Antenna Tuner (Ultimate Transmatch) from ARRL 1970
ฝัง
- เผยแพร่เมื่อ 5 ม.ค. 2022
- www.arrl.org/files/file/Techno...
A small antenna tuner, I have three of now, but wanted a small one to match my auto-tune tranceiver to the input of my 833A RF amplifier. This one is a lower power tuner good for the 200-300 watt power range and tunes 40 meters to 10 meters. A larger inductor is required to tune 80 and 160 meters.
I might also add that my measurement of the third harmonic (attenuation) is not the same as the third-order-intercept (TOI). Third order distortion is very close to the fundamental frequency and can not be attenuated by filtering of harmonics but it is the best I could do in this video at the moment. Here is a good explanation of TOI. • How to Make Third Orde... - บันเทิง
Very knowledgeable, and a master builder. Have been an Amateur and avid homebrewer for 69 years, so I think I know something about the subject. Keep up the good work, and the very best of 73's Jim WA5WRE
I learned more about my Rig Expert(s) in this video than I have in the 5 years or more than I've owned them. Thanks for taking the time to make this.
You do VERY NICE work!
I love to watch your videos because you show everything you have done, and explain it in great detail!
NEVER feel that any of your videos are boring!!! Besides, if someone doesn't want to watch all the detail, they can skip ahead or go somewhere else!
Your efforts are appreciated... Thank You!
Antenna tuners are a necessary device... it maximizes the output power to the antenna (or device) and it can help with the longevity of the output stage it is driving.
Super construction job and example tuneup!
Loved the whole thing! Now, on to the _next video!_
Hi Bill - I can't directly respond to your other comment on the video about how to properly tune the unit as TH-cam does strange things and even though I get email I won't be able to see the comment in the video. I don't know why. This happens quite a bit and it is not in the, "held for review" queue.
You describe the procedure much clearer than the Collins manual on how to use their 180S-1 tuner. Collins reverences everything to the KWM-2 (2A) in a convoluted way that I had to read a bunch of times. In the end, it is like all tuners and the L should be minimum with output C at max for a good match and least loss. I think I saw that in a measurement with the SA and harmonic content at the output in my video that I commented on.
I understand the type capacitor you mentioned that when one half is fully meshed the other is fully open but I was not aware that was what should be used in this case. In their pictures they show the type of input split stator capacitor that I used in the first picture, the second picture may look like what you describe (not a good picture) and nothing can be determined about this capacitor in the third picture,
Back to the Collins 180S-1 tuner - it is just a Pi network but the tuning is the same procedure.
collinsradio.org/archives/manuals/180S-1_2nd-ed-02-62_.pdf
I see all tuneers as always trying to keep the L low and the C hi to increase Q and minimize loss.
Q is an interesting subject. I have always thought of Q = X/R and the Q of a series or parallel resonate circuit limited by the series R in L. The ratio of Xc to R in a capacitor would be very high and not degrading the Q as the L would with lower Xl to R ratio. Here is what the Internet says that I think is correct.
Q = Pstored/Pdissipated = I2X/I2R Q = X/R where: X = Capacitive or Inductive reactance at resonance R = Series resistance. This formula is applicable to series resonant circuits, and also parallel resonant circuits if the resistance is in series with the inductor.
I assume in either case (series or parallel resonance) R would always be in series with R and not shunt to R. I could be wrong.
Assuming the above is correct, I know that the Q of a output Pi tank circuit in a RF amplifier for say, 80 and 40M should be around 10 and for 10M it should be higher, say 16, as an example. In my experience of building amplifiers, I have found (using roller inductors) that power output increases as L gets smaller and C gets larger to a point where it becomes unstable and then I add a bit more L into the tank circuit to stabilize it ultimately lowering the Q and increasing the bandwidth.
Lastly, if the proper tuning procedure is to use minimum L, could this not possibly raise the Q of the tuner to an unstable condition and require readjustment for a small change in frequency? I am not trying to split atoms here but find a reasonable compromise so tweaking is not necessary with moving 10 KHz or so.
