Jump to content

To be or not to be...swr inline


WROA675
 Share

Recommended Posts

6dB loss is a waste, regardless of frequency. You are picking an argument with the wrong guy here.

1. At a very high level, on paper, more power would translate into more range on FREE SPACE, but that should be taken more like the exception than the rule. I know for a fact that TX IMD will trash your TX range no matter how much power you run as well, to the point of damaging stuff if you keep adding more power.

"More power equals more range" was the kind of really bad advice that people gave me when I got back into radio, along with buying garbage CCR radios with more power... and piss poor dynamic receiver sensitivity... 

2. First off, using s-meters to diagnose radio problems is like using chainsaws to do eye surgery... please, use a calibrated RSSI meter and a spectrum analyzer. Being in the fringe zone of your "s-meter" can mean a host of different things. Is the reading because your receiver is garbage? or is it because you are already operating at noise-floor? or is the other station radiation pattern pointed to the clouds?

If you want more range, add more filtering. That was what the best advice ever given to me (thanks Marc)

G.

Link to comment
Share on other sites

1 hour ago, gman1971 said:

please, use a calibrated RSSI meter and a spectrum analyzer.

Great statement, and even better is to use a dedicated communications service monitor, combined: spectrum analyzer, frequency counter, tracking generator, etc, I currently use Aeroflex/Viavi 3920, HP8920 and Singer test sets. (This could be a debate in and of itself on these forums, which test equipment to use for testing your radio. Just as we are seeing the arguments about radios in use - Chinese, Japanese, and "other", I still prefer my many Motorola commercial gear to my one Radioddity DB20-G for example). "S" meters are not accurate enough to tell very much and using one that is part of the device under test would not pass for accurate measurement, let alone anything that is regulated by any agency related to radio. (Especially for any radio in use on board aircraft or vessels that also fall under other regulation.) I work with many people that think their radio's own RSSI meter is infallible as it is built into the radio itself (mostly with APX4000 and XPR7550e handhelds), as I take it over to my Aeroflex 3920 to check for sure....using the Autotest II setting for APX or Trbo series radios. 

Link to comment
Share on other sites

18 minutes ago, PACNWComms said:

"S" meters are not accurate enough to tell very much and using one that is part of the device under test would not pass for accurate measurement... I work with many people that think their radio's own RSSI meter is infallible...  

 

I fully agree. I segmented out the statements above, specifically to note that I used the radio's S meter as an example because it's an easy visual reference for people who don't have the knowledge and experience that a select few here have from working in some RF engineering related career.  I definitely don't encourage anyone to rely on them for anything beyond decoration, in most cases.  Especially in the OTC GMRS world.

 

 

Link to comment
Share on other sites

45 minutes ago, PACNWComms said:

Great statement, and even better is to use a dedicated communications service monitor, combined: spectrum analyzer, frequency counter, tracking generator, etc, I currently use Aeroflex/Viavi 3920, HP8920 and Singer test sets. (This could be a debate in and of itself on these forums, which test equipment to use for testing your radio. Just as we are seeing the arguments about radios in use - Chinese, Japanese, and "other", I still prefer my many Motorola commercial gear to my one Radioddity DB20-G for example). "S" meters are not accurate enough to tell very much and using one that is part of the device under test would not pass for accurate measurement, let alone anything that is regulated by any agency related to radio. (Especially for any radio in use on board aircraft or vessels that also fall under other regulation.) I work with many people that think their radio's own RSSI meter is infallible as it is built into the radio itself (mostly with APX4000 and XPR7550e handhelds), as I take it over to my Aeroflex 3920 to check for sure....using the Autotest II setting for APX or Trbo series radios. 

Showoff!! hahahahaha :D LOLOL...I am saving to get me one of those... but in the meantime, the RSSI meter on all my 7550e/5550e radios has been found accurate to <1 dB with various signal generators... so, while its not an Aeroflex service monitor, its certainly a huge step up from an s-meter, and when used in combination a spectrum analyzer/SG will give you a pretty good picture of what is going on.

G.

Link to comment
Share on other sites

I don't want to beat this horse into pulp, but marcspaz proves my point. When you in the fringe, you can't afford loss and can't reduce power. I'm always dumbfounded when people say "it's only one step on S-meter", because in reality it's the "whole whopping 400%" of tension of electromagnetic field.

