In the time since I published the post on the WBR, it has been far and away the most popular post in this blog. Every now and again, my build of this receiver is featured on another blog or in a forum, and the page views peak for a few days. Currently the Yahoo QRP-tech group are looking for a regen receiver for one of their group builds, and the WBR is one of the designs under consideration.  I hope that at least some of the members choose to build it. Not all regen designs are created equal; I’ve read of some builders having problems with hard-to-control regeneration, or hum issues caused by the local oscillator signal being radiated by the antenna. The WBR doesn’t suffer from these issues.

As if all this attention online isn’t enough, my build of the WBR (Wheatstone Bridge Regenerative) Receiver is about to be featured, along with photographs, in a new edition of an ARRL book to be released soon.  As I mentioned in an earlier post, Daniel N1BYT is either very gratified, or thoroughly fed-up, with all the attention his design is still receiving over 10 years after the date of it’s first publication!

After building it, I spent a month or two happily listening to, and fiddling around with it, then got caught up with building a beta version of NT7S’ CC-series QRP transceivers, and then building a K2.  Since finishing it, most of my other projects, including the WBR, have been boxed away, leaving pride of place at the operating position to the K2.

Then a couple of days ago, I pulled the WBR out of storage and hooked it up. I connected it to a 2 transistor TX powered by a 9V battery that I built based on W1FB’s implementation of the Pixie 2, and this evening called CQ with a whopping 200mW coming from the plastic 2N2222A in the final.  The Reverse Beacon Network showed a 20dB spot from N7TR 180 miles away in Reno and I figured it was worth continuing to call.

Eventually, NY6G in Tracy, CA gave me a 429 and we chatted for about half an hour. Stan lives only 46 miles away from my QTH in Oakland so although it was quite gratifying to know that he was hearing the flea power signal from my little 2 transistor transmitter, the thing that was really satisfying about the QSO was more to do with the fact that it connected me to the world of amateur radio that I remembered from my boyhood in the 1970′s; a world where there seemed to be more camaraderie and gentlemanly behavior.  Stan told me that he was born and grew up in Oakland, where I currently live.  He then moved to Alameda, served in the Air Force and left the immediate area after WW2, but remembers his Mum taking him to Lake Merritt to watch the boats. (I was watching the boats on Lake Merritt just 2 days ago.)  He also remembers when the streets were lit by gas lamps, a job which was performed by a man carrying a long pole.

Sitting at my desk with a separate transmitter and receiver that I had built from schematics Manhattan-style and using them to hear about what the city I live in was like in the 1930′s from a former resident was pure magic.  Stan was getting a kick out of my home-brew separates too. I wasn’t able to adjust the color balance of this picture to look right due, I think, to the spectrum from the CFL bulbs that were used to light the shot.  I normally take pictures of my gear outside in indirect natural light, which always looks terrific.  Luckily, it looks pretty good in black and white:

The Altoids tin on top of the receiver is the N0XAS PicoKeyer.

This is a fun little set-up. The next day, I powered the Pixie 2 TX from 12.8V which allowed it to go QRO and output 500mW. Over the next couple of evenings I worked KI6ON Joe in Santa Clara CA, KE7GKM Bob in Boise ID, W6VJJ Rex in Half Moon Bay CA, N0EK Ed in Bergen ND, KF6RMK Bill in San Rafael CA and Jerome VA7VV in Vancouver, BC

Jerome had a couple of traditional receivers in the shack on which he was having trouble copying my flea-power signal – an FT-950 and a ProIII. However, on his SDR-IQ (a state of the art SDR receiver) with the bandwidth dialed down to 75Hz, he was copying with no problem.  He said it was the first time that he had experienced such a substantial difference between copyability between conventional receivers and SDR receivers. The thought of the signals from that little 2 transistor TX being heard in Vancouver almost 800 miles away was pretty neat.

