Testing hardline or coax

[VETCOMMS]

I recently acquired some hardline. How do I test it to see if it's still good?  What equipment is needed? 

Similarly,  how do I test hardline at a tower site to see if it's good?

[tcp2525]

1 hour ago, VETCOMMS said:

I recently acquired some hardline. How do I test it to see if it's still good?  What equipment is needed? 

Similarly,  how do I test hardline at a tower site to see if it's good?

I use a pet squirrel, which is really the only scientific way to do it. He loves 1-5/8" Heliax the most. Last 700' run he tested for return loss took a record breaking 15 minutes to scale that length and come back down. Seriously, here's a video that might help. Check Youtube for other videos to get a full understanding.

 

[WRUE951]

1 hour ago, VETCOMMS said:

I recently acquired some hardline. How do I test it to see if it's still good?  What equipment is needed? 

Similarly,  how do I test hardline at a tower site to see if it's good?

get yourself a Nano VNA.. They're great for checking Coax, Antennas and other things..  Lots of various how to videos on Google..   https://www.amazon.com/AURSINC-NanoVNA-H-Vector-Network-Analyzer/dp/B07Z5VY7B6/ref=sr_1_1_sspa?crid=27K9G2O94D6NI&dib=eyJ2IjoiMSJ9._c0Hx-JK1n0L41oe77KD7fcLIRsFX4_XZT_H7ZxdIs8BCuulklYWSZi7bTrGHD8BF5z2nq9d8KApRHbUSVwUAgta_Ua95QfM8DPnc4-tA2DhuxMPbV3MIXo2Mx5sF585EG8W2sSQ6wvgY9C8-kgPsGcS3mn3b6tKW01ocBWjju-1rDEXX_kIkdR_YyEidg6hl9HR8HPx1PGcYOS141bEaHxJBpwGmQ8UPK5D1Dd7bYc.oIILvBvlLqcs08bDNYLGdvdRu9BbUXTzf5XOjxbRaKo&dib_tag=se&keywords=vna&qid=1725726595&sprefix=vna%2Caps%2C164&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

[gortex2]

VNA is the proper way to test it. DTF and RL is the base tests I run on all lines. 

[VETCOMMS]

3 hours ago, gortex2 said:

VNA is the proper way to test it. DTF and RL is the base tests I run on all lines. 

OK thx for the help/ video.    What are normal readings?  How do I know if the hardline has a problem?

 

[VETCOMMS]

4 hours ago, gortex2 said:

VNA is the proper way to test it. DTF and RL is the base tests I run on all lines. 

OK thx for the help/ video.    What are normal readings?  How do I know if the hardline has a problem?

 

[VETCOMMS]

I have this end, I assume it's what people call an N connector?

Says Andrew  L5NF on it.   Is there a video that describes how to put the terminations on the hardline?  How do you terminate at the antenna vs at the repeater?

[SteveShannon]

30 minutes ago, VETCOMMS said:

I have this end, I assume it's what people call an N connector?

Says Andrew  L5NF on it.   Is there a video that describes how to put the terminations on the hardline?  How do you terminate at the antenna vs at the repeater?

Before buying the connectors, see what the manufacturer has for resources for the exact connector you need.  The better manufacturers provide training videos.  Some (okay, nearly all) strongly recommend using their preparation tools, but once you understand the process you will understand what tools you really need.

Here is an example:

 

[VETCOMMS]

2 hours ago, SteveShannon said:

Before buying the connectors, see what the manufacturer has for resources for the exact connector you need.  The better manufacturers provide training videos.  Some (okay, nearly all) strongly recommend using their preparation tools, but once you understand the process you will understand what tools you really need.

Here is an example:

 

Great,  thank you for that.   Do the connectors need to match the brand of hardline?  I need to see what brand it is still. 

Also,  I understand every installation is unique, but are there pigtails of smaller diameter coax that people will use to allow for a smaller hole to be made in the building housing the repeater and to make connecting to the repeater easier?

Is a similar technique used on the antenna end to allow for drip loops?  What type of coax/ connectors is used for these pigtails (not sure what the proper term is).

