Friday, February 29, 2008

Elecraft K3 Hardware Changes: Ham Radio's Worst Kept "Secret"

The K3 kerfuffle du jour on the Elecraft reflector is the "scary" proposition that Elecraft is making "secret" hardware changes to correct problems with the original design, and that by not sharing this information with K3 owners and prospective buyers, Elecraft's honesty is in question. Oy vey...

The argument that Elecraft is "secretive" regarding their updates and changes is belied simply by the fact that we're discussing the updates and changes at all. If anything, Elecraft and their field testers talk too much about these things - otherwise, how would anyone know about such changes in the first place? So much for the "secrecy" theory.

Elecraft should be commended for the frankness, openness and accessibility to their customers; for quickly responding to customer requests; for their willingness to improve the K3 with new features (for example, CW-to-PSK, and improvements to the filtering and noise reduction programming) that go above and beyond the published specs of the radio); and for (up to now) offering these improvements to the end user free of charge. Yet some still complain and excoriate because they are being kept out of a loop that they are not, in fact, in. It is not my business (nor anyone else's) what goes on inside the design shop at Elecraft. The only reason we know as much as we do is that Wayne, Eric, Lyle, and others choose to share such things with us; they are not obligated to do so.

Most other manufacturers would say nothing at all and either make changes unannounced, or simply say, "Don't like the AGC [or QSK, or filtering, or third-order IMD, or whatever]? Deal with it - that's the way it is. Maybe we'll fix it in the next model." As for adding previously unadvertised features free of charge as Elecraft continues to do with the K3, consider this: when I purchased the original Icom IC-706, it had coverage from HF through 2m. When Icom added the 70cm band to the '706 my upgrade path was simple: Sell the '706 and buy a '706mkII. Was Icom being "dishonest"? Of course not - I got what I paid for when I bought the original '706. A free or inexpensive upgrade path would have been nice, but by no means was Icom required to offer one.

Now let's pause for another boring JRC allegory...

WWJD? (What Would JRC Do?)

When JRC first released the NRD-535D receiver, it had a Murata CLF-D8 filter in the WIDE position, the BWC (variable bandwidth control) only worked in SSB modes and only with the INTER filter (2.2 kHz), and the RS-232C command set was lacking several useful commands (though it performed exactly as advertised).

It soon became apparent that the CLF-D8 filter was a poor choice - it was as wide as a barn door and did little to reject adjacent interference on the SWBC bands for which it was primarily intended. After much consideration JRC decided to offer free filter replacements for early NRD-535 owners and a box of CLF-D6S filters (the same as used in the NRD-525) was promptly sent to me at JRC-NY. I did my best to spread the word through the dealers and hobby grapevine (as it existed back then before the internets) that people could either have a filter mailed to them for self-installation or they could send me their radio (or just their IF Filter circuit board) and I'd happily swap it for them free of charge. There were no accusations of "secrecy" because we didn't notify owners that the CLF-D8 sucked before we devised the solution to the problem or keep them informed with progress reports; nor was JRC's character questioned because we did not prostrate ourselves before the marketplace and beg forgiveness for making a poor filter choice. People were happy - their original filter performed as promised, but a better filter was offered free of charge. Who wouldn't be happy?

We also started to receive a lot of requests from software developers for additional commands to improve the way the '535 interfaced with computers for remote control. Almost every useful suggestion was implemented, resulting in a series of firmware upgrades which necessitated the replacement of two EEPROM ICs, one of which was buried deep inside the front panel assembly - not as easy an upgrade as hooking a K3 up to a computer and running a utility app! Once again, these upgrades were offered for free, even though the original firmware worked exactly as specified. Some people took advantage of the offer, many who did not use computer control (or used software that did not utilize the new commands) chose not to do the upgrade. In any case, people were happy - it was nice to see a manufacturer pay attention to the wants and needs of its end-users. (Does this remind you of any current American manufacturer? Perhaps one located in Aptos, CA? Think hard...)

Later on, we started receiving question about why the BWC was disabled in the AM mode and not used with the WIDE filter. I, too, thought this was a good idea. The factory was persuaded to modify the BWC design to make it work with the WIDE filter and in all modes; this was done through a hardware change (the crystal filter on the BWC circuit board was replaced) and modification to the radio's firmware. All future production runs would incorporate the new BWC features, and again an upgrade was offered to early NRD-535 D owners. However, this time there was a nominal charge for the upgrade kit ($129.95, as I recall) because it was not a bug fix, but rather an improvement to the original design. I don't recall too many complaints about how unfair it was to charge early owners for the same features that later purchasers enjoyed for free. The fact was, JRC (once again) listened to it's customer base and improved an already excellent product, and (once again), people were happy. But this was back in a time before no good deed went unpunished.

