What is the disadvantage of using 100' of RG-8X verses RG213-U on a 25 to 2000 MHz receiver only? I don’t have any means to measure dB gain or loss so I’m not sure I would notice much, if any difference.
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Comparing coax
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mmckenna
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Try this:
Coax Calculator
You can figure it out for yourself.
Lower frequencies will fare better with coaxial cable, as there is less loss. Higher frequencies will suffer more.
100 feet of RG-8x will lose 1.488dB at 25MHz, and 23.472dB at 2000MHz
100 feet of RG-213 will loose 1.004dB at 25MHz and 12.814 at 2000MHz
So, on the lower end (25MHz) you won't notice a difference. At 2000MHz, you will notice a difference.
If you are purchasing new, look at LMR-400. It's about the same size as RG-213, but is way more efficient. 100 feet of LMR-400 will loose 5.992dB at 2000MHz. You should be able to find fairly close pricing between the 213 and the LMR-400.
Of course, you can keep adding better and better coaxial cable, but the price goes up, the size goes up, and the installation difficulty goes up. LMR-400 is a pretty tolerable cable, all things considered.
Coax Calculator
You can figure it out for yourself.
Lower frequencies will fare better with coaxial cable, as there is less loss. Higher frequencies will suffer more.
100 feet of RG-8x will lose 1.488dB at 25MHz, and 23.472dB at 2000MHz
100 feet of RG-213 will loose 1.004dB at 25MHz and 12.814 at 2000MHz
So, on the lower end (25MHz) you won't notice a difference. At 2000MHz, you will notice a difference.
If you are purchasing new, look at LMR-400. It's about the same size as RG-213, but is way more efficient. 100 feet of LMR-400 will loose 5.992dB at 2000MHz. You should be able to find fairly close pricing between the 213 and the LMR-400.
Of course, you can keep adding better and better coaxial cable, but the price goes up, the size goes up, and the installation difficulty goes up. LMR-400 is a pretty tolerable cable, all things considered.
I've already got a new 150' roll of RG-213U. It's a lot heavier and a lot harder to handle than RG-8X. I was thinking about selling the RG213-U to a local amateur operator and buying something a little easier to handle.
This may be a loaded question but how much am I going to be able to hear at 2000 MHz with my R7100? My D3000N antenna is going to be 35' high.
I'm a novice at this so you'll have to bear with me.
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mmckenna
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Honestly, no much.
There isn't a whole lot of analog signals above the 1.2GHz ham bands. So much of the stuff is going digital that unless you have a digital capable radio, you're out of luck.
I have an AOR AR2300 that covers 50khz to 3500MHz, and once you get above 800MHz, there isn't much to listen to.
If you've already got the RG-213, then use that. If you go with a smaller/easier to handle cable, you will start losing more of your signal up in the 700MHz and 800MHz band. I stick with that stuff and call it done. Honestly, unless you are near someone that is running an analog system in the 700 - 800MHz range, or just really want to listen to the hams up in 900 or 1200MHz, you likely won't hear much above 500MHz worth your time. If that saves you some money, then good. I certainly wouldn't invest in better coax unless you have something specific you need to listen to up that high.
There isn't a whole lot of analog signals above the 1.2GHz ham bands. So much of the stuff is going digital that unless you have a digital capable radio, you're out of luck.
I have an AOR AR2300 that covers 50khz to 3500MHz, and once you get above 800MHz, there isn't much to listen to.
If you've already got the RG-213, then use that. If you go with a smaller/easier to handle cable, you will start losing more of your signal up in the 700MHz and 800MHz band. I stick with that stuff and call it done. Honestly, unless you are near someone that is running an analog system in the 700 - 800MHz range, or just really want to listen to the hams up in 900 or 1200MHz, you likely won't hear much above 500MHz worth your time. If that saves you some money, then good. I certainly wouldn't invest in better coax unless you have something specific you need to listen to up that high.
Thanks, that's what I was hoping you would say. I'll use the RG213-U and will shorten it 50'.
Moved to the Coax Cable forum. The ICOM Receivers forum is for topics specific to their equipment.
mpddigital
Member
Good Idea. Shortening to 50 feet will cut your loss in half right off the bat. Since you are new it this, standard rule of thumb is always use the shortest cable run you can. Also, the thicker the coax the less loss (construction parameters being equal) so you will be better served with heavier cable in the higher frequencies.
