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- Опубликовано: 27 авг 2019
- Episode 375
Cool DIY antenna tuner found at garage sale for $20
also a quick measure of the capacitor and inductor using a VNA
watch W2AEW videos here:
• #275: Smith Chart: Z, ...
• #297: Basics of the Sm...
• #278: Smith Charts: Us...
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"In the late 1950s, the Delta A.R.C [The Stockton-Delta Amateur Radio Club] included a small number of genuine VHF experts. Chief among them [...] Clarence Hermance, W6RRN, who had remarkable skill at designing a building first-rate 6 Army TU unitmeter transmitters and receivers. The picture here shows an Army Signal Corps TU-series tuning unit, widely available after the war. Clarence used them as the foundation for his homebrew 6 meter radios. Other club members built their own from his design. With the likes of Clarence and Rod guiding the path to success above 50 mHz, the Delta club began to attract new members, young and old, who contributed to the expansion of the club beyond its VHF experimenting roots."
Thank you for the story on Clarence.
Obituary posted Mar 16, 2001:
Clarence J. Hermance
Sheriff’s sergeant
Clarence J. Hermance, 75, of Stockton died Thursday in a hospital. He was born in Dos Palos and lived in San Joaquin County for 59 years. Mr. Hermance worked for San Joaquin County for 20 years. He was a deputy sheriff and a sergeant. He was a member of Sheriff’s Team of Active Retired Seniors, Eagles Lodge and Elks Lodge. He served in the Army Air Corps in the 22nd bombardier group as an airplane armorer gunner during World War II.
www.recordnet.com/article/20010316/a_news21/303169996
Some nice unobtainium components there. Great score!
The practical demonstration of the roller coaster and Nano VNA were really useful, thank-you.
Brilliant visual explanation. Very much appreciated.
Excellent video, I now understand a little bit about smith charts, thank you!
outstanding demonstration!
Thank you for that excellent explanation!
Thank you for your simple explanations and demonstrations. Keep up the good work! KX4LP or 9Z4Z.
Geez. I can only give one thumbs up. I wanted to give it more! It finally gave me a clue how a Smith chart works.
The best explanation! Thanks
Great explanation
Great video. Thank you.
That's a nice capacitor, but it's a receiver cap. It will work with very low power transmitters (think QRP.) But the high voltages of higher power transmitters tuning capacitors require large gaps between the plates to avoid arcing.
you are right. I replaced it: ruclips.net/video/6h3IySCS0-s/видео.html
The switch on the back is a bypass/tune switch. Allows you to take the tuner out of the equation without disconnecting everything.
Yes, I've heard of the Stockton club. I believe they may have a repeater on 146.115 which I can reach here from Redding. Who knows how many people fiddled with it after the original builder. In fact, were they not kits ? I have three videos showing tuning of a typical tuner by using the smith chart. Its the most amazing method, quick and to the point. I have a freind who still uses a manual tuner and I need to demo the method, but I'll probably share videos as he is 100 miles away. Might have used the huge capacitor for 160?
Total bargain. The roller inductor alone was the star. Your demonstrations are slowly demystifying the Smith chart and it's applications. Karl
I'd replace that BCB capacitor with a larger transmitting type. It's certainly an L network tuner, good for end fed wires.The inductor is from a Navy transmitter, TCN IIRC.
When theory becames practice!
Interesting school on smith chart. Great demo. Barry, KU3X
Great video & explanation on whats going on, TNX 4 the upload !
73 N8AUM
A good way to clean up a dirty roller inductor is to use a product called Never Dull... It is a metal cleaning chemical designed to remove tarnish off of copper, silver, aluminum, ect. Impregnated in a cotton wadding.... This stuff works great!
Wow! Thanks for helping me understand these concepts more clearly than ever! K6TJO
I Have Old USSR Antenna Tuner. I Would Love To Know What It Does And Stuff
So proudly built by Clarence J Hermance W6RRN, silent key 2001, aged 76.
This is a good video, lots of gold nuggets in it. I've always wanted to do the same experiment, but couldn't find the parts. Thank you. 73 de 4G1FBL.
thanks
Like that meter. Can't recall seeing a dual movement SWR meter that has scales in opposite directions. I assume they did it so manufacturing of the movements is simpler - both are clockwise. Concur with scharkalvin re C vane spacing unless you are planning on just QRP work :-) Cheers, VK3CI
I saw the meter used in a old dual truline Bird watt meter. do you think the cap is good for 100W?
