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.
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.
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.
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 »
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.
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…
I thought I would share a few of my notes on tuning up a 6BTV 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.
This review of the Palstar AT2KD tuner will start off with a few comments about tuners in general, and will not get too technical. There are many other places to find technical reviews of this device… eHam ratings indicate that it is a 4.8 out of 5, which is a pretty darn good rating, and some pretty good technical reviews there as well.
Over time I have had both auto tuners, and manual tuners. I have used differential tuners, and standard tuners… I always return to manual tuners, using roller inductors, and large caps every time… An auto tuner is simpler to operate, but the power levels just are not there yet for me on anything I can afford, nor have I been able to get an autotuner, (of the ones I have used), to tune to an exact 1:1, every time, on every band. It is always something like 1.x:1, I have seen as high as 1.7:1, which can cause issues with the new solid state amps, such as the ALS-1306, which I own. See the section under “Conclusions”, for more on that subject. Read more »
This article on adding an external keypad to the K3 was created to make it simpler for the next poor sod down the road to add a Genovation CP48USBHID, 48 key keypad, or the Genovation CP24USBHID, 24 key device to their K3/P3 devices. I initially learned about the Genovation keypads on the Elecraft mail list. It sounded to me like several people were talking as if they had them working, so I asked how to set one up, and got nothing back… I asked again a few weeks later, only this time on both the Elecraft, and the Yahoo mail lists. I received several replies, all saying they would like to have one of these working as well. I did get one lone reply from a person who said, “yes, but I did it a year ago, and have now forgotten how”. From that I concluded I was on my own in getting these two devices connected. Given I agreed with the general premise that having a keypad available to send macros to the radio would be good, I decided to move forward with this project and see how far I might get. I contacted the Elecraft support team first, and got, “only the listed keyboards will work”, response. However, in the discussion, I got what would later turn out to be a vital piece of information in making the connection between these two devices work. Read more »
As the name suggests, this article, “I have RFI, now what– Locating it”, will show how I located several RFI sources in my area. This is part three of a three part series– Part one covered what tools I needed to locate RFI, while Part two covered internal removal of RFI sources within the shack, and finally, Part three covers how I located a number of RFI sources external to the shack, and how I got them corrected. A new section has been added to this site, showing the SDR based signatures of various RFI events, or look over the entire RFI series here.
Over the past few years, I have been plagued with RFI on 40 and 80 Meters. Most of it has been Horticultural lighting, (read that as Grow Lights), and most of it has been pretty easily located. In fact most have been found in under 15 minutes! For the most part the folks I have contacted have all been decent types, and have all to a fault, done what it takes to either remove the RFI, or stop generating it. For that I am thankful to them, it saves me the time in getting the Federal Communications Commission, and the ARRL involved. It also saves the person generating the RFI, the problem of federal involvement.
I suspect a lot of this “good luck” has been because I never threaten, or wave the Federal Communications Commission at anyone. I simply tell them, in writing, what I will do to get the RFI to stop, by giving them a handout the ARRL provides, which approaches the entire issue in a kind, friendly manner. The goal is to solve the RFI problem at the lowest possible level, not just go straight to the Federal Communications Commission, but to give the person a chance to solve the issue locally, so I don’t have to involve the Federal Communications Commission. Read more »
This review of Ameritron’s ALS-1306 was prompted by my selling my older ALS-82 in order to get a no tune amp. This will not be a technical review, as there are many of those around, and the amp is based on the older designed ALS-1300, with some protection added.
I decided that I wanted an auto tuning amplifier, as opposed to the manual tune, AL-82 I was using. So I sold the old AL-82, (see my review here), and purchased an Ameritron ALS-1306. Read more »