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0ldman
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Plastic standoffs?

Tue Oct 23, 2007 7:13 am

For those that put together their own units (I assume most here), where can I find the standoffs for use in Rootennas or anything else for that matter?

I've found plastic standoffs with adhesive backs, can't find them again, can't figure out how I stumbled across them.

Thanks!

edit: I have an unfinished order with Streakwave if anyone knows what they have on hand. It would save on shipping. If not, I just need them, yesterday.
 
CarulloS
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Re: Plastic standoffs?

Tue Oct 23, 2007 7:57 am

A suggestion...

Use metal standoffs like the ones that come for most motherboards. Wisp-router sell them in packages, I think titanwirelessonline sells the plastic ones.

If you use the metal ones I have found them to hold much better and to help ground the equipment which is important. Plastic standoffs do not last well in all conditions and do not help ground the equipment to the metal case.

A drill bit, tap and a nut driver all the correct size make this an easy job.

Scott
 
steveloomis
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Re: Plastic standoffs?

Tue Oct 23, 2007 4:47 pm

I use Digikey @ http://www.digikey.com/ You can get all types of standoff's there. I use:

.750 x 4-40 threaded metal standoffs part no. 1895K-ND
1/4" x 4-40 screws part no. H342-HD
1/4" x 4-40 nylon screws same size as above H542-ND

I use lots of these to assemble units. You can find hinged, threaded standoff in numerous lengths. These work well if you need to reach the bottom side of a routerboard.
Steve Loomis
 
bushy
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Re: Plastic standoffs?

Tue Oct 23, 2007 7:04 pm

I use long 3mm bolts in this way , put the bolt through the backing plate , thread on spacer , then a 3mm nut(for grounding) then the board, then use a hex threaded standoff as a nut.
It is a small bit more work initialy , but much it is much easier to unscrew the hex standoffs used as nuts if you have no choice but to change a board on top of a tower.

Quick drawing below , red = routerboard , yellow = nylon threaded standoffs, blue =3mm nut
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Last edited by bushy on Thu Oct 25, 2007 4:16 am, edited 1 time in total.
 
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BrianHiggins
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Re: Plastic standoffs?

Wed Oct 24, 2007 6:01 am

i've heard metal are better for various reasons, but we use plastic ones, and we've got roughly 500 mikrotik CPEs in the field, and had no problems at all.

Talk to Matt @ streakwave, I set him up with the contact info for the company we buy our plastic stand off's from earlier this year, he was talking about stocking them because we've had such good luck with them. If he doesn't have them, make a note on here and I'll track down the info again (may not be on here tomorrow, so if it's urgent and you need it tomorrow, don't hesitate to ask Matt to shoot me an email and I'll re-send him/you the info)
 
oz_gr
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Re: Plastic standoffs?

Wed Oct 24, 2007 6:33 pm

i use plastic stufs that used to hang curtains :lol: , with slicone(normal ; not the glue ones) no problems yet =)
 
Gerard
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Re: Plastic standoffs?

Wed Oct 24, 2007 8:08 pm

We use these when we assemble all of our CPE's..
standoff.gif
6-32 threads, 0.57" tall..

If you need some please contact me. gerard.at.quiclinkwireless.com

-Gerard
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BrianHiggins
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Re: Plastic standoffs?

Thu Oct 25, 2007 4:33 am

We use these when we assemble all of our CPE's..
those require threaded mounting holes, which do not normally exist in rootenna's and many other devices... I prefer the stick on standoff's, no drilling or tapping required.
 
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tjohnson
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Re: Plastic standoffs?

Thu Apr 10, 2008 3:37 am

I'm curious about the difference when comparing the plastic vs. metal standoffs. If the Rootenna (or DCE or whatever) is being mounted to a J-mount on a roof, does have the routerboard grounded to the case really matter at all? We normally don't run a seperate ground cable, so in our case it won't matter, correct?
Travis
 
CarulloS
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Re: Plastic standoffs?

