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Posted: 3/8/2021 10:40:51 PM EDT
[#1]
Did you seriously not even bother to crack the MFJ catalog?
The 962, the 989, the 986...the list goes on... |
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Posted: 3/8/2021 10:50:21 PM EDT
[#2]
I have the 986 model. With the roller inductor and differential capacitor, it matches over a wide range and there's only two knobs to adjust.
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Posted: 3/8/2021 10:58:08 PM EDT
[#3]
Quote HistoryQuoted: Did you seriously not even bother to crack the MFJ catalog? The 962, the 989, the 986...the list goes on... Yes, I looked in the catalog. The auto tuners have a matching range listed, from what I have found the manual tuners do not. I was looking for someone who has run both the 949 and a higher power tuner. |
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Posted: 3/8/2021 11:04:18 PM EDT
[#4]
Quote HistoryQuoted: I have the 986 model. With the roller inductor and differential capacitor, it matches over a wide range and there's only two knobs to adjust. I have looked at the 986. How does its matching range compare to the 949? |
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Posted: 3/9/2021 8:18:28 AM EDT
[#5]
With some exceptions, most notably the tuner you currently own, the impedance matching range of MFJ tuners is listed in the tuner manual. So you have to crack the manual for each tuner. Luckily MFJ makes them freely available on their website.
Your best bet is the 989 by far. |
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Posted: 3/9/2021 9:18:32 AM EDT
[#6]
Palstar AT2K. Palstar site Shop around for price.
73, Rob ETA: Ham Radio Outlet in Denver shows in stock but low. |
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Posted: 3/9/2021 10:29:45 AM EDT
[#7]
Palstar AT2K: 15-1500 Ohms
MFJ-989: 6.5-3200 Ohms. |
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Posted: 3/9/2021 10:35:55 AM EDT
[#8]
a kilowatt and largely mismatched antenna impeadance is a recipe for trouble
you’ll be miles ahead improving your antenna instead . |
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Posted: 3/9/2021 11:15:30 AM EDT
[#9]
Quote HistoryQuoted: I have looked at the 986. How does its matching range compare to the 949? I don't know, it just works. My fan dipole can get insanely high on bands it's not cut for, so high the SWR meter pegs out. I'd estimate 8 to 10:1. While I don't have a 949, I do have an old 941D, which is basically the same matching circuit. The bells and whistles are different, though. 
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Posted: 3/9/2021 12:06:28 PM EDT
[#10]
I use the Cobra Senior and Cobra Junior Ultralite antennas, made by K1JEK.
On the senior antenna, with a TL-922A amp and the TS-990s radio, I use a Palstar AT2KD tuner. I am able to tune 10-160M with no issue and the amp puts out around 800W as it's only pulling 110V. On the Junior antenna, I use the Yaesu FTDX-10 and run a Palstar AT500 tuner and have no problem with tuning. Currently running 100W, but that will change when and if Elecraft gets my KPA500 too me. The only MFJ tuner I have left is the 300W MFJ-993B. The others, the 986 and the 949D died by gunfire after one self destructed. |
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Posted: 3/10/2021 1:22:36 AM EDT
[#11]
Thank you for the replies!
I appreciate the advice. |
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Posted: 3/10/2021 6:09:42 AM EDT
[#12]
I’m not a fan of anything MFJ, but I picked up a used 989C and it works just fine tuning my 40 meter EFHW on all bands but 160. I typically run 800-1200 watts.