Making a correction here. I was asking the original question about the 100' of coax before I actually bought the 150' of RG213-U. I'm not shortening a coax to 50'. I am only considering cutting 50' off of a 150' long coax. The antenna is 35' in the air. It's 50' to my receiver.
What will I gain in reception by cutting off 50' of coax? Does this mean I will only receive a stronger signal of what I am already receiving?
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mpddigital
Member
If you have a 100ft run of coax with 4Dbi of Loss at 800MHz and cut it to 50ft your loss would be 2DBi. Standard loss measurements are for 100ft of X type coax at X frequency. The thicker/better designed/better materials coax has the less loss.
Loss calculations take into consideration the conductor steel/aluminum/copper/silver/gold, the dielectric plastic/foam/Teflon, and shield braid (+%of coverage)/ Braid+Foil - This is why cable that LOOKS the same and even is the same size can have completely different characteristics.
RG213 is fine for what you are doing but you will have less signal loss the shorter the cable run from a well placed antenna. Sorry to over-complicate
Loss calculations take into consideration the conductor steel/aluminum/copper/silver/gold, the dielectric plastic/foam/Teflon, and shield braid (+%of coverage)/ Braid+Foil - This is why cable that LOOKS the same and even is the same size can have completely different characteristics.
RG213 is fine for what you are doing but you will have less signal loss the shorter the cable run from a well placed antenna. Sorry to over-complicate
Just for everyones benefit, the main use for RG213 is to make phasing cables between cavities in duplexer assemblies and the like. If you look at the propagation velocity, it is .65/.66 versus the normal .8 to .9 for other coaxes in this size range. The slower velocity makes the cables shorter and makes for a more compact phasing harness for any duplexer or phased combiner assembly.
It will be fine for regular antenna feed line use if it is short, but I would trade it for LMR400 if I could. The LMR400 and 600 cables are hard to beat for price and low loss; they are my very strong preference.
As for cutting the RG213 from 150' to 100' you will save about 2.7 dB of loss at 440 MHz (UHF). A marginal, noisy signal will become noticeably less noisy with a 2.7 dB stronger receive signal. It won't be dramatic, but it will be noticable with very weak signals. Going from 150' of RG213 to 100' of LMR400 will save you over 5.5 dB of coax loss at UHF; that loss reduction will be quite noticeable. I would not hesitate to do that changeout; the extra 5 to 6 dB loss of the 150' of RG213 will make thing notably worse for reception.
AND at 800 MHz Public safety frequencies, the extra loss of 150' of RG213 versus 100' of LMR400 will approach 10 dB. That difference is huge; an extra 10 dB loss will turn a good signal in to a noisy mess. Go to the shorter LMR400; you will be glad you did.
It will be fine for regular antenna feed line use if it is short, but I would trade it for LMR400 if I could. The LMR400 and 600 cables are hard to beat for price and low loss; they are my very strong preference.
As for cutting the RG213 from 150' to 100' you will save about 2.7 dB of loss at 440 MHz (UHF). A marginal, noisy signal will become noticeably less noisy with a 2.7 dB stronger receive signal. It won't be dramatic, but it will be noticable with very weak signals. Going from 150' of RG213 to 100' of LMR400 will save you over 5.5 dB of coax loss at UHF; that loss reduction will be quite noticeable. I would not hesitate to do that changeout; the extra 5 to 6 dB loss of the 150' of RG213 will make thing notably worse for reception.
AND at 800 MHz Public safety frequencies, the extra loss of 150' of RG213 versus 100' of LMR400 will approach 10 dB. That difference is huge; an extra 10 dB loss will turn a good signal in to a noisy mess. Go to the shorter LMR400; you will be glad you did.
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When referring to loss in cable its simply expressed in dB and not dBi (referenced to an isotropic radiator). Also, the d is lower case and the B is upper case since it refers to someone's name (Bell).
prcguy
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Actually RG-214 is what you should be using for interconnecting cables for duplexers, Not RG-213.
beachmark said:
Actually RG-214 is what you should be using for interconnecting cables for duplexers, Not RG-213.
Rule of thumb... The larger and harder to handle the coax is, the lower the loss. That effect gets more noticable as frequency goes up. So, you've been provided a link to a coax calculator. Figure out the difference.
If its FM you're listening to, you won't notice much less than 4-5 dB difference. Unless signals are real weak.
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Any excess coax is wasted signal not getting to your receiver. Use the coax calculator to figure out how much.
