Best coax for 800 mhz trunking

[scottybo14]

I will solely be using my scanner on an 800 Mhz trunking system and am wondering what the best 'bang for the buck' coax is that I can get away with? 50 ft length to connect to an outdoor omnidirectional antenna. I know LMR400 is highly recommended from what I read, but I'm wondering if something else will suffice at this frequency range (800-900)? Just making sure LMR400 isn't over-doing it.

Thanks.

 

[Ramathorne]

LMR400 Ultra Flex is what I have always used.

 

[W8RMH]

LMR400 is a minimum for 800. And the ultra flex mentioned above is superb. Just make sure you get cable made by a reputable manufacturer as there is some cheap chinese imitation stuff out there

 

[cg]

There is not any one setup that works for every situation. Antennas, coax, and receivers need to all work with what you can't change: topography, location, system strength, to make it monitorable.

RG58 would work if the tower on the only system you were going to monitor was nearby. On the other hand, LMR1200 probably wouldn't work if you were 50 miles away from a lower power system.

I use LMR400 & 600 because of trying the cheaper setups first. I use a 12db gain yagi with LMR600 for one system and LMR 400 on my other 6 antennas.

LMR400 is made by Times Microwave. Many other makers of similar size cable compare themselves to TM products for good reason. They make reliable, high quality coax. Much of the EBAY stuff is not LMR400 regardless of what is posted in the ads.

chris

 

[tilt404]

I use TM LMR400FLEX also and its been good to me over the years. Only used about 25' max in my install though. I don't think its overkill since something like hard line (Heliax) would be I think. Well, not overkill but overly expensive. There is solid LMR400 but I highly recommend getting the FLEX. Its easier to run and bend slightly over the solid core. Like the person above said also, make sure it is Times Microwave LMR400FLEX.A lot of stuff out there is a knock off.

 

[LIScanner101]

I will solely be using my scanner on an 800 Mhz trunking system and am wondering what the best 'bang for the buck' coax is that I can get away with? 50 ft length to connect to an outdoor omnidirectional antenna. I know LMR400 is highly recommended from what I read, but I'm wondering if something else will suffice at this frequency range (800-900)? Just making sure LMR400 isn't over-doing it.

Thanks.

If you want "premium" reception at these frequencies I think you're going to accept the possibility of shelling out big bucks for cables and connectors.

If your systems are local and strong you can get away with LMR-400.

However, if you're talking about distant systems that sound scratchy when you're "mobile" in your area then you're probably going to have to go with LMR-600 or even Andrews Heliax.

How far away are your "target" systems?

 

[WA0CBW]

Fifty feet of LMR400 would have approximately 1.8 db loss at 824 Mhz. LMR240 (like RG8X) would have 3.6 db. Choose which one will give you the signal you need.
BB

 

[LIScanner101]

LMR240 (like RG8X) would have 3.6 db.

I believe RG-8X performs especially poor at those frequencies because LMR-240 has braid and foil, while RG-8X only has braid.

 

[scottybo14]

I'm within 8 miles of the closest tower on the county trunk system. Alabama has statewide link that I would like to listen in to every once in a while. Closest tower being 25 miles away on that system.

 

[Kimberson]

wow, LME1200?!

 

[KA1NTG]

Get real (watch out for Chinese Fakes) LMR400FLEX, you'll thank us later

 

[Thayne]

If it only for receiving, the best bang for the buck is a good RG-6---the impedance mismatch is not a bad as spending big$$ for LMR or hardline 50 ohm IMHO
Just use good compression BNC connectors-no adapters

 

[VE2XWA]

If it only for receiving, the best bang for the buck is a good RG-6---the impedance mismatch is not a bad as spending big$$ for LMR or hardline 50 ohm IMHO
Just use good compression BNC connectors-no adapters

Agree...

 

[Project25_MASTR]

What would a good feedline be for 800/900 in a mobile? NMO on the roof. Transmitting but sounds like those who would know are am this thread.

Sent from my ME173X using Tapatalk

 

[n5ims]

What would a good feedline be for 800/900 in a mobile? NMO on the roof. Transmitting but sounds like those who would know are am this thread.

Sent from my ME173X using Tapatalk

In the 15' or so used with common NMO mounts, the supplied RG-58 generally works quite well. Be aware that I'm talking about the Larsen quality mounts, not the el-cheapo ones that may use standard RG-58. Even with Larsen quality mounts, there are several types of coax available on them. They are generally marked with what type of coax is used on the mounts, but you'll need to know what to look for.

The CX style coax (standard RG-58 A/U coax) is not recommended for use above 512 MHz. Those mounts are designed for VHF-Low band use, but will also work OK on VHF-Hi. The loss makes it not recommended for UHF or 700/800 MHz use. One variety of these would be the NMOKHFCX mount.

The DS style coax (Dual Shield RG-58 A/U coax) would be the minimum grade you'd want for 700/800 MHz use. The Larsen products indicate this type of coax by having "DS" in the part number. This should work fine for most standard installs. One variety of these would be the NMOKHFDS mount.

The UD style coax (Dual Shield RG-58 U coax) is their premium grade coax. This is the grade coax that Larsen generally provides with their 800 MHz kits although if the mount is purchased separately (read not part of a Larsen bundle of mount and antenna) you may not get this grade of coax. The Larsen products indicate this type of coax by having "UD" in the part number. One variety of these would be the NMOKHFUD mount.