It was great to QSO with KF6RMK too. Bill lives locally and we run into each other on the air from time to time.  We exchanged e-mails after our QSO and Bill sent me a picture of an old regen that he bought as a kit from Radio Shack many moons ago. He put it into his own case and wound some coils for it to turn it into an all-bander. Neat looking regen Bill! He said that our QSO has inspired him to drag it out and see if he can get it going on 40M  (photo credit Bill KF6RMK):

It’s been fun putting the WBR and Pixie 2 TX back into service for a while.

Now what can I build next……?

Designed by David Cripe NM0S, the Hi-Per-Mite provides a -3dB bandwidth of 200Hz with no ringing. The center frequency as supplied is 700Hz, but this is user selectable at time of building. The filter response is bandpass as opposed to lowpass, meaning that it will help to filter out any remaining traces of 50Hz hum you may have in that homebrew direct conversion receiver of yours (or an older vacuum tube receiver perhaps?)  After the filter is an LM386 audio amplifier with a gain that, once again, can be set by the builder. If you set it to the maximum of 50dB, you have a combination bandpass filter and audio amp that can provide the complete audio chain for a regenerative or direct conversion receiver. If you already have the receiver, you can set the gain to a lower figure and you still have a really useful CW filter.

I’m thinking that for those who like to build simple receivers, this could be a very handy kit to have around.

All this for US$19 including shipping within the US (more for overseas).

You can find the 4SQRP Hi-Per-Mite here (opens in a new browser window).

A few days later, it arrived in a medium flat-rate Priority Mail box, and what a beaut. Terry very thoughtfully gave the battery a full charge and then internally disconnected it before shipping, for the sake of safety.  The unit does beep in operation if the mute switch is not engaged and as Terry pointed out, a beeping package may never make it to my house! Terry included a sheet of instructions detailing how to reconnect the battery:

Another view, showing a little of the internals:

The 12V DC power cable is fitted with a popular size of coaxial power plug.  It plugs into my K2 and other QRP rigs too. Not much else to say really.  I plugged it into the AC, the other end into the K2, and it has been happily powering it all weekend. If AC power goes out, my K2 will keep happily chugging along for many hours with no interruption in service. Fitted with a handle, or placed in a carry pouch, this would be a great grab and go unit for emergency ops or QRP outings.  My friend Antoinette lives a mile away, and we use MURS HT’s between our homes to keep in touch.  This will make the perfect uninterruptible power supply for her radio.

Terry hopes to have more of these units available, but he doesn’t know how many, if, and when. Keep an eye on the QRP-L mailing list if this looks interesting to you. The main purpose of this blog was to give you a heads-up as to what to expect if you do order one of these.  They are well worth the money. Thank you Terry!

I know that 16 QSO’s and 744 points doesn’t sound like a whole lot, but for a 2 hour QRP sprint with me at the key,  it’s quite a bit. It was so great to hear a lot of stations on – and especially exciting to have XE2IF as my very last QSO of the contest.

Another thing that makes these Sprints gratifying is the way that the results go up on the NAQCC site very quickly. Just a little over 2 hours after it had ended, I saw the first of the results posted.  The logs haven’t yet been cross-checked, so the first postings include claimed scores only – these will be amended if necessary as the cross-checking proceeds, and final results posted after the log submission deadline of this Sunday at 2400z.  I like how things move swiftly along.  Currently I am the leading CA station, but there are still a few days to go. This immediacy of posting the results makes it fun to follow along.

I have taken part in a few NAQCC Sprints where conditions weren’t so great and QSO’s – especially for a west-coaster like me – were thin on the ground, so the combination of good conditions and the ever-increasing popularity of this monthly event leading to greater and greater participation, made this a good ‘un.   You don’t have to use a straight key, but the use of one will allow you to double your points, and seeing as the majority of stations are sending at around 14 – 18wpm, there’s no advantage to using a paddle or bug.

Nearly all the stations in this contest use simple wire antennas. When band noise is low and propagation good, there is something magical about sharing a few KHz of spectrum with a whole bunch of other stations all using similar power and antenna set-ups.  It is eye-opening to hear a bunch of moderate-strength and weak signals that are all easily copyable and readily workable.  QRP paradise – and the K2 with it’s excellent filtering just shone.

