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Mounting Ubiquity on a base-insulated HF tower

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km5l
km5l's picture
Mounting Ubiquity on a base-insulated HF tower

Hey everyone.

I have a 52' aluminum tower that I'll be putting up for 160-10 meters.

It's going to be base-insulated and it is mechanically suited to mount the Mesh hardware at the top. So I'm planning this out.

Does the group have experience in mounting WISP devices or our devices on base-insulated AM broadcast towers? I'm wondering about high RF voltage and the impact on the WISP device, depending of course on the HF frequency and where the voltage and current maximums are located - so to make it easy assume high RF voltage.

What considerations? What about the CAT 5 POE cable as well? Should I used special cable?

Thanks in advance.

73,
Patrick KM5L

AE6XE
AE6XE's picture
I'll defer to others on co
I'll defer to others on co-located with SSB/AM-HF shared tower with a mesh node, but I do share and have sector antennas a few feet away from VHF, and UHF on the tower with no issues.   Make sure the cat5 is extra shielded, the Ventura County group ran into issues with noise, surprisingly, on the cat5 interfering with 6M.    

These devices are such low cost it should be a given in every tower install:
https://www.ubnt.com/accessories/ethernet-surge-protector/

I'm using the Ubiquiti ToughCable Carrier grade, have not had issues.   Also, RF shielding is best if budget allows.

Joe AE6XE
KG6JEI
I'll add a note that you will
I'll add a note that you will also need to make sure you use isolated mounting hardware to mount the node otherwise your mesh node becomes the ground conductor for the tower (most antennas tie the shield to their case and the shield connector of the Ubuiquit hardware is attached to the Ethernet ground)

Ubiquiti threads may help as commerical deployments are relateable(just much much higher power)
https://community.ubnt.com/t5/Business-Talk/AM-Radio-Towers/td-p/222947
https://community.ubnt.com/t5/airMAX-General-Discussion/Radio-station-to...

From what I generally hear the hardware itself handles high RF environments (at least FM band AM I haven't researched), the big issue is the Ethernet line (You don't use the low shield Ethernet cables you go for the heavy shielded cable) (I use the Ubuiquit Carrier grade, pain to work with but ya know I'm not going argue with that double shield in high RF environments)
km5l
km5l's picture
Thanks, and
I read those threads. Interesting. These M2s are plastic body, so, I'd think just mounting directly would be good insulation, dunno. I don't really need ethernet up there, just power. Definitely some options!

Thanks,
Patrick
KG6JEI
If your talking a NanoStation
If your talking a NanoStation I would suspect so yes, but if we are talking about a device that has metal RF ports (SMA or N) the "sheild" of the connector is also attached to the Ethernet Sheild and the Power Ground Return pins. If those connectors or any antenna they are attached to makes metal contact with the tower it is highly likely that (I have not found a single WIFI antenna yet made commercially that wasn't grounded for lightning) there is a full electricial connection from tower to antenna(or even just the RF connector) through the Ubiquiti device to the Ethernet power ground pins and Ethernet shield (which is suppose to be grounded for lightning bleed per warranty)



 
KE2N
KE2N's picture
why base insulated?

Is the idea to feed the tower at HF and use it as a top-loaded vertical?

In that case, you cannot just run the Ethernet cable across the base insulators.  One approach would be to wind the Ethernet cable on a form so that it looked like, say, 500 ohms reactance, at the lowest frequency at which you will feet the tower.  If you run the cable *inside* the tower, will help to keep RF current off of it. You want to avoid getting a high RF voltage tower-to-cable at either end of the cat 5 cable, so the best thing to do is to bond the cat 5 shield to the top *and* bottom of the tower (edit: above the insualtors) - then use the choke where the insulator is. If you are running high power, you might want to consider making the data connection by way of fiber optic. Or send only DC up there and use another radio for the link.
GL

 

km5l
km5l's picture
hmm.. good info

I was thinking about mounting 3 to 4 Nanostation 2 at the top. By the way the question of top loading, I don't have a goal of top loading for HF, there's a corona ring at the top but not large - and the Nanostations won't present much top loading.

(Edit - is my thinking sound on the 3-4 nanos on the top? 50 feet high, just building out here and so I don't really know what I'll need - so I just assumed gain in every direction would be a good thing).

Anyway just thinking on this.. perhaps your idea of running DC only, and focus on choking out the RF is the wisest. I don't think I need ethernet at all. I could simply use a small node in the shack to communicate with the 3 to 4 NSs on the tower?

73,
Patrick KM5L

km5l
km5l's picture
Finalizing plans - dual use of tower - HF plus AREDN
Hey I reread this from a few years ago - refresher - about to put up a light aluminum tower, which is base insulated (see pictures). I am planning to only send DC up the tower, not POE. My objective should include the ability t use a small mesh dish with a radio. Suggestions on that? Can't have much wind-load on that tower. Then I need a short backhaul radio to the house, about 100 ft from top of tower to house. What suggestions? I need to ensure a KW on HF/LF isn't going to mess with AREDN or the back-haul and vice versa, so I figure I just need good insulation from the tower, and blocking caps on both top and bottom of DC power feed.

Am I thinking through correctly? back in '16 I ended up doing something else, don't like it, so back to this idea.

73,
Patrick KM5L
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