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Posted: 3/13/2021 5:49:03 PM EDT
[#13]
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Posted: 3/19/2021 8:18:23 AM EDT
[#14]
Quote HistoryQuoted: I use the Cobra Senior and Cobra Junior Ultralite antennas, made by K1JEK. On the senior antenna, with a TL-922A amp and the TS-990s radio, I use a Palstar AT2KD tuner. I am able to tune 10-160M with no issue and the amp puts out around 800W as it's only pulling 110V. On the Junior antenna, I use the Yaesu FTDX-10 and run a Palstar AT500 tuner and have no problem with tuning. Currently running 100W, but that will change when and if Elecraft gets my KPA500 too me. The only MFJ tuner I have left is the 300W MFJ-993B. The others, the 986 and the 949D died by gunfire after one self destructed. Newbie question: I see that some of the antenna tuners have a wattage rating. What is the purpose of that? Is the tuner acting as an amplifier to the transmitter's signal? |
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Posted: 3/19/2021 8:31:40 AM EDT
[#15]
Quote HistoryI just bought one of those locally for $50 Now I have 2 of them The idea is to make a balanced tuner with the parts, but now I am not sure I should part them out |
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Posted: 3/19/2021 8:33:31 AM EDT
[#16]
Quote HistoryQuoted: Newbie question: I see that some of the antenna tuners have a wattage rating. What is the purpose of that? Is the tuner acting as an amplifier to the transmitter's signal? Quote HistoryQuoted: Quoted: I use the Cobra Senior and Cobra Junior Ultralite antennas, made by K1JEK. On the senior antenna, with a TL-922A amp and the TS-990s radio, I use a Palstar AT2KD tuner. I am able to tune 10-160M with no issue and the amp puts out around 800W as it's only pulling 110V. On the Junior antenna, I use the Yaesu FTDX-10 and run a Palstar AT500 tuner and have no problem with tuning. Currently running 100W, but that will change when and if Elecraft gets my KPA500 too me. The only MFJ tuner I have left is the 300W MFJ-993B. The others, the 986 and the 949D died by gunfire after one self destructed. Newbie question: I see that some of the antenna tuners have a wattage rating. What is the purpose of that? Is the tuner acting as an amplifier to the transmitter's signal? about the maximum power you can put into it and not have it arc the capacitors, although for most of the ratings, you can still do it if you match at the wrong spot, it needs to be the least inductance match, you can get more than one solution for a match but the others may create much higher voltages. |
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Posted: 3/19/2021 9:13:06 AM EDT
[#17]
Here is a tutorial on tuning the "T" match antenna tuner. Tuning the T network tuner for best efficiency.
73, Rob |
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Posted: 3/19/2021 9:51:31 AM EDT
[#18]
An additional way to minimize tuner losses is to use a really big tuner with a really big inductor.
But I am not sure how much the difference is. |
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Posted: 3/19/2021 2:52:18 PM EDT
[#19]
Quote HistoryQuoted: a kilowatt and largely mismatched antenna impeadance is a recipe for trouble you’ll be miles ahead improving your antenna instead . ^^^^THIS^^^^ Also, you'll have a hard time finding a new tuner for sale. Just about all sellers are sold out. My buddy was at HRO in Atlanta today. Their shelves are nearly empty. They have less than 10% of normal inventory. Find a manual tuner. Most likely it'll be more efficient and will have several output options (like balanced line and long wire). Relying on a tuner with extreme tuning ranges is a poor choice. A tuner won't make a crappy antenna perform better but I'm not going to keep repeating this. |
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Posted: 3/19/2021 5:50:25 PM EDT
[#20]
Quote HistoryQuoted: ^^^^THIS^^^^ Also, you'll have a hard time finding a new tuner for sale. Just about all sellers are sold out. My buddy was at HRO in Atlanta today. Their shelves are nearly empty. They have less than 10% of normal inventory. Find a manual tuner. Most likely it'll be more efficient and will have several output options (like balanced line and long wire). Relying on a tuner with extreme tuning ranges is a poor choice. A tuner won't make a crappy antenna perform better but I'm not going to keep repeating this. Quote HistoryQuoted: Quoted: a kilowatt and largely mismatched antenna impeadance is a recipe for trouble you’ll be miles ahead improving your antenna instead . ^^^^THIS^^^^ Also, you'll have a hard time finding a new tuner for sale. Just about all sellers are sold out. My buddy was at HRO in Atlanta today. Their shelves are nearly empty. They have less than 10% of normal inventory. Find a manual tuner. Most likely it'll be more efficient and will have several output options (like balanced line and long wire). Relying on a tuner with extreme tuning ranges is a poor choice. A tuner won't make a crappy antenna perform better but I'm not going to keep repeating this. Sure it will. A tuner will very much make a crappy antenna shine, assuming you are using balanced line ( the more open the better like 600 ohm ladder line ) and not coax |
