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Topics - ultravista

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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.

Spy Numbers / UNID CW at 4870 KHZ
« on: December 31, 2018, 1654 UTC »
UNID CW at 4870 KHZ received most mornings in Las Vegas, NV.

Didn't find much on the net other than references to M89 Chinese Military. When I am able to receive this unknown CW station, Asia SW stations are also very strong.

I am unable to decode the CW - can't figure out how to get HDSDR, FLDIGI, and the Virtual Audio Cable to play nice to decode anything. Something with my configuration is wrong as I can't decode anything despite being able to see it in the tools. If anyone is willing to help, I will sure appreciate it!

Anyone know what/who is broadcasting CW @ 4870 KHZ?

I plan on installing an under the eaves horizontal loop antenna for receive only. The wire is spooled so I don't know the exact length but I estimate it to be 250 - 300 feet.

The wire 'mount' is a long screw to bring the wire off the wood. I wrapped the wire once around the screw to keep it taught until the next screw.

A few questions:
1) For a receive only loop, what is the best way to attach the coax feedline?
2) Which is better - using it as a long wire (free terminating end) or a loop (coax attached to each end)?
3) Would a dipole (terminated or not) perform better than the random length wire or not?
4) Does wrapping the wire around the screw 1 time affect performance?

Looking for feedback on making this antenna efficient.

I am running Windows 10 with HDSDR & FLDIGI configured with VAC 4.51.

FLDIGI is configured for the VAC Line 1 and can 'see' the data streams from HDSDR when Windows 10 pipes the audio through VAC Line 1. This configuration appears to be working; however, the output of the FLDIGI decoder is gibberish.

For example, CW is unreadable despite being tuned properly in HDSDR and FLDIGI. Squelch on/off doesn't matter - everything is trash.

The FLDIGI decoder becomes legible only if I enable the Audio Repeater (KS) that comes with FLDIGI. When running, the FLDIGI ouput appears to be correct. Validated with WEFAX and CW.

In other words, FLDIGI only works properly with the Audio Repeater (KS) running; otherwise the output is trash.

I though the Audio Repeater was to pipe the audio elsewhere post FLDIGI, not into FLDIGI.

Does everyone else run the Audio Repeater too?

It doesn't make sense (to me) that I can see the signal in FLDIGI with and without the Audio Repeater running.

Equipment / FLDIGI w/HDSDR Controlled by a Yaesu-FT-950
« on: July 12, 2018, 2040 UTC »
I control HDSDR with a Yeasu-FT-950 via an RSP2 and OminiRIG. All is good here ...

I would like to use FLDIGI to decode digital modes. For reasons unknown, I cannot get anything into FLDIGI.

Nothing appears in the FLDIGI waterfall and the output screen is just a string of gibberish characters. The gibberish characters appear with and without the radio on.

Since the rig is controlled by OmniRIG, I cannot get rig control to work within FLDIGI. Not that big of a deal.

I would like FLDIGI to 'listen' in the background and decode what is hears. With that said, how the heck can I get this to work?

Using the machines microphone, and configured in FLDIGI, doesn't seem to do anything. I must me missing something and it is driving me nuts.

Other / 6666.66 KHZ UNID CW
« on: July 01, 2018, 1548 UTC »
Received July 1 @ 8:40 AM PT from Southern Nevada.

I regularly tune unknown data signals from 5-9 MHZ (possibly higher). It sounds like HDFL (bursts of uniform 'hiss') that may or may not include anything other that the bursts.

I have found a few have CW either before or after, can't tell which, but probably at the end of the transmission.

The waterfall pattern width is about as wide as  HFDL or STANAG.

I have listened to the identified signals in the WIKI and can't narrow this down.

General Radio Discussion / Rolling QRM - Grow Lights RFI?
« on: June 02, 2018, 1736 UTC »

Rolling QRM. It starts fast, slows, then stops. When it stops, the interference is present for 12 hours. Some have suggested this is Grow Lights RFI.

The fast rolling begins at roughly at the 2 minute mark

It lasts approximately 5 minutes before stabilizing, just like the ARRL states.


Grow lights tend to exhibit several unique and identifiable characteristics. So far, they typically produce a broad band noise, particularly across the 40m band. It propagates over much greater distances than one might expect from devices that meet the applicable FCC limits. Other clues include:

  • Generally grow lights are set by a timer for 12 hours on and 12 hours off but this can vary

  • Once you have established the turn on time, listen to the noise as the lamp turns on. Itís generally noisier with less of a flat spectrum. This generally lasts about 5 minutes until the lamp is warm

Now ... how do I locate the source in a densely populated neighborhood? Homes, homes, everywhere ..

https://youtu.be/Y5SGkI7NUg8 <--- video

I was lucky to catch the QRM start this morning @ approximately 10 AM Pacific Standard time. It was wide, starting around 3000 khz up to 10000 khz.

It starts fast then slows to a crawl. The noise has pronounced high/low bumps as you'll see in the video. Almost like a train with high/low boxcars rolling through ...

The rolling was faster before I started recording.

Once it stops, it is very still with minor drift +/- and is present until approximately 10 PM Pacific Standard time. When it stops rolling, it does not start up again. It present periodically throughout the bands from 80 -> 30 meters.

Before and after 10 AM/PM, it is not present anywhere that I can see.

What would cause rolling QRM like this?

I caught it yesterday and powered-down my house at the breaker only leaving one circuit up for the radio and switching circuits to validate whether or not it was the house. To the best of my knowledge, it is not my house but something in the environment radiating RFI.

Living in Las Vegas, NV, we have a lot of solar rooftops that could perhaps contribute to this in some way. However, it lasts until 10 PM which is far past sunset.

Radio FT-950
Astron RS-35M power supply
Active Mini-Whip antenna

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