49-1 Balun Design and End Fed Antenna Experiment
HTML-код
- Опубликовано: 27 авг 2024
- I was trying to get a good 160M antenna working on my property. Turns out my experiment somewhat failed on the intended band however, the 80, 60, 40 and 20 meter bands performed superbly with no tuner needed on any of those bands. By paralleling the G5RV with the End Fed antenna I'm able to
use the upper portion of the 160 band.
My still all time favourite TRX's from back in the Day. IC-720 (A), 745 and 751A. I am very happy with my home made EFHW 49:1 antennas. I got a short version with almost 40ft. lenght + extension coil with 34µH. And a long version with 67ft. lenght. They working fine with me outdoors in the Fields. 73's de Your Friend Uncle Guenter
Nicely done. Very informative. Using the punch is a nice touch but not everybody has one on their shelf. I do but I don't use
it for holes in plastic. I just a Uni bit or as some people call them, a step bit. They make nice clean holes. I've also use a
spade type bit but the hole is not as clean.
Like you, I always use SS hardware.
Barry, KU3X
I am surprised nobody mentioned safety issue of the proximity to power lines. Noise is not the only problem Definitely not something I would do.
Thanks for sharing
Did you need any vent holes in the box to dissipate some heat?
What about a EFLW using 1 Mile long wire antenna.
If the power lines were not between my back lot and the lake lot, a EFLW would be great. I have a bid on the lot next door which, If I get it, would solve lots of issues. Thanks
What kind of balun would you use on a eflw at a mile long? I live in the country and have plenty of room would love to try it.
9:1 UNUN
@@DAVIDGREGORYKERR thanks for the information
You could pick up submarines with that. I Haven't a clue what the impedance would be. Stray high voltage would be of a concern. If you remember, Art Bell made an antenna like that, lots of induced high voltage. Good luck.
@@kevinaponte7078
Greetings could you tell me what gain have the EFHW antenna. Excellent your video
I have to wonder about the location of the loading coil. I recently constructed an EFHW @ roughly 66'. Once tuned, I added a 110mh loading coil and about 8' more wire to get 80M. It even tunes as a quarter wave on 160, but I won't win any contests with it. As I understand it, the length of the wire after the loading coil will be far less than the remainder of your 160M half-wave. I'd be inclined to remove it from the 136' point and add it toward the far end. Maybe before the 9.5' section. Frankly, you should not need a loading coil, as you appear to have 245' of wire. Something's not right. 243 would be resonant at 1.8 mhz. Keep experimenting. Maybe a 64:1 transformer would be better. Thanks for sharing your experience.
You should not use ANY tape on your cores. Per K1RF, this degrade primary inductance and performance.
Tape is transparent to magnetic fields. It adds insulation and protects the winding. I add electrical tape to all my toroid cores.
ruclips.net/user/shorts4ibYv2cnPy4?feature=share What's this white stuff at the factory?
I’m gonna type the hell out of mine
I didn't see any mention of RF ground wires or a counterpoise - did you use one?
I have an 8ft ground rod at the feedpoint. No counterpoise per say. The chicken wire fence around the garden probably helps.
Very nice! Where did you get the hole punch?
What's the purpose of using two cores taped together?
I used two cores to avoid transformer saturation at lower frequencies. Best to do this on 160 and 80 meter bands if one plans to use large amounts of power. Thanks
strange setup. to reach a good swr on 160, you should place the coil in the radiator at about the resonance length for 80m as a trap, so the part after the coil will only be for 160m ans extended by the coil itself. look at the examplex of a shorted multiband endfed 80-10 or 40-10 73 HB0HJK
if you used 2.4 k resistance for 49: 1. What resistance could I use for 64: 1?
50 Ohms x 49 = 2450 Ohms. 50 Ohms x 64 = 3200 Ohms. You would need a 3.2k resistor.
Core mix is your issue on 160m. I'm picking you used 43.
43 works good for 80-20 meters.
Why did you use so much glass tape?? And then wrap the entire transformer with the tape?? Using tape will only trap moisture.... Also, why did you not use a drill to twist the wires? ...a drill works much better than doing it by hand. The case should not be "extra tight"....most people recommend ADDING additional holes to prevent accumulation of moisture. You should probably use a crimp tool for the terminals to make a reliable connection...not a vice grip pliers.
Right? It looks so much better in your video.
I think this core prep is a total waste of time. Use teflon wire instead. Covering the core doesn't allow the core to quickly cool off if it gets warm. I have been using teflon wire for decades and it works very well. And the core can be dismantled easily when desired.
Do yourself a favor and remove that tape ! It only serves to hold in heat that can and will cause your swr to rise ! The 49:1 does heat up and needs air circulation to keep it cool!
Lots of concern about the tape. I should have shown the entire process of making the transformer in the video. I designed it as a class "H" transformer for high temperature operation. The magnet wire I used is "NEMA-H" good for 180deg c. The glass tape is "3M #69" good for 200deg c. The trick here is to use an Epoxy Resin under vacuum. I used "Royapox 502FC". By submerging the transformer into the Epoxy and pulling a vacuum, creates a solid mass which dilutes hot spots within windings when cured. Transformer can also operate with 100% humidity. Still working great after several years in operation.
Swr very bad.