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Elecraft K3 Review


Ham Radio Nerd
Apr 14, 2002
About a month ago, I decided to purchase an Elecraft K3 kit, sight unseen. Actually, I had seen the rig at Dayton, but I hadn't given it much attention. After reading a few very technical reviews of the Elecraft K3 touting the technical specs and merits of this very interesting rig, as well as talking extensively to a long time K3 user (and field tester for Elecraft), I decided to take a chance on a rig I had never actually touched. If you pause to think about it for a minute, this is actually how most ham operators probably make purchase decisions that don't live near a major ham radio store of some type. Now that I have the rig in place, it's time for a long term review.

While you're researching the K3, you will undoubtedly come across the detailed technical Clifton Labs series of articles. They are excellent and should be read in detail if the technical specs are your thing. The articles can be found here: Elecraft K2 and K3 Transceivers. My purpose with this review is not to comment on Clifton's findings, but to give a more general functional and practical review that more ham operators can identify with. If you have any questions or opinions of your own, please feel free to ask or comment.

The Build

If you would like to follow along with the build process, I've put together detailed photos of the major steps here: http://www.worldwidedx.com/hf-bands-hf-rigs/68225-elecraft-k3-build-photo-diary.html. To sum it up, the build process is fairly straight forward. It isn't something that you should be afraid to try and it will familiarize you with the major components should you decide to purchase upgrades later. An additional plus for building the kit yourself is that Elecraft occasionally comes out with updates that require you replace or modify various component boards. If you've already experienced the build process, disassembly and reassembly will be a snap. The primary issue that you need to be careful about with the build process is making sure that you're using all the proper length machine screws and washers at each step. I feel that there are a few places where Elecraft should take some simple steps to ensure that you're using the correct screw lengths, but they don't, and you've been warned.


The K3 interfae can probably best be described as utilitarian but simplistically elegant. The LCD display is smaller than the higher end Icom, Yaesu, and Kenwood rigs, but larger than some of the more entry level rigs. While the display is small (the whole rig has a small footprint), it does a remarkably good job of showing you all of the important information at one time. The digital S meter, SWR meter, TX power, ALC, compression, VFO A & B, mode, antenna selection, and filter selection are all easily visible. Here is a pic of a typical display:


One of the reasons that the display is able to be smaller than other rigs is because the K3 does not make use of soft keys that change function depending on the screen. This type of user interface is typically found in the Icom rigs. The advantages of this approach are that learning the functions and usage of the various buttons and knobs is fairly easy; you don't have to remember any complex menuing system. However, since the K3 is truly a Software Defined Radio, the lack of soft keys might actually be limiting to the future growth potential for new features.

Most buttons have at least two functions, and some have three. The function printed on the button is the function that is activated by tapping the button, while the label printed below is activated by pressing and holding the button. If the button you're pressing activates a variable settings, VFO A or B will adjust the setting. When there are more than two adjustments necessary, Tapping the 1 or 2 button will activate the other toggle adjustments. It may sound a little complicated, but once you understand the operation, it really is easy to remember because it is consistent throughout all operations. Here are a couple of pics of the main front panel and the various functions:

Front left:

Center controls:

The center controls are examples of knobs with three functions. You toggle from the left side labeled function to the right side by pressing the knob quickly. You adjust the setting by rotating the dial and activate the third setting by pressing and holding the dial.

Right side:

Standard Interface Features

The K3 comes standard with a built in, isolated sound card interface. By plugging in a basic stereo 1/8" and another mono 1/8 cable to your computer you can easily use sound card modes without purchasing or building any type of external interface. Because the built in sound card interface is RF isolated, you don't have to worry about nasty ground loops causing ground hum problems. The RS232 is a standard serial interface used for rig control, memory programming, and firmware updates. The ACC port provides inputs and outputs that include band data, PTT, Transverter control, external ALC, and other functions. The other ports on the bottom of the rear are standard ports for a CW paddle, key, PTT, and amplifier keying. A pic of the rear standard interface is shown here:


The blank panel directly below the standard I/O panel is the location of the optional RX antenna input/output, transverter I/O, and IF Out that you would use with panadapters.

This left rear pic shows the two standard antenna ports (ANT 2 comes with the optional auto tuner) and the location where the optional sub receiver port and 2 meter port would be. The power adapter is a standard Anderson Power Pole adapter.


