaining its physical length. Again way to many things and so I did the tests. I think I will put the cable in the freezer again and do the tests again which seems like the right thing to do. Am confident the VNA is accurate. I have some short pieces of cable and I will add some cable to the DUT to verify the VNA sees the difference. I will report on this again soon. Lee K7TJR. These numbers seem too good to be true. The tempco works out to less than 7 PPM/°C. Consider that the coefficient of thermal expansion of copper is +17PPM/°C. Refer to Figure 7 of this: https://www.timesmicrowave.com/DataSheets/Literature/Current%20innovations%20in%20phase%20stable%20coaxial%20cable.pdf The graph on the right shows non-linear tempco curves. When you have non linearity like this, it is possible to pick two points on the curve such that a line drawn through them has a slope of zero. Maybe you ran into that. The numbers you reported for the loss seem roughly consistent with what the thermal coefficient of resistance of copper predicts. Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
On 4/8/2020 12:28 PM, Lee STRAHAN wrote: What I do know about that also is mathematically those 8 elements theoretically can produce an RDF of right at 16 dB. The rub is the element amplitudes and phasing has to be controlled to some remarkable unobtainable accuracies to do that. Just maintaining 2% amplitude accuracy and 1 or 2 degrees phase stability 10 years ago when the 8 array was put into production was all I thought I could squeak out with the then current components and measuring ability I could a fford. Buying 1% resistors and capacitors in surface mount is now common which has helped available accuracies and my test equipment is much better than I had at the time. Chasing these things is part of what I do trying to push the barriers of low band Receiving. Filling the gaps, nulls in a pattern are the result of cancellation of multiple signals from two or more antenna elements. Cancellation is maximized by very precise matching of amplitude AND phase; small errors in either result in less cancellation. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
On 4/8/2020 10:37 AM, Lee STRAHAN wrote: Good morning from Oregon Top-Band people, Cable loss was -.61 dB at 59 Deg. F, And -.58 dB at an averaged cable temperature of 23 Deg. F. 59 Deg. F 23 Deg. F 1 - 74.59 DEG -74.60 DEG. 2 - 74.59 DEG -74.60 DEG. 3 - 74.59 DEG -74.60 DEG. 4 - 74.59 DEG -74.60 DEG. 5 -74.60 DEG -74.60 DEG. 6 -74.60 DEG -74.60 DEG. 7 -74.60 DEG -74.60 DEG. 8 -74.60 DEG -74.60 DEG. 9 -74.60 DEG -74.60 DEG. 10 -74.60 DEG-74.60 DEG. My bottom line conclusion is that for our purposes on the top-bands I no longer wonder if the cable delay and attenuation remained constant with winter deployed arrays. Incidentally, T Snap and Seal have been the best connectors here for repeatability. Lee Strahan K7TJR These numbers seem too good to be true. The tempco works out to less than 7 PPM/°C. Consider that the coefficient of thermal expansion of copper is +17PPM/°C. Refer to Figure 7 of this: https://www.timesmicrowave.com/DataSheets/Literature/Current%20innovations%20in%20phase%20stable%20coaxial%20cable.pdf The graph on the right shows non-linear tempco curves. When you have non linearity like this, it is possible to pick two points on the curve such that a line drawn through them has a slope of zero. Maybe you ran into that. The numbers you reported for the loss seem roughly consistent with what the thermal coefficient of resistance of copper predicts. Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Hi Mike, I make the Hi-Z Antennas receiving arrays and I am always looking for ways to make them work better. Attention to detail has been the key to success in my endeavors. I had made some early tests on this cable going on 15 years ago when I did not have as good equipment. As I design or redesign things I find modern technology has paved the way for even better performance. Here is the situation. The 8 element all active array whose model shows 13.48 dB RDF remains the top of the list as far as I know for that performance. What I do know about that also is mathematically those 8 elements theoretically can produce an RDF of right at 16 dB. The rub is the element amplitudes and phasing has to be controlled to some remarkable unobtainable accuracies to do that. Just maintaining 2% amplitude accuracy and 1 or 2 degrees phase stability 10 years ago when the 8 array was put into production was all I thought I could squeak out with the then current components and measuring ability I could a fford. Buying 1% resistors and capacitors in surface mount is now common which has helped available accuracies and my test equipment is much better than I had at the time. Chasing these things is part of what I do trying to push the barriers of low band Receiving. It has always been in the back of my mind that not knowing accurately the stability of the delay cable was one of the error terms greatly affecting how the array could match the model. Just something that had to be done in my mind. Here is some more shocking cable data I took several years ago https://www.k7tjr.com/coaxial_tests.htm Cheers, Lee K7TJR OR -Original Message- From: Topband On Behalf Of Mike Smith VE9AA Sent: Wednesday, April 8, 2020 11:49 AM To: topband@contesting.com Subject: Re: Topband: RG-6 Delay cables Interesting Lee. I guess I never thought anything about delay lines in our weather here. I have RG-6-like cables on all my 4-squares. I was unaware electrons cared whether it was +35*C or -35*C (or general temp range here in NB) What prompted you to do such testing? Thanks Mike VE9AA ".My bottom line conclusion is that for our purposes on the top-bands I no longer wonder if the cable delay and attenuation remained constant with winter deployed arrays. Incidentally, T Snap and Seal have been the best connectors here for repeatability. Lee Strahan K7TJR." Mike VE9AA Mike, Coreen & Corey Keswick Ridge, NB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
