Opinion regarding Coax upgrade.

[Fixitt]

'cold shrink' kits

I ordered this along with a roll of 3M Super 88 tape. Going to follow your instructions to the letter. Getting too old to get on the roof and manhandle a discone on a 10 foot pole. Hopefully my guardian angel can handle it again.

Thanks for the advice.

 

[Ubbe]

A 3 element yagi are not particulary directional. It will pick up most everything in 1/4 circle in front of it. As site 5 are the closest one and 9 behind it the furthest away it would be the best one to use. But before you seal everything up, connect the scanner so that you can watch the display in system analyze mode and look at its quality bar while aiming the antenna. Start pointing it east and then slowly turn more to north and you will see the quality increase and then go down again. Then move back more to the east where you had the highest quality.

/Ubbe

 

[Fixitt]

Hope I didn’t mess up. Wife was helping me feed the LMR400UF and it got into a circle about 1” diameter. I read the minimum bend radius is much more than that. Did I break something inside the coax by bending it that tight? It is hooked up and I am getting everything I was before and the signal strength meter on the SDS200 shows more bars.

Second goof - I forgot to turn the scanner off before I cut the old coax. Did that harm anything on my SDS200? Again, everything seems to be fine.

I’m too old to be on the roof.

 

[a417]

Hope I didn’t mess up. Wife was helping me feed the LMR400UF and it got into a circle about 1” diameter. I read the minimum bend radius is much more than that. Did I break something inside the coax by bending it that tight? It is hooked up and I am getting everything I was before and the signal strength meter on the SDS200 shows more bars.

Second goof - I forgot to turn the scanner off before I cut the old coax. Did that harm anything on my SDS200? Again, everything seems to be fine.

I’m too old to be on the roof.

If it just got into a kink, and you didn't yank on it to forcefully pull it thru a binding point, and you carefully worked the kink out and untwist it - you are likely ok.

If you got it into a bind and then yanked the hell out of it to force it loose, damage is considerably more likely. Check for continuity from center conductor to shield if you are that concerned. If this is RX only, you'll probably be ok. If you're pushing huge wattage out it - i'd be more leery.

Here's a screenshot from the Times LMR spec sheet to calm some of those nerves. Look at the top line on the left. It's almost like they foresaw that happening...



Disconnecting a RX only devices' antenna is significantly less likely to damage it, as you are not transmitting. Transmitter finals dislike that significantly more.

 

[Fixitt]

Thank you for the reply. I am receive only. No yanking was involved. I happened to notice the bend and straightened it carefully before continuing.

Did I damage the scanner by cutting the coax without powering it off?

 

[mmckenna]

Did I damage the scanner by cutting the coax without powering it off?

No. Worst thing that would have happened would have been that the outer shield and center conductor were shorted when you cut it. There are plenty of DC grounded antennas that will show a short between the center conductor and the outer shield as part of their normal function.

No damage done.

As for the kink, the risk is that the center conductor migrates through the foam dielectric and contacts the outer shield. That's unlikely to happen unless you really wailed upon it with great force.

 

[Fixitt]

No. Worst thing that would have happened would have been that the outer shield and center conductor were shorted when you cut it. There are plenty of DC grounded antennas that will show a short between the center conductor and the outer shield as part of their normal function.

No damage done.

As for the kink, the risk is that the center conductor migrates through the foam dielectric and contacts the outer shield. That's unlikely to happen unless you really wailed upon it with great force.

 

[Fixitt]

You have set my mind at ease. Thank you. The tight bend wasn’t really a kink, and was noticed when feeding the coax. No force was used.

 

[Fixitt]

Call me a dumba$$. Was tidying up the coax and rotated the 90 degree N connector to make it fit in the weatherproof enclosure better. Apparently I broke the center pin because traffic is way down.

Using the antenna that came with the SDS200 for now.

Now I get back on the roof once again. I don’t have the tools or the skill to replace the connector.
And I will make sure it doesn’t get kinked this time.

Unless someone near Collinsville wants to make some cash to put a 90 degree N connector on the LMR400UF.

 

[Fixitt]

Now that I have calmed down, decided to replace the coax once more, but this time both ends will have regular type N connectors and I will use a 90 degree type N adapter on the end that had the 90 degree type N connector. Was trying to eliminate as many connections as possible.