Now that I've covered the major physical attributes, the next topics will cover actually using the rig. More to come...

The Filters

Anytime the merits of the K3's design are discussed, the conversation usually starts with the IF roofing filter architecture and DSP implementation. Unlike other high end HF rigs, the K3's 8.3Mhz IF is at very low frequency by comparison. For example, Icom's 7600 IF is at 64.455 Mhz. By lowering the first IF, Elecraft has enabled the K3 to accept much more narrow roofing filters than would otherwise be possible. This is nice because it gives you the capability of filtering out strong adjacent signals at very close spacing in various modes before they get past the IF and into the DSP filtering.

As a point of comparison, we can look at the Icom IC-7600, which is in the same price range as a fully configured 100 watt, 5 filter K3. The Icom 7600's narrowest roofing filter is 3khz. If you want a more narrow filter because of strong adjacent SSB, CW, or other digital mode signals, you adjust the DSP filter to make the filter however narrow is suitable for you. The problem with having only a 3khz roofing filter is that if there are stations within that passband with strong signals a number of problems arise that the DSP cannot overcome, including receiver desense or blocking. Having to rely on such a wide DSP range of filter adjustment also can introduce DSP related artifacts like ringing.

The K3, on the other hand allows you to have the rig automatically switch in more narrow roofing filters as you adjust the filter width. One of the first configurations you do after the build process is tell the rig which roofing filters you installed, and what modes they should be available for. Here is a screen shot of my rig's configuration:


You can see that I have both 2.1khz and 400hz roofing filters installed, which are much more narrow than is possible with the Icom 7600. When a very strong adjacent SSB signal is within the 2.8khz passband, narrowing the filter down to 2.1khz and a small shift the IF passband makes that adjacent station's signal not even enter the first IF of the rig!

My first experience with how powerful this design feature is came a few nights ago when I was having a casual scheduled QSO with another station on 40 meters SSB. There happened to be a contest going on, so we had to find an open spot on the band in between contesters so we could talk. Well, a local contester with an especially strong signal decided to shift his frequency right down on top of us to make us go away - there was no doubt that this was intentional. Initially, his signal was so strong that it started causing blocking in my receive, wiping out the other station I was talking to. Unfortunately for him, both of us were using K3's, so we just narrowed up the filter, shifted the IF slightly and kept talking. The K3 filter architecture made it seem like the other station wasn't even there. It's one thing to describe something like this, but until you've actually experienced in action, it's difficult to appreciate. Of course, having the capability to use this type of filtering at your fingertips is incredibly useful for CW and digital modes where a lot of signals are crammed into a small bandwidth.

An important thing to understand about how the filters are used in the K3 is that it uses the widest filter available for transmit, with the DSP adjusting the TX bandwidth as appropriate. That means if you plan on using FM for 10 meters or 2 meters, you need the 13kHz FM filter. If you only plan on using SSB, CW, and digital, you can stick with the 2.7khz or 2.8khz as the widest filter. If you want to do AM or ESSB, you should order the 6kHz AM filter.

Once you've told the rig what filters you have installed, you can either select them manually by pressing the XFIL button, or let the rig switch between them automatically by simply adjusting the passband width. Here is a short video I did that shows the filter automatically changing between the 3,4, and 5 filter as I change the passband. You can also hear the effect in action by listening to the PSK31 signals. As a side note, you can also see the PSK31's decode function in this video.

I must admit that I both laugh and shake my head about all this talk about "roofing filters" (new name for an old thing) and how good they are. In reality manufacturers had a good thing going years ago with IF filters and then took the cheap route by expecting AF DSP to be the wonder circuit of the new radios. After the idea of AF DSP was found to be a very poor replacement to actual front end or IF filters they introduced these roofing filters that have been greatly accepted. Those of us that have been in radio for a while now are just glad to have an old friend back. You cannot beat a REAL RF/IF filter for keeping crap out of your passband and I am glad to see them coming back to double and triple (even quad) conversion radios. It looks like Elecraft has a good thing going with actual hardware filters as well as software filters. (y)
I must admit that I both laugh and shake my head about all this talk about "roofing filters" (new name for an old thing) and how good they are. In reality manufacturers had a good thing going years ago with IF filters and then took the cheap route by expecting AF DSP to be the wonder circuit of the new radios. After the idea of AF DSP was found to be a very poor replacement to actual front end or IF filters they introduced these roofing filters that have been greatly accepted. Those of us that have been in radio for a while now are just glad to have an old friend back. You cannot beat a REAL RF/IF filter for keeping crap out of your passband and I am glad to see them coming back to double and triple (even quad) conversion radios. It looks like Elecraft has a good thing going with actual hardware filters as well as software filters. (y)