My point is, hardware and software changes are a normal part of production. No product is perfect, so it is a good thing to take customer feedback and fix things that need fixing, and if possible add things that can be added to an existing design. JRC understood this over 15 years ago just as Elecraft understands it now. Many other companies could care less, as long as the product is "good enough" to meet the published specs. The K3's transmit 3rd Order IMD of -27dB as measured in the QST test currently puts it in the same league as the Icom IC-746PRO and Kenwood TS-480; that is not "poor" as some have suggested but "average" performance and unless I'm very wrong falls completely within Elecraft's claimed specifications for the K3 as well as FCC spectral purity requirements. Elecraft could easily just leave it alone and be content to offer a rig with a superlative receiver but only an average transmitter, and they'd still be considered to be acting ethically and honestly; instead they've pledged to improve the TX side of things and offer a solution to early purchasers. I applaud them.

We now return to our regularly scheduled rant...

As an early adopter of the K3 I fully accept the fact that I am one of the test pilots of a complex piece of equipment, produced by a pioneering and evolving company in a way that is diametrically opposite the standard business model of the Big Three of JA-land. I considered this fact carefully when I sent in my deposit check to get one of the first production run. I could have waited for all the bugs to be shaken out of the K3, or I could have purchased a different radio with a more proven track record. In the end I chose to be part of the K3 bug-shaking process.

The moral of the story is, when you pre-order a version 1.0 product as complex and specialized as the K3, any expectation that it will work 100% as advertised right out of the starting gate is both unrealistic and unreasonable. On the other hand, it is perfectly reasonable to expect problems that pop up after the initial release of the K3 to be addressed in incremental updates (1.1, 1.2, 1.3, etc.); that seems to be the path Elecraft is on and nothing that they have done so far suggests otherwise.* Furthermore, if new features or functionality not originally specified or promised in the 1.0 version are added to later versions, Elecraft has every right to charge those who wish to implement those new features a reasonable fee, just as they have every right not to offer any such improvements at all. As someone else pointed out, how many Orion I's have a color LCD display?

* In fact, the official response from Elecraft to the specific question of transmitter spectral purity raised by the ARRL's lab test is pretty much what anyone familiar with Elecraft would expect: "We're looking into this already. Any improvement we make in firmware (or hardware, for that matter) will immediately be made available to all K3 owners." Who could ask for more? (Don't answer - we know who they are...)

Contrast Elecraft to the auto industry: I've received manufacturer recall notices for just about every car I've ever owned, each telling me that my car has a bug and I should bring it in to have it fixed. The manufacturers did not issue a series of prior reports informing me that they think there might be a bug, nor did they provide me with regular updates from their engineering departments letting me know what they were doing about it. A CEO of an automobile company is not going to be active in the owner's groups responding to individual questions and complaints. Instead, when a problem is confirmed and a solution is found, owners are notified and offered a remedy. If I buy a completely new model car when it is first introduced, I understand that I'll be much more likely to receive recall notices for it than if I wait a couple of model-years. This would be no different for any other type of hi-tech, non-disposable product; in recent years I've had to perform upgrades - both software and hardware - to fix bugs in countless computers and software applications, not to mention my iPod, my Celestron NexStar 8 GPS telescope, my Line 6 POD, many other amateur radio products, and God knows what else. This situation is by no means unique to the K3, and no other amateur radio product's upgrade path in my experience has been as smooth and painless as the K3's.

As Elecraft grows I fully expect them to learn from their K3 experiences and clam up a bit more about what is going on behind the magic curtain, as it will soon be impossible to respond to every gripe from every customer as they have so nobly done in the past. This will fundamentally change the character of the company, but it is an inevitable side effect of market growth. Like Apple, they will soon have to move out of the garage and start behaving like a "real" company - and I don't say "real" like it's a good thing; I like Elecraft just the way they are! Before the K3 there were a relatively small number of Elecraft users and the company enjoyed an almost exclusive, club-like following; now the K3 will likely push Elecraft to a new level in the industry and the "family" feel that Elecrafters now enjoy (and that I only recently became aware and part of) will by necessity have to give way to more mainstream business practices - including real secrecy, not the kind they are imagined by some to have now. My advice to the bitchers and moaners is: Enjoy it while it lasts.