Thu Apr 10, 2008 6:46 am

Forepoint... You do not have to thread the hole if you don't want to, just drill a hole (or use pre-driled in like arc enclosure) and put a nut on the back :)

Travis... If its working for you then I wouldn't make a deal over it, but here is my opinion: The radio will be grounded via the poe power (7+8) supply even if you don't use shielded cable. If you use shielded cable then it will also be grounded via the shield if installed properly. In the rootenna scenario if you use the little ground clip provided (whos purpose is to electrically connect the front and back of the rootenna) and have the radio grounded via metal standoffs then then all the metal is connected to same ground. Even if you can't notice a difference physics says the noise must be less for the grounded option vs the non-grounded option.

So, if it works it really doesn't matter, but if its the same either way might as well ground the thing...

I wouldn't mount a motherboard in a computer with plastic standoffs for the same two reasons I wouldn't do it in a radio - stability (metal is more secure) and grounding.

Scott
 
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tjohnson
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Re: Plastic standoffs?

Thu Apr 10, 2008 7:08 am

I was asking because using the plastic standoffs with adhesive backing is MUCH faster than using metal standoffs that have to be screwed in. We are currently building 120 units per month, so whatever we can do to save time is worth it for us. BUT, if we need to be grounding the boards for static discharge, etc. then we'll figure out a way to make it happen.

Are the 4 screw holes on the RB411 actually grounded to the rest of the board somehow? We don't see any traces or otherwise indicating they are providing a ground?
Travis
 
jcremin
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Re: Plastic standoffs?

Thu Apr 10, 2008 8:05 am

Even if you can't notice a difference physics says the noise must be less for the grounded option vs the non-grounded option.
So far, I have always thrown the little grounding strap away... Now I'm wondering if I should be using it.. I'm thinking that it really shouldn't make much difference if it's mounted to something that isn't grounded anyway, right?

You say the noise should be less... do you think it would actually make a difference for the performance of the antenna and helping the noise floor?

Joe
 
CarulloS
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Re: Plastic standoffs?

Thu Apr 10, 2008 9:00 am

realistically... I doubt it. But I still think its the best practice to ground it all. Pac wireless doesn't have pieces made and shipped that cost them money if their engineers hadn't designed it that way for a reason.

It does not take a long time to drill 4 holes and tap them with a drill. Maybe 2 minutes. I'm not sure saving any real amount of time is an argument. Maybe lose 5 minutes a day? If you use epoxy you have to let it dry. If you use tape its fast but I don't think it would last as long.

if your plastic stuff works use it. I just prefer to ground mine and use metal standoffs and drill and tap the holes. Some people mount radios in rubbermaid boxes - I use stainless steel eurobex enclosures :)

Scott
 
Tanker
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Re: Plastic standoffs?

Sat Apr 12, 2008 1:57 pm

I might just get my head blown off for this..... :lol:

Here's my 02cents worth...

We have ± 250 CPE's (grows by about 5 - 8 per week) and 27 BSS scattered around the area...

Approx ½ of them are mounted on plastic stand-offs in plastic boxes (UV stabilized) - which effectively isolates the components from any naughty little sparks damaging the equipment ...

The rest are in metal enclosures with all the sweets, grounding straps and the rest...

Here's the thing...

We have LESS component damage / destruction on the plastic assemblies (non-grounded) than we do with the rest... In fact (touch wood) we have had NO damages to the plastic enclosures at all.

Like I said - just our experiances...

We operate in a summer season which has SERIOUS - and I mean SERIOUS thunder storms and lightning.

It remains an ongoing debate in our offices whether to ground or not to ground...

Earthing and grounding is a science on it's own - I know - so I'll be interested to hear other opinions.

regards

Tanker
 
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sdischer
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Re: Plastic standoffs?

Mon Apr 14, 2008 5:04 am

Defactowireless has the best standoffs, heavy duty, stay stuck, great quality and inexpensive.

http://www.defactowireless.com
Steve Discher
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