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Posted: 3/19/2021 5:52:35 PM EDT
[#21]
Quote HistoryQuoted: a kilowatt and largely mismatched antenna impeadance is a recipe for trouble you’ll be miles ahead improving your antenna instead . not really. I tune about a 9:1 mismatch just fine. As long as you use balanced line and not coax, and a big coil tuner rated for a lot of power, and you tune it properly, the losses are small. |
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Posted: 3/20/2021 12:23:14 AM EDT
[#22]
Quote HistoryQuoted: Sure it will. A tuner will very much make a crappy antenna shine, assuming you are using balanced line ( the more open the better like 600 ohm ladder line ) and not coax It depends on what we define as a crappy antenna. You can't connect a tuner to a 20m dipole or a 30 ft long wire at 15 ft above ground and make it "shine" on 160 meters. But again, we need to define what "shine" means. I wish I had a dollar each time I've seem people try to do this and then complain that their tuner can't tune it. I've seen a guy connect 2 tuners in series to make his crappy antenna work and the tuners did tune but he couldn't understand why no one could hear him. Many new hams think that as long as their tuner can tune, they are good to go and their antenna works. 99% of them use regular 50 Ohm coax and keep the tuner next to the radio. |
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Posted: 3/20/2021 6:54:34 AM EDT
[#23]
Quote HistoryQuoted: It depends on what we define as a crappy antenna. You can't connect a tuner to a 20m dipole or a 30 ft long wire at 15 ft above ground and make it "shine" on 160 meters. But again, we need to define what "shine" means. I wish I had a dollar each time I've seem people try to do this and then complain that their tuner can't tune it. I've seen a guy connect 2 tuners in series to make his crappy antenna work and the tuners did tune but he couldn't understand why no one could hear him. Many new hams think that as long as their tuner can tune, they are good to go and their antenna works. 99% of them use regular 50 Ohm coax and keep the tuner next to the radio. Quote HistoryQuoted: Quoted: Sure it will. A tuner will very much make a crappy antenna shine, assuming you are using balanced line ( the more open the better like 600 ohm ladder line ) and not coax It depends on what we define as a crappy antenna. You can't connect a tuner to a 20m dipole or a 30 ft long wire at 15 ft above ground and make it "shine" on 160 meters. But again, we need to define what "shine" means. I wish I had a dollar each time I've seem people try to do this and then complain that their tuner can't tune it. I've seen a guy connect 2 tuners in series to make his crappy antenna work and the tuners did tune but he couldn't understand why no one could hear him. Many new hams think that as long as their tuner can tune, they are good to go and their antenna works. 99% of them use regular 50 Ohm coax and keep the tuner next to the radio. very good point I was assuming a long non-resonant antenna with a high SWR Not a lawn chair or a short vertical Shine meaning efficient even with a high SWR |
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Posted: 3/20/2021 7:47:30 AM EDT
[#24]
Quote HistoryQuoted: ...Shine meaning efficient even with a high SWR In my mind, . . . "efficient" means resonant with low SWR, like a tuned dipole. which means you don't need an antenna tuner. , , "antenna tuner" should really be called " Impedance matcher " |
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Posted: 3/20/2021 9:53:48 AM EDT
[#25]
Back again, Here is a discussion on SWR readings, antenna tuning and the conjugate match I alluded to earlier. Taken with some faith it will clear up some misconceptions. It's on QRZ.com amd dates back to 2010. Pay attention to posts by the author, KL7AJ, W5DXP, and W8JI. I belieive Walt Maxwell, W2DU himself chimes in later. The whole thing is entertaining and informative.