its always amazed me why good RF/IF filters are optional extras especially on high end transceivers,in my opinion they are essential.i've never been a fan of audio dsp,it gives a very unnatural robotic/metallic sounding audio,i much prefer a high quality RF/IF filter.

I must say Mole that is one very fine looking radio and is very well laid out in comparison to most of the big three's off the shelf transceivers.The k3 isn't a radio i'm very familiar with,does it do general coverage transmit?
Other Receive functions

The K3 has a very interesting Noise Blanker implementation that has proven to be very effective in the brief time that I have used the rig. Unlike other rigs that I've used that just have a variable noise blanker on a linear scale of aggressiveness, the K3 implements both IF noise blanking and DSP noise blanking. When you press and hold the NB button, the configuration screen comes up which looks like this:


The large text is the DSP NB adjustment, and the smaller text below is the IF adjustments. The first number next to the "t" on the DSP adjustment shows the relative pulse integration time and the second number shows the blanking level. On the IF adjustment, the NAR/MED/WID refers to narrow, medium, and wide blanking pulse widths and the number next to that refers to the blanking level. If you adjust the NB too aggressive on either setting, the audio will become choppy, which is typical. They may be out there, but I don't know of any other rig that lets you have complete control of the NB at the IF and DSP stages. An additional feature is that the NB setting is saved on a per-band basis, although you can override that behavior in the Config menu.

How well the Noise Blanker works is actually a testament to Elecraft's commitment to continually improving the K3 through firmware and hardware updates that they make readily available to their customers. I have been told that the original versions of the NB were very crude and didn't work well at all. That is quite a contrast with what I see now. This example demonstrates the main point that so many of the Elecraft "fan club" users make: when you buy Elecraft, you are purchasing a product that will be supported with updates and improvements over the long haul.

Noise Reduction

The K3 implementation of Noise Reduction is also a little different than most other rigs on the market. The first difference is that the NR adjustment level is saved in the rig's memory on a per-mode basis. Other rigs just have a NR level setting and it stays the same as you move between bands. In the real world, we use different antennas on different bands and have various devices around us (especially in the city) that cause various types of noise to interfere with our receiver that are worse on some bands than others.

Most rigs have a continuous, linear adjustment for Noise Reduction that is accessible by either a knob on the rig or a setting through a menu. The K3, however does not use a continuous, variable adjustment. It uses a series of step levels indicated by a label that looks like: F2-1. As I understand it, the first number following the F indicates how aggressive the NR is, while the second number indicates the level. Once you read a figure that reads: F5-1, an indicator with a small M appears indicating a different algorithm is in affect, mixing between DSP processed and unprocessed signals. The manual recommends using settings below F5, but I find in my location, the F5-1 setting works awesome.

Even though the NR adjustment is a little foreign compared with what I am used to, I find that it really works incredibly well. I attempted to capture a video with audio that demonstrates its usage, but I don't think it does the rig justice.

The k3 isn't a radio i'm very familiar with,does it do general coverage transmit?
Yes it does, with some exceptions. I'll cover the extended TX/RX capabilities in an upcoming installment.

Whoa, PSK31 text on the display?
It will also decode CW, AFSK A, FSK A, and RTTY.
a DB-9 (aka RS-232) connector :confused::confused::confused:

are any computers still made that use them:pop:
a DB-9 (aka RS-232) connector :confused::confused::confused:

are any computers still made that use them:pop:

The outdated DB9 Serial / RS-232 connection on the back was my first complaint when I was looking at the specs. Regardless of all the "reasons" posted by the Elecraft fanatics :rolleyes: on their email list, an RS-232 port is still a bad idea. The "reasons" typically given are that USB chipsets are difficult to maintain drivers for, a lot of hams still have PC's with serial ports (really??), etc.