Link to comment
Share on other sites

On 1/8/2022 at 2:09 PM, PACNWComms said:

One poster even mentioned that their Chinese made radios ran "clean"......a point that I find hard to believe.

Well, not knowing the gear I own (and didn't mention) I can understand the skepticism.  The spectrum analyzers on my bench were calibrated about three months ago, and I have a 10MHz Rubidium standard driving all three of them. My favorite is my IFR/Aeroflex 1200S Super. The other two are a CT Systems 3000B and a Shenzhen AT-5011. All three have tracking generators.

I used my XPR5550 and XPR7550 as "benchmarks" and any of my Chinese/Malaysian/Japanese made radios that generated spurs were taken out of service. The only ones that failed were several early release UV-5Rs, and a TYT MD-2017.

Link to comment
Share on other sites

On 1/8/2022 at 2:09 PM, PACNWComms said:

One poster even mentioned that their Chinese made radios ran "clean"......a point that I find hard to believe.

Well, not knowing the gear I own (and didn't mention) I can understand the skepticism.  The spectrum analyzers on my bench were calibrated about three months ago, and I have a 10MHz Rubidium standard driving all three of them. My favorite is my IFR/Aeroflex 1200S Super. The other two are a CT Systems 3000B and a Shenzhen AT-5011. All three have tracking generators.

I used my XPR5550 and XPR7550 as "benchmarks" and any of my Chinese/Malaysian/Japanese made radios that generated spurs were taken out of service. The only ones that failed were several early release UV-5Rs, and a TYT MD-2017.

Link to comment
Share on other sites

7 minutes ago, n4gix said:

My favorite is my IFR/Aeroflex 1200S Super. The other two are a CT Systems 3000B and a Shenzhen AT-5011.

Very nice. Thank you for clarifying, as many do not. The XPR5550/7550/e version's are a great benchmark, and ones I use as well,. The Rubidium standard in my case comes from a Trak9100 which may be replaced with newer Spectracom equipment, I am beginning to lose modules on that aging time source. I wish more people would check their cheaper radios, but that does get expensive, if they do not own the equipment or have to pay someone to do the work for them. Chinese radios are getting better in time, a decade ago they were a whole lot worse. Test equipment is getting the same way, I now include a Surecom SW102 meter in line with many of my RoIP shelf builds (Motorola UHF FDMA/TDMA or analog, mobile with Zetron interface to connect a remote site radio system to an ASTRO dispatch system at another site) as they work very well......even with being a cheap meter and made in China.

Trak9100.jpg

Link to comment
Share on other sites

3 hours ago, axorlov said:

I don't want to beat this horse into pulp, but marcspaz proves my point. When you in the fringe, you can't afford loss and can't reduce power. I'm always dumbfounded when people say "it's only one step on S-meter", because in reality it's the "whole whopping 400%" of tension of electromagnetic field.

Proves your point? Sorry, but I disagree; range problems are NOT solved with "more power", which is what marc tried to explain.

Why not? well, b/c 1 W @ VHF will already reach like 3000 miles in free space, given a -124 dBm receiver sensitivity... but most obstructions will dampen the signal well beyond what you can achieve with a troglodyte approach of "more power". You need height and radiation pattern to reduce that attenuation factor, along with a Fresnel zone initial clearing so the signal behaves closer to free-space... etc... all that well before you even consider adding a single watt of power.  (well, unless you need more than 3000 miles range and you are only using 1W) Otherwise, there is no amount of power that will allow a radio signal go through a mountain (or the curvature of the Earth)... but instead, if you place a small 1W repeater atop that mountain, boom, your range is now 100+ miles... on just 1W. Also, there are times where a radio will just not work, no matter what, and just because you have a hammer, not all problems are a nail.