73, Rob |
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Posted: 3/20/2021 10:57:14 AM EDT
[#26]
Quote HistoryQuoted: In my mind, . . . "efficient" means resonant with low SWR, like a tuned dipole. which means you don't need an antenna tuner. , , "antenna tuner" should really be called " Impedance matcher " Quote HistoryQuoted: Quoted: ...Shine meaning efficient even with a high SWR In my mind, . . . "efficient" means resonant with low SWR, like a tuned dipole. which means you don't need an antenna tuner. , , "antenna tuner" should really be called " Impedance matcher " for a coax fed antenna, that is true, because the majority of the loss is due to heat generated in the coax with high SWR. Open line has no such loss. Using open line, even a non-resonant antenna with a high SWR can be efficient.if done properly. |
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Posted: 3/20/2021 10:57:35 AM EDT
[#27]
Quote HistoryQuoted: Back again, Here is a discussion on SWR readings, antenna tuning and the conjugate match I alluded to earlier. Taken with some faith it will clear up some misconceptions. It's on QRZ.com amd dates back to 2010. Pay attention to posts by the author, KL7AJ, W5DXP, and W8JI. I belieive Walt Maxwell, W2DU himself chimes in later. The whole thing is entertaining and informative. 73, Rob when I get time, I will read that, thanks |
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Posted: 3/20/2021 11:27:18 AM EDT
[#28]
Quote HistoryQuoted: Back again, Here is a discussion on SWR readings, antenna tuning and the conjugate match I alluded to earlier. Taken with some faith it will clear up some misconceptions. It's on QRZ.com amd dates back to 2010. Pay attention to posts by the author, KL7AJ, W5DXP, and W8JI. I belieive Walt Maxwell, W2DU himself chimes in later. The whole thing is entertaining and informative. 73, Rob Eric, KL7AJ, has written an excellent book on the various modes of propagation. It's very informative and well worth reading, especially if you're into DX. LINK |
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Posted: 3/20/2021 12:34:10 PM EDT
[#29]
A resonant antenna isn't always efficient. It depends on antenna design, dimensions, Q etc.
For example, my mobile antenna requires no antenna tuner as it has a "tuner" integrated with the antenna (a variable inductance coil). It "shines" on many bands and I've worked lots of DX with it. I often check into several 80 meter nets with this antenna. It shows 1:1 SWR and it's resonant from about 3 Mhz to 29 MHZ (even to 6m band with a shorter whip). The antenna is far from being efficient but it's a compromise and I know it's limitations. Realistically it only radiates about 5 - 10 watts out of 100 Watts delivered to it from the radio, on 80 meters. It's not very shiny performance but it's a calculated compromise. |
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Posted: 4/16/2021 9:47:01 PM EDT
[#30]
I thought I would update this.
I ended up picking up an Ameritron ATR-30. So far it has matched anything I have hooked it up to, it's kinda amusing to see how various large metal objects function as antenna.  I am currently looking for an amplifier, preferably solid state. The mercuryIII kit looks interesting. |
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Posted: 4/17/2021 6:33:37 AM EDT
[#31]
Thought you wanted an auto tuner but you can't beat an ATR-30 with a stick.
I'd buy a Mercury III in a heartbeat if it supported remote operation. Great specs, great price. Beware, though, I've read elsewhere that support and some attention to detail in the kit is a bit sketchy. The guy is a hobby-time kit manufacturer, after all. |
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Posted: 4/19/2021 8:09:13 PM EDT
[#32]
Quote HistoryQuoted: Thought you wanted an auto tuner but you can't beat an ATR-30 with a stick. I'd buy a Mercury III in a heartbeat if it supported remote operation. Great specs, great price. Beware, though, I've read elsewhere that support and some attention to detail in the kit is a bit sketchy. The guy is a hobby-time kit manufacturer, after all. I'll probably get an auto tuner at some point,, but for now I like how robust manual tuners are. Plus once you have the settings for various frequencies it takes less that 20 seconds to tune up. I wasn't aware of any issues with the Mercury III kit, I'll have to see what else I can dig up about it. Even if the quality isn't commercial level, I'm not to worried,, it is a kit after all. |
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Posted: 4/19/2021 8:15:05 PM EDT
[#33]
Palstar's auto tuner uses steppers to spin knobs on a typical manual tuner vs relays to add inductance or capacitance. Depending on future interests you might could find source code for a diy version...