Your thoughts?
73
@@ElPasoTubeAmps My general notion about external "transmatches" is that you always want to keep L as low as possible because inductors have inherent loss. They operate in accordance with current flowing which generates magnetic fields that then collapse when the oscillation reverses "polarity". In the case of capacitors, they operate in accordance with electrostatic charges, rather than magnetic fields, in which electrons charge a plate. Although desirious of flowing over to the "uncharged" plate, the electrons cannot flow until the oscillating signal passes through its polarity peak and begins to reverse itself. When it passes through zero, maximum electron flow (current) to the other plate. Thus maximum current flows in this electrostatic dynamic when the signal passes through zero during its oscillation.
Given these two different ways of getting RF current to flow, it is the inductor which has most "loss", _beginning with the resistivity of its wire._ In roller inductors, this resistivity is compounded by mechanical contrivances required for its operation (fingerstock brushes, wheels touching wire, interiors of wheels sliding along rods, etc) . Each mechanical gizmo adds resistive loss not found in an electrostatic capacitor whose dielectric is air, let alone a vaccum.
So when you look at the Q of a tuned circuit, I have generally thought that the losses inherent in the coil, beginning with its resistivity, plays a dominant role in limiting the circuit's overall Q. This is why the Q of a tuned circuit increases dramatically when nothing is done other than cooling it to superconductive temperatures. This is also why the Q of a tuned circuit is increased by using silver wire, rather than copper or aluminum, or by increasing the diameter of the wire in the inductor regardless of what type of wire is used. Doing anything to lower the coil's resistivity _without altering its dimensions_ raises the circuit's overall Q. In the practical world of ham radio, one attempts to acquire the inductance needed by a tuned circuit by making a coil whose _length is about 1.5 times its diameter._ I think this practice minimizes the length of wire needed for a given inductance, thus minimizing the coil's resistivity and therefore raising the tuned circuit's overall Q.
Now, I might be wrong. But this is the type of thinking that has caused me to assume _minimizing L in a transmatch minimizes its insertion loss._
This is a great reference for building a tuner and how to use it. I will definitely be building one. Thanks for posting it! 73 W4VXH
Nice to see home construction is still alive, its sad that many hams these days have no knowledge or interest in this. Good to see you're cat still doing well, I've been through the joy & pain of my cat friends, my last one died in September, fortunately it was a sudden death. best wishes nick
Building homebrew equipment is a passion. It keeps me going and the good people I have met on TH-cam is a true blessing.
As mentioned, it would be difficult to determine exact needed parts and order them off Ebay or Amazon or where ever. Probably end up costing more than a store-bought one - however - the ones we build may very well be much better quality than the commercial ones often times built form parted-out military equipment. I figure if a commercial one says it will do 300 watts it doesn't mean 310 watts. When we build we don't have the restrictions of saving pennies on each one to raise our profits so our "300 watt" one may handle 1000 watts... :-) I am sorry to hear about your kitty. A sudden death would be preferred to euthanasic but at the moment, Mr. Pinto is doing great. It is sad and stressful to look too far ahead.
I like the black case color---looks very nice.
Buen trabajo, 73, CE1GWX
Thank you for this!
Great tuner, great cat! ❤️😸
Hi David, enjoyed another excellent video you produced.
73 de Glenn WA4AOS
Hi Glenn,
Always good to hear from you. I hope all is well. I am carrying on down here getting on 20 and 40M a little. 73
My mouth hit the floor when I saw that hole cutter. Never seen one before. I have to get some of those!
Yes, they are the way to go. They are very expensive new and lots of different sizes. Best to buy used. The small ones take a 1/4 inch pilot hole, the next sizes up are 3/8 inch pilot hole and the big ones are a 3/4 inch pilot hole which usually takes a 3/4 inch punch to get a hole that big or maybe a stepped-bit. I might mention that particularly in 8 pin octal tube sockets, they are definitely not all the same size. Some are 1" and some are 1 1/8 inch and so on. Just throwing out some things to keep in mind when buying.