[SteveShannon]

26 minutes ago, VETCOMMS said:

Great,  thank you for that.   Do the connectors need to match the brand of hardline?  I need to see what brand it is still. 

Also,  I understand every installation is unique, but are there pigtails of smaller diameter coax that people will use to allow for a smaller hole to be made in the building housing the repeater and to make connecting to the repeater easier?

Is a similar technique used on the antenna end to allow for drip loops?  What type of coax/ connectors is used for these pigtails (not sure what the proper term is).

The connectors do not need to match the brand of hardline, but they must be sized correctly.  The connector you showed in your picture (L5NF) was made by Andrews. The L5NF is no longer manufactured, but I would think they make something similar.  I don't know if it could be reused with the correct preparation, but it looks like it might be an N female, rather than N male. It looks like someone used it with a jumper of coax, possibly something like LMR.  I know some people are against using LMR400 for repeaters because it has two different shield metals.  If you subscribe to that theory, get M&P Ultraflex 10 jumpers; they are copper for all layers of shielding.

So, with the connector you have, with N female on the ends (male thread on the outside, but a female socket on the inside) you would use an N male to N male coax jumper.  A short jumper of M&P Ultraflex from Gigaparts will work well.

 

[VETCOMMS]

1 hour ago, SteveShannon said:

The connectors do not need to match the brand of hardline, but they must be sized correctly.  The connector you showed in your picture (L5NF) was made by Andrews. The L5NF is no longer manufactured, but I would think they make something similar.  I don't know if it could be reused with the correct preparation, but it looks like it might be an N female, rather than N male. It looks like someone used it with a jumper of coax, possibly something like LMR.  I know some people are against using LMR400 for repeaters because it has two different shield metals.  If you subscribe to that theory, get M&P Ultraflex 10 jumpers; they are copper for all layers of shielding.

So, with the connector you have, with N female on the ends (male thread on the outside, but a female socket on the inside) you would use an N male to N male coax jumper.  A short jumper of M&P Ultraflex from Gigaparts will work well.

 

Looks like female to me, you agree?

[SteveShannon]

24 minutes ago, VETCOMMS said:

Looks like female to me, you agree?

From that picture I can’t tell if the center socket is whole or not. Here’s one:

 

[SteveShannon]

Yeah, zoomed in on your picture, it doesn't look right.

[VETCOMMS]

OK thx.   If i buy one of these Nano vna units off Amazon,  will I need to buy additional coax/adapters to test the hardline and antennas?  I appreciate the help as this is all learning for me!

[SteveShannon]

7 minutes ago, VETCOMMS said:

OK thx.   If i buy one of these Nano vna units off Amazon,  will I need to buy additional coax/adapters to test the hardline and antennas?  I appreciate the help as this is all learning for me!

Yes. Most of the NanoVNAs have SMA connectors. I bought one that has N female connectors on the NanoVNA. 

 

[tcp2525]

2 hours ago, SteveShannon said:

From that picture I can’t tell if the center socket is whole or not. Here’s one:

 

The picture he is showing is of the backside of a regular N connector without the hardline/coax installed. See the nut on the back? I assume it's a male N Connector that someone put on the larger hardline connector to protect it.

Update: Here's a pick of it in his previous post.

[SteveShannon]

2 hours ago, tcp2525 said:

The picture he is showing is of the backside of a regular N connector without the hardline/coax installed. See the nut on the back? I assume it's a male N Connector that someone put on the larger hardline connector to protect it.

Update: Here's a pick of it in his previous post.

Ahhh, I see. Instead of taking the two connectors apart where they’re supposed to break, he took the L5NF apart. Good catch!!!

[VETCOMMS]

On 9/8/2024 at 3:51 PM, SteveShannon said:

Yes. Most of the NanoVNAs have SMA connectors. I bought one that has N female connectors on the NanoVNA. 

 

Forgive me for my lack of knowledge but where do I get the adapters to go from the sma connectors to the n type connectors or any other connector typically found on coax/antennas?  I don't even know what they're called.  Is it a matter of calling Gigaparts or another amateur radio online store?