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Posted: 4/19/2021 10:54:44 PM EDT
[#34]
135’ of wire across the top, fed with ladder line and tuned by a MFJ-986. Works 6m through 80m.
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Posted: 4/19/2021 11:03:01 PM EDT
[#35]
Quote HistoryOriginally By glazer1972: 135’ of wire across the top, fed with ladder line and tuned by a MFJ-986. Works 6m through 80m. That sounds similar to what I'm using. My home HF antenna is 110' end to end, fed with twin lead in an inverted V configuration. |
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Posted: 4/20/2021 9:59:20 PM EDT
[#36]
Quote HistoryQuoted: That sounds similar to what I'm using. My home HF antenna is 110' end to end, fed with twin lead in an inverted V configuration. I would like to get enough in the air to do 160m but I don’t have room. |
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Posted: 4/20/2021 11:20:34 PM EDT
[#37]
Quote HistoryQuoted: I would like to get enough in the air to do 160m but I don’t have room. You should be able to tune what you have on 160. I can tune what I have on 160. It's not very efficient and I had to actually shorten the length slightly to get my old 949 tuner to stop arcing at full power. But like an older amateur told me "the best antenna for you is one that gets you on the air". |
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Posted: 4/21/2021 11:42:04 AM EDT
[#38]
Quote HistoryQuoted: You should be able to tune what you have on 160. I can tune what I have on 160. It's not very efficient and I had to actually shorten the length slightly to get my old 949 tuner to stop arcing at full power. But like an older amateur told me "the best antenna for you is one that gets you on the air". You are right. It will tune there and works good fairly close. It don’t do real good way off. |
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Posted: 4/21/2021 12:31:50 PM EDT
[#39]
Quote HistoryQuoted: You should be able to tune what you have on 160. I can tune what I have on 160. It's not very efficient and I had to actually shorten the length slightly to get my old 949 tuner to stop arcing at full power. But like an older amateur told me "the best antenna for you is one that gets you on the air". That "Older Amateur" didn't finish the advice. It should have been "The best antenna for you is the one that gets you on the air so you can communicate with the people you need to communicate with.". If you can't make the communications that you need to because the antenna isn't efficient or properly resonant then it's just a piece of wire in the air. Your comment about your antenna not being very efficient is the key phrase that many people don't understand. Antenna tuners aren't magic boxes that improve the resonance of a non-resonant antenna, they should be called "Impedance Matchers" since that is all they do. They adjust the impedance so that the transmitter works within the impedance range that it is supposed to work with. The antenna is just as bad (or good!) as it was without the tuner, the transmitter just doesn't know it. Many new hams don't understand that and think that they must have a tuner which is not true. I went for decades without one because I kept my antennas resonant and worked within the limitations that the bands imposed on me. Plus I was using equipment with vacuum tube final amplifiers that are much more tolerant of higher SWR than solid-state equipment is. The biggest advantage I've found with a tuner is that they can widen the acceptable range of an antenna. For example my vertical has a very narrow range of 95 kHz on 80 meters where the SWR is 2:1 or lower. That is pretty much the limit I'll subject my transmitter to and my amplifier doesn't even like that, it wants 1.5:1 or lower. A tuner allows me to widen that range without having to constantly adjust my antenna for resonance at the frequency I need. My tuner allows me to use most of the 80 meter band with an SWR that my equipment will accept. My antenna is still out of resonance across most of the band, so it is terribly inefficient, but as long as the tuner can get the SWR down my radio and amplifier will work there. |