Thanks to all at NAQCC who voluntarily put the work in to make the Sprints so enjoyable.

The page with the download link is here. If you’re interested, download it now, as it may not be up after Feb 13th.

Thank-you to The SWLing Post for the tip-off!

EDIT:  The link has already been de-activated. It was a very short window of opportunity.

After completing the Norcal 2N2/40, I got to thinking that it would be really neat to achieve WAS with it – that would be QRP CW WAS on just the one band – 40M. I didn’t get close unfortunately, though I didn’t make a concerted effort either.  On completing the K2, all the other QRP rigs with the exception of the CC-20 were packed up and put into a box; I wanted the operating desk cleared and simplified so I could spend time with my precious new fixation – the K2. With that, the prospects of QRP CW WAS with the Norcal 2N2/40 faded somewhat, but I realized that with the multiband capability of the K2, achieving QRP CW WAS should be pretty straightforward – and it was.

In my entire amateur radio career, I have never won any kind of award – and I’ve been licensed since 1978.  This has been due mainly to very occasional periods of activity interspersed with longer periods of inactivity; a pattern of operating that I know I share with quite a few other amateurs. I’m also not a very competitive person, but it seemed that it was about time I qualified for something, and QRP CW WAS seemed like the obvious first choice.

Not much to say really.  I operate almost daily, and many of those QSO’s from normal operating provided QSO’s for WAS. Add in the odd contest here and there (the ARRL 10M Contest was very helpful, as was NAQP).  Predictably, as my list of states still needed got down to a mere half-dozen, Delaware and Rhode Island were in that list. Luckily, NAQP allowed me to nail both those states through QSO’s with WW3DE and W1WBB.  At the end of my last blog-post, I asked if anyone could give me a QSO with WV, as that was the last state I needed. Frank KA8SYV very graciously responded and did indeed give me a QSO with West Virginia.  It was quite fitting that the QSO with Frank was the one to complete my WAS, as it was he who bought my FT-817 back in June of last year.  We did try to make the QSO with his FT-817, but I couldn’t quite copy his sigs, so he went up to 100W, and the difference was like night and day. Luckily he copied the 5W sigs from my K2. Thanks Frank – your 40M loop was doing a fine job.  Not only was the personal connection with Frank a good reason for him being the final QSO of my WAS attempt, he has an excellent QSL card too, which gave me another reason to want a QSL from him. Here it is:

Frank said that so many people commented positively on that image that he had it made into a QSL. I love it! A few days after receiving it, a card arrived in the mail from John N8ZYA, for a QSO we’d had a few months earlier.  John noticed from my blog that I needed a confirmation from WV and sent me his card.  How did I miss that WV QSO when looking back through my log? Even more perplexing is that John and I have exchanged e-mails and blog comments before, so are well familiar with each other.  Aah well – better to have too many confirmations than too few. Thank you John.  For dog lovers, my Alabama QSO provided me with this QSL:

I now have all the contacts I need. I am waiting for one confirmation from W1SJ in Vermont, but his QRZ page states that QSL’s are generally answered 6 weeks after a contest, so I have every reason to believe that a confirmation from him is forthcoming. When it arrives, I’ll be able to apply for a WAS certificate from ARRL, or if I want to stick to my original goal of having a paper QSL from each state (and not just a combination of paper and LoTW) then I think there are one or 2 more states I need paper QSL’s from. However, they are all states with which I have enough insurance QSO’s so it’s not a problem.  I’m not sure if I will even apply for the certificate. I’ve already achieved WAS. Once the confirmation arrives from W1SJ, I’ll have confirmation that I’m in the log in 50 states for QRP CW contacts and that’s enough for me. Mission accomplished!

