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Post by 321 treeclimber on Feb 4, 2019 18:40:03 GMT -5
What is an acceptable swr reading on a maco v58 ? 321
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Post by ytradio on Feb 4, 2019 20:40:07 GMT -5
With any antenna most people will say anything lower than 2 is ok. I like to get as low as I can, but with some installations it can be very frustrating. This is one reason I personally love having an antenna tuner.
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Post by 321 treeclimber on Feb 4, 2019 21:23:15 GMT -5
Some say an antenna tuner or matcher only masks a poor swr. How does it really work and is it good for 11m ? 321 needs to know!
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Post by ytradio on Feb 4, 2019 22:48:03 GMT -5
Everyone has their own opinion about tuners, and some say it is just RF bouncing around inside a metal box. And well, it is. But realistically coax can handle more SWR than operators like to see on the meter and still be ok, at least as far as the coax goes. Sure there is a limit, but even at 5 to 1 the loss on 100 ft of rg8 is not that high. The radio on the other hand likes a good match, and will overheat, or if equipped with the circuitry most ham radios have had for about the last 25 years, will fold the power back. This reduces the power going down the coax to the antenna. The tuner matches the radio to the impedance on the coax letting it produce full power out to the antenna. This is where the RF bouncing around inside the box happens. But unless the match was really bad to begin with, there is really not all that much loss. Not everyone agrees with this, and you can listen to hams arguing on the HF bands all the time about this subject. If you are just working 11 meters on that antenna, and you can get it to match with an SWR you are happy with, that will be best as far as cost and slightly better on performance, than if you used a tuner. I already have a tuner on the other hand, and it saves me a lot of work sometimes of either climbing a tower or lowering an antenna. I am currently using a direct fed homemade beam with no matching network. When I built it, it had an SWR of 1.2 to 1, after a storm broke part of an element off it went to 2 to 1. The tuner matches 2 to 1 SWR without missing a beat, the antenna is still on the tower after 2 years of being broken, and still works like a champ. Is it "masking" a poor SWR? Well that is one way to look at it, but it still works very well.
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Post by 321 treeclimber on Feb 4, 2019 23:08:19 GMT -5
For the time being, 11meter is where I'll be. So your description is what I've learned about and have come to understand. Here's what I got, maco 5/8 ground plane at 40 ft. To the bottom of the antenna. 50'ft coax(low loss),a galaxy 959 and 1.4-5 to 1 across the 40 chnnls. It was best ten ft. Off the ground where i tuned it to 1.2 to 1. When i put it up it changed. Dead key its 1.4 but with audio swing swr also swings up. As high as 3.0+ or more. Is this normal? Or acceptable? 321
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Post by ytradio on Feb 4, 2019 23:27:37 GMT -5
No not normal or what I would want for acceptable. If the match down low was that much better something has changed. Either the antenna was near something that changed the SWR down low, or is near something up high, or there is a coax problem. As high as you say it is now I would doubt it has interference up there. Are you using a meter that you trust?
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Post by 321 treeclimber on Feb 5, 2019 5:33:50 GMT -5
The meter has always been reliable, not necessarily deadly accurate, but consistent.when the antenna was low it was surrounded by things.up high its fairly clear. Tried to get it really low like my sirio 1/2wave but no. So you've answered my question,readings not acceptable. Ok now if i could only sprout wings...hahaha hired my buddies bucket truck last time. Thanks for all your insight yt. 321
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Post by tubefan on Feb 5, 2019 9:20:59 GMT -5
SWR should be read on a dead key. When you modulate if you look at the cal position it will go up so the SWR reading will also go up. Dead key SWR is what you are looking for.
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Post by 321 treeclimber on Feb 5, 2019 10:21:14 GMT -5
Ok. That answers big question for me and it also helps me to understand that maybe it's not quite as bad as I thought it was. It's about 1.4 on Channel 1 channel 20 and channel 40.
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Post by ytradio on Feb 5, 2019 11:39:09 GMT -5
Full power is not at dead key, and SWR should be checked at the full power you will be running.
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Post by tubefan on Feb 5, 2019 12:06:03 GMT -5
Yes and no. Dead key is how you check swr. You can whistle in mic and set cal then check swr with a whistle. But if you cal with dead key then check with dead key. Also 1.4 is a good swr. I wouldn't worry. Just enjoy the radio. Full power is not at dead key, and SWR should be checked at the full power you will be running.