On 4/8/2020 11:48 AM, Mike Smith VE9AA wrote: I was unaware electrons cared whether it was +35*C or -35*C (or general temp range here in NB) Hi Mike, The possible variables are variations in the electrical properties of the transmission line with temperature, which are factors of the materials it's made with. BTW -- it's not the particle velocity of electrons, it's the fields, the behavior of which is described by Maxwell's equations. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Interesting Lee. I guess I never thought anything about delay lines in our weather here. I have RG-6-like cables on all my 4-squares. I was unaware electrons cared whether it was +35*C or -35*C (or general temp range here in NB) What prompted you to do such testing? Thanks Mike VE9AA ".My bottom line conclusion is that for our purposes on the top-bands I no longer wonder if the cable delay and attenuation remained constant with winter deployed arrays. Incidentally, T Snap and Seal have been the best connectors here for repeatability. Lee Strahan K7TJR." Mike VE9AA Mike, Coreen & Corey Keswick Ridge, NB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
On 4/8/2020 10:37 AM, Lee STRAHAN wrote: Cable loss was -.61 dB at 59 Deg. F, And -.58 dB at an averaged cable temperature of 23 Deg. F. Great work, Lee. Thanks. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: RG-6 Delay cables
Lee, Tnx for the info and taking the time for the test. The differences are in the noise level. Stay safe N2TK, Tony -Original Message- From: Topband On Behalf Of Lee STRAHAN Sent: Wednesday, April 8, 2020 1:38 PM To: topband@contesting.com Subject: Topband: RG-6 Delay cables Good morning from Oregon Top-Band people, I decided to re-do some previous tests of the common 75 ohm RG-6 cable I use and is used for delay cables in many places for top-band receiving systems. I just thought I would share the results of yesterday's tests. I took a delay cable that I had used in the field here several times. The temperature in my shack at the time was only 59 degrees measured on the coaxial cable itself with a non-contact meter. I did an OS ( Open Short) feed through calibration with minimum loss 50 to 75 ohm conversion pads installed on my VNA. Calibration was done immediately before each test below, so two calibrations were done. The cable under test measured 74.59 degrees delay at 1840 KHz initially. I watched the VNA make 10 sweeps, each about 10 seconds long for 10 observations of phase delay for two cable temperature tests. This particular cable was imported by the Steren Co. for sale in The USA, part number 200-931 . After the first test at 59 Deg. F I chucked the cable into the food freezer preparing for the second. One and one half hours later the cable surface temp measured between 20 and 25 Deg. F Cable loss was -.61 dB at 59 Deg. F, And -.58 dB at an averaged cable temperature of 23 Deg. F. 59 Deg. F 23 Deg. F 1 - 74.59 DEG -74.60 DEG. 2 - 74.59 DEG -74.60 DEG. 3 - 74.59 DEG -74.60 DEG. 4 - 74.59 DEG -74.60 DEG. 5 -74.60 DEG -74.60 DEG. 6 -74.60 DEG -74.60 DEG. 7 -74.60 DEG -74.60 DEG. 8 -74.60 DEG -74.60 DEG. 9 -74.60 DEG -74.60 DEG. 10 -74.60 DEG-74.60 DEG. My bottom line conclusion is that for our purposes on the top-bands I no longer wonder if the cable delay and attenuation remained constant with winter deployed arrays. Incidentally, T Snap and Seal have been the best connectors here for repeatability. Lee Strahan K7TJR _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: RG-6 Delay cables
Good morning from Oregon Top-Band people, I decided to re-do some previous tests of the common 75 ohm RG-6 cable I use and is used for delay cables in many places for top-band receiving systems. I just thought I would share the results of yesterday's tests. I took a delay cable that I had used in the field here several times. The temperature in my shack at the time was only 59 degrees measured on the coaxial cable itself with a non-contact meter. I did an OS ( Open Short) feed through calibration with minimum loss 50 to 75 ohm conversion pads installed on my VNA. Calibration was done immediately before each test below, so two calibrations were done. The cable under test measured 74.59 degrees delay at 1840 KHz initially. I watched the VNA make 10 sweeps, each about 10 seconds long for 10 observations of phase delay for two cable temperature tests. This particular cable was imported by the Steren Co. for sale in The USA, part number 200-931 . After the first test at 59 Deg. F I chucked the cable into the food freezer preparing for the second. One and one half hours later the cable surface temp measured between 20 and 25 Deg. F Cable loss was -.61 dB at 59 Deg. F, And -.58 dB at an averaged cable temperature of 23 Deg. F. 59 Deg. F 23 Deg. F 1 - 74.59 DEG -74.60 DEG. 2 - 74.59 DEG -74.60 DEG. 3 - 74.59 DEG -74.60 DEG. 4 - 74.59 DEG -74.60 DEG. 5 -74.60 DEG -74.60 DEG. 6 -74.60 DEG -74.60 DEG. 7 -74.60 DEG -74.60 DEG. 8 -74.60 DEG -74.60 DEG. 9 -74.60 DEG -74.60 DEG. 10 -74.60 DEG-74.60 DEG. My bottom line conclusion is that for our purposes on the top-bands I no longer wonder if the cable delay and attenuation remained constant with winter deployed arrays. Incidentally, T Snap and Seal have been the best connectors here for repeatability. Lee Strahan K7TJR _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