Thursday, February 21, 2008

Shortwave Listening With The K3

I would love to see the K3 receive the attention it deserves from the too-often ignored hardcore shortwave and mediumwave DXers and believe that with a few minor software tweaks the K3 could fill a huge void in the high-performance communications receiver market since it has been all but abandoned by major manufacturers.

Twenty years ago when I first started out in the radio business there were a good number of new desktop shortwave receivers to choose from including the Yaesu FRG-8800 ($639.95), Icom IC-R71A ($799,95), Kenwood R-5000 ($859.95), JRC NRD-525 ($1189.95), not to mention many used late-model receivers such as the JRC NRD-515, Drake R7, Yaesu FRG-7700 and Icom IC-R70. With sadness I've watched as radios like these have been slowly disappearing from the market, replaced by small portable radios aimed at the broader consumer market while serious hobbyists have fewer and fewer choices other than
prohibitively expensive mil-com HF receivers, or amateur radio transceivers which more often than not perform awfully in the AM mode.

With the K3, I see hope;
a basic 10W K3 costs only $1600 (or $1400 if self-assembled), less than the soon-to-be discontinued NRD-545 is currently selling for, and even with only the stock 2.7 kHz roofing filter the K3 would likely run circles around the '545 not to mention most of the classic receivers mentioned above. However, it will take a little fine-tuning by Elecraft for it to realize its potential as a top-notch SWL receiver.

AM Mode Filtering:
There was talk on the Elecraft reflector a while back about the way the filtering works in the AM mode, specifically the 3 kHz maximum "audio" bandwidth. From an SWL's perspective, this makes no sense; it is counter-intuitive and non-standard compared to all other high-end communications receivers (I'll use the NRD-535D as a reference, since I'm most familiar with JRC equipment). With the '535, the filtering in AM mode works like one would expect; no matter which filter is selected, when the passband shift (PBS) control is centered the filter passband is centered on the carrier frequency and shifting the passband shifts tha actual i.f. passband, not the audio passband. So if a 2.4 kHz filter is used, it will pass 1.2 kHz of each sideband when PBS is centered. Offsetting the PBS 1.5 kHz to the right, for example, will move the entire filter passband to pass only the upper sideband while rejecting the lower sideband. This is useful to the SWBC DXer in cases where there is a strong signal 5 kHz below a weaker station that I'm trying to receive and the lower sideband suffers from adjacent channel QRM but the upper sideband is clear. And vice versa, if the interfering signal is 5 kHz above, tweaking the PBS to the left passes the lower sideband while rejecting the upper sideband and the QRM.

I'm not sure what actually happens in the same scenario when using the K3. If I set the filter width to 2.4 kHz and shift the passband to the right, it seems to work as expected - audio frequency response gets higher; but when the passband is shifted to the left, frequency response gets lower, which indicates that the filter passband is either not centered on the carrier, or it is split similar to the way it works in RTTY mode, and passes equal slices of both passbands. Whatever the case, the way it currently works is at odds with what is expected by a true SW or MW broadcast DXer.

Synchronous Detection:
There is also the unanswered question as to whether the K3's forthcoming AM Synch mode will allow independent sideband selection. With synchronous AM detection, the ability to select sidebands independently is pretty much mandatory, otherwise the synchronous mode is useless on all but the strong, clear signals which frankly sound just fine without synchronous detection. The NRD-535 selects AM-USB and AM-LSB with the ECSS (exalted carrier selectable sideband) button. Most other receivers that have this feature work similarly. The Sony ICF-2010 does it a little differently - it lets you select sideband by adjusting the main tuning dial up or down slightly, and a little LED indicates which sideband is selected. The Drake R8, by comparison, does not directly allow selectable sideband; its synch mode was DSB, and although you could move the passband shift it isn't as effective as the JRC and Sony systems which totally reject the unwanted sideband.