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Post by 321 treeclimber on Feb 5, 2019 12:19:13 GMT -5
Yt, what is your steps or formula for testing and reading swr in my situation? And i have to say that i called maco and was told by a technician that 1.4 is not bad for that antenna,especially if its from chnnl.1 thrugh 40
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Feb 5, 2019 16:50:42 GMT -5
Personally, I would not worry or pine over a 1.4:1 SWR. Especially if it's that way across all 40 channels. That indicates a fairly wide bandwidth, which is a good thing to have. SWR should not change regardless how much power you are running. But certain SWR meters (IE Cheapies), will indicate differently because of the differences in current flow through the diodes as the RF voltage changes. They SHOULD be a matched pair, but like I said.... cheapies. Check your SWR with a dead carrier, as this is the most stable reference. Modulation can't be held steady with a whistle.
I absolutely would NOT run a tuner to bring a 1.4:1 SWR down to 1:1. That's a waste of time, and the insertion loss of the tuner will more than negate any benefit gained by the minuscule improvement in SWR.
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Post by 321 treeclimber on Feb 5, 2019 17:52:45 GMT -5
10-4 bagger. At this point that makes sense . As i mentioned to yt and tube fan, any further adjustments will require a bucket truck and my buddy's truck will be busy for awhile... 1.4 will afta work
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Post by ytradio on Feb 6, 2019 9:47:02 GMT -5
Like I said, everyone has their own opinion.
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Post by 321 treeclimber on Feb 6, 2019 10:34:50 GMT -5
Ok YT, clue me in on how you would test this, 5w out of my connex 3400 into an swr meter then into a tx800 then my dosy meter?
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Post by ytradio on Feb 6, 2019 11:20:11 GMT -5
I personally put a tone in with a code key in CW mode, not sure if you have a radio with CW or not. To be honest though, I run ssb almost all the time, one reason that I go to the full amount of power that I will be running. Also, I am adjusting a tuner at this point so putting out full power helps to see lowest SWR. If I tune in am mode with just a carrier, SWR meter will sometimes bounce as I modulate in ssb mode. Another way I tune is going to RTTY mode, which puts out a full 100 watts. I recently set up a 3’ Firestik on my truck and checking with 3 different meters, had to use a CW tone to get SWR set properly. If just keyed on AM reading was 1.0 to 1, with modulation it bounced to 1.7 to 1. I kept adjusting until the SWR was 1.0 to 1 with a carrier and full output. If I were you though, I would run how you are now and see if you are happy with it. You can always adjust it later. Also Sandbagger is right, I would not go out and buy a tuner for your present use. But, where I disagree is that if someone already has one, using it does not cause that much loss. And saves me some work on the tower, at 57 years old I don't bounce worth a crap anymore. That’s just my opinion. 73 Whitey
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Post by 321 treeclimber on Feb 6, 2019 14:02:46 GMT -5
10-4. I ,as a 55 year old tree climber, understand bouncing completely. Also want to announce that this is why i am a proud member of this forum. You guys are all willing to help, regardless of opinion. That is what its all about. So thank you all, again. I do have a rci2950 which has cw input.how do i set it up? I will try and adjust again in spring when the bucket truck is available cause i ain't shimmi'n up a 50ft. Mast! 321
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Post by cbrown on Feb 6, 2019 14:31:07 GMT -5
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Feb 6, 2019 18:19:36 GMT -5
Ok YT, clue me in on how you would test this, 5w out of my connex 3400 into an swr meter then into a tx800 then my dosy meter? So just as a point of clarification, you have 2 SWR meters, one between the radio and the amp, and one after the amp and before the antenna? If that's the case, then the one that really matters is the SWR reading you get on the Dosy after the amp. That's the one that's measuring the antenna's match. But I would not check it with the amp on, as any "dirt" coming out of the amp will power add in the meter and show up as additional reflected power and a higher SWR. But it's not the antenna's fault. The SWR before the amp will change depending on whether the amp is on, and how well designed the input matching network is in the amp. When the amp is off you should be looking at antenna SWR, but the additional impedance "bumps" caused by the other items in line may affect the SWR reading. When the amp is on, you are looking at the SWR of the amp's input tuning network. If it's well designed and/or has a swamping resistor or T-pad resistive 50 ohm attenuator, the match will be really good (<1.2:1). If it's poorly designed, you could be looking at a 2:1 or higher SWR. SWR is a ratio. A ratio of forward power vs. reflected power. It should never matter how much power you put out, as the SWR ratio will be constant, even if the SWR meter may not always be. In the grand scheme of things, it really doesn't matter if a true 1.4:1 SWR shows up as a 1.5:1 or 1.3:1 over a wide variation of power levels. As long as it's under 3:1, you're safe (and actually most tube rigs with a antenna load can match a 3:1 SWR with no problem) and anything under 2:1 is acceptable. An SWR of 1.5:1 or less is considered excellent. At 1.5:1, you are only losing 4% of your total power out. Not worth worrying about.