I've learned this the hard and very expensive way: managing to extract 20+ miles out of a site that originally was lucky to reach <1 mile... with power output kept constant at 50W. So, how did I do it? Elementary, by increasing the antenna elevation from 30 feet to 45 feet, then ditched all the hammy grade garbage, including but not limited to garbage CCR radios, garbage cables, garbage connectors, and garbage antennas, and installed a 2-bay dipole, heliax, trimetal/silver/gold/ N/TNC connectors with double shielded coax patches, plus added a crap-ton of filtering, plus isolator and a preamp. None of those things even remotely resemble adding more power to the system, yet range improved by 20-fold.

If you think you need more power then chances are you are doing something wrong, and that is not the advice I want to spread around, misleading others.

Also, you still haven't defined "fringe"... is a "fringe" because you use piece of garbage bag radios? or because the signal is truly under the site noise floor threshold? Do you know? Because this is kinda important to know. Have you done a site noise evaluation? have you iso-teed the receiver? Have you measured the RSSI at the different places where there is a so-called "fringe"? 

I solved all my "fringe" problems by fixing the real underlying problems, none required adding "muh powah"...

G.

Link to comment
Share on other sites

2 hours ago, gman1971 said:

Proves your point? Sorry, but I disagree; range problems are NOT solved with "more power", which is what marc tried to explain.

In his example, at 10 miles with 800mW no signal, with 42W is a signal. The difference between no communication and communication is very significant. This is how he proves my point.

2 hours ago, gman1971 said:

You need height and radiation pattern to reduce that attenuation factor, along with a Fresnel zone initial clearing so the signal behaves closer to free-space... etc... all that well before you even consider adding a single watt of power

What?? The height reduces the attenuation??? The radiation pattern reduces the attenuation??? Dude... With UHF frequencies anything higher than 1.5m off the surface is close to a free space. It's a roof of the SUV or just tippy-toe with your HT.

2 hours ago, gman1971 said:

Elementary, by increasing the antenna elevation from 30 feet to 45 feet, then ditched all the hammy grade garbage

You guys do not get one thing here: you are already in the field with top of the line non-hammy garbage. You have your mast in place with antenna made of pure gold and coax is 33" hardline. You cannot get more god-beloved non-hammy stuff here (Amazon trucks do not go where you're hiking and you're broke from the hardline), you have to roll with what you have. Now you have a choice: transmit at 20W or transmit at 40W. Which will reach farther?

In real life most of this talk about LOS and Frensel cleaning does not make much sense because other factors are in play. In dense forest it's attenuation by the greenery. In urban canyons it is reflection, refraction and scattering. In mountain setting it is also reflection, refraction and scattering. The only place when LOS and antenna pattern is an absolute king is a flat field (marcspaz's Florida?) and even there there are some imperfections of our sinful world that allow for reflection and scattering and increase of the distance when power is bumped up. He told it himself.

In dense forest, where attenuation of UHF by the leaves is the biggest problem, quadrupling the power always (always!) doubles the distance. It is repeatable. Go try yourself with your Motorola gear. In mountain canyon quadrupling the power will easy quadruple the distance, at very least. No LOS here.

2 hours ago, gman1971 said:

None of those things even remotely resemble adding more power to the system, yet range improved by 20-fold

And now, what's going to happen when you quadruple the power? Nothing?

 

Link to comment
Share on other sites

2 hours ago, gman1971 said:

I've learned this the hard and very expensive way: managing to extract 20+ miles out of a site that originally was lucky to reach <1 mile... with power output kept constant at 50W. So, how did I do it? Elementary, by increasing the antenna elevation from 30 feet to 45 feet, then ditched all the hammy grade garbage, including but not limited to garbage CCR radios, garbage cables, garbage connectors, and garbage antennas, and installed a 2-bay dipole, heliax, trimetal/silver/gold/ N/TNC connectors with double shielded coax patches, plus added a crap-ton of filtering, plus isolator and a preamp. None of those things even remotely resemble adding more power to the system, yet range improved by 20-fold.

I just re-read the conversation and want to add something. The quoted above is about improving the reception of your base (repeater?) station. You could have saved a ton and a half by quadrupling the power of your remote nodes (HTs) from 5W to 20W. That's a joke, of course, 20W HT is not practical and not safe for RF exposure. However, I bet that your remote nodes (HTs) did not feel any of these improvements when they are receiving, except for the heliax and connectors. And this is what the thread was originally about: the loss in the feeder line.

