LMR-400 direct to antenna or no?
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Thanks!
-Scott, K4KDR Montpelier, VA USA
I would do like I did to my 9913. This is rather stiff cable. I went a couple of turns loosely around the mast and around the boom for elevation. I would do this with the antennas at 0 elevation and 360/0 degree azimuth. In this way it acts like a simple spring which opens or tightens slightly as the rotation of the mast and/or boom occur. I had my 9913 this way for over 15 years without a problem. I suspect the LMR400 should work the same. In this way you are not inducing any losses with additional cables and connectors.
Just my two cents.
Reid, W4UPD Amsat: 17002
On 3/31/2016 9:35 PM, Scott wrote:
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Thanks!
-Scott, K4KDR Montpelier, VA USA _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I use LMR-400 DB on the VHF side. With a 130' run it's lossy. Previously, it was on both UHF and VHF.
Replaced the UHF side with LDF4-50A that was dumpster retrevial just after an unnamed blue and white railroad ran their last train out. Much better.
With a 130' run was lossy at UHF. Preamp is necessary. On the VHF side, a preamp is usually un-necessary.
Rotator loops are 9913F7. Be sure to get the correct N connectors as this has a larger center conductor. Several stranded strands can be trimmed if they are unavailable.
On Thu, Mar 31, 2016 at 9:43 PM, w4upd [email protected] wrote:
I would do like I did to my 9913. This is rather stiff cable. I went a couple of turns loosely around the mast and around the boom for elevation. I would do this with the antennas at 0 elevation and 360/0 degree azimuth. In this way it acts like a simple spring which opens or tightens slightly as the rotation of the mast and/or boom occur. I had my 9913 this way for over 15 years without a problem. I suspect the LMR400 should work the same. In this way you are not inducing any losses with additional cables and connectors.
Just my two cents.
Reid, W4UPD Amsat: 17002
On 3/31/2016 9:35 PM, Scott wrote:
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Thanks!
-Scott, K4KDR Montpelier, VA USA _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
What he said. In other words, I concur. I have had a whole bunch of VHF/UHF antennas fed witl plain LMR400 for years, and with a bit of a coil around the mast, it all worked fine. 73 de W0JT/5 EL09vu
On Thu, Mar 31, 2016 at 8:43 PM, w4upd [email protected] wrote:
I would do like I did to my 9913. This is rather stiff cable. I went a couple of turns loosely around the mast and around the boom for elevation. I would do this with the antennas at 0 elevation and 360/0 degree azimuth. In this way it acts like a simple spring which opens or tightens slightly as the rotation of the mast and/or boom occur. I had my 9913 this way for over 15 years without a problem. I suspect the LMR400 should work the same. In this way you are not inducing any losses with additional cables and connectors.
Just my two cents.
Reid, W4UPD Amsat: 17002
On 3/31/2016 9:35 PM, Scott wrote:
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Thanks!
-Scott, K4KDR Montpelier, VA USA _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
There is an "ultraflex" version of LMR-400, with the UF suffix. It has a stranded center conductor and wont break as quickly as -400 when flexed repeatedly. I use jumpers made of this between the antenna and mast mounted preamps, around the rotors.
73, Drew KO4MA
Sent from my iPhone
On Mar 31, 2016, at 9:35 PM, Scott [email protected] wrote:
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Thanks!
-Scott, K4KDR Montpelier, VA USA _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I used LMR-400UF around the rotators for years. It worked very well. I did need to replace one length due to a broken center conductor, but that was after years of heavy use. When I rebuild my array, I bought some 9913F (sometimes called 9913F-7 or 9913F7). Same electrical specifications as LMR-400UF, +/-, and noticably more flexible to handle. It has only been up for about 2 years, but so far, so good. I also use it for the mode-L loop to the helix from the hard line feed to the shack.
Shameless plug for an AMSAT Journal advertiser: The folks at The RF Connection, www.therfc.com, were very accommodating and knowledgeable.
73s,
Alan WA4SCA
Use LMR-400 around the rotor if you want to have to replace the cable every few days! LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times! Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way. I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net
From: Scott [email protected] To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no?
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
As I mentioned before, I used 9913 (rigid) for years without a problem. After taking the arrays down, I was able to reuse some of the 9913. The 9913 I had, had a large solid center conductor. By doing a loose spring type of installation around the mast and boom, there was very little flexing of the cable. This only adds about 2 - 4 foot to the length of the cable.
I did this to keep the number of connectors and connections down (especially on 70cm) to reduce cable loses. The more turns (for example maybe 4) the less flexing of the cable will occur.
Again, just my 2 cents, but the installation mentioned above was very successful for years. If I ran into any problems it was due to the "known" problem of water getting into the 9913. However, I had little problem with that as well.
If the runs are short (less than 50') you could use other methods which requires additional coax fittings and barrel connectors. My goal was to prevent that. I would still recommend a preamp on 70cm at the mast to over come any installation. I found it to be a good addition, especially if we get any HEOs up or for near AOS or LOS operation, trees or weather.
