Best type of coax to use between preamps and antennas
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI
Ron,
There are a variety of flexible, low loss cables. Over a 10-15 foot length the differences in loss would be inconsequential. Probably the most important factor is that it has excellent shielding, and preferably double shielding, to prevent pickup between the RX and TX bands. Over the years I have used RG-213, Davis Bury-Flex, LMR-400UF, and probably AirCom around the rotators. I have used the original "water pipe" 9913 only, but I suspect the modern flexible version would be fine as well. Even with heavy use back in the pacsat and HEO days, I have never had a failure of a cable, except for one of my bad connector installations where I did not provide proper strain relief.
Alan WA4SCA
Ron
Did you diagnose what your problem was ? Water in the coax ? Where is your preamp mounted ? If very near (10 feet) the antenna you can use RG8. If you feel intimidated by N connectors (many folks are), Henry Radio and others sell a two (2) piece N connector that is installed much like a PL 259 which you have probably installed many times. Check out Henry Radio on Ebay. If you need more info on this email me direct. I think they get around $4 a connector. A short run (10 ft) of RG8 at 432mhz or 144mhz is not too prohibited, in my opinion. Or you can have somebody put together a jumper as you have noted. Self reliance provides better quality control in my opinion.
Jim W9VNE ----- Original Message ----- From: "Ronald Nutter" [email protected] To: [email protected] Sent: Monday, June 30, 2008 8:49 PM Subject: [amsat-bb] Best type of coax to use between preamps and antennas
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI
I used the same setup that I have at the house. I did find one piece of suspect coax once I returned home. According to my 259B, it had a higher loss for a short run than I would have expected. There were several transformers in proximity to where we were located that could have been putting out some noise. The other satellite op could hear the noise I didnt hear that subsided later in the evening. The preamps were located within 10-15 feet of the antennas.
I have ordered replacement LRM400 to use in place of the Mini8/U coax that I was running from the preamps to the antennas. Will see what happens.
Ron
Jim Danehy wrote:
Ron
Did you diagnose what your problem was ? Water in the coax ? Where is your preamp mounted ? If very near (10 feet) the antenna you can use RG8. If you feel intimidated by N connectors (many folks are), Henry Radio and others sell a two (2) piece N connector that is installed much like a PL 259 which you have probably installed many times. Check out Henry Radio on Ebay. If you need more info on this email me direct. I think they get around $4 a connector. A short run (10 ft) of RG8 at 432mhz or 144mhz is not too prohibited, in my opinion. Or you can have somebody put together a jumper as you have noted. Self reliance provides better quality control in my opinion.
Jim W9VNE ----- Original Message ----- From: "Ronald Nutter" [email protected] To: [email protected] Sent: Monday, June 30, 2008 8:49 PM Subject: [amsat-bb] Best type of coax to use between preamps and antennas
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI
LMR-400 works very well, and for higher flexibility requirements, you can use LMR-400 ultra flex. It's loss is very close to 9913, without some of the 9913 varieties problems. I replaced all my 9913 with LMR-400 years ago, and all my water problems went away, never to return.
73,
hasan, N0AN
Ronald Nutter wrote:
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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Thing is with that short of a run, any of the smaller coaxes will work just fine and he'd never know the difference 10 to 15 feet anything will work!
hasan schiers wrote:
LMR-400 works very well, and for higher flexibility requirements, you can use LMR-400 ultra flex. It's loss is very close to 9913, without some of the 9913 varieties problems. I replaced all my 9913 with LMR-400 years ago, and all my water problems went away, never to return.
73,
hasan, N0AN
Ronald Nutter wrote:
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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As Dom noted in another post, any loss ahead of the preamp detracts from the NF of the preamp (which you paid good money to get as low as possible). Throwing that away by using small/cheap cable is not a wise investment when relatively inexpensive low loss (preserving the NF) cables are readily available. If you plug the losses of a 15 ft run of smaller coax into a link budget calculator (referenced in this forum many times), you will be astounded at how much your sensitivity drops by placing these kinds of losses ahead of a 0.2 or 0.5 dB NF preamp.