Link to comment
Share on other sites

@axorlov The point behind sharing my road test results are to demonstrate how insignificant a 6 dB loss is in the world of recreational family radio.  In my example, it took more than a 7 dB improvement in power to add spotty communications for about 1/2 mile.

Link to comment
Share on other sites

58 minutes ago, axorlov said:

In his example, at 10 miles with 800mW no signal, with 42W is a signal. The difference between no communication and communication is very significant. This is how he proves my point.

What?? The height reduces the attenuation??? The radiation pattern reduces the attenuation??? Dude... With UHF frequencies anything higher than 1.5m off the surface is close to a free space. It's a roof of the SUV or just tippy-toe with your HT.

You guys do not get one thing here: you are already in the field with top of the line non-hammy garbage. You have your mast in place with antenna made of pure gold and coax is 33" hardline. You cannot get more god-beloved non-hammy stuff here, you have to roll with what you have. Now you have a choice: transmit at 20W or transmit at 40W. Which will reach farther?

In real life most of this talk about LOS and Frensel cleaning does not make much sense because other factors are in play. In dense forest it's attenuation by the greenery. In urban canyons it is reflection, refraction and scattering. In mountain setting it is also reflection, refraction and scattering. The only place when LOS and antenna pattern is an absolute king is a flat field (marcspaz's Florida?) and even there there are some imperfections of our sinful world that allow for reflection and scattering and increase of the distance when power is bumped up. He told it himself.

In dense forest, where attenuation of UHF by the leaves is the biggest problem, quadrupling the power always (always!) doubles the distance. It is repeatable. Go try yourself with your Motorola gear. In mountain canyon quadrupling the power will easy quadruple the distance, at very least. No LOS here.

And now, what's going to happen when you quadruple the power? Nothing?

 

Wrong: I can reach 60 miles on 1 w, I've done it easily with an UV8000E on crossband strapped to a drone. All you need is elevation, not power. 1 W on VHF will reach 3000 miles in free space. If you need more range you increase height in UHF and VHF.

1.5 meters off the ground, in UHF will reach about 2, 2 1/2 miles at best to another 1.5 meter located portable radio in suburban terrain. No amount power is not going to give you 100 miles at 1.5 meter elevation. You are welcome to try.

Well, it seems to me that it doesn't make much sense to you, because you seem to be defending that four times the power = double the range...  which is wrong, and then you keep changing the goalposts while at it too... so now we are inside a dense forest.... which BTW, I've already taken the time to thoroughly test with RSSI meters, spectrum analyzers and even performed iso-tee on the radios too and all that as well. You see, I don't leave shit to chance anymore, I measure everything so there is zero voodoo magic, zero broscience and any other magical formula like four times the power is double the range involved... haha... As measured, my best UHF portable radios, two XPR7550e on 5W ground to ground inside a Wisconsin forest, can barely reach a mile before you can't hear anything. Two 5550e (albeit VHF), both on a backpack with a 5/8 wave antennas, on 50W are lucky to reach more than 4 miles inside the same dense forest, that is on VHF!!, which has a 10dB advantage over UHF in free space... 4 miles at best. Now, here is the kicker, I can talk from inside this particular forest to the base 5550e radio located about 16 miles out... why? because the base antenna (2bay dipole) happens to be about 120 feet above the 5550e radio inside the forest. Is that simple. 25W reaches base at 16 miles too, ... but that radio on 50W can't reach another radio 4 miles inside the forest, but my base repeater, which has a 120 feet advantage can talk to any radio inside the forest. Elevation is king.

As for radiation pattern, this feat of 16 miles to a backpack inside a forest couldn't be achieved with anything else but a 2-bay dipole... so, whatever radiation pattern the 2bay dipole has it made a huge difference in reaching this far, reliably. So yeah, radiation pattern and altitude are pretty much what determines how far you reach, and a receiver that can actually hear things too... 

Quadrupling the power on the base won't reach 40 miles (double the range ) as you claim it will, not even close! At 20 miles, current measured RSSI levels are already in the -118-124 dBm range... so adding 6 more dB to the signal (4x power) won't make it to 40 miles, not even close. But according to your bro-science magical formula, if I added 5kW I should be able to reach all the way to Iowa from Madison, WI... LOL... If I ever needed to reach 40 miles, reliably, I will need to increase the mast height probably by about 150 feet.