Larsen also has some mounts that use LMR-200 for the coax. These are generally specialty mounts and aren't generally easy to find. They indicate the LMR-200 type coax with a "200" in the part number. One variety of these would be the NMOMMR200N magnetic mount.

You should also be aware that there are two styles of NMO mount 800 MHz antennas as well as two types of NMO mounts. The older style has a flat plate where the antenna makes contact with the mount. This worked well until the 800 MHz radios became popular. This contact point didn't work as well on the higher frequencies so it was redesigned. The newer style mount has "HF" as part of the model number. It has a flat plate like the old style and is fully compatible with antennas that use them. This flat plate can be pulled out, revealing a pin type connection where antennas designed for it can snuggly plug in and make a better contact. While there aren't many antennas designed to use that pin type mount just yet, those that are available will give a much better connection. Those antennas will indicate that they require the HF NMO mount while the older style will just specify NMO.

 

[Kimberson]

Great info on this thread. Presently, I'm trying to troubleshoot an issue which probably has a simple explanation (hindered by my lack of experience):

Simple mobile setup, receive only (396xt), two antenna on car-roof: one is for 2m (super cheap, mag-mount is the size of a half-dollar coin, coax is unknown to me, the "cable" looks like it came off a set of ear-buds)...the 2nd antenna is an Austin/Spectra. The mag mount which was supplied with the spectra has no visible identifiers- the coax is R58A/U. I have both leads going in a CO-201 switch.

El-cheapo antenna works well- no complaints.

The $$$ spectra however...

Had to ask for a replacement mount. The one which was shipped with the spectra was missing a washer and part of the split in the mount looked as if it was cut clean. Also there was (I assume insulator) a wax-like substance which was sloppily applied, covering parts of the inside of the mount not needing it.

Company was good- sent a new (same model) mount. Upon inspection, coax solder to mount looks fine.

The frustrating issue- spectra on mount->coax through trunk space->hooked to the scanner. Same thing with el-cheapo.

The signal coming from the Spectra vacillates wildly- don't know precise measurement in dB- but in "396xt" language, sig varies between 1-4 bars. From what I gather the problem comes from either the end connection (faulty BNC connector?) or the coax itself or both. The reason I think this is because when I physically move the coax-BNC terminus point (same effect /w the splitter/without) the signal on the scanner changes. I can find a quasi sweet spot but it makes no sense i.e the signal goes lossy irrespective of the connection points' location (front of car, rear seat/bottom, near door etc.). The band being scanned has no effect upon signal flux.

Meanwhile- super el-cheapo made for 144ish band is perfect. It grabs 800mhz signals (a lot of the time) better than the expensive spectra! At 2m, the cheap 15$ antenna kills the spectra, even when I manage to find that "sweet spot".

All the info n5ims provides plus my "exhaustive methodology" waving around objects in my car seem to make the mount culpable.

I've read a few posts of others using a spectra near my geo-loc with fantastic results (one of the reasons I purchased it).

I was going to get a new BNC-adapter/housing for the R58AU next week, but after reading what n5ims has posted about mounts, that maybe a fruitless endeavor.

Any ideas? Does it appear to be the mount and if true, which mount would be best for the spectra? I know it's advertised as 3-band, I've read others experienced with the subject tuning theirs, hitting 30-35mhz like a champ+same time receiving 800mhz apco-p25 casts better then /w other prior configs.

I purchased the spectra with the scanner. That was last year going into this hobby with no prior XP.

This brings up another related question(s): Antenna wise, is the spectra (or similar 3+ band made for) fit into the AIO-overly ambitious category of gadgets? I didn't expect el-cheapo to be able to (sometimes) pick up other bands.

Is using 3 or 4 separate antenna (1 antenna for 1 band) into a switch/in car "generally" result in better reception vis a vis using a Spectra-Like one-size-fits-all antenna?

It may help(?) if I mention at this stage of learning I'm sticking with the "popular" 140-800 freq range for now.

Also I maybe going about this in a clunky way. Any facts/opinions of the ideal antenna-combo setup for car/scanner would be great. Edification is more than welcome!

(Have a good weekend)

 

[Project25_MASTR]

I wouldn't use a switch. Receive is much more forgiving than transmit when it comes to antenna length. I've got a friend who will monitor from 25 MHz on his scanner all the way up through 900 MHz with just a 19" magnetic mounted whip on the roof of the truck.

I've heard a lot of weird stories about the spectra. Some similar to what you've experienced and some not, Eham kinda makes it sound hit or miss. Sounds like your spectra mount needs a new BNC connector though.

 

[N1JGE]

I doubt that the ear will hear the difference @ 50 ft.

 

[K5MPH]

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If it only for receiving, the best bang for the buck is a good RG-6---the impedance mismatch is not a bad as spending big$$ for LMR or hardline 50 ohm IMHO
Just use good compression BNC connectors-no adapters

I 2nd that,you can use rg-6 cable I use it and hear 800 MHz stations from over30 miles away why spend money on something you don't need to spend it on....

 

[Kimberson]

Thanks, this is the specific information which if ignorant of is hard to find. Many 2-way folks out there giving their best advice can confuse those like myself. 1 way receive/scanning seems like a good way into the hobby; I am studying for the technician test, which is helping me understand things. Getting into two-way isn't cost prohibitive, just costs a lot!

Ty