Reid, W4UPD
On 3/31/2016 11:33 PM, Glen Zook via AMSAT-BB wrote:
Use LMR-400 around the rotor if you want to have to replace the cable every few days!LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times!Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way.I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net From: Scott [email protected] To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no? I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex") Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either. My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)? Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees? If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm. _______________________________________________Sent via [email protected]. AMSAT-NA makes this open forum availableto all interested persons worldwide without requiring membership. Opinions expressedare solely those of the author, and do not reflect the official views of AMSAT-NA.Not an AMSAT-NA member? Join now to support the amateur satellite program!Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Hi Reid,
I understand the desire for minimal use of connectors, but the coupling between the rigid cable coming from the shack to the rotor, and the flex cable going to the antenna, is a good place to put a nice little preamp. Think of it as a barrel connector with attitude. Yes, putting it at the antenna feed point is better, but unless you're working EME, the practical difference is pretty small.
Your luck with 9913 and water ingress is significantly better than mine ever was. I had one 60' run that kept getting worse over time. It got so bad that I drilled a hole in the lower end connector so I could suck out the water until I could find some hardline to replace it. Never used the stuff ever again.
Greg KO6TH
w4upd wrote:
As I mentioned before, I used 9913 (rigid) for years without a problem. After taking the arrays down, I was able to reuse some of the 9913. The 9913 I had, had a large solid center conductor. By doing a loose spring type of installation around the mast and boom, there was very little flexing of the cable. This only adds about 2 - 4 foot to the length of the cable.
I did this to keep the number of connectors and connections down (especially on 70cm) to reduce cable loses. The more turns (for example maybe 4) the less flexing of the cable will occur.
Again, just my 2 cents, but the installation mentioned above was very successful for years. If I ran into any problems it was due to the "known" problem of water getting into the 9913. However, I had little problem with that as well.
If the runs are short (less than 50') you could use other methods which requires additional coax fittings and barrel connectors. My goal was to prevent that. I would still recommend a preamp on 70cm at the mast to over come any installation. I found it to be a good addition, especially if we get any HEOs up or for near AOS or LOS operation, trees or weather.
Reid, W4UPD
On 3/31/2016 11:33 PM, Glen Zook via AMSAT-BB wrote:
Use LMR-400 around the rotor if you want to have to replace the cable every few days!LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times!Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way.I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net From: Scott [email protected] To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no? I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex") Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either. My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)? Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees? If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm. _______________________________________________Sent via [email protected]. AMSAT-NA makes this open forum availableto all interested persons worldwide without requiring membership. Opinions expressedare solely those of the author, and do not reflect the official views of AMSAT-NA.Not an AMSAT-NA member? Join now to support the amateur satellite program!Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I had better luck after protecting the connectors with pill bottles. This worked for a while but the UV would wipe out the bottles in a short period of time. After that I used short pieces of SCH 40 PVC with modified end caps for the cable and didn't bother to glue. This worked much better, plus allowed me access to the connectors when needed. I also did this to the rotor connectors.
Reid, W4UPD
On 4/1/2016 11:45 PM, Greg D wrote:
Hi Reid,
I understand the desire for minimal use of connectors, but the coupling between the rigid cable coming from the shack to the rotor, and the flex cable going to the antenna, is a good place to put a nice little preamp. Think of it as a barrel connector with attitude. Yes, putting it at the antenna feed point is better, but unless you're working EME, the practical difference is pretty small.
Your luck with 9913 and water ingress is significantly better than mine ever was. I had one 60' run that kept getting worse over time. It got so bad that I drilled a hole in the lower end connector so I could suck out the water until I could find some hardline to replace it. Never used the stuff ever again.
Greg KO6TH
w4upd wrote:
As I mentioned before, I used 9913 (rigid) for years without a problem. After taking the arrays down, I was able to reuse some of the 9913. The 9913 I had, had a large solid center conductor. By doing a loose spring type of installation around the mast and boom, there was very little flexing of the cable. This only adds about 2 - 4 foot to the length of the cable.
I did this to keep the number of connectors and connections down (especially on 70cm) to reduce cable loses. The more turns (for example maybe 4) the less flexing of the cable will occur.
Again, just my 2 cents, but the installation mentioned above was very successful for years. If I ran into any problems it was due to the "known" problem of water getting into the 9913. However, I had little problem with that as well.
If the runs are short (less than 50') you could use other methods which requires additional coax fittings and barrel connectors. My goal was to prevent that. I would still recommend a preamp on 70cm at the mast to over come any installation. I found it to be a good addition, especially if we get any HEOs up or for near AOS or LOS operation, trees or weather.