If I would've followed your advice of quad power equals double the range, then I would still be fumbling around like a moron wondering why my CCRs don't work beyond half a mile... wait a minute... I did.... I followed this kind of advice before and where did it get me? to a thousand dollar hole in my wallet caused by moer powerful CCRs and garbage equipment...

I really don't care if you make fun of me, or my golden antenna (its aluminum, really) I currently own and operate my own infrastructure that boasts reliable range that was absolutely unthinkable 2 1/2 years ago, especially given all the limitations I had to face, a range that was only achieved by listening to what people who do this for a living had to say. 

G.

Link to comment
Share on other sites

36 minutes ago, axorlov said:

I just re-read the conversation and want to add something. The quoted above is about improving the reception of your base (repeater?) station. You could have saved a ton and a half by quadrupling the power of your remote nodes (HTs) from 5W to 20W. That's a joke, of course, 20W HT is not practical and not safe for RF exposure. However, I bet that your remote nodes (HTs) did not feel any of these improvements when they are receiving, except for the heliax and connectors. And this is what the thread was originally about: the loss in the feeder line.

My remote nodes are 50W mobiles installed on delivery vehicles. 50W gets me 20 miles at best, or around an average of -120 dBm as measured that far out. Nearly 100% reliable coverage is up to 15 miles out, or in the -105-115 dBm range. Given where the base is located, the antenna elevation I have, which I cannot change, and the extreme difficulty of the surrounding terrain around base, along with the high noise floor, reaching 20 miles out is already a miracle. To achieve that on 50W the system needed preamps and a crapton of filtering to be able to hear signals that far out. And no, 200W doesn't yield 40 miles as you claim it would.  And before you go claiming that a 20dB preamp is like adding 20 dB of power... no, let me stop you right there.... those super low noise LNA +20dBm Preamps only improved the overall sensitivity of the base radio by about 2 dBm.

The two thing that made the biggest difference in range were raising the mast to 45 feet and adding the 2-bay dipole, and the reliability across the entire coverage area was noticeably improved when the preamp was added along with all the extra filtering to prevent IMD. 

G.

Link to comment
Share on other sites

Gman, either I can't formulate it's clear enough, or you choose not to understand what I'm saying.

7 minutes ago, gman1971 said:

As measured, my best UHF portable radios, two XPR7550e on 5W ground to ground inside a Wisconsin forest, can barely reach a mile before you can't hear anything. Two 5550e (albeit VHF), both on a backpack with a 5/8 wave antennas, on 50W are lucky to reach more than 4 miles inside the same dense forest, that is on VHF!!, which has a 10dB advantage over UHF in free space... 4 miles at best.

You are comparing apples with bulldozers here, but ok. Try same with 5W and 50W on UHF. You will get same increase of the distance. Why same, you may ask? The VHF has 10db advantage in free space? Because we are not in free space, that's why. When we will be talking to colony on Mars we can get back to this tidbit.

And I'm not changing goalposts it's you who do.

15 minutes ago, gman1971 said:

Quadrupling the power on the base won't reach 40 miles (double the range ) as you claim it will, not even close!

Where did I say that? Care to quote me? In space it will. On earth it won't. In the forest, on UHF, quadrupling 5W to 20W will double the distance from 0.5 mile to 1 mile. It it clear now?

In the mountains quadrupling 5W to 20W may (may! not guaranteed!) increase distance from 0.5 mile to 2 miles. Is it clear? Although, I routinely experience more.

 

22 minutes ago, gman1971 said:

Quadrupling the power on the base won't reach 40 miles (double the range ) as you claim it will, not even close! At 20 miles, current measured RSSI levels are already in the -118-124 dBm range... so adding 6 more dB to the signal (4x power) won't make it to 40 miles, not even close. But according to your bro-science magical formula, if I added 5kW I should be able to reach all the way to Iowa from Madison, WI... LOL... If I ever needed to reach 40 miles, reliably, I will need to increase the mast height probably by about 150 feet.