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Posted: 4/21/2021 12:51:15 PM EDT
[#40]
Quote HistoryQuoted: That "Older Amateur" didn't finish the advice. It should have been "The best antenna for you is the one that gets you on the air so you can communicate with the people you need to communicate with.". If you can't make the communications that you need to because the antenna isn't efficient or properly resonant then it's just a piece of wire in the air. Your comment about your antenna not being very efficient is the key phrase that many people don't understand. Antenna tuners aren't magic boxes that improve the resonance of a non-resonant antenna, they should be called "Impedance Matchers" since that is all they do. They adjust the impedance so that the transmitter works within the impedance range that it is supposed to work with. The antenna is just as bad (or good!) as it was without the tuner, the transmitter just doesn't know it... Your points are well taken. I am curious about what happens to the antenna output when you use a tuner to "correct" a big SWR number. For example, my existing MFJ-2012 OCFD is NOT resonant on 80. It measures something like a 12:1 SWR on 80, so I do not dare ever transmit on that band. If I got a Tuner and adjusted it down to a happy 1.5 or 2, how much would that reduce my otherwise mighty 100w output? |
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Posted: 4/21/2021 1:28:55 PM EDT
[#41]
Quote HistoryQuoted: Your points are well taken. I am curious about what happens to the antenna output when you use a tuner to "correct" a big SWR number. For example, my existing MFJ-2012 OCFD is NOT resonant on 80. It measures something like a 12:1 SWR on 80, so I do not dare ever transmit on that band. If I got a Tuner and adjusted it down to a happy 1.5 or 2, how much would that reduce my otherwise mighty 100w output? A 12:1 SWR equates to about 71.5 watts of reflected power with 100 watts output so you are effectively only transmitting about 28.5 watts of radiated power. A tuner isn't going to change that. The antenna and feedline will STILL have a 12:1 mismatch but the transmitter doesn't see it because the tuner compensates for the impedance mismatch. I'm not exactly sure where that 71.5 watts is dissipated, I just remember that the article I was reading got into complex RF waveforms and how they interact at that point and my brain went into overload. |
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Posted: 4/21/2021 1:46:57 PM EDT
[#42]
Quote HistoryQuoted: A 12:1 SWR equates to about 71.5 watts of reflected power with 100 watts output so you are effectively only transmitting about 28.5 watts of radiated power. A tuner isn't going to change that. The antenna and feedline will STILL have a 12:1 mismatch but the transmitter doesn't see it because the tuner compensates for the impedance mismatch. I'm not exactly sure where that 71.5 watts is dissipated, I just remember that the article I was reading got into complex RF waveforms and how they interact at that point and my brain went into overload. This is exactly the sort of info I was looking for!  Very helpful when thinking about potential next steps for me, i.e., an antenna resonant at 80m sounds like a far better investment than a tuner to force my current antenna to an impedance match.
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Posted: 4/21/2021 2:15:45 PM EDT
[#43]
Quote HistoryQuoted: This is exactly the sort of info I was looking for! Very helpful when thinking about potential next steps for me, i.e., an antenna resonant at 80m sounds like a far better investment than a tuner to force my current antenna to an impedance match.I agree, and that's why people emphasize the point that you can always benefit more from an efficient antenna than with things like an amplifier or tuner. Of course once you HAVE an efficient antenna system then things like an amplifier and tuner are still beneficial. Keep in mind that you probably won't find "An" antenna that will cover all of 80 meters without high SWR on portions of the band. As I mentioned above mine has a very narrow usable segment (95 kHz on a 500 