Messages

61

10/11 meters / Re: Fuchs antenna.. LC end fed antenna.. tapped coil, EFHW resonate

« on: September 23, 2019, 2107 UTC »

BTW there is one good thing about my playing with this stuff, I learned about toroidal cores and what the numbers mean. Sounds silly to the experts I am sure, and honest to God I have built RF electronics and it took me this long, but now I know the first number means size, the next number means mix. I feel like such an idiot lol. We all learn something new every day. Built radio transmitters for years but never knew that lol, just went by frequency spec, or tested them the hard way  by winding equals and sending RF through to see if they'd pass it, but I was over-complicating things like usual. Though it doesn't hurt to do the wrap and test method to test, never know if these companies sell legit core material until hitting them with RF.

62

10/11 meters / Fuchs antenna.. LC end fed antenna.. tapped coil, EFHW resonate

« on: September 23, 2019, 2045 UTC »

Going a bit nuts here as usual from my manic state of mind.

Been researching to replace my DIY resonant fuchs 1/2 wave end fed antenna for 11 meters. Original design I used was a 1:8 ratio coil with two windings primary and 16 secondary going into around 15 or so pF capacitance using of all stupid things a trimmer cap. Well I learned my lesson with weather and rain using this as a base antenna. Thought I had it waterproofed but every rain or humidity would climb SWR and lower frequency. NP0 trimmers are useless in outdoor weather and moisture.

This time I am going with a straight up lumped LC tuned stage, long story short there are three kinds of these end fed antennas for 1/2 wave end fed feed, the fuchs (better known as EFHW transformer coupled pri:sec transformer, sometimes resonate air core or powdered iron core, or non-resonate on ferrite which is lossy by a dB or more for multiband but gives flat SWR at expense of low efficiency and energy transfer). The single coil tapped version to convert a range of 1:6 to1:9 ratio (50 ohm to 2500-4700 ohm end fed), and my current setup which simplicity wins for efficiency the LC coil, a coil in series with transmitter output to antenna input and a capacitor across antenna to ground to convert current to voltage fed. There has to be very little loss using this method because it's direct and no cores used or lossy link coupling.
I think the drawback is the fact it isn't linked coupled will cause more standing waves on coax back to the shack.

With CB radio and 4 watts of power, got to make every watt count!

My question here before I complicate shit more is how many people have used these? I know the Antron/Solarcon a99 and other antennas use the same exact thing. The 99 uses an LC coil/cap, one coil inside of the other to act as a hairpin impedance match but I'm not even sure it's really that, it just looks like an RF coil to ground so that the antenna is connected to ground for static, otherwise the A99 is a simple LC match network into a 1/2 wave wire.
Here is an article on the A99 deconstructed to show how overpriced hype this thing is, it's literally an ordinary LC coupled half wave end fed...
http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf

I love EFHW antennas because the simplicity of mounting being in a small lot, got to use whatever I can. Wire types allow inverted V and other configs too.

I'd love to know if using an LC with a 130-2 toroid is as effective as an open air coil at 27MHz. I am testing both but can't figure out which is less lossy. The toroid seems to give less SWR across the CB band which leads me to believe it has a bit of loss, so I am currently testing with house copper stripped wire to make my coil, and a coax stub for the high voltage capacitor.

It looks ugly as shit right now but so far it tunes up with ~1.2 SWR over 26.5 to 27.5MHz but the coil is so sensitive to size change, it will take some glue to clamp it and lots of RTV silicone to seal it up before connecting the top bolt to my 18' adjustable 1/2 wave conduit pipe in the air...
https://imgur.com/a/jmUv4GI

Not even sure how well the open air core copper coil will do. Seasonal changes here are extreme and rain got into my last "fuchs" coil match which led me to this simpler design. I want to use my 130-2 toroid donuts for this but I feel they have some sort of loss at CB since they technically are good to 10MHz on the paper, no idea how to calculate loss over air wound when used as purely an inductor like this.

After this coil cures the RTV silicone I plan on making the same coil but using the red 130-2 coiled torroid in place of the air coil design in a different water proof unit with snipped coax capacitor and compare the two. Hard to do at my location because CB is dead right now. Hoping to get some skip in with that short spirt in wintertime. I guess there is always field strength metering. If torroidal wins out or comes in equivalent I think we just found the new best DIY end fed design for goofed setups like I have. Though only a few hundred watts can run through them, but I honestly run barefoot and enjoy the challenge of antenna design over idiotic power into thimble antennas.

63

The RF Workbench / Re: Stretchyman 40w GaN TX is sick

« on: September 23, 2019, 1943 UTC »

Damn I was hoping this post would be about how sick, as in awesome his transmitters are. He seems to be quite the tech guru and knows a hell of a lot more than me on class D and E hands on work. Sure he will chime in Really no idea why I am replying, just thought the title of the post was about how cool his little rigs are and I probably drank a few too many beers or something.

64

North American Shortwave Pirate / Re: Pee Wee 6955 USB 2147 UTC 21 Sept 2019

« on: September 22, 2019, 0335 UTC »

Glad others caught it. I listened while working on a project and didn't have my SSTV software handy and didn't catch ID but the signal was really strong through the storms here in the midwest. Wondered if the DJ was playing live guitar for a bit.