[SteveShannon]

13 hours ago, VETCOMMS said:

Forgive me for my lack of knowledge but where do I get the adapters to go from the sma connectors to the n type connectors or any other connector typically found on coax/antennas?  I don't even know what they're called.  Is it a matter of calling Gigaparts or another amateur radio online store?

DX Engineering, Ham Radio Outlet, Gigaparts, Max Gain, R & L Electronics, and Amazon all have a wide variety of adapters. Until you gain more knowledge your surest option might be to go to a nearby radio dealer or amateur radio club with your radio, antenna, and transmission line and get some personalized help. 

Edited to add: no forgiveness is necessary for your lack of knowledge.  We all started out with little or no knowledge at some point in time. I think what’s making this more challenging is that you are introducing several different extreme levels of technology at once, like expensive hardline and cheap NanoVNAs.  You’re trying to determine whether hardline is good but without a background that would make it easier to discuss. We’re making it worse (unintentionally) by using jargon, or speaking in technical shorthand that probably is just word salad to you. We’re saying things that might end up costing you lots of money in tools you might not even need.

When I was getting started I ended up buying a large assortment of SMA adapters from Amazon.  I never used most of them, but because they were extremely cheap I didn’t care too much. 

So, let me back up a little:

What tools do you actually have that might be helpful?  Do you have a plain old electrical multimeter with an ohmmeter or continuity tester?  The most important tests you can initially do for a used cable of unknown quality can be done with your eyeballs and an ohmmeter:

1. First, visually inspect it to make sure it’s not skinned, pinched, crushed, kinked, or any other kind of obvious physical damage,
2. Then use the ohmmeter to make sure the shield is continuous from one end to the other,
3. Next, make sure the center conductor is continuous from one end to the other, and 
4. Finally, put one lead on the center and one lead on the shield and check to make sure that they are not shorted together.  An ohmmeter will use DC for this test, so you should see a very high impedance, probably in the mega ohms range. Using a NanoVNA (or an antenna analyzer that covers the correct frequency range) will allow you to test more conclusively, but really, if you’ve passed the above basic test, hooking it up to a radio will tell you if it works or not.

Next, let’s figure out that connectors that you included in the photograph.  You actually have two connectors screwed together in that photo which appears below.  The large connector on the bottom has been cut off the hardline. The small connector on top may be unused or may have been removed from a piece of smaller coax, possibly LMR400 or RG8, I can’t tell. The photo shows a finely knurled section.  Unscrew the knurled collar from the piece immediately below it. They should be separated at the red line. Then show us what two connectors you really have. I think the upper, smaller, connector is probably N male and the hardline fitting should be N female.

[VETCOMMS]

On 9/11/2024 at 10:17 PM, SteveShannon said:

DX Engineering, Ham Radio Outlet, Gigaparts, Max Gain, R & L Electronics, and Amazon all have a wide variety of adapters. Until you gain more knowledge your surest option might be to go to a nearby radio dealer or amateur radio club with your radio, antenna, and transmission line and get some personalized help. 

Edited to add: no forgiveness is necessary for your lack of knowledge.  We all started out with little or no knowledge at some point in time. I think what’s making this more challenging is that you are introducing several different extreme levels of technology at once, like expensive hardline and cheap NanoVNAs.  You’re trying to determine whether hardline is good but without a background that would make it easier to discuss. We’re making it worse (unintentionally) by using jargon, or speaking in technical shorthand that probably is just word salad to you. We’re saying things that might end up costing you lots of money in tools you might not even need.

When I was getting started I ended up buying a large assortment of SMA adapters from Amazon.  I never used most of them, but because they were extremely cheap I didn’t care too much. 

So, let me back up a little:

What tools do you actually have that might be helpful?  Do you have a plain old electrical multimeter with an ohmmeter or continuity tester?  The most important tests you can initially do for a used cable of unknown quality can be done with your eyeballs and an ohmmeter:

1. First, visually inspect it to make sure it’s not skinned, pinched, crushed, kinked, or any other kind of obvious physical damage,
2. Then use the ohmmeter to make sure the shield is continuous from one end to the other,
3. Next, make sure the center conductor is continuous from one end to the other, and 
4. Finally, put one lead on the center and one lead on the shield and check to make sure that they are not shorted together.  An ohmmeter will use DC for this test, so you should see a very high impedance, probably in the mega ohms range. Using a NanoVNA (or an antenna analyzer that covers the correct frequency range) will allow you to test more conclusively, but really, if you’ve passed the above basic test, hooking it up to a radio will tell you if it works or not.