kHz band). I have it tuned so that the lowest natural SWR is 1.25:1 at 3.575 mHz . That's pretty much the center of the FT8 area and my tuner lets me get into the Extra CW portion of the band and into the bottom of the SSB segment relatively efficiently so I'm happy with it. That, to me, is what a tuner is good for and where it shines. If your radio has a built-in tuner it will probably handle 3:1 or more so that will allow you to stretch your antenna out some. Just get it resonant where you will use it the most and then let the tuner help you out at the edges. I used to use an inverted V for 80 meters. I cut the wire a little bit short and soldered a ring terminal on the end of the wire on each side of the dipole. I then cut wires long enough to give me resonance at different points on the band to use as stubs to complete the appropriate length. I had 2 or 3 sets of stubs set up with ring terminals on one end and an insulator on the other. When I wanted to use a different section of the band I unbolted the stub that was on the wire, bolted the appropriate stub onto the main wire using the ring terminals, and I could change the resonant point in a couple of minutes. |
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Posted: 4/21/2021 3:04:07 PM EDT
[#44]
Quote HistoryQuoted: A 12:1 SWR equates to about 71.5 watts of reflected power with 100 watts output so you are effectively only transmitting about 28.5 watts of radiated power. A tuner isn't going to change that. The antenna and feedline will STILL have a 12:1 mismatch but the transmitter doesn't see it because the tuner compensates for the impedance mismatch. I'm not exactly sure where that 71.5 watts is dissipated, I just remember that the article I was reading got into complex RF waveforms and how they interact at that point and my brain went into overload. This is not really true. This only holds for when the transmitter is seeing the bad VSWR directly. When you match the output impedance of the transmitter to the impedance of the antenna/feedline system, the situation becomes much more complex. You wind up in a situation whereby the intrinsic loss in dB/ft, measured at the feedline characteristic impedance, of the feedline comes into play. The higher the feedline loss, the higher worse the situation that occurs after the antenna tuner. The math gets complex enough so that even I don't want to figure it out. However, there are lots of folks who have done the work for us. Using the calculator provided here, one can easily see that for a case involving 100W, 100ft of feedline, 10MHz frequency, and a really bad, 10:1 VSWR, even 450ohm window line will let you get away with murder, whereas even a really good coaxial cable like LMR-400 still sucks. Under those conditions we get the following results for power delivered to the antenna: Wireman 554 450ohm window line: 85W LMR-400 coaxial cable: 69W Things get even better if you use "real" ladder line, i.e. two wires separated by mostly air (and you can get it here). So with a low loss transmission line, like ladder line, even with very poor VSWR you can get good power delivered to the antenna, very little reverse power at the output of the tuner, no reverse power at the transmitter, and do a creditable job of radiating energy. That's why the ladder line fed doublet has been, and remains, the best solution where a non-resonant antenna topology is utilized. |
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Posted: 4/23/2021 11:07:47 AM EDT
[#45]
Quote HistoryQuoted: Your points are well taken. I am curious about what happens to the antenna output when you use a tuner to "correct" a big SWR number. For example, my existing MFJ-2012 OCFD is NOT resonant on 80. It measures something like a 12:1 SWR on 80, so I do not dare ever transmit on that band. If I got a Tuner and adjusted it down to a happy 1.5 or 2, how much would that reduce my otherwise mighty 100w output? It's easy. If your tuner can't tune, just get another tuner and connect them in series. I kin tune a 10 inch roofing nail on 160 meters with 3 of my tuners! It's all about tuners! You don't need no fancy antennas! Disclamer: Just kidding. Couldn't resist. 