Joe, W4TV, gets it; in one of his reflector postings on AM filtering he pretty much describes how the JRC ECSS system works in principle (the exception being that JRC doesn't do it with DSP):
Given the DSP demodulation in the K3, it's a shame that there isn't an "offset" option to do "vestigial sideband" demodulation (offset the AM filter to the upper sideband or lower sideband) and demodulate carrier and one sideband for better fidelity.
I'm not sure if Joe is talking about syncing the carrier and replacing it with an internally generated one, but that is what a good synchronous ECSS system does
in a nutshell. Without selectable sideband capability, synchronous AM detection is like tits on a bull.

SWL Mode: Another easy software mod that would be welcome for people who wish to use the K3 solely for SWL purposes would be to include a setting to disable the transmitter, similar to the TX TEST mode but without requiring it to be set each time the radio is turned on. This can be done by at least making the TX TEST mode persistent so that the K3 would remember it was in test mode when it was last powered up. Preferably there would be an additional CONFIG menu parameter that would put the radio into SWL mode in which the TX indicator will be turned off (not flashing like in Test mode); if the PTT line is keyed while in SWL mode the K3 would display a message like "SWL MD" and there will be no RF output - basically extending the out-of-band transmitter disability to K3's the entire frequency coverage while in SWL mode.

And that's it - just modify the firmware code and send a K3 off to Larry Magne for testing! The rest will be history.

Monday, February 18, 2008

Specs, Lab Tests, and Other Myths

Rob Sherwood's K3 test results have been published. Key strong-signal performance specs include:
  • 100 kHz Blocking: 140 dB
  • Ultimate Rejection: 105 dB
  • Wide-Spaced (20 kHz) Dynamic Range: 104 dB
  • Narrow-Spaced (2 kHz) Dynamic Range: 101 dB
All is well in Elecraft-land as the K3 takes the prize over the Flex 5000, IC-7800, Orion II and, well, everything else Sherwood has tested, at least in the Narrow DR category. Predictably many early K3 owners are pumping fists and doing the Happy Dance, and I'm sure there are going to be IC-7800s and Orions on eBay in the coming weeks.

But what does it all really mean? I don't have any overwhelming sense of validation for choosing wisely, nor do I intend to take Rob's receiver tests as liberty to taunt the unfortunate fools who bought the FT-2000 about how much better my K3 is, because frankly they're not unfortunate fools and I'd love to have an FT-2000. Performance is certainly important - no one wants a complete dog - but my ears can't tell the difference between 105 dB dynamic range and 95 dB. If you think you can, then you probably can hear the difference between Monster Cable and Radio Shack speaker wire, too. Bless your heart.

Myriad reasons I picked the K3 without hesitation have already been mentioned in my previous posts. Sure, the claimed (but at that time, unconfirmed) performance was a factor, but equally important were Elecraft's reputation, the K3's feature set, its elegant design, portability, price, the ability to configure it to my needs with just the options I require - all these things are much more subjective than the K3's now-documented performance advantage over all the megabuck rigs. I spent years toying with the idea of a new HF rig (MK V, Pro2, Pro3, FT2K, Omni VII, K2) but never pulled the trigger; when the K3 was announced and I sent in a deposit check within a week. It was preference, not performance, that sold me - the K3 simply has everything I want in a radio at this time.

Having a large radio with a beautiful display might be an important enough preference for some people that they would gladly sacrifice the 21 dB dynamic range advantage (and $6,000+ price difference) of the K3 for the IC-7800. Honestly, if I could afford the '7800, I'm pretty sure there would be one on my desk right now. Maybe an FTDX-9000MP, too. But they would certainly be in addition to - not instead of - the K3.

I'm of the opinion that test specs are useful for marketing purposes, splitting hairs, winning bets, and endowing nitwits with bragging rights, but in most cases specs tell only half (or less) of the story. I'd rather have a radio that has an 85dB dynamic range but is a joy to use, for example, than one with 105 dB DR but also crappy audio quality, drill-down menus for important settings, and a loud fan. A radio is much, much more than the sum of its specs. What makes the Elecraft K3 special is that it delivers on both fronts: performance and usability. Or, as they say on the Elecraft reflector, it's got mojo.

Friday, February 8, 2008

K3 vs. JST-245: The Road To Victory

With the addition of a stereo line splitter to feed K3 audio into two separate channels on the Multi-RX, it is now far easier to compare the two rigs. The following observations refer to SSB mode only; testing in CW and data modes to come as time allows.

