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Topics - ultravista

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Equipment / Optimal EFHW Configuration for Low Angle DX?
« on: June 14, 2023, 1305 UTC »
Looking for configuration recommendations for running an end-fed half wave, or non-resonant wire, for best low angle radiation. My current configuration for a MyAntenna's 80-10 is top fed @ 30 feet sloping to 20 feet.

My primary interest if HF DX on 10-40 meters.

General Radio Discussion / Garage Door Opener Damaged by HF RF?
« on: December 11, 2022, 0123 UTC »
Yeah, this is a crazy one.

My wife's garage door opener stopped working yesterday. I replaced the battery and it works when very close to the garage door receiver, like underneath.

Today, my son tells me his garage door opener isn't working. His is 2 weeks old and opens a different door (not the same as my wife). It works when you elevate it to the window and a few feet from the receiver.

So I tested mine, the same door as my son, and it took has a extremely limited range. I could not open the door unless I held the opener up high @ the window.

Previously, we could open the door at the top of the driveway, at least 30 feet away. Now, unless it is in line-of-sight with the receiver, the receiver doesn't receive.

The only thing different is my operating an end-fed @ 100 watts on 40 meters. Prior to my operating @ 40 meters, the garage door receiver had a decent +30 foot range. Now, it's practically deaf.

The low receive occurs when not transmitting, like tonight, when we went out to eat. This is when my son told me his door opener doesn't work.

So ... did my amateur radio operation permanently damage the garage door receivers?

Equipment / Non-Resonant EF Antenna Wire Lengths
« on: December 04, 2022, 1642 UTC »
I have a Palomar Engineers 9:1 HF Unun for non-resonant wire lengths and trying to figure out what length of wire to start with for 160-10m. There are many different recommended lengths from several different manufacturers/expert and the lengths are different for each one. I do not have an analyzer at this point so measuring SWR is not an option. I can run up to 150ft easily.

For those of you with a non-resonant end-fed, what length of wire and counterpoise(s) do you find optimal for 160-10m?

Palomar Engineers 9:1 Unun
* Bands Covered 160-80-40-30-20-17-15-12-10 wire recommendations in feet = 135, 141, 173, 203

Balundesigns 9:1 Unun
* Coverage of 160m through 10m (wire recommendations in feet = 53, 59, 7,2 88.5, 98.5, 124.5, 146, 162, 175

VE3EED the "Best" Random Wire Antenna Lengths
* 29, 35.5, 41, 58, 71, 84, 107, 119, 148, 203, 347, 407, 423

Other / Re: 14.313mhz usb ? 2:18utc
« on: November 26, 2022, 1628 UTC »
I had an interesting conversation with VE7KFM today. Based on his ramblings, I googled his call sign and found this page.
11 years after the first posting .. he's still going strong @ 14.313.

For Sale / Wanted / Barter / VEF-SIGMA 260 1980s USSR Shortwave Radio
« on: October 23, 2022, 0241 UTC »
I am interested in selling a VEF-SIGMA 260 Shortwave Radio w/Cassette. I have too many radios and no longer use this one. I prefer to sell it to another SWL enthusiast vs. eBay.

I do not know the value and I am open for offers.

Located in Georgia USA.

Equipment / LOG Not Performing Well
« on: September 07, 2021, 1447 UTC »
I built a 60 foot LOG yesterday using a DX Engineering BFS-1 at the feed point. The wire is solid core thin telephone cross-connect wire.

The LOG is very quiet and barely picks up distant signals. Compared to my Pixel 1B mag loop, this thing is practically dead.

I have watched numerous videos and read a lot about the LOG and mine is not as effective as others. This LOG is deaf on160 and 80 meters.

Any suggestions on what to do?

Equipment / Long Wire RX Antenna - How Long is Too Long?
« on: August 23, 2021, 1926 UTC »
Is there a point of diminishing return when it comes to the length of a long wire RX antenna?

In other words, does doubling the length provide measurable benefits?

I ran a 500 foot spool of 14 gauge wire through the woods this weekend. Run through screw-on insulators at a height of 14 foot. 500 foot is a long run, I underestimated just how long it would be.

So ... will this 500 foot long wire 'capture' more signal say a 250 or 100 footer?

Equipment / Random Wire or Large Loop and Height?
« on: August 12, 2021, 1441 UTC »
I have the space to run a random wire (+500 foot) and would like advice whether the same length configured as a loop would provide benefits?

Does the same length of wire configured as a loop provide any value vs. running the wire in (semi) straight line?

Also, I can easily add ceramic insulators to my trees at a height of 15-20 feet. Higher than that will be problematic.

Does a height of 15 feet vs. 30 feet provide a perceivable impact?

Equipment / Loop or Longwire?
« on: April 03, 2020, 0123 UTC »
Will a loop out perform a long wire of similar length?

I have two spools of black 14 gauge wire and enough backyard & tall trees to string up at least 500-700 feet.

A 600 foot loop or longwire?

Equipment / Pixel Pro-1B Mag Loop vs. PA0RDT Mini Whip
« on: February 20, 2020, 2017 UTC »
I bought a 2nd-hand Pixel RF-PRO-1B antenna and unimpressed thus far when comparing it to a PA0RDT (Roelf Baker made) active mini whip.