And where did I say that? Care to quote me? Stop the BS

Link to comment
Share on other sites

1 hour ago, gman1971 said:

And before you go claiming that a 20dB preamp is like adding 20 dB of power...

Care to quote me?

 

Edit:

Re-reading the post carefully I now have a question. Why 20dB pre-amp is not like adding 20dB of power to the signal from the remote transmitter? You seem to imply it's better, the pre-amp. Why? I'm seriously, genuinely curious.

Link to comment
Share on other sites

38 minutes ago, gman1971 said:

because you seem to be defending that four times the power = double the range..

The the power density is proportional to the inverse square of the distance. In open space. On earth it is often not because other factors at play. What's so hard to understand. You're dense tonight.

Link to comment
Share on other sites

36 minutes ago, marcspaz said:

@axorlov The point behind sharing my road test results are to demonstrate how insignificant a 6 dB loss is in the world of recreational family radio.  In my example, it took more than a 7 dB improvement in power to add spotty communications for about 1/2 mile.

And I disagree. Should you repeat your test 800mW -> 42W in the center of the city, you would likely experience 2000% increase of the distance: from around the corner to 8 blocks.

Link to comment
Share on other sites

Here is another place where you claim this nonsense:

"Where did I say that? Care to quote me? In space it will. On earth it won't. In the forest, on UHF, quadrupling 5W to 20W will double the distance from 0.5 mile to 1 mile. It it clear now?"

Goalpost again, now we are back in free-space... not inside a forest anymore?

And you are wrong, 5W to 20W does NOT achieve double the range,that is some serious BS you've been told. Max UHF/VHF radio range in the real world is determined by antenna height above ground, not by power. 

Bumping power to 200 Watt doesn't allow my mobile radios to reach 40 miles. Period.

A 6dB loss, while a waste, it will only affect my max range by about 5 miles at worst, not cut the range in half as you claim it would. Now, if my antenna was placed 150 feet, 6 dB loss will be insignificant, as stated by Marc.

G.

Link to comment
Share on other sites

1 minute ago, gman1971 said:

Here is another place where you claim this nonsense:

"Where did I say that? Care to quote me? In space it will. On earth it won't. In the forest, on UHF, quadrupling 5W to 20W will double the distance from 0.5 mile to 1 mile. It it clear now?"

Goalpost again, now we are back in free-space... not inside a forest anymore?

And you are wrong, 5W to 20W does NOT achieve double the range,that is some serious BS you've been told. Max UHF/VHF radio range in the real world is determined by antenna height above ground, not by power. 

Bumping power to 200 Watt doesn't allow my mobile radios to reach 40 miles. Period.

A 6dB loss, while a waste, it will only affect my max range by about 5 miles at worst, not cut the range in half as you claim it would. Now, if my antenna was placed 150 feet, 6 dB loss will be insignificant, as stated by Marc.

G.

I underlined important part. We are still in the forest. You need to have some sleep.

Link to comment
Share on other sites

16 minutes ago, axorlov said:

And I disagree. Should you repeat your test 800mW -> 42W in the center of the city, you would likely experience 2000% increase of the distance: from around the corner to 8 blocks.

 

It's okay for you and I to have a different opinion on that. 

 

I may make that urban test. I think 8 blocks is generous. Especially at night. LoL 

 

I just realized that would mean going to Tampa, Orlando metro or DC and playing in traffic, which doesn't sound fun.

Link to comment
Share on other sites

Wrong, measured data proves that adding 6dB inside a forest did NOT yield double the range, adding 10dB on a more favorable frequency with a 5/8 wave antenna (vs a rubber duck) increased range only by about 2.7 times, at best, so a 6dB increase will NOT double the range inside a forest as you claim. Now, the data did prove that adding 120 feet of antenna elevation showed at least a four-fold increase in range, from <4 miles to at least 16 miles.  Do you have any data collected? or you just guess stuff up with some formulas? Back at a previous job I used to joke that everything done in simulation is doomed to succeed...

And where did you say that you ask? What about you just told Marc that going from .8W to 42W will likely experience a 2000% percent increase in distance.... , so adding x52 times the power yields a 2000% range increase too...  do you really guess this stuff?

I guess sometimes not even sleep can fix the problem, darling...

G.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use and Guidelines.