Audio Quality: The most obvious thing is, the K3's audio is much more crisp than that of the JST-245. By "crisp" I mean it has a bit more high frequency response, while the '245 has more punch at the low frequency end. Which is better is more a matter of preference than science. My ears generally find the weakest signals more easily readable with the K3, while signals S9 or better tend to have a more natural tone with the '245. But the differences are subtle, neither radio sounds dramatically better than the other when using a common audio system (in this case, the Multi-RX feeding a pair of small Sony speakers left over from my home theater surround sound installation, as well as a pair of JRC ST-3 communications headphones). The K3's stereo audio effects (AFX) settings can tremendously improve the quality of reception and reduce listening fatigue, and works equally well with speakers and headphones; the AFX feature gives the K3 a slight edge.

Noise Reduction: Most notable is the DSP Noise Reduction (NR). Even at it's lowest setting, the NR removes so much background hash with the push of a single magic button that I find myself turning it on and off just to come to grips with the fact that it actually works. There are several NR settings selectable by holding the NR button and dialing in the level. Lyle Johnson KK7P, Elecraft's DSP genius, says:
NR is more properly Signal Enhancement rather than Noise Reduction. The distinction is subtle but important if you wish to understand how it works and how to best apply it. If ti were noise reduction, the implication is that it passes everything until it figures out what is more likely to be noise, which it then attempts to suppress. Since it is signal enhancement, it tends to pass nothing until it figures out that which is more likely signal, which it then attempts to pass.

With this understanding there is one more concept I must explain: correlation. This is the degree to which a signal is similar to itself; conversely, it can be used to figure out how noise is dis-similar to itself (more random). This is the basis on which NR works.

In the current implementation of the K3, we have four (4) basic NR filters. These are displayed as F1..F4. F1 is the gentlest, F4 the most aggressive. Recalling that the filters tend to suppress everything until they can sort out what is probably a signal, there is some time delay involved in their application. Further, especially with voice signals, some components of the signal may not be recognized as well as others. THis gives rise to distortion.

So, we added a second field to the NR. This is the -1..-4 which specifies a certain amount of "bleed through" of the original signal. This reduces the apparent distortion and delay, but limits the ultimate S/N improvement. -1 provides the least distortion but limits the S/N improvement on weak to moderate signals to about 6 dB. -4 provides no "mixing" whatsoever and can result in dramatic S/N improvements, but at a cost of slight time delays and increased distortion.

NR is not appropriate for very weak signals, so a -1 or -2 is best if you wish to hear them.

Having said all this, the correct way to use the NR is to listen and adjust it for the best compromise between noise reduction and distortion. Everyone is different in this regard. Some tolerate noise better than others, while some don't tolerate distortion very well at all.

I live in a quiet location, and use NR1-2 as my most common setting. This is low in distortion, allows me to hear weak signals, and shows no apparent delay as I tune through the bands. On the rare occasions when things get noisy here, I crank it to higher values.
Noise Blanker: The K3 Noise Blanker (NB) is also a masterpiece - between the separate IF and DSP blanker settings I've been able to remove all sorts of crap that would otherwise make it impossible to hear any but the big gun signals. It's as simple as this: When I hear any sort of electrical noise, I first crank the DSP NB up to see if it has any effect. If not, I try the IF DSP. Usually one or the other does the trick, I haven't found any noise that requires both at the same time. The '245 NB is useless by comparison; if it works at all it must be against a very specific type of impulse noise that I've never encountered, because I've never found it to be of any use at all (unless distorting a desired signal is of use to anyone).

Notch Filter: With the '245 I almost always use the manual notch filter as a mid-cut to tailor the receive audio to my liking. I find this technique to be a bit more effective with the '245 than the K3 as the latter takes an awful lot of dial turning to adjust the notch range from 200 Hz to 3.92kHz in 20 Hz steps. Also, the K3 notch width is much sharper than the '245 so the effect is more subtle. Of course the K3 has built-in graphic equalization for the purpose of shaping the audio response, so this issue is pretty much moot and leaves the notch filter to be used for its intended purpose - to remove heterodyne interference. To this end, the K3's Auto Notch is superb. The manual says it will, in some cases, remove multiple carriers although I've yet to find a situation that will confirm this. The '245 does not have an auto notch function, but it has Notch Tracking which will offset the manually adjusted notch filter when the VFO is tuned slightly; this is useful but not nearly as effective as a fully automatic system. Notch depth is adequate on both rigs.