@@ElPasoTubeAmps Yes, I generally try to buy most things used when possible. Thanks for the extra tips, too---didn't know about the tube socket differences. My main use for now would be for connectors like you showed, but eventually I want to start building tube stuff as well.
th-cam.com/video/BIHwJ28Z9P4/w-d-xo.html
No Views yet......but even before I watch it, I know I am going to like it !
I used to watch them before letting them go public so it would have at least one view... :-) Now I just hit goooooo....... what could go wrong....
Nice job and good advice, something you might find interesting is to swap the input and output cables, changing it from the "Ultimate" to the "SPC" configuration. Allegedely it results in less loss but better harmonic attenuation. (Although from memory one used a differential capacitor) By the way a useful thing to save for the junkbox is the excess scraps from nylon pot spindles, they can be ideal if you run out of the insulated shaft couplings but they do twist with torsion a bit if your capacitors don't turn too easily. 73
FYI - the Heathkit SA2040 uses the ultimate transmatch configuration. Essentially a ‘T’ tuner with a ‘twist’ using the split stator input cap, 1/2 of which is connected to ground. I understand from ARRL tests that this type of tuner design is obsolete in that it really didn’t reduce harmonics as ‘advertised’. I’ve had an SA2040 and used it for years. It works well, I love the tuner, but there are better tuner topologies.
That is interesting to know. I also have the Collins 180S-1 tuner that I keep inline with my 40M antenna that people seem to like and it is simply a Pi network. They all seem to work just fine, as you mention. Thanks for the comment. 73
10:30 For holes up to about 1.5 inches, I use a stepped drill bit.
Absolutely, I use a stepped drill bit also.
The reason the ARRL method is considered best is because it uses the least amount of inductance for the match. Coils are lossy and caps are not. For the moderate +-jX loads you tested the two methods are comparable. For more reactive loads you can find a low SWR match that has a high circulating current - not good.
My Titan III has the blinky lights showing the PEP as well as the meter which is good and I tend to watch the blinkys from the corner of my eye in preference to "reading" the meter. The KAP500 amp also uses blinkys for both forward power and SWR for a quick scan that all is well.
I never thought about it in terms of lossy coil and added XL as I thought it would be most beneficial to have that added shunt capacitance to ground to attenuate harmonics and and any anomalies higher up in frequency. But I believe you. I do know in all the Pi tank coils I have built, too much L will definitely lower output power. Too little L and the amplifier is just too eager to go into some parasitic. Speaking of blinky lights - I do the same thing with a homebrew LED wattmeter that has no discriminator between forward and reflected power so SWR must be low to be accurate but the blinky lights is what I run off watching the antenna. In my case, a high reflected power will sum with the forward power and drive my blinky meter LEDs thru the ceiling so, as you say, it is an instant quick way to check on performance.
hello David, excellent video very much instructive..can you add a meter to that tuner>
i am working in a tuner and need to know is doable..
keeo teaching us..
god bless!!
37's
Hiram. AG4KH
Hi Hiram - the meter circuit would need to be some sort of a directional coupler and not just a simple voltmeter type. In my case I use an external directional wattmeter like a Bird line section or any of the nice RF watt meters available today. It would be very nice to have it built in to the tuner... There are schematics and instructions in many of the older ARRL books about directional couplers but they would add some complexity to the build. 73 WA4QGA
Did you say you covered that LED watt meter build in a video? I'd love a schematic and link to that vid if you have one... hell, I'd buy one from you if you made it. I like blinky lights at my station. ;)
Here are two links
th-cam.com/video/d0z5D4SoL30/w-d-xo.html
th-cam.com/video/n5a9w2M7h5I/w-d-xo.html
I needed to get my Boyalstad book on circuits first year AAS in EE and my TI RPN to follow you! But the rig master costs more than my rig I.e. TS-520s ! But I must say I love your channel. John Boy Utah KJ7TBR new ham:. What company were you an engineer for? My grandson has a Master’s in EE I am proud of him!