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Post by 321 treeclimber on Feb 6, 2019 21:10:31 GMT -5
Roger that ! Yes to the way its set up, as you described. So the dosy counts most, makes sense. The amp is not great. I like using my tx800 because it gives me just enough to get a complete message out to my forester working in the hills here and its not bad but my texas star 500v is not great regarding its swr readings. 321
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Post by ytradio on Feb 7, 2019 9:52:38 GMT -5
So just to be clear, when we started talking about this, your SWR was rising to 3 to 1 and above on modulation, is that correct? And if so is this still the condition that you are seeing?
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Post by 321 treeclimber on Feb 7, 2019 10:48:31 GMT -5
Yes. With modulation i can easily swing 3.0 or more. Example, with 5w in my 500v swinging to 475w. Output my swr is 3.5+ nothing is overheating or squeeling or smoking and im getting good reports and comparisons on with and without amplification at 60miles
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Post by tubefan on Feb 7, 2019 10:55:06 GMT -5
Again, if you check SWR with dead key and it's good. Then you modulate and it goes up, this is because the cal is also going up from the swing power. Dead key good. Stop looking at the meter and talk
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Post by 321 treeclimber on Feb 7, 2019 11:02:57 GMT -5
I like the way you think! Done...321
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Sandbagger
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Post by Sandbagger on Feb 7, 2019 19:40:28 GMT -5
Roger that ! Yes to the way its set up, as you described. So the dosy counts most, makes sense. The amp is not great. I like using my tx800 because it gives me just enough to get a complete message out to my forester working in the hills here and its not bad but my texas star 500v is not great regarding its swr readings. 321 A couple of things come to mind. First, and most obvious, but I have to ask, you do re-calibrate the forward reading on the SWR meter when you turn the amp on right? The calibrate setting will need to be reduced when the amp is on, from where it was set barefoot. Second, if you have a radio/amp setup that swings a lot, then yes, the SWR will rise on voice peaks, because your average power will increase with modulation, and the calibration would have to be reset again. But you can't properly set the calibration on a rapidly changing modulating signal. That's why SWR should only be checked with a steady (dead key) signal. Don't worry what happens when you talk. Lastly, it's possible that the amp is producing out of band spurs or harmonics that increase with the extra drive power while modulating. That will also show up as radically changing SWR. I've actually had the opposite happen with a dirty amp. The SWR was close to 3:1 on a dead key but dropped to 1.8:1 on a whistle, (even though the actual power increased) because the higher drive power made the amp more stable. It all depends on how the amp is designed. Antennas rarely change SWR under different power levels. Unless you are running so much power that you are exceeding the antenna's power handling rating, then in that case yes, you might be changing the SWR, and likely permanently in short order.
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Post by 321 treeclimber on Feb 7, 2019 23:40:21 GMT -5
Ok, yes i recalibrate when turning on and off amp. Ive also experienced today swr drop on modulated audio above normal talk levels. I have the low pass filter that you guys recommended i buy but hadn't thought to use it till just now. It worked on cleaning up some harmonics issues with my amp before. I guess i should try it again...
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Feb 8, 2019 21:16:18 GMT -5
Ok, yes i recalibrate when turning on and off amp. Ive also experienced today swr drop on modulated audio above normal talk levels. I have the low pass filter that you guys recommended i buy but hadn't thought to use it till just now. It worked on cleaning up some harmonics issues with my amp before. I guess i should try it again... Put the filter after the amp and before the SWR meter. I'll bet you see a big difference in SWR with the amp on compared to not having the filter.
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Post by ytradio on Feb 9, 2019 7:34:58 GMT -5
Yes. With modulation i can easily swing 3.0 or more. Example, with 5w in my 500v swinging to 475w. Output my swr is 3.5+ nothing is overheating or squeeling or smoking and im getting good reports and comparisons on with and without amplification at 60miles Sounds like you got her by the short hairs, let er eat big meat.
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Post by SIX-SHOOTER on Feb 12, 2019 11:23:14 GMT -5
Full power is not at dead key, and SWR should be checked at the full power you will be running. If that is true then an Antenna Analyzer is Useless since they produce almost no output power at all. I have never seen anyone since 1965 when I started in radio set the SWR at full output power. If the SWR is changing when adding power then I would think there is an issue that should be addressed. Of course there is more reflected power as more power is added which makes sense but if you have a 1.5.1 SWR barefooted then adding power of any amount should not result in a terrible SWR just more reflected power which is Normal. SIX-SHOOTER
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