Next, let’s figure out that connectors that you included in the photograph.  You actually have two connectors screwed together in that photo which appears below.  The large connector on the bottom has been cut off the hardline. The small connector on top may be unused or may have been removed from a piece of smaller coax, possibly LMR400 or RG8, I can’t tell. The photo shows a finely knurled section.  Unscrew the knurled collar from the piece immediately below it. They should be separated at the red line. Then show us what two connectors you really have. I think the upper, smaller, connector is probably N male and the hardline fitting should be N female.

I separated the connector with pic to follow.   I received a NanoVNA yesterday and have yet to unbox it.   I also have a cheap needle style multimeter.  I will need to look at the label/ print on the hardline when I get it out of the shed.  It's all about learning,  right?  Thanks for being willing to help.   I need to find a local Elmer 

[SteveShannon]

1 minute ago, VETCOMMS said:

I separated the connector with pic to follow.   I received a NanoVNA yesterday and have yet to unbox it.   I also have a cheap needle style multimeter.  I will need to look at the label/ print on the hardline when I get it out of the shed.  It's all about learning,  right?  Thanks for being willing to help.   I need to find a local Elmer 

That’s more like it.  The big one on the left in the picture is female N.  The smaller one on the right is a male N.

A local Elmer helps, but if you don’t mind us occasionally getting flustered we can help you learn some of the basics.

[LeoG]

I have a question about the hardline itself.  The center conductor is hollow.  Is it acting as a waveguide or just a conductor?

[SteveShannon]

21 minutes ago, LeoG said:

I have a question about the hardline itself.  The center conductor is hollow.  Is it acting as a waveguide or just a conductor?

At high RF frequencies the signal travels along the outside of a conductor. That’s called the “skin effect.”  So, the inner portion of the conductor becomes less necessary.  

From Pasternak: In some applications, a hollow metal center conductor can be used to decrease weight and cost while increasing flexibility. Yet this solution is specific to high-frequency applications that do not need to channel high power at low frequencies.

[LeoG]

I know of the current characteristics of the skin effect.  Nice they are taking advantage of it and reducing the need for the copper resource and weight.  I didn't think it was a waveguide but I just had to ask. 

[WRKC935]

6 hours ago, LeoG said:

I know of the current characteristics of the skin effect.  Nice they are taking advantage of it and reducing the need for the copper resource and weight.  I didn't think it was a waveguide but I just had to ask. 

At one point they did make 7/8 cable with a solid center.  But that was YEARS ago. 

My first question would be how long is this run of 7/8 that you have.  There is so much out there that guys believe that they NEED big cable for everything, but fail to realize that short runs (under 50 feet) other, more manageable cable is fine for the application.  If the piece of cable is in the hundreds of feet, putting effort into testing it is worth the effort.  If this is some 20 or 30 foot piece of line, it's really not worth the trouble to mess with it.

[VETCOMMS]

35 minutes ago, WRKC935 said:

At one point they did make 7/8 cable with a solid center.  But that was YEARS ago. 

My first question would be how long is this run of 7/8 that you have.  There is so much out there that guys believe that they NEED big cable for everything, but fail to realize that short runs (under 50 feet) other, more manageable cable is fine for the application.  If the piece of cable is in the hundreds of feet, putting effort into testing it is worth the effort.  If this is some 20 or 30 foot piece of line, it's really not worth the trouble to mess with it.

I was told it was approximately 80 feet long.   I have it stored in a shed and once I get a chance I'll unroll it,  take pics of it and get more pictures/ info on here. Thank you for the reminder that short runs don't require hardline.  I know there is no right answer but what do folks here like for 30 -50 foot runs,  LMR400?  Heliax?