lmr400 (or better) w/bnc

[kd0fx]

Does anyone sell (good) preassembled LMR400 (or better) jumpers with BNC terminals? I'm trying to avoid adapters and I suck at assembling my own. The only place I've found so far is Scanner Master and $35.95 for 4' seems a bit excessive even factoring in convenience.
Using these as jumpers from the multicoupler to the scanners. If I have to I'll give making my own a try but I wanted to make an educated decision before I went that way.

 

[mmckenna]

https://www.tessco.com/products/dis...Id=3402639&CAT_ITEM_RF_Connectors_ST=BNC Male

List price for a 4 foot LMR 400 with BNC males on each end is $36.62. The price with an account is around $22.00.

LMR-400 is good cable, but using it as a jumper to connect to a scanner might be problematic. Since the cable is pretty stiff, it can put a lot of strain on the radio connectors.
Since the amount of loss you'd see in 4 feet of cable is pretty negligible on most types of cable, you might be better served by using a smaller and more flexible cable. LMR 200 or even LMR 195 is really good stuff and easier to manage. The antenna connectors on your radio will thank you.

 

[kd0fx]

Point taken. I'll take a look.

 

[mmckenna]

4 feet of LMR-195 at 860MHz will have 0.4db of loss.
4 feet of LMR-200 at 860MHz will have 0.4db of loss.
4 feet of LMR-240 at 860MHz will have 0.3db of loss.
4 feet of LMR-400 at 860MHz will have 0.2db of loss.
4 feet of RG-58 at 860MHz will have 0.6db of loss.

It would be difficult, verging on impossible, to tell the difference between 0.6db and 0.2db of loss. If your system is designed that 0.4db of loss makes or breaks your system, then you likely have bigger issues.
From that point, ease of use really starts to play into things. LMR-195 or even RG-58 is a heck of a lot easier than running stiffer cable. Price is going to be lower, too.

 

[doublescan]

I've seen ads on Amazon for dozens of jumper-type cables, from some large cable outfits. Several different sizes of cable, and lengths, with connectors. Just bought 100' of rg6 from some company called mediabridge that sells thru amazon, premium look, feel to it. Other sellers hawking Times Microwave cable there also.

 

[zz0468]

For short jumpers like that, RG-58 is fine, and a foam version with a stranded center conductor is nice and easy on the radios.

There's also ultraflex versions of the LMR cables. Just add a -UF to the end of the number. OK for patch panel jumpers and stuff like that, but I still wouldn't want to dangle a portable scanner on a piece of it.

Mouser and Digikey have RG58 BNC assemblies for a reasonable price, and at MPJA.com you can get 3' RG59 BNC jumpers for $4 each.

I agree with mmckenna... don't nit pick about LMR cable so you can save a few tenths of a dB. It's not worth it.

 

[kd0fx]

I can't argue with the math, so I'll take a serious look at these alternatives.

at MPJA.com you can get 3' RG59 BNC jumpers for $4 each.

Can we trust a $4 cable? That seems like it would be lacking in build quality. Or am I just used to overpaying? $4 is pretty appealing.

 

[737mech]

Patch cables

You could make your own if LMR-400 patch cables are that important to your setup? My local shop sells lmr-400 by the foot about $1 to $1.50 a foot. Then you could buy these BNC Clamp Plug Connector for LMR400 | eBay So you'd have a 5 foot patch for $13 to $16.

Just an idea if it had to be done. Patch cables don't really introduce much loss. The 50 ohm 6 footers can be found just about everywhere.

 

[kd0fx]

You could make your own if LMR-400 patch cables are that important to your setup? My local shop sells lmr-400 by the foot about $1 to $1.50 a foot. Then you could buy these BNC Clamp Plug Connector for LMR400 | eBay So you'd have a 5 foot patch for $13 to $16.

Just an idea if it had to be done. Patch cables don't really introduce much loss. The 50 ohm 6 footers can be found just about everywhere.

Sorry, our posts must have crossed. I'm willing to take a look at just about anything, but I'm questioning if these $4 cables are decent quality or if they are just dummy loads. I don't have any experience with them so I'm in the dark. Why is one 3' cable $4 and another made with the same kind of coax $18? Is there actually a difference? Is the smart money to purchase as cheap as you can or is there a point at which it's smarter to spend a couple extra bucks? Obviously there's a point at which cross over into throwing away money but I'm not sure where that is yet.

 

[mmckenna]

Good connectors cost money. I'd be wary of a $3 cable. Also, not all coax is created equal. Some cheap stuff has less than 100% outer shield, and that can be a place that noise can get in. Make sure that whatever coax you get is good quality, 100% shield.

 

[kd0fx]

Well, I've got some mini-8u hanging around. It supposedly has <.4 db attenuation for a 3' ft run. Guess I'll invest in some crimping tools and make some. Even if they don't turn out so well I'll learn something from it. And tools.

 

[ridgescan]

Just take your sweet time making those ends right. I make my own here and I aint even a Ham. Such a small thing but gets to be fun and gives you the satisfaction of having done up your own. Youtube has a bunch of how to videos too.

 

[zz0468]

Can we trust a $4 cable? That seems like it would be lacking in build quality. Or am I just used to overpaying? $4 is pretty appealing.

For a scanner? Sure. Consider that it's Chinese cable, and Chinese connectors, and the build quality is quite decent. It's not mil spec cable, and you don't want to sweep them past a ghz or so, but for hobby use, they're fine.

 

[zz0468]

I don't have any experience with them so I'm in the dark. Why is one 3' cable $4 and another made with the same kind of coax $18?

Chinese child slave labor vs. American labor?

And even if it's "RG-58" coax, there are many grades and qualities. If you want to go the other way, you can get your cables at Pasternack where you'll pay $25 for a 3' RG-58 cable with a BNC connector on each end.

Is there actually a difference? Is the smart money to purchase as cheap as you can or is there a point at which it's smarter to spend a couple extra bucks?

Yes, there's a difference. The real question is, would YOU notice the difference? I would suggest that on a scanner behind an active multicoupler that sets the system noise figure BEFORE your cheap cables, no... I'm almost 100% certain you wouldn't notice the difference.

If you're making precision RF measurements where accuracy and repeatability are important, then you would notice the difference, and those $25 3' RG58 jumpers would actually make economic sense. Especially when the source of the cables needs to be traceable and documented.

Obviously there's a point at which cross over into throwing away money but I'm not sure where that is yet.

Always buy the best that you can afford. If money is tight, and you need to make it go a long way, get the cheaper cables. If you're fabulously well to do, and can only be satisfied with having the best of everything, then get the more expensive cables.

Well, I've got some mini-8u hanging around. It supposedly has <.4 db attenuation for a 3' ft run. Guess I'll invest in some crimping tools and make some. Even if they don't turn out so well I'll learn something from it. And tools.

Then don't cheap out on the tools. Get a good ratcheting type crimp tool. RF Industries has a good selection.