I appreciate all of the feedback but since I'm such a novice at this I think I will wait before cutting the coax shorter. I may want to extend the antenna pole another 12' to 20'.
I do have one last question. With the D3000N antenna being at only 35', what's the chances that raising it another 12' to 20' will help the reception more than leaving it where it is and cutting 50' of the coax off?
I do have one last question. With the D3000N antenna being at only 35', what's the chances that raising it another 12' to 20' will help the reception more than leaving it where it is and cutting 50' of the coax off?
There's no 'good' or 'set' answer to that. In general, meaning that there are always exceptions in either direction, higher means the -possibility- of hearing something you may not other wise hear. There's no guarantee that you will notice any appreciable difference. But, you might.
One way of looking at cutting that coax is that if you don't, you have a sort of 'worst case' situation. If you raise your antenna there would be no additional losses from having to add to that feed line. If there's no chance that you will ever raise the thing, cut it off. The difference in most cases isn't going to be all that noticeable. All this is frequency dependent. What would be unnoticeable as lower frequencies will possibly be more noticeable at higher frequencies (bands would probably be a better way of saying that).
And just a word about 'dB's. Fractions of a dB are almost meaningless unless you have a huge number of them. A very rough rule of thumb is that the human ear can't hear differences of less than about 3 dB. Another 'thingy' to keep in mind is that all 'RF' is always propagation dependent. What you can't hear today will probably be hearable some other time. That's about as 'normal' as it get's, talk to "Momma Nature" about it...
- 'Doc
And the 'bottom line' with any feed line is how much you can afford and is it worth the cost. That's different for everyone.
One way of looking at cutting that coax is that if you don't, you have a sort of 'worst case' situation. If you raise your antenna there would be no additional losses from having to add to that feed line. If there's no chance that you will ever raise the thing, cut it off. The difference in most cases isn't going to be all that noticeable. All this is frequency dependent. What would be unnoticeable as lower frequencies will possibly be more noticeable at higher frequencies (bands would probably be a better way of saying that).
And just a word about 'dB's. Fractions of a dB are almost meaningless unless you have a huge number of them. A very rough rule of thumb is that the human ear can't hear differences of less than about 3 dB. Another 'thingy' to keep in mind is that all 'RF' is always propagation dependent. What you can't hear today will probably be hearable some other time. That's about as 'normal' as it get's, talk to "Momma Nature" about it...
- 'Doc
And the 'bottom line' with any feed line is how much you can afford and is it worth the cost. That's different for everyone.
reconrider8
Member
so are you implying that the 400 is better or the 213?
I'll apologize to disagree as I don't want to be the least contentious. Many of the old Decibel Products VHF duplexers shipped from the factory with RG213. The power handling of RG214 and 213 are identical so either can be used. And RG-214 and 213 will be pretty good down on the HF ham bands since both can handle good power and the losses are lower and acceptable in most cases..
And I did look up the prop vel on 214 and it is the same as 213 so I stand corrected on that item; thanks!
I'm not implying.....I'm a-sayin'! For 800 MHZ, the OP is going to be much better off with LMR400 than RG213 for his scanning use. I can't see any need to hamper one's scanner's performance with a lot of un-necessary coax loss. You won't know what your'e NOT hearing....
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If it is stong, yes, no noticeable difference. If it is very weak however, an added 4-5 dB will take it from noisy to unreadable. And if you are listening to a weak mobile in a picket-fencing situation, that extra 4-5 dB will make the noise bursts noticeably less. How often that happens depends on your siting and where the sites/mobiles are that you are scanning.
As for going from 35' to 45', maybe not.....35' to 55' maybe so. You would typically expect to get more benefit more from raising the antenna than you lose from the extra loss. But it depends again on your siting: if you are on the edge of cliff over the shore, it won't make any real difference. But if it helps get the antenna clear of some houses nearby or the brow of a small hill or a metal barn nearby, then it will. We install cell antennas on buidlings all the time and we strive to go as high as we can.
And I don't mean to be disrespectful, but avoiding an extra 4-5 dB coax loss is worth the effort, and much more so the 10 dB of these lengths at 800. I can easily hear a 1-2 dB difference in weak FM signal recpetion levels. (Hint: I do these types of sensitivity tests regularly....so don't jump on my case guys!)
But, I also understand the $$ aspects of this too and having the coax already and so forth. It won't be like you will hear nothing.... it's just that you will never know what you AREN"T hearing.
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