Look, the RS-232 standard is from 1969. It is obsolete. My teenagers don't even know what a serial cable is. There is so much more that could be done with a USB bus connection, if they would only stop to think of the possibilities. Radio manufacturers need to stop taking the lazy, easy route with PC interfaces and use up to date standards.
The outdated DB9 Serial / RS-232 connection on the back was my first complaint...
The "reasons" typically given are that USB chipsets are difficult to maintain drivers for...

exactly! so INSTEAD we have to use DB9:USB emulators and we STILL have to maintain those drvers too.

someone at elecraft can't see the forrest for the trees.:oops: other than that, it IS a nice rig
8 Band Receive and Transmit Equalizer

Another really nice set of features that the rig comes with is a built-in 8 Band Receive Equalizer and 8 Band Transmit Equalizer. Along with stereo speaker/headphone outputs, the Receive Equalizer really lets you tailor the audio to suit your ears and speaker configuration. Of the competing rigs, the only one that I'm aware of that offers this same level of control is the Flex series of radios. Setting either the RX or TX EQ is done through the normal menu controls and is very easy to adjust. Here's a short video I did that demonstrates the RX equalizer usage. Unfortunately the station we're listening to is using a very narrow mic, so you don't get the full affect, but you'll get the idea. The 8 Band TX EQ is set using the same method, on a different but similar menu setting.

The 8 Band TX EQ works really well, making external EQ's unnecessary. There are still reasons why you might want an external audio stack however, and I'll cover those in an upcoming update.
On the K3, you can adjust or calibrate just about everything through either the standard menu, the "Config" menu, or the "Tech MD" menu because they are software defined. For example, after I added the 100 watt PA, I needed to calibrate the power output. To do that, you just set the mode to CW, tell the rig to put out 50 watts, hook up a good power meter (if you have one) into a dummy load, and adjust the appropriate settings until the actual power output matches what you told the rig to do. If you can think of any setting, it can probably be calibrated or adjusted through the menu.

Speaking of power output, I did some testing for the sake of comparison with my Icom 746 Pro and Yaesu FT-897D. I hooked up my Heil GM-5 mic to the W2IHY audio stack which includes the iPlus switch box to all three rigs and ran the output through a coax switch to a Bird 43P meter with a 100 watt element into a dummy load. I had already tested and calibrated the CW power output of the K3 to verify that it's actual output matched whatever I told the rig to do. Now I wanted to see how they compared on SSB under normal voice.

Each rig was using it's own power supply, set at 14.1v for the K3, 14.2v for the Icom 746Pro, and 13.8v for the Yaesu FT-897D. Close enough for a simple comparison. I set the audio output to each rig independently on the iPlus to make sure I'm driving each one the way it likes to achieve a reasonable modulation level. I actually even tried to max it out for the test, but that didn't really change the results much. Once it is set where it should be for modulation and healthy ALC levels, you leave the audio output from the iPlus and mic gain/compression on the rig alone.

The test results were interesting. At the 100 watt output setting, the K3 shows about 90 watts PEP using steady voice audio into the mic. When I push the setting to 110, I see around 95 watts PEP on the needle. When I switch to the average measurement on the meter, I see right at 40 watts on the Bird meter with voice input. On the 746Pro, I see 100+ watts PEP and 65 watts AVG with normal voice using the same mic. On the FT-897D, I see 98 watts PEP and right at 40 watts AVG. These tests were performed with a reasonable amount of compression from the EQPlus with compression settings turned off on the K3 and 746Pro. I had to turn the compressor on a a low level on the FT-897d to get any audio into the rig.

I like to look at the PEP to AVG power ratio because it helps give some definition and meaning to what people commonly call "talk power". Initially it looks to me like the K3 has about 1/3 less average output power on SSB than the 746Pro.

After doing a little research, I find that what the K3 calls "compression" on the rig is actually RF clipping. This is interesting because you wouldn't typically want to run compression both the audio stack and on the rig (pick one or the other), but if the rig actually does RF clipping, you can use them both effectively. So, I went back to the tests.