...hasan, N0AN
Joe wrote:
Thing is with that short of a run, any of the smaller coaxes will work just fine and he'd never know the difference 10 to 15 feet anything will work!
hasan schiers wrote:
LMR-400 works very well, and for higher flexibility requirements, you can use LMR-400 ultra flex. It's loss is very close to 9913, without some of the 9913 varieties problems. I replaced all my 9913 with LMR-400 years ago, and all my water problems went away, never to return.
73,
hasan, N0AN
Ronald Nutter wrote:
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft. The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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ISS Amateur Radio Status: July 7, 2008 By Miles Mann WF1F,
MAREX-MG News www.marexmg.org
Manned Amateur Radio Experiment
Mir SSTV images collection. ARISS Moscow ISS Status meetings Slow Scan TV from Space Station Mir, 10 years later.
******** Mir SSTV images collection: Hello all, it has been a while:
I have posted a new web page link with approximately 300 SSTV images from the Marex SSTV project on Mir from 1998-2000. I am sure there are more images out there, so if you find any that are not currently posted, please forward them to Marex and read the section below.
ARISS Moscow ISS Status meetings:
The annual ARISS / ISS meeting for 2007 was canceled due to schedule conflicts. The next meeting will be in Moscow July 16 – 20, 2008
At these meetings we discuss may topics including the Status of current Amateur Radio hardware on the International Space Station. And we discuss proposal for possible Future Amateur Radio projects for ISS.
I have posted a few of the MarexMG proposals on the MarexMG web page. These are Just proposals at this time. However, with your support, some of these proposals could become reality.
Our goal at Marex”
Keep ISS on the air as much as possible. Keep the projects very simple for Hams and SWL around the world. And Keep it easy for the ISS crew to use (KISS).
ISS can be your stepping stone into Space.
Project Proposal List:
Let’s get Digital into Space. I believe the ISS crew would have a blast using the Digital Repeater network. With the Aid of a few discrete frequencies, the ISS crew could use Digital repeaters to link to their home town digital repeater or make person to person digital link calls.
What do you think?
Look over the rest of the proposal’s and constructive comments welcome.
www.marexmg.org
Slow Scan TV from Space Station Mir, 10 years later.
On December 12, 1998 the crew members of the Russian Space station Mir activated the Marex SSTV system. Over the next two years the system broadcasted over 20,000 SSTV images back to earth via Amateur Radio.
Many of the images were quiet spectacular.
To celebrate the 10 year anniversary of the successful imaging project, the Marx team is planning on upgrading our web page system to accommodate the many images that were transmitted during the projects 2 year run. In 1998 we just did not have the resources in place to handle the hundreds of images coming in every day. As a result only a small select on of the images were ever posted for public enjoyment.
Here is where we need your help. Out of the 20,000 images sent to earth, we believe that only approximately a 1,000 images were saved by the general amateur radio public around the world. We would like you to search your disk drives for those images that you received during the project which ran from December 1998 until 2000. Please send the images to Marex so that we can add them to our new web page.
We are interested in high quality and unique images.
In December 98 and January 99, there were many times when the Mir crews would put on Slid shows for the public and demonstrate the Musical skills and show us scenes of the holidays.
One good string of images came from the Mir shutdown in August 1999. The Mir crew left the SSTV system running showing inside shots while the crew packet up the Space Station just before leaving the station.
So start searching your disk dive and see if you can find some good images.
When you find them please send the Marex and will add them to our web page. Here are a few scattered pages with some of the Mir SSTV images
http://www.marexmg.org/imagessstv/SpaceCamImages1.htm
Images and links for SSTV images from Mir 1998-2001 http://www.marexmg.org/moscow98/index.htm
If you have any more that are different or have better quality, please forward those images to Marex. Mail your images to Marex at:
In order to properly catalog the images we request that you use the following image naming format. After you receive you images, please rename the images using the following format, All Lower case letters.
Year 99, Month 07, Day 31, (UTC time), Call sign, .jpg
In many cases you many not know the exact date or UTC time. Sometimes you can derive this information from the time stamp of the original image. Just take your best guess on the date and time.