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Posted: 4/23/2021 11:53:02 AM EDT
[#46]
Quote HistoryQuoted: It's easy. If your tuner can't tune, just get another tuner and connect them in series. I kin tune a 10 inch roofing nail on 160 meters with 3 of my tuners! It's all about tuners! You don't need no fancy antennas! Disclamer: Just kidding. Couldn't resist.  |
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Posted: 4/25/2021 12:54:28 PM EDT
[#47]
Quote HistoryQuoted: This is not really true. This only holds for when the transmitter is seeing the bad VSWR directly. When you match the output impedance of the transmitter to the impedance of the antenna/feedline system, the situation becomes much more complex. You wind up in a situation whereby the intrinsic loss in dB/ft, measured at the feedline characteristic impedance, of the feedline comes into play. The higher the feedline loss, the higher worse the situation that occurs after the antenna tuner. The math gets complex enough so that even I don't want to figure it out. However, there are lots of folks who have done the work for us. Using the calculator provided here, one can easily see that for a case involving 100W, 100ft of feedline, 10MHz frequency, and a really bad, 10:1 VSWR, even 450ohm window line will let you get away with murder, whereas even a really good coaxial cable like LMR-400 still sucks. Under those conditions we get the following results for power delivered to the antenna: Wireman 554 450ohm window line: 85W LMR-400 coaxial cable: 69W Things get even better if you use "real" ladder line, i.e. two wires separated by mostly air (and you can get it here). So with a low loss transmission line, like ladder line, even with very poor VSWR you can get good power delivered to the antenna, very little reverse power at the output of the tuner, no reverse power at the transmitter, and do a creditable job of radiating energy. That's why the ladder line fed doublet has been, and remains, the best solution where a non-resonant antenna topology is utilized. Quote HistoryQuoted: Quoted: A 12:1 SWR equates to about 71.5 watts of reflected power with 100 watts output so you are effectively only transmitting about 28.5 watts of radiated power. A tuner isn't going to change that. The antenna and feedline will STILL have a 12:1 mismatch but the transmitter doesn't see it because the tuner compensates for the impedance mismatch. I'm not exactly sure where that 71.5 watts is dissipated, I just remember that the article I was reading got into complex RF waveforms and how they interact at that point and my brain went into overload. This is not really true. This only holds for when the transmitter is seeing the bad VSWR directly. When you match the output impedance of the transmitter to the impedance of the antenna/feedline system, the situation becomes much more complex. You wind up in a situation whereby the intrinsic loss in dB/ft, measured at the feedline characteristic impedance, of the feedline comes into play. The higher the feedline loss, the higher worse the situation that occurs after the antenna tuner. The math gets complex enough so that even I don't want to figure it out. However, there are lots of folks who have done the work for us. Using the calculator provided here, one can easily see that for a case involving 100W, 100ft of feedline, 10MHz frequency, and a really bad, 10:1 VSWR, even 450ohm window line will let you get away with murder, whereas even a really good coaxial cable like LMR-400 still sucks. Under those conditions we get the following results for power delivered to the antenna: Wireman 554 450ohm window line: 85W LMR-400 coaxial cable: 69W Things get even better if you use "real" ladder line, i.e. two wires separated by mostly air (and you can get it here). So with a low loss transmission line, like ladder line, even with very poor VSWR you can get good power delivered to the antenna, very little reverse power at the output of the tuner, no reverse power at the transmitter, and do a creditable job of radiating energy. That's why the ladder line fed doublet has been, and remains, the best solution where a non-resonant antenna topology is utilized. exactly good post people get wrapped up in using coax losses and think that is all there is. All of the loss is due to heat. Coax generates lots of heat with SWR Sure you have minor losses in the tuner, but the bigger the components the less loss because the less heat I use coax for resonant antennas I use homebrew 600 ohm ladder line and it is cheap to make, much cheaper than buying coax, for none resonant antennas right to the tuner in the shack. But running coax to an autotuner st the base of the antenna or an appropriate unun or balun will also significantly reduce coax losses. |
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Posted: 4/27/2021 10:21:12 PM EDT
[#48]
I’ve had good results using a Palstar AT2K.
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Posted: 5/1/2021 12:10:23 PM EDT
[#49]
Quote HistoryQuoted: Palstar AT2K. Palstar site Shop around for price. 73, Rob ETA: Ham Radio Outlet in Denver shows in stock but low. I highly recommend Palstar equipment. I also have one of their antenna analysers. Palstar gear is built like a tank.  |
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Posted: 5/1/2021 12:52:09 PM EDT
[#50]
Quote HistoryQuoted: I thought I would update this. I ended up picking up an Ameritron ATR-30. So far it has matched anything I have hooked it up to, it's kinda amusing to see how various large metal objects function as antenna. I am currently looking for an amplifier, preferably solid state. The mercuryIII kit looks interesting.
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