NK7Z.NET | Amateur Radio reviews, setups, and RFI information

Propagation Part I

Posted on July 3, 2022 by Dave

“The Ionosphere“

Overview

This is the first in a multi part set of articles that will help you understand how to work more DX by understand band openings, and band closings. In order to work more DX you will need to understand what bands are open, when they are open or closed, and, if they are open, where they are open to. That said, let’s get started, in this first article, atmospheric, and ionospheric structure will be covered. That will give you the basis for understanding how, and why, DX comes about. What you learn today, will be useful tomorrow, and in understand the rest of this series. Throughout this series of articles, you will see links to other articles, and web pages. These links are to assist you in learning more if you want. You do not need to follow these links to understand what this series of articles is trying to teach. Read more »

Categories: Propagation | Leave a comment

Notes: tinySA

Posted on April 1, 2021 by Dave

tinySA device, click to enlarge.

Overview:

Having just purchased a tinySA, I went through the upgrade, and tools location process one does with every new piece of hardware. I thought it might be a good idea to document the steps I used to process this item into my lab, so I thoughts I’d make a few notes on setting up the tinySA for the next person… This is not a review, it is a few notes I might need later on to reinstall it from scratch, and I thought I might share them with you!

I have always wanted a spectrum analyzer, I have looked at the multi thousand dollar ones for decades. Not having several thousand bucks in throw away, I bought a used ATTA spectrum analyzed for $65.00 several years ago. It does the job, not as well as a good HP, but it does OK for my needs.

I still want the expensive HP type of Spectrum Analyzer, but alas, I doubt I will have $45,000 bucks to throw at it. When I saw the “tinySA”, (tiny spectrum analyzer), come to market a few months ago, and saw that R&L was selling them for $54.98, I just had to have one… Not that the tinySA will replace a $45,000 spectrum analyzer but it does the job I need, and for $50.00 I am happy as I could be with it. Read more »

Categories: Accessories reviews, Direction Finding, Info, Notes, Quantification, RFI Mitigation, RFI Signatures, Setups, Tools | 8 Comments

Review of Front Panel Designer

Posted on April 22, 2020 by Dave

Overview:

I decided to redo my operating position with the inclusion of a patch panel. I am always moving antenna between my K3, and my SDRs. Also, I wanted to have the IF from the radio available without tearing the operating position apart every time.

A patch panel would help in all of these needs. I looked at making one by hand, using a drill press, or by building it in a home workshop, and decided I was not skilled enough to do this and still have all my digits intact when finished. After reviewing all the options, I decided to use a company that builds panels via an easy to use software interface. Read more »

Categories: Construction, Info, Reviews, Software reviews | 1 Comment

Review of DX Engineering’s 6BTV 17 Meter add on kit

Posted on March 6, 2020 by Dave

Overview:

Over the past few years I have been using a Hustler 6BTV vertical antenna as my primary antenna for 80, 40, 30, 20, 15, and 10 Meters. The antenna has worked very well for me, and I have worked much DX with it. Over the years I have spent a great deal of time getting things tuned as I want them, putting a large, (40 radials), radial field in place, and getting the antenna exactly the way I want it.

I have been using a BWD-90 for 60, 17, and 12 meters. The BWD-90 is basically a Dummy Load you suspend in the air, then feed it power. Some of that power leaks out and is radiated, the rest goes up as heat. The BWD-90 is about 6 db down from a dipole performance wise. You might ask yourself why in the world would anyone use a BWD-90? The answer is it is flat across the 3-30 MHz., spectrum at under 2:1 SWR.

As you can guess, the BWD-90 is not a stellar performer, but it will load on almost any frequency. I have been on a station simplification quest now for a few years, removing equipment where I can, and in general reducing the complexity of my station.

Part of that quest was to try DX Engineering’s DXE-A0KB-17M-INS 0c, 17 meter add on kit for the Hustler 6BTV. I have had a lot of trepidation with regards to making any change to the 6BTV, as it is working very well, and I want it to continue that way. I have literally spent years, tuning and setting this antenna and its associated radial field up. As a result of all that work, and time spent, I don’t want anything to mess with the performance of the 6BTV. I was quite worried about what would happen to the antennas performance if I added the kit. Read more »

Categories: 6BTV, Antenna Reviews, Construction, DX, Info, Reviews | 2 Comments

KPA500 Input vs. Output Power

Posted on February 6, 2020 by Dave

Having just purchased a KPA500 amplifier by Elecraft, I thought it might be a good idea to characterize a few important things about the amp. One being the input vs. output power levels. I had occasion to send the amp to Elecraft for testing, and updating. The amp has been recently returned, as up to specs by Elecraft.

The amp was fed into a KAT500 tuner, and an actual antenna was tuned and used for all tests, save 30 Meters. A dummy load was used for all 30 Meter testing.

The power on each band was increased in small steps while the output power was entered into a spreadsheet. I used the spreadsheet to graph the amp in/out ratios. Below you will find the input vs. output graphs for my KPA500. This dataset is not designed to show the 1 db compression points, just a general feel for how the amp should behave.

