LMR400 vs LMR600

[videobruce]

I have come to the conclusion that GR8 is as outdated as vacuum tubes. While it is ok for below 200 MHz, it really isn't from UHF and up especially for longer runs. Hence the question of the replacement LMR400 (or equivalent) or the next step up LMR600 (or equivalent).
Other than cost, my concern is flexibility or lack of. I do understand it is stiffer, but I'm willing to trade that as long as I can deal with it.

The antenna that gets the cable will be above a TV antenna with a rotor. Hence the concern of the stiffness. At present I'm running RG11 and a RG8 (9913 equivalent) cables with no issue. How stiff is this stuff??

 

[cg]

There is a LMR400 that is more flexible, LMR400 Ultraflex. The center conductor is stranded. The LMR600 is in no way flexible. I have seen much smaller coax run for several feet around a rotor then connected to a larger, stiffer coax. The small coax is so short that the loss is minimal. Some additional loss with a connector. Don't use adapters, use the proper connecters and seal them correctly.

chris

 

[videobruce]

At a cost of greater loss that defeats the purpose.

Looks like 600 might be out of the question.

 

[Francosis]

This site appears to offer that allband AIRCOM PLUS coax.

SSB ELECTRONIC NEW Low Loss Coaxial Cable

 

[LtDoc]

The biggy, I think, would be getting around the rotor. What says you can't use a more flexible section of coax to do that, then reconnect to that LMR-600? Will there be some losses with doing that? Sure, but they probably won't be large enough to be very 'much'. It would certainly make the system usable. so, what's it worth to you?
- 'Doc

(Or, just 'up-size' the rotor?)

 

[prcguy]

If your running 9913 now its got almost identical specs to LMR400 except for the fact that 9913 will fill up with water over time.
prcguy

 

[videobruce]

What says you can't use a more flexible section of coax to do that, then reconnect to that LMR-600? Will there be some losses with doing that? Sure, but they probably won't be large enough to be very 'much'.

Every connect adds close to 1db loss I have found which would partially defeat the purpose of going with the better cable.

Francosis; Thanks for the link but that surely looks like that Aircom would have the same problem 9913 has; water/moisture ingress! One good reason I stopped using 9913 equivalent cable since it happened to me. No specs on diameter.

 

[Token]

Every connect adds close to 1db loss I have found which would partially defeat the purpose of going with the better cable.

How sure are you of that 1 dB/connector and at what frequency? More typically I see 0.1 to 0.25 dB / connector up to about 1 GHz and depending on the connector type. N type and SMA I see those kinds of losses well above 1 GHz.

I don't run LMR 600 anyplace, and I only use a couple of long runs of LMR 400. Most of my long runs are Heliax, 3/8" to 7/8" depending on which runs (most of mine are 3/4" and 7/8"). Heliax has a moisture issue at times, but you can put dry air through it if you are really worried about it, and I have done that in wetter climates, here in the desert moisture is not a big deal. But to get around rotors I run the Heliax up to about the base of the rotor and then LMR 400 from the rotor up to the feed. I find the LMR 400 is flexible enough for that application, remember you have to provide a loop out around the rotor anyway and the loop allows enough flexibility.

All LMR 400 is not created equally (and this goes for ANY coax). The cheap knock-offs that you often find on Ebay have quite a bit more loss than Times Microwave does. Given the choice between knock-off LMR 400 and quality name brand RG-213, 214, or 8 I will take the 213 / 214 / 8 every time.

T!

 

[scannerfreak]

I use Andrew CNT-600 on a Yagi with a rotor and it works fine. Just need to make sure to leave enough play in the line, but I don't have any issues at all.

 

[GTR8000]

Every connect adds close to 1db loss I have found which would partially defeat the purpose of going with the better cable.

Your estimate of 1dB loss per is way too high. It's more like a fraction of a dB per.

You never mentioned the length of your run, or the highest frequency monitored. Remember that most stated loss figures are per 100' of coax at a given MHz. So unless you're running a few hundred feet and trying to pull in distant 800 MHz signals, LMR600 is almost certainly overkill as compared to LMR400. Additionally, using a very short jumper for the rotor is not going to introduce any noticeable "real world" loss, provided you use quality cable and quality connectors that are installed correctly.

Forgive me for being blunt, but your assertion that anything less than the "absolute perfect" setup of the thickest, lowest loss coax you can buy running directly from radio to antenna will be unacceptable is, frankly, going a bit overboard. You should start by dealing with real world numbers when factoring in each connection. Even at 800 MHz, you're never going to be able to discern a 1 or 2 dB loss.

 

[videobruce]

I like to error on the high side as far as loss is concern. I also use the highest frequency as a bases of loss.
I wasn't looking for the "absolute perfect" setup, just something with the lowest loss possible without going way overboard with anything thicker.

I hate to see if I suggested using 900.

 

[videobruce]

One thing I didn't figure since I never thought of it, is the fact the 400 is solid. So is the 9913 equivalent, but with the open dielectric design, there is more flex.
After purchasing both, I see that the 600 is too stiff for a rotor, at least the lower grade "TV" type that is in use (it is being used for a TV antenna, the affected antenna would go above that).

 

[SCPD]

Another thing to consider to is the type of connectors. If you're using PL259s then those can be very expensive with LMR600. They are monster-size connectors. The coax itself is 3/4" thick and the connector is probably 1.25" thick -- and yes, it's tiresome to uncoil 100ft of that stuff.

Stick with quality TM LMR400 with "N" connectors and you'll be fine. It's far cheaper and the gains are probably not worth it.

If you look at this thread and the first picture -- you can see the RG-213 compared to the LMR-600 cable on the fence. The LMR-600 is used for my 36ft HF vertical and the RG-213 for the loop.

http://forums.radioreference.com/hf-mw-lw-general-discussion/222770-we-have-nulls.html

 

[videobruce]

Bite your tongue. PL259's are a four letter word with me if I have a choice.
I have a pair of 'N' 600 connectors and will save those and the cable I bought for another, separate project since trying to use 600 with a small rotor is out of the question.

 

[LtDoc]

Do yourself a favor, stick with LMR-400, and use a short section of something else to get around that rotor. It's your time and money, spend it anyway you want.
- 'Doc

 

[videobruce]

The 600 install will have no rotor.

 

[LtDoc]

Well, you'll definitely be making an error on the high side.
- 'Doc