After messing around with the settings on the K3, I settled on a "compression" (rf clipping level) setting of 14 with the mic gain on the rig turned just high enough to get the necessary modulation. I settled on this figure because it pushed the PEP output to 100 watts and between 40-45 watts AVG on the meter without sounding distorted in the rig's monitor. So, by adding a little RF clipping, I got a bit more "talk power" out of the K3. After playing around with it a bit, it seems that the K3 likes to have at least some RF clipping applied to produce robust SSB modulation and power levels.

Incidentally, the K3 manual says that the SSB power measured will be slightly lower than the CW output. There is a config option called TXG VCE (voice transmit gain) that allowed you adjust the rig so SSB output measures pretty close to CW. The figures above reflect adjustments made to that setting.

Now, I realize full well that the few watts of difference that we're talking about is not going to make any difference on the air. But it is fun to compare rigs. :love:

For what it's worth, when I use the K3 MH2 mic directly into the rig, I see more like 50 watts AVG, but to make to do a fair comparison, I also see about 65 watts AVG with the stock 746 Pro mic.

EDIT: I did some more testing on the AVG power output capabilities which are posted later in the review here: http://www.worldwidedx.com/threads/elecraft-k3-review.73806/page-3#post-232679
I have a couple of extra thoughts on the SSB power output testing that I wrote about yesterday that come to mind as I read through it again. As I watch the meter on the K3, it is more typical to see around 30 watts average with normal voice, even after all the tweaking I did. It was really difficult to get it up to the higher average numbers. The 746 Pro just does a higher average output with much less effort and tweaking.

Like I said, it's not really anything to be concerned about, but it makes for interesting conversation.
Transmit Noise Gate

Another feature that comes standard with the K3 is a Noise Gate that can be activated and adjusted to your liking. For those that are unfamiliar, a Noise Gate gets rid of unwanted background noise picked up by your mic. For example, it can be used to help get rid of fan blower noise from a nearby linear amplifier, computer, or power supply. Here's a pic of the menu item that turns it on, off, and sets the aggressiveness (level) of the gate:


I'm told that the K3 Noise Gate also has some voice intelligibility logic to help eliminate background noise while talking. This is an important distinction because that behavior makes it a little different than most noise gates. The typical noise gate just opens and closes when you talk. While it is open though, it lets anything through the audio chain that is picked up by the mic. That means that a loud background noise can still be heard along with your voice. When you stop talking (or pause between words), the gate closes and you can't hear the background noise. If the K3 adds voice detection intelligibility, that means it is trying to detect the difference between voice and noise and filter out the noise.

Since I already have a noise gate that I use on the W2IHY 8 band EQ, I figured it would be a good comparison to switch back and forth between the K3 noise gate and W2IHY noise gate while monitoring through some headphones. The test I gave it was the "world's worst" scenario, which is my very LOUD Ameritron AL-800H amplifier blower that is only about 3 feet from the mic.

My initial reaction was that the K3 Noise gate didn't work very well as compared to the W2IHY 8 Band EQ. In fact, my first words were, "This noise gate sucks". However, after playing with a few different settings, I finally got it to work pretty good. The trick with the K3 Noise gate is to make sure that you are running very little mic gain on the rig (duh!). The way I had it set initially was with the mic gain set a little higher and the ouput from the audio chain set a little lower. While this provided a good combination for modulation, it didn't allow the Noise Gate to work well. By lowering the mic gain on the rig, it was able to do a reasonably good job of filtering out the huge amount of background blower noise in between words. It does indeed seem that it is doing some type of voice detection because I also hear less of the blower noise during words. It's possible that the noise gate also has some downward expansion built in which would facilitate this.

After I compared the Noise Gates, I compared the K3 noise gate to the EQPlus Downward Expander, which gets rid of background noise between words and while talking. I think that the EQPlus Downward Expander works better than the K3 Noise gate. I also think the W2IHY 8 band EQ's Noise gate works a little better than the K3 under severe conditions like my test. The W2IHY noise gate is much less sensitive to mic gain and will filter out the noise regardless. However, the K3 noise gate does work and it is probably all that most people need.

The included transmit and receive 8 band EQ and noise gate are a good example of the value proposition that you get with the K3. You basically get functionality that rivals external audio devices like the W2IHY 8 band EQ and Noise gate included,which would cost you at least $270 if purchased separately.

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