The Pixel is ~5 feet off the ground, mounted to a tripod, isolated properly (per instructions), sitting on a cement patio, about 5 feet from the house. 50 feet of 75 ohm coax connects the antenna to RSP2 SDR w/HDSR software.

The PA0RDT is ~20 feet off the ground, mounted to a PVC pipe, no grounding, sitting on a wooden deck, about 5 feet from the house. 50 feet of 75 ohm coax connects the antenna to RSP2 SDR w/HDSR software.

While tuning through the HF dial last night, all signals were significantly stronger with the PA0RDT. Changing the orientation of the loop made no difference.

Shannon Volmet was easily understood with the PA0RDT; with the Pixel, it barely produced a signal in the waterfall. Greece beacon "SVO" likewise was strong and very audible w/the PA0RDT; the Pixel was non-existent. STANAG signals were very pronounced and strong w/the PA0RDT while the Pixel was pulling in the signal, it was much weaker and very evident in the waterfall display.

Why would the PA0RDT mini whip outperform the Pixel mag loop? The PA0RDT should be grounded to improve signal and lower noise. Mine is not grounded; it is not performing as efficiently as it could yet it runs circles around the Pixel mag loop.

Does height above ground affect the Pixel?

Am I incorrect to assume that the Pixel mag loop should outperform the PA0RDT?

General Radio Discussion / QRM Question ~ 15000 KHZ to 50000 KHZ
« on: March 17, 2019, 1535 UTC »
I am in Southern Nevada and finding QRM spikes on my SDR that are also present on other SDRs in area (Southern California, etc). I am can see these noise signatures above 15000 KHZ spaced somewhat evenly all the way through 50000 KHZ.

When tuned in AM, it is like a rushing sound - every one sounds the same. The QRM is always present across multiple antennas and geographically distant SDRs.

I see the same QRM on a California SDR at exactly the same frequency. It appears day and night.

I would like to know the source of this QRM. Perhaps a natural source?

Broad view from my SDR

Close view from my SDR

Close view from Tokens Southern California SDR

I have been using a PA0RDT active mini whip from Roelof Bakker for about a year now. The PA0RDT antenna has served me well. Clean and able to pull in signals that a 260 foot loop and various long wires cannot.

I recently bought a RA0SMS active mini whip from Anton Gavrilov and having major noise issues.

Both the PA0RDT and RA0SMS are powered by a 12v wall wort (same model #), on a non conducting mast @ 20 feet, and fed with 50 ohm coax. The radio is a Yaesu FT-950 with an RSP2 as a panadapter. The 12v power supply is choked with snap-on ferrites.

The RA0SMS produces noise approximately every 10 KHZ - the noise is present from LF all the way through HF. The noise is visible and is rendering the antenna unusable. You can see the noise spikes in the first three photos, and the lack of noise with the second set of three photos.

Below is a comparison on of the two antennas switched through an Alpha Delta 4 position coax switch.



What could be causing the noise across all bands with the RA0SMS? All things are equal with the exception of the antenna and power feed unit. The PA0RDT is clean and rarely overloads, even with Broadcast AM, with the Yaesu FT-950.

HF Mystery Signals / UNID Voice & Sounds @ 3397 or 3400 KHZ
« on: January 16, 2019, 0312 UTC »
Received 01/15 @ 7 PM PT in Las Vegas, NV and also on Tokens KIWI SDR.

I couldn't determine whether it was USB or LSB. The voices were very disjointed, almost digital like and the signals sounded like garbled ALE (to this novices ear).

Very strange. I was not able to receive via the WebSDR in the Netherlands.

Equipment / Outdoor Under the Eaves Loop vs. Active Mini-Whip Antenna
« on: January 09, 2019, 1802 UTC »
I have been using an active mini-whip antenna (PA0RDT) at approximately 20 feet on a non-conducting mast. From my QTH, the mini-whip has been exceptional for RX.

Over the weekend, I ran a wire around the house under the eaves, approximately 200ft of wire @ 10 feet or more off the ground. As a loop, the coax braid connects to one side and the conductor to the other. It is two conductor alarm wire and I am only using one in the pair. No balun, just a simple PL-259 connector connecting the conductor and braid to the wire.

The mini-whip wholly outperforms the loop antenna. Strong signals present on the mini-whip practically disappear with the loop. On a scale of 1-10 for RX, the loop is a 1 or 2 compared to the mini-whip. Using the loop is like not having an antenna at all.

As a novice, I thought for sure, the long wire around the house would be at least as good if not better due to the electrical length. Not at all.

Can someone help me understand why the mini-whip @ 20 feet is outperforming the 200 foot loop @ 10 feet?

What can I use to identify digital radio signals to determine the signal type (FSK, MFSK, PSK, PSK31, STANAG 4***), then the Mode (LSB/USB), and Bandwidth to determine whether or not it is encrypted?

Knowing the details of the signal is the first step in decoding.

The question is for signals found outside of the amateur radio bands.

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