LMR-400 cable management?

[WMaScanner]

Hello,

I am trying to make the best of apartment living and was able to get permission to mount a D-130N in the attic and route ~50ft of LMR-400UF to it, with a couple LMR-240 jumpers to get through existing holes in the ceiling and through doorways.

I'm looking for a way to secure the LMR-400UF to the wall, along a baseboard and over another doorframe, without making any holes in the walls. The landlord prefers Command Strip-type mounts for pictures, etc as it won't damage the wall. I was able to find some Command Strip cable clips, but they are ~.350" while the LMR-400UF is .410". I've read that compressing foam insulated coax can damage it and degrade your signal. Any suggestions on how to secure the coax?

Thanks.

 

[prcguy]

Self adhesive hold downs don't stick very long, especially with large cable that wants to migrate. Ty-Raps are ok for holding the cable down to something as long as they are just snug and not distorting the cable. You also don't want to start a bend right at a Ty-Rap where it will start to dig into the cable even if loose. For running along baseboards I might try 1ft long chunks of 1" steel angle stock upside down on the cable every 4-6ft, that might be heavy enough to keep it in place. No Ty-Raps needed for that as the weight of the angle stock should hold it down.

 

[mmckenna]

Or, if you were doing several jumpers, you may come out ahead by not having so many transitions/connectors. Each connector adds some loss, so in the end you might come out ahead if you just used LMR-240 for the entire run. Easier to route, easier to secure, and ultimately cheaper in the long run. Depending on your original plan, you might come out ahead on the losses, too.

 

[prcguy]

Or, if you were doing several jumpers, you may come out ahead by not having so many transitions/connectors. Each connector adds some loss, so in the end you might come out ahead if you just used LMR-240 for the entire run. Easier to route, easier to secure, and ultimately cheaper in the long run. Depending on your original plan, you might come out ahead on the losses, too.

There is a lot more loss in LMR240 vs LMR400 on a 50ft run. N or even BNC connectors should be under .1dB loss for a pair at 1GHz so not a problem for several in line.

 

[mmckenna]

I agree, but sounded like there were a few LMR-400 to LMR-240 transitions. Maybe the OP can clarify.

 

[ramal121]

I've used Wiremold sections with the peel and stick backing, but as prcguy states glue-on tends to fail especially on sheetrock. If you back it up with 3 or 4 screws down a wall it holds much better and you only have to spackle some some small holes when you move out (unless your landlord is completely anal about this).

 

[WMaScanner]

Thank you all for the suggestions. Glad to get some feedback on my cable run as well, trying to make the most of my relatively compromised living situation. I have been scanning for a long time and am relatively tech savvy/handy but new to the more serious side of RF. Hoping to maximize my VHF & UHF reception, as well as get the 850mhz trunked system well enough to decode P25. Getting some ADSB would be nice but not essential, I don't think the D-130N is particularly good at that anyway from what I have read.

@mmckenna, my original plan was:

D-130N
15ft LMR400 N-N
1ft LMR240 N-SMA (needed the SMA to snake between doorbell & thermostat cables in ceiling)
SMA-N connector
42ft LMR400UF N-N
N-BNC adaptor
MCA204MIL

Unfortunately, I mis-measured and the LMR400UF won't fit under a door so I will now have to do:

D-130N
15ft LMR400 N-N
1ft LMR240 N-SMA (needed the SMA to snake between doorbell & thermostat cables in ceiling)
SMA-N connector
10ft LMR-400 N-N
3ft LMR-240 N-N
42ft LMR400UF N-N
MCA204MIL

May end up sticking a FM attenuater on there at the end if I can find a good one for a good price, I have several strong FM stations nearby and can't imagine that will do my scanners all that well, I was seeing a lot of imaging on my HackRF from that. I have had decent results with the Nooelec Flamingo+ FM, but that seems to cut into air and more than I would want, and is currently in between my Youloop and a Nooelec HF+ preamp. (Having poor results on HF but that is a story for another day - a ton of RFI - although if anyone has tips for reducing RFI in this setup it would be appreciated).

@ramal121 perhaps I will have to use a couple of screws in strategic places, but was hoping to avoid that if at all possible.

 

[rajames53]

I would use the square ty-wrap mounts and replace the foam tape with Command strips. Install the mounts approximately 3 ft apart. the Thing about Command strips both mounting surfaces must be clean. I have used Command strips for years holding different loads and never had them fail and LMR 400 should not be an issue for them. Just one bit of advice make sure you do not cut off the removal tab, Command strips will take the paint off the wall as my grandkids have recently demonstrated for me.

 

[RCBi-Dave]

I'm looking for a way to secure the LMR-400UF to the wall, along a baseboard and over another doorframe, without making any holes in the walls. The landlord prefers Command Strip-type mounts for pictures, etc as it won't damage the wall.

Many clients that rent in commercial buildings, have had the same exact need for management of antenna system coax cables.

I have had good results securing LMR240, LMR400, and LMR600 cables using ALIEN TAPE cut into 0.250" wide strips 1.0" long place 16 inches apart. When removal is needed, just pull out on the alien tape material under the LMR400 with needle nose and the painted surface is left untouched (if it was a good quality paint job).

Best Regards

 

[Ubbe]

The attenuation of LMR400 at 900Mhz and 50ft are 2dB and for RG6 its 3dB. If there's impedance mismatch it will be a couple of tenths added at each transition. If using an amplifier directly at the antenna you will compensate for any coax and connector loss as well as a loss in a passive splitter at the receivers and will also work as a buffer to keep the impedance more constant both to antenna and coax when the impedance will change depending of frequency.

RG6 are a lot more easy to route and cost will be minimal as well. Look at the FM broadcast filter comparison hear at the RR forum to select the one that doesn't interfere with VHF airband. The D190 have been measured and a SWR of 2:1 means it's either double or half of the nominal impedance, 25 or 100 ohm. Also remember that a full size discone like the D190 will have some 10dB or more loss at 900MHz due to its direction pattern no longer points at the horizon.

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/Ubbe

 

[WMaScanner]

Many clients that rent in commercial buildings, have had the same exact need for management of antenna system coax cables.

I have had good results securing LMR240, LMR400, and LMR600 cables using ALIEN TAPE cut into 0.250" wide strips 1.0" long place 16 inches apart. When removal is needed, just pull out on the alien tape material under the LMR400 with needle nose and the painted surface is left untouched (if it was a good quality paint job).

Best Regards

I would use the square ty-wrap mounts and replace the foam tape with Command strips. Install the mounts approximately 3 ft apart. the Thing about Command strips both mounting surfaces must be clean. I have used Command strips for years holding different loads and never had them fail and LMR 400 should not be an issue for them. Just one bit of advice make sure you do not cut off the removal tab, Command strips will take the paint off the wall as my grandkids have recently demonstrated for me.

This is exactly what I was looking for. Thank you very much.