65

Equipment / Re: Yet more KitchenAid stand mixer RFI

« on: September 06, 2019, 1554 UTC »

<reply to: ChrisSmolinski>
I think that's a matter of muntzing. I hate to say it but I often do that to my own circuit too but only to the point to simplify things, not malfunction it. Think Apples Woz style muntzing. However these imported electronics take it to another extreme and don't care about our standards and that's how we end up with junk that causes RFI at best or a burnt down house at worst.
BTW I updated my last post since you replied. Sorry I have a tendency to do that thinking no one is online to read it.

66

Equipment / Re: Yet more KitchenAid stand mixer RFI

« on: September 06, 2019, 1542 UTC »

Reminds me recently of a wallwort transformer. Had two 24v 500ma ones from different manufactures but looked identical on the outside with same plug. One I used plugged in would cause the nastiest RFI I have ever experienced. Thought it wasn't that big of a deal as I was using it on an audio device until I used it while transmitting and it caused my transmitter to hum like crazy. After pulling out hair and going nuts I remembered I had the other almost identical one and swapped them. Problem gone!
It makes me wonder sometimes how this shit is built. Sure I can open it up and investigate but there are times even when doing so I find myself stumped. It's like the chinese have some special ability to make the most noisy RFI devices feasible, and I couldn't generate that much RFI if I tried and I know how to build electronics that can!

Food mixers have a special place in my heart though. My mother had one when I was a kid and back when we had cable TV, yes cable.. not antenna. When she'd fire that thing up to mix stuff the TVs in the whole house would get visual lines going through them. I could hear the motor through the audio on the TV. Still no idea how such a simple device caused so much RFI. Kind of astounding to me now considering what I know about transmitters. All I can figure is that the thing was a giant spark gab transmitter motor somehow. Remember every weekend she'd make mashed potatoes and use it and... there goes The Simpsons for 10 minutes lol.

67

Equipment / Re: Inverted L ground plane

« on: September 05, 2019, 1758 UTC »

I actually replied without actually responding to your post here by accident, didn't even see your post until now here but over on that other forum we use I talked about ground planes for Inverted L's.

There's a claim that placing an equally length wire along the ground as the horizontal; aired part of the vertical section is beneficial. I'm not sure if that's fact though, might take some computer analyses. That horizontal section is not really radiating much anyway so I feel the most important part of that section acts as a loading coil for the vertical section or capacitance hat, and by placing a length of ground plane along the same direction will simply add to aerial capacitance thus probably plays with overall loading efficiency.

Now as far as directional qualities of the L, the long part horizontally longitudinal is the direction with a possible loss of 1dB. Put the length of the inv. L behind the area you want to give the strongest signal, but 1dB is so little it probably will have little effect anyway.

I've also noticed that sloping L's exhibit some interesting features. If you slope the inv. L the sloped section seems to have a far lower angle of radiation, thus if you are on the outskirts of town like me and want to hit your town strongest with frontal ERP, you put the sloping section toward your town and the ground screen same direction.

I may be wrong on some of this, but these are my observations in reality when testing.

68

Huh? / Re: Scientists prepare to farm puffy pink seaweed that stops cows burping methane

« on: August 29, 2019, 1732 UTC »

Both the seaweed and Pepto Bismol are pink, coincidence?

69

Equipment / Re: The SW200 LPAM, Part #15, Amateur Radio AM, Audio Processor.

« on: August 27, 2019, 0831 UTC »

Sorry to raise an old thread but that audio processor I was working on is now complete. It has all of the features of the SW200 but with some differences under the hood including a much steeper NRSC compatible filter reaching out to 9.5kHz instead of 6kHz. Included is the ability for asymmetrical modulation, optional VU and clip/AGC LED lights and other features.
Full schematics and R&D from the beginning to the end can be found here... Page 2 of the thread gets more in depth with progress snapshots.
http://darkliferadio.proboards.com/thread/1029/diy-audio-broadcast-processor-scratch

I designed this for the pirate and part 15 community for those willing to take the effort to roll their own but trust me it's no easy undertaking. In time we will have PCB files online to simplify a lot of it for hobbyists who don't want to solder the insane protoboard work I did which took many months and instead slim it down to a few days worth of soldering onto a prefab board. This is simply my "thank you" back to the pirate community for all the incredible schematics and information you have all shared that helped me with my interests in broadcast audio and RF.
Not here to take the steam out of the SW200, I'm sure it's a fine audio processor too and is offered as a complete unit, however I wanted to design something similar *from scratch* and release the full design as open source for those wanting to build their own.

Video of my complete AM broadcast processor here..
https://www.youtube.com/watch?v=utZTQc_K0j0

Components like the Schlockwood SW200 are all generic for easy to source parts. Only exception is the VCA chip I used but that's still available from a few part sources. Tried to keep simplicity in mind and was inspired by the Dorrough DAP 310 and Texar Audio Prism circuits and sound from the 70s and 80s.