Ergonomics: Both of these radios are a joy to use. The '245 has a solid feel and a heavy, balanced main VFO knob that spins like a top. All of it's buttons have a nice positive 'click' when pushed, and the smaller knobs and controls feel good and not overly 'plastic'. And the color LCD! - it's about the finest looking display of it's generation and, in my opinion, better than anything even today short of the newer Icom color TFT displays of the IC-7800, IC-7700, etc. Because JRC took the time and effort to find out what amateur radio operators really wanted and where things were supposed to go on the front panel, all of the most commonly used controls are assigned to individual buttons or knobs with very few alternate functions or hidden menus to toggle through; outstanding ergonomics was a chief goal during the JST-245 design review, especially after the JST-135 got raked over the coals by Dave Newkirk in his QST review (and deservedly so). So although I may be biased as a member of aforementioned JST-245 design review team, I find the JST-245 to be a more enjoyable radio to sit in front of and operate.

The K3, however, is no slouch. Elecraft had different design criteria, one of which was to make the K3 compact and easily transportable. Neither of these adjectives can be applied to the '245, therefore JRC had a whole lot more front panel real estate to work with than did Elecraft. Consequently many of the K3's controls are doubled up, several often-accessed settings are menu-driven, and some things which take a single button push with the '245 take two or more with the K3. But by and large I think Elecraft got it right, the K3 has just the right amount of compromise between keeping the size of the radio down, making it attractive to the field user and people with limited space, and including all the high-performance features demanded by discriminating users such as contesters and DXers. So while I may have to toggle through different modes to set the K3 instead of pressing a single button, it's not a big deal to me. The K3's buttons have a soft feel to them which reminds me of the Drake R8 receiver's front panel buttons. While the main tuning dial does not have the same flywheel feel of the JRC it still spins nicely. The main liquid crystal display is very sharp and has a wide range of backlighting levels (including OFF), though it must be viewed at a fairly straight-ahead angle. All in all, from a usability perspective, the K3 is a nicely designed little rig.

The one area in which I find the K3 to be deficient is in its selection of memory channels - unlike the '245 which has a dedicated Memory Channel knob that lets the user dial through channels one by one, the K3 has a more convoluted process of pressing the M>V button, dialing up the memory channel with the VFO knob - without being able to hear what's going on at that channel's particular frequency! - then pressing M>V again to set the rig to the stored frequency, mode and other parameters. If I could change one thing with the K3 it would be to let me hear what's on each channel as I dial through the memories, before I hit the M>VFO button. This should be an easy firmware fix.

And the winner is...: In the tweakability department the K3 has a few bells and whistles that are missing (or ineffective) in the '245. In practice I find that I am able to get similar reception with both rigs by using each radio's tools to maximize the desired signal and minimize the junk. I am still amazed at how well the JST-245 holds up to the latest and greatest in DSP technology, and it is such a pleasure to use. Therefore I've abandoned any thoughts of selling the '245 to finance the acquisition of a second K3; it is simply too good a rig to let go of.

That said, the K3 is clearly the future of HF transceivers, and it looks to be a pretty bright future at that. While the above observations are subjective and based narrowly on SSB reception under less than perfect antenna and propagation conditions I think it's pretty clear that the K3 is a gem of a rig. Of course many of the design elements that on paper put the K3 in the league of the mega-buck rigs from JA-land do not come into play with my limited antenna system - for example, I rarely see a signal stronger than S9+10dB, and have yet to find two such signals close together as in a contest situation, therefore the benefit of the narrow roofing filters and strong front-end performance remain untested by me in any real way. In any case, others (ARRL, Sherwood*, etc.) will confirm or deny Elecraft's published dynamic range and IP3 specs soon enough, so I'll leave it to the pros to do the scientific evaluations.

If held at gunpoint and told to choose one of these two radios, subjectively, emotionally, and based solely upon my ears, fingers and eyes... it would have to be the K3. But barely.

* Update 09-Feb-08: Serendipitously, Rob Sherwood has released some of his K3 test results which were promptly passed on to the Elecraft reflector by Wayne Burdick:

Rob Sherwood, NC0B, an independent and well-known receiver performance specialist, has completed his K3 receiver tests. We're pleased with the results, which will place the K3 at the top of his comparison chart.

Rob will be updating his web site in a few days. For now, I'll just mention a couple of his numbers (with his permission).