Example:
New format: 9907311905wf1f.jpg
If we break this down Year =99 Month = 07 Day = 31 Time = 1905 UTC Call sign = wf1f Image format = jpg
Image Quality Please do not put any text over lays on the images, Example, do not put web page or advertisements in the image.
We would also like to know the following Optional information in your email.
Name or Call sign Country / State Receiver Software decoding tool Elevation or range of ISS when you decoded the image.
Ps, If you also find any SSTV pictures from the 2 Space Shuttle Missions or any from ISS in 2006, please forward them to the same address. Thanks
If you are interested in learning more about Slow Scan TV, here are a few links. SSTV Decoding Software http://www.barberdsp.com/
There are many choices in SSTV software, some Free, others with more features cost a few bucks. http://www.marexmg.org/fileshtml/sstvlinkpage.html
SSTV on ISS: The Marex SpaceCam1 is currently on ISS. It was successfully tested in August 2006 using a “Borrowed” laptop. The laptops computers are in very short supply on ISS. We are patiently waiting permission to Borrow another laptop.
Marexmg Web page http://www.marexmg.org
ARISS Web page and other great Space projects http://www.rac.ca/ariss/
73 Miles WF1F MAREX-MG
Until we meet again
DOSVIDANIYA Miles WF1F
----- Original Message ----- From: "Ronald Nutter" [email protected] To: [email protected] Sent: Tuesday, July 01, 2008 2:49 AM Subject: [amsat-bb] Best type of coax to use between preamps and antennas
After problems I had on Field Day in trying to operate the satellites, I am looking to upgrade the coax I use between the preamps and the antennas. I am using 9913FX from the IC-910H and the preamps. I had been using RG Mini 8/U for the connection between the preamps and antennas. Should I also use 9913FX between the preamps and the antennas? The run between the radio and the preamp is 50 ft.The run from the preamp to the antennas is about 10 - 15 ft depending on where I set the antennas up. I am concerned about how flexible the 9913FX would be in terms of the antennas rotating back and forth. I was planning on ordering the cables pre-made from CableXperts since working with N connectors isnt my strong point and dont want to worry about my soldering and having a good connection on both ends of the cable.
Any suggestions appreciated.
Thanks, Ron KA4KYI
Hi Ron, KA4KYI
Any loss introduced by the coax cable between the antenna and the preamplifier add directly to the noise figure NF of your preamplier alone.
Example:
Preamplifier noise figure NF= 0.5 dB
Attenuation of coax cable + both connectors = 1 dB
In this condition the overall noise figure of your preamplifier becames 1.5 dB i.e. like to have a bad preamplifier with NF= 1.5 dB directly connected to the antenna connector without any cable.
What is the attenuation in dB of 10 to 15 ft of RG Mini 8/U including connectors ? Make your calculations by your self and add it to the specified noise figure of your preamplifier.
By the way the attenuation of the coax cable between the output of your preamplifier and the input of your IC-910H do not degrades significantly the overall noise figure of your receiving system because in general the gain of a good preamplifier is in the order of G= 20 dB wich is enought to compensate for the losses intoduced by 50 ft of 9913FX
More important the attenuation introduced by 50 ft of 9913FX reduces directly the power generated by your TX and reaching the antenna.
Example: In general if the attenuation of the coax cable between TX and antenna is 3 dB and your TX is 100 watt then the power at the antenna connector will be only 50 watt and this is no good. By the way if the gain of your preamplifier is 20 dB and the attenuation betwen preamplifier output and RX input is 3 dB then instead to have a preamplifier with G=20 dB it is like to have a preamplifier with G= 17 dB but only from the receiving point of view this is not too bad because it do not make a significant degradation of the overall noise figure of your receiving system.
For more information about the above matter read the following article:
"Receiver Noise Figure Sensitivity and Dynamic Range. What the numbar mean" by James R.Fisk, W1DTY Ham Radio Magazine october 1975
If you cannot find the above super article I have it scanned and I can send a file to everybody is interested.
73" de
i8CVS Domenico
participants (7)
-
Alan P. Biddle -
hasan schiers -
i8cvs -
Jim Danehy -
Joe -
MM -
Ronald Nutter