70

Huh? / Christmas time

« on: July 31, 2019, 0504 UTC »

Sometimes when I put my step button to 1kHz intervals and tune across the AM MW band it sounds like slay bells and steel drums between stations. Sometimes it sounds like Charlie Browns adult. Good way to fall to sleep if the static and blips on longwave doesn't work or Radio Havana Cuba isn't enough fun on acid. To each their own.

71

Propagation / Re: Is my radio dead though?

« on: July 13, 2019, 1344 UTC »

Last night things were mostly back to normal. Lots of strong SW stations and every MW channel packed pegging my S meter.
I think it's just these summer conditions and I should know that since it's nothing new to me during this time of year. I do think the solar cycle is playing a hand in it though because when things get quiet they get real quiet. Sure there's static when connecting the aerial but there are times when I wonder if my radio is dead but of course it isn't. I have other rigs and antennas to compare it to 

Even my friend who I helped convince to buy an ATS909 like mine asked me the other day if there are less stations to listen to or what the deal was. He's new to DXing so he was confused why he wasn't pulling in the stations he normally hears in winter. Had to explain to him that summer kind of sucks to begin with for MW and that we're at the lowest part of the 11 year cycle which effects SW. Glad I'm not the only one living here wondering.

72

Huh? / I love you all

« on: July 11, 2019, 1746 UTC »

Feeling pretty, might delete later.
God bless the pirate radio community! 

73

Propagation / Is my radio dead though?

« on: July 05, 2019, 0401 UTC »

I've never heard it this bad before. The last week has been a clustersuck of thunderstorms and local stations only. I'm not talking just SW either but even the MW band that I trust in has been getting weak in the X-band range.

I seriously thought for a bit that it was my radio or antenna or a lightning storm that deafened my radio because I have never heard it get this quiet. Doesn't help that this data station on LW around 300Kc I use as a test station to make sure everything is fine that usually gives me a full signal strength reading is now gone quiet but I think it finally went off air.
The only station that helped me confirm things are still working somewhat was the pirate X-FM with his booming signal and WBCQ, but even those were below the norm I am used to (outside of the superstation).

It's not my radio though, I tested a few radios, then really thought either I am losing my mind or my antenna broke connection somewhere. I have an inverted L up 35' with about 100' horizontal that I also use for AM pirating when the itch hits. Well just for shits I ran a low power TX test through my usual untouched tuning unit and sure enough my SWR was fine through the old wire, so it's not my antenna or ground system.
It is REALLY THIS QUIET! Time to toss the radios and go to stringed can communication?

74

The RF Workbench / Re: Audio jacks/plugs as QRP RF wire quick connects

« on: June 20, 2019, 1410 UTC »

Lots of those older emergency CB radio walkie talkies that were meant to be kept with a road kit used RCA jacks for the magmount antenna and they worked just fine for TX. I suspect because in emergencies they are one of the fastest connectors to plug in and most familiar to ordinary people.
I've also used RCA jacks for <30MHz without problem but wouldn't trust them for anything other than QRP since they can easily be yanked out and would cause a PA transistor to pop.

If you have some of the higher quality A/V RCA cables around and are like me and often split the audio cables from the video and toss the video (yellow) cable to the side often those video cables have better shielding and can be used well into the higher SW frequencies with low power since they are made to carry wideband composite video. Impedance may be unpredictable but at low power it's not much of an issue. I often keep the yellow video RCA cables around for mono only interconnects too for the same reason.

This reminds me that I found 50' of 5 connector A/V RCA cables (red/green/blue left/right) in the trash and should try to push some RF down one to a dummy and see what kind of SWR and power loss they have on 11m since I have RCA to PL259 adapters

75

Equipment / Re: You guys using TX pre-emphasis or RX de-emphasis, how about bandwitdths?

« on: May 26, 2019, 1931 UTC »

Awesome replies so far. My curiosity was peaked on this topic because of the analog audio processor I am designing and picking filter frequencies. Currently have an 8 pole overshoot corrected NRSC-1 compliant filter designed for the final stage which is flat that sharply rolls off around 9.2kHz and is down 15db at 10kHz, 25db at 11kHz and so on, but was thinking of adding a toggle to flip between that and something else which is part of why I asked.

Can't decide if I should add a 5kHz or maybe wideband 12kHz+ filter as the option. Guessing the earlier would be more useful for shortwave broadcasting but my ears say otherwise
I guess as the old saying goes.. if they can't hear it with their radio why broadcast it? Going out past 5kHz is probably fruitless but for now I will stick to the mediumwave broadcast standard that is the NRSC mask and after looking at the replies will probably add the 5kHz filter as an option for restricted bandwidth

If anyone is curious about the audio processor project I am working on you can find it here. It's slowly coming along and is a blog style post so always updating it. Only recently got the overshoot corrected filtering soldered up. Hopefully when it's all designed the info will be useful to other pirates that are electronics hobbyists too that want to get their feet wet in audio processing. In the meantime I will use Stereo Tool which is simply the best option out there on the digital side, I just prefer real-time analog.