I never earned my MSEE just the BSEE and the first company I worked for was Sperry Corp in Huntsville starting 1970 on contract with NASA, then in 1976 with Lockheed at WSMR and NASA. I had all the clearances so I worked at other places like HAFB and Sandia Labs in Albuquerque and where ever at government sites, as needed. All that lasted 26 years until 1996 then I went to work for Northrop Grumman but changed into management. Congratulations to your grandson and you. That is a real accomplishment to earn his MSEE. I assume he is going to be in design? I was always in the field.
How much would the top cover make? Being aluminum, it shouldn't but it could setup eddy currents and couple across the input to output.
I was concerned about that also but measurements on the bench, without the cover, then putting the top cover on and checked the matching again and it was insignificantly different in the settings of the capacitors and inductor. I have a large tuner built to this same schematic and ran it with a KW of power and noticed some RFI in my room, this was a few years ago, then I surrounded it with an aluminum casing and the RFI was resolved but the tuner still worked the same. The large tuner has a bypass relay in it also but I chose not to put such a feature in this one (not much room, for one thing) and I will likely use it just for matching the input of my 833A amplifier to my exciters. Crazy as it may seem, one single component, in this case, the little inductor, inspires a functional unit to be built. I have another roller coil exactly the same - who knows what I am likely to built with that one. I also have a monster Gates roller inductor - probably a good 5KW+ ... heaven knows what I might do with that one. :-)
Link to original ARRL article from 1970
www.arrl.org/files/file/Technology/tis/info/pdf/7007024.pdf
So, the input capacitor does not go directly to ground, but the inductor does. Is that right? And either side of the input capacitor can be connected to the center connection of the so239?.
You described it perfectly. Both capacitors are "floating" on ceramic insulators and they have to have an insulated coupler to the tuning knob. The input capacitor is a split-stator type capacitor and the input goes to the common of the two capacitors, then one side goes to ground and the other to the top of the coil and the output capacitor is in series with the junction of the coil and top capacitor. Here is the ARRL article with schematic.
www.arrl.org/files/file/Technology/tis/info/pdf/7007024.pdf
Another version of a good antenna tuner is simply a Pi network. I have a Collins 180S-1 antenna tuner and it is nothing more than a Pi network (for coax connection) which is easier to build as both capacitors are grounded but the coil is above ground.
collinsradio.org/archives/manuals/180S-1_2nd-ed-02-62_.pdf
If you look at the Collins tuner, the Series and Ground are connected together with a jumper on the outside of the tuner for unbalanced (coax) connection and it is just a Pi network and works great.
Who makes that inductor! Very nice.
I don't know who makes the inductor. The numbers on it looks like a US government number and for some reason I think it might be Collins Radio but I don't know that for sure. Got two of them off Ebay and use the second one in the cathode circuit of my 4-1000A amplifier. Probably found them on Ebay searching for roller inductors.
www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1311&_nkw=variable+roller+inductor&_sacat=0
What would one of those transmatch units cost if you were part with one?.
Thanks for reading!
Probably somewhere between free and a million dollars. If one adds up the cost of parts from Ebay + shipping and tax, who knows, $300 for parts maybe more since Covid-19 has raised the price of everything . How much is my time worth - free because I love it or 50 cents per hour or $300 or $1000 per hour? You know what I mean? I don't know the answer to homebrew equipment. Mostly homebrew equipment is sold as parts for someone to use to build their own. Is the cost supposed to be inline with Chinese equipment? Not trying to be disrespectful without being mindlessly political correct to the least of all the entities of the universe. I know I am a little out-there but it takes an irrational amount of obsession to develop a sense of building your own equipment. We all have our passions, some constructive and some destructive. The details of how to build equipment is just as hard to get from the Internet today as it was 50+ years ago out of textbooks because of the misinformation propagated over the Internet. The Internet is an amazing thing but here is a lot of misinformation out there. Study every detail and make your own. You will love the energy you put into it and it will be yours, so make your own.
Is that a fixed or variable catacitor in the background ?
Both of the capacitors in the tuner are variable.
I meant the cat.
@@timmcilraith8762 🙂That is Mr. Pinto 🙂