Reid, W4UPD
On 3/31/2016 11:33 PM, Glen Zook via AMSAT-BB wrote:
Use LMR-400 around the rotor if you want to have to replace the cable every few days!LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times!Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way.I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net From: Scott [email protected] To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no? I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex") Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either. My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)? Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees? If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm. _______________________________________________Sent via [email protected]. AMSAT-NA makes this open forum availableto all interested persons worldwide without requiring membership. Opinions expressedare solely those of the author, and do not reflect the official views of AMSAT-NA.Not an AMSAT-NA member? Join now to support the amateur satellite program!Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I had a dualband 2M/70cm vertical that was fed with 9913 from antenna to the house, and whtn properly prepared N connectors on both ends, it never leaked water. Well, at least not until I tried to drill another hole into the house next to the first one, and the drill bit went in at an angle and drilled right into the run of 9913. Ouch. I replaced that run with LMR400 and never looked back. It survived for over 10 years, but of course with no motion involved there. ;^)
73 de W0JT EL09vu
On Fri, Apr 1, 2016 at 10:45 PM, Greg D [email protected] wrote:
Hi Reid,
I understand the desire for minimal use of connectors, but the coupling between the rigid cable coming from the shack to the rotor, and the flex cable going to the antenna, is a good place to put a nice little preamp. Think of it as a barrel connector with attitude. Yes, putting it at the antenna feed point is better, but unless you're working EME, the practical difference is pretty small.
Your luck with 9913 and water ingress is significantly better than mine ever was. I had one 60' run that kept getting worse over time. It got so bad that I drilled a hole in the lower end connector so I could suck out the water until I could find some hardline to replace it. Never used the stuff ever again.
Greg KO6TH
w4upd wrote:
As I mentioned before, I used 9913 (rigid) for years without a problem. After taking the arrays down, I was able to reuse some of the 9913. The 9913 I had, had a large solid center conductor. By doing a loose spring type of installation around the mast and boom, there was very little flexing of the cable. This only adds about 2 - 4 foot to the length of the cable.
I did this to keep the number of connectors and connections down (especially on 70cm) to reduce cable loses. The more turns (for example maybe 4) the less flexing of the cable will occur.
Again, just my 2 cents, but the installation mentioned above was very successful for years. If I ran into any problems it was due to the "known" problem of water getting into the 9913. However, I had little problem with that as well.
If the runs are short (less than 50') you could use other methods which requires additional coax fittings and barrel connectors. My goal was to prevent that. I would still recommend a preamp on 70cm at the mast to over come any installation. I found it to be a good addition, especially if we get any HEOs up or for near AOS or LOS operation, trees or weather.
Reid, W4UPD
On 3/31/2016 11:33 PM, Glen Zook via AMSAT-BB wrote:
Use LMR-400 around the rotor if you want to have to replace the cable every few days!LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times!Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way.I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net From: Scott [email protected] To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no? I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex") Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either. My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)? Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees? If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm. _______________________________________________Sent via [email protected]. AMSAT-NA makes this open forum availableto all interested persons worldwide without requiring membership. Opinions expressedare solely those of the author, and do not reflect the official views of AMSAT-NA.Not an AMSAT-NA member? Join now to support the amateur satellite program!Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I beg to differ. As long as there is a reasonably-sized, loose loop around the mast, LMR400 will last for years to decades, not days. Mine did, for 20 years, in Minnesota weather (temps ranging from -30F to +100F). Planning to do it again when the tower goes up here in Texas.
73 de W0JT/5 EL09vu
On Thu, Mar 31, 2016 at 10:33 PM, Glen Zook via AMSAT-BB <[email protected]
wrote:
Use LMR-400 around the rotor if you want to have to replace the cable every few days! LMR-400 has a solid center conductor and it will definitely break after being "flexed" for not that many times! Frankly, for short runs like around rotors and to most antennas, plain old RG213/U works fine and the loss is very low. Run the LMR-400 up to just below the rotor and then install the RG213/U the rest of the way. I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my antenna runs from 160-meters through 70 cm. Where a rotor is involved, the Heliax goes up the tower to just below the rotor and then RG213/U the rest of the way. Most of the antennas have been "up" for a pretty long time (decades) and they are working just as well today as they did when first erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net
From: Scott <[email protected]>To: [email protected] Sent: Thursday, March 31, 2016 8:35 PM Subject: [amsat-bb] LMR-400 direct to antenna or no?
I hope to put up my first rotating antenna soon and just received a nice length of LMR-400 to use. (regular, not "super-flex")
Having never seen LMR-400 before, I did not know how flexible it would be. I would call it "medium"... not stiff as a pipe but not floppy, either.
My question is whether anyone using LMR-400 can recommend whether I should attach it directly to my antenna (with slack loops, of course)?
Or, should I get a few meters of something more flexible to attach to an antenna that needs to be free to rotate 360 degrees?
If a jumper is recommended, I would appreciate suggestions on what cable would work best for the task. The frequency for this project is 70cm.
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (8)
-
Alan -
Andrew Glasbrenner -
Glen Zook -
Greg D -
John Toscano -
Norm n3ykf -
Scott -
w4upd