Raw spreadsheet here… Read more »

Categories: Elecraft K3, Info, Reviews | Leave a comment

Elecraft K3: KSYN3A synthesizer installation notes

Posted on June 27, 2018 by Dave

Elecraft K3

Overview:

At one point, myself and K7OLN were living about 700 feet apart. Both of us were very active, and as a result could not operate on the same band at the same time. I purchased an Elecraft K3, and that helped, K7OLN then purchased a K3 and that helped more. Then Elecraft came out with a low phase noise synthesizer, the KSYN3A. This helped a lot. As it turns out I was able to document the changes as we each added the new sensitizer boards to our radios. This set of notes contains a set of images that were taken shortly after Elecraft made the new synthesizer available, and as we made the changes to each K3.

Setup:

Two K3s were used in this test and the old synthesizers were replaced in stages. The K3s were separated by approximately seven hundred feet, both feeding resonant antenna, and both running approximately 50 watts each when tested. K3 A, was owned by NK7Z, and K3 B, was owned by K7OLN. Both started with the old synthesizer in place.

Results: Read more »

Categories: Cleanup, Elecraft K3, Info, Setups | 2 Comments

RFI Site survey – Part II, interpretation

Posted on February 5, 2018 by Dave

Overview:

Annotated 40 meters showing various RFI events

This is part II in a series of articles which will cover how I interpret and use SDR captured spectrograms as they relate to my RFI mitigation efforts. See Part I, Using a SDR as a Site Survey Tool for how I setup and use the SDRPlay RSP1 as my SDR of choice, while using HDSDR as the radio control program. The concept was to view my RFI environment as a whole, not in real time, but across long periods of time, and very wide frequency spans. Once you have looked over part I, and part II, take a look at the RFI Samples page. This page presents various forms of RFI so you might be able to tell what is causing your RFI issues.

Real world examples of RFI will be used here showing how I can infer what appear to be disparate RFI sources, as related sources. Part I covered my choice, installation and setup of HDSDR, and an SDRPlay RSP1 SDR for use as a site survey tool. Read more »

Categories: I have RFI: Series, Info, RFI Mitigation, SDR as Site Survey tool | 1 Comment

RFI Snapshots

Posted on January 20, 2018 by Dave

Grow lights on 80

If you click the image at the left, or here, you get to a set of pages containing snapshots of the various categories of RFI generating devices. Once you arrive at the category page, you will find another set of images, each representing some form of RFI. Clicking on any of the images on the RFI category page will take you to yet another page, which contains any number of RFI signatures. This may be helpful in identifying a source of RFI. While it is not a a RFI fingerprint, it is an indication of what may be causing your RFI. These indications can help in the location of RFI. For instance, if you see something here like a street light, and it matches what you see at home, then you can reasonably suspect streetlights in your area, and watch them. There are many types of RFI, not all of them will match, so do not expect to find an exact match… For more information on locating RFI see the “I have RFI” three part article located here.

Important:

If you have any sort of KNOWN RFI signatures, please send them to me, with a note as to what they are. If you have an audio sample please include it. My email is good on QRZ.COM. Clicking the QRZ link will open a tab, you can get my email there…

Categories: I have RFI: Series, Info, RFI Mitigation, RFI Signatures | Leave a comment

Notes on tuning a Hustler 6BTV

Posted on July 24, 2017 by Dave

80 Meters, no choke, 8 radials.

Overview:

I thought I would share a few of my notes on tuning up a 6BTV, (review of the DX Engineering 17 meter add on kit here), antenna, and constructing a radial field. I have been using a GAP Challenger DX, (review here), for the past fifteen years, unbeknownst to me, and over that time, water had been slowly seeping into the tuning harness of the antenna.

The harness finally gave up the ghost one day, presenting a dead short to my Solid State ALS-1306 amp, (review here), as I increased power. At about 800 watts CW, the harness shorted out, killing the ALS-1306, and necessitating the amp make a trip back to ALS-1306 heaven, (Ameritron), to have a replacement RF output device installed.

Replacing the Challenger was one of the options on the table, but I did not want to do a new install of a Challenger– I remember the last install. The entire phasing harness installation process is not fun, nor is it easy, so– given there were a few things about the Challenger I was not happy with anyway, I began looking for a different antenna.

Categories: 6BTV, Antenna Reviews, Construction, Info | 22 Comments

Using a SDR as a RFI site survey tool

Posted on September 7, 2016 by Dave

Overview

Twenty Four hours of RFI on 80 Meters

This is Part One of a multi part article dealing with setting up a SDR as a RFI site survey tool to assist in RFI detection, location, and mitigation. Further, part one will set the stage for how captures of the RFI were accomplished, and visualized. Part one will also touch upon some of what can be seen and learned from this data. Methods I used to locate RFI can be found here. Also some RFI sources signatures have been captured here.

Part two will deal with interpretation of the SDR spectrogram. Part two can be found here. Part three will deal with actual location methods, using that portable SDR tool.