Personally I wouldn't put anything like that power through it. However, if you are determined to try, there's a few things I'd consider. Looks like the rotor vanes are not centered between the stator vanes so first step would be to adjust that. Air breakdown is about 3kV/mm in a best case situation - e.g. between 2 polished spheres. When you have sharp point or edges you will get charge buildup, corona and then arcing at dramatically lower voltage gradients. This is also made worse by any crud between the plates - attack it with some compressed air. Although humidity increases the breakdown voltage (pure distilled water is a better insulator than air) water can dissolve crud on the plate surfaces making it conductive and leading to arc over. I saw someone drop a TV into distilled water to test how good an insulator it is. Trouble is the water became conductive fairly quickly due to all the dirt and the whole thing failed catastrophically in only a matter of seconds. But I digress. What I have seen done is ripping out some of the vanes, but you need to have enough play in the centering adjustments to symmetrically place the ones that remain. It will be difficult to measure the gap but you might be able to measure the thickness of one vane then knowing the number of vanes and width of one of the 3 sections you could estimate the gap, with an allowance for manufacturing tolerance and any bent vanes - it's only the smallest gap that's important, not the average. With 100W pure sinusoidal carrier and 50 ohms you are looking at 280V pk-pk but the nature of that unit is to match impedances other than 50 Ohms so you could be looking at much higher voltages across the cap, compounded further by the modulation used. With a solid state transmitter I'd be reluctant to risk it but with a slightly more tolerant valve-based Tx (e.g. 6146 or similar) you could for instance output at least double your expected power (4 x the voltage) into your chosen antenna, so the voltage at the LC junction is realistic. Then, if it doesn't arc over and you keep dust etc away from the cap you should be ok at reduced power. Note also, if it does arc over inside the box, you may be unaware of it, especially with SSB, where any power measurement will be bouncing all over the place, masking the arcing, but, while it might not cause damage to the transmitter, it will splatter significant RF noise across the spectrum, helped by the antenna connected directly to the device doing the arcing. I assume anyone that knows their way around a Smith chart would know all this but I've added it here in case anyone else in a similar situation trips across your video and is tempted to put serious power across a variable cap designed for receiving. Bottom line: an appropriate wider spaced cap is generally cheaper than a new transmitter, unless you also found a $20 transmitter at a hamfest or similar. ;-) Cheers
@@iholland I picked up a large single-gang variable capacitor in an antique shop here in Southern England a few weeks ago. The spacing of the plates is about 2-3 times that of the old-type receiver capacitor like the one in the video. The total capacitance swing was 40-1535pF, so I guess it was used in some sort of antenna tuner like this one. Nice explanation of the Smith Chart, by the way.
Another interesting / educational video but , what I do not understand and perhaps you could explain …when you put the roller inductor in parallel with 50 ohm load on the nanovna and wound it to minimum inductance , ie 50 ohm in parallel with short circuit why did you still get meaningful readings on the nanovna ???
Regards
The old fart in wembley
I actually explained that backwards in the video. since is it a parallel circuit to ground, max inductance is at the 50ohm center and min inductance (short) is at the left hand edge of the smith chart. if the circuit was inductor in series then it would be the opposite. min L at 50 and max L at the right hand edge. it's easy to get confused as I did
Roller coaster from BC 375 TX 😅😅
20 bucks for that roller inductor "you done well there"
I need to get some good caps now
thats a reasonably nice RI. Don't know about the rest.
How do you like the 612?
@@gbowne1 I think it is good value for the price.
The meter is cool too. The rest I agree.
@@IMSAIGuy I looked at the 612. I might get one to test out. Yeah it sure is a interesting SWR meter.
I noticed that he called the capacitor and inductor three times in a row.
sorry, brain problems....
what is the model number of that meter.nice meter
Weston Instruments, Inc. P/N 182953
Model 888
Type 61-96030
let me know if you find one. I feel I have the only one on the planet
@@IMSAIGuy i think you do to. No luck yet.lol.
@@IMSAIGuy found one on eBay just now. yes I had to buy it at 45.00. I like how he used an ordinary swr meter and eliminated the forward reverse switch by using this dual meter. smart idea....
@@daviddavidson1372 thats the way all dual meters work. I will be doing a video on my update to that box. I'm putting in a new cap and a new SWR circuit.
@@IMSAIGuy great cant wait to watch.
If I remember correctly in another of your videos, you mentioned getting common current back in you shack. You might try and convert this to an "Artificial Ground" and try to tune a counterpoise wire on the floor . Se the two links for how it might work?ruclips.net/video/e0UMpynuODQ/видео.html
This video shows how to use a manual ATU as a tuner ground! ruclips.net/video/__odbyw0o7k/видео.html