Elecraft K3, S/N 00149, 20 meters, preamp off:

Dynamic Range 20 kHz 104 dB
Dynamic Range 5 kHz 102
Dynamic Range 2 kHz 101*

* with 200 Hz 5-pole filter

Blocking above noise floor at 100 kHz spacing, AGC On: 140 dB
Phase noise (normalized) at 10 kHz spacing: 138 dBc/Hz

Rob performs some tests differently that we (and the ARRL) do, but in general we're all in close agreement. Note that the unit under test had only Elecraft 5-pole filters. Our tests show the 8-pole filters to be as good or better, and we sent some of them to Rob to test when he gets a chance.


Tuesday, February 5, 2008

Back in business...

The K3 is in place, the Multi-RX is back in action, the MFJ-267 watt meter/dummy load finally arrived, the antennas still suck...

With the playing field level - both rigs hooked up to the same antenna and speakers - I can do some fair and honest comparisons between the K3 and the JST-245. I must still fine-tune the system a bit - an adapter to split left and right channel audio from the K3 speaker output is first on the list, and I think I can do something with an antenna that is somewhat temporary yet still effective (and quiet) and will tide me over until I get to the new QTH later this spring.

Monday, February 4, 2008

K3 Testing Pt. III

A week on, and the K3 continues to impress.

RS232 Interface: Got the computer interface working, using a Keyspan USB Serial adapter. MacLogger DX has actual K3 support. Running Windows 2000 via Paralells on the MacBook Pro, allows me to finally try HamRadioDeluxe by HB9DRV - a very cool program which will take a bit of poking around on my part before coming to grips with all the features. HRD, however, does not support the full K3 command set, instead uses the K2 subset which is backwards compatible with the K3.

Firmware Updates: With the serial port tested and working I downloaded the Mac OS X version of the K3 Utility software. A couple of clicks later, my K3 has the latest firmware revisions installed (MCU: 1.66, DSP: 1.52). Kudos to the design team for such a smooth and elegant update process. Oh, the thought of all those times I had to disassemble the NRD-535's front panel to change EEPROMs... [shudder].

Headphones: I am not 100% satisfied with the audio quality of the Heil Proset headphones, and the frequency response of the Audio-Technica ATH-M3X stereo phones that I sometimes use is a little too broad for radio communications. Then I remembered that I got a pair of JRC ST-3 phones with my recent NRD-515 acquisition so gave them a try. Awesome... except that they are monophonic and will not work with the stereo AFX settings. But the gears are turning - can I rewire the ST-3 for stereo? Can I add a boom mic? Hmm...

RX Antenna: The Outbacker antenna is awful. Maybe that's because it's old and decrepit, maybe it's the installation, maybe it just never worked as well as I thought it did. In any case, it really sucks, no signals appear to be more than S5-S7 on the 40m band and even worse when tuning 80m, so I ran that Bell Imel eBay special to the RX Ant In and now see strong signals in excess of S9+10dB on all of the low bands which gives me a better idea of how the K3 will work when I finally get it hooked into a real antenna. Of course the noise level is also increased to S9 or so. This gives the NR and NB a good workout, and I'm pleased with the amount of noise reduction I'm able to dial in - not always enough to completely eliminate the noise but almost always sufficient to make a thoroughly unintelligible signal copyable. I also discovered that with antenna connected to RX ANT IN and second radio connected to RX ANT OUT, simultaneous reception on both radios is possible* making receiver comparisons easy.

Birdies: There are some nasty birdies on 80m band, especially down in the CW portion. They are heard with no antenna connected and vary in pitch when I adjust the filter controls, so I suspect they are being generated by either the DSP board or the MCU. I will go back into the rig and check that all screws are tight when I install the 100W PA.** Haven't noticed any loud birdies on other bands.

Miscellany: Decoded my first PSK31 signal. Figured out how to set and recall memory channels. Ditto CW messages. No further sign of PL1 ERR.

* Update 08-Feb-08: I've discovered that while reception on both radios is indeed simultaneous, when the RX ANT is selected the K3 will receive from the antenna connected to the RX ANT IN jack, but the second rig connected to RX ANT OUT will receive from the K3's main antenna (ANT 1 or ANT 2).

** Update 10-Feb-08: KPA3 is now installed, and although I didn't find anything loose that may have caused the birdies, after the PA was bolted in and the rig reassembled the birdies on 80m seem to have disappeared!