Yesterday morning, a QSL I’ve been hoping would materialize actually did. It was for a contact I made with special event station W0O in Frankenstein, MO on Oct 31st. What a fine card. I can’t think of a more fitting QSO on Halloween than with a station in Frankenstein. Thank you very much to the Mid-MO Amateur Radio Club:

The postmark on the envelope was equally impressive. Can you see the word “Frankenstein” spelled out in the tree branches?

Another QSL to arrive yesterday was this one from the fictional TV character Mike Baxter KA0XTT, played by Tim Allen in the series Last Man Standing.  In return for my QSL, the production team sent Mike’s QSL, autographed by Tim:

A group of hams on Twitter decided to send our cards in as a bundle together in the hope that our cards will all be displayed on the wall at Tim’s operating position in a future episode.  I suggested that they send their cards to me so that I could send them on their way, my reasoning being that as I’m in California, the last leg of the trip will be a day or two quicker. Here are the cards from our Twitter group before being bundled up and sent to Studio City:

N9VN and KE7JTU’s cards didn’t arrive for some reason. Perhaps they will be the subject of a QST article in a few decades along the lines of “QSL cards long considered lost finally arrive 30 years later”!

In other news, I was excited to be able to contribute some text and photos to the next edition of the ARRL book “Low Power Communication” written by Rich Arland K7SZ. The subject will be my build of the WBR Receiver, which has generated quite a lot of interest. Poor Daniel N1BYT must be getting a bit fed-up with the renewed interest in his excellent regen receiver design, 10 years after it was initially published in QST.  I noticed that his e-mail address has disappeared from his QRZ page and did wonder if he did it so that we’ll all stop bothering him with questions about the WBR! It will be the project for the group build at this year’s OzarkCon, a number of people have commented to me that they have also built, or are building, their own copies of the WBR, and at least 2 individuals/groups have expressed interest in making a kit of parts available, though I don’t know whether a kit will materialize. To this day, the post on this blog about the WBR is by far the most popular, consistently receiving more views than any other post. Thanks Rich – I have never had anything I’ve written or taken pictures of published in a book before, so this will be thrilling!

Last but very definitely not least, the news has just come out that Jason NT7S will be heading up a seminar at FDIM this year. While I know that he would be well-equipped to talk about the logistics of providing day-care for a toddler and a boisterous (yet affectionate) golden lab, while still managing to find time to design circuits and occasionally even operate on the air, the tentative subject of the talk will be the use of free and open source tools in the development of his products, but he may tweak the subject and content of the talk as time progresses.  If you want to learn about etherkit and Jason’s planned product line, FDIM this year will be a good place to be. He will also have a vendor booth.

However,  I am an INTJ.  After a day spent DJ’ing and reaching out to people,  my social energy was all used up. I’d typically go home and veg after work.  No Hollywood night-life for me. As a semi-retiree, I have become quite reclusive; I think this is just my true nature. I only blog when I feel a particular urge or duty to do so. Sorry about that folks – please don’t look to this blog for regular updates. There are many other hams in the blogosphere who are much better at that – a few of them on my blogroll.

The next post with photos of a construction project will most likely be the next add-on I get for my K2.  The Part 15 AM broadcast band transmitter that I placed on eBay did sell, adding to the funds that I can use for future projects;  currently a KAT2 internal ATU for the K2 is looking like the most likely candidate.  However, I’m very good at practicing the art of delayed gratification (one reason I’m an early semi-retiree), so cannot say when I’ll be putting my order in with Elecraft.

In the meantime, I’ve been meeting some interesting hams, having fun with contests, and working to achieve QRP CW WAS.  As a rule, I’m not much of a rag-chewer.  Mike Rainey AA1TJ in an interview somewhere said that he looks at short QSO’s as the equivalent of hams giving each other high-fives.  I like that description.  While some may think of a brief exchange of names, signal reports, and basic station information as being somewhat perfunctory, I enjoy these kinds of QSO’s. They let me know that my station is getting out and although WSPR could do the same thing, a brief CW QSO requires some effort and input from me, and in putting in that effort I have, in a basic way, reached out and made contact with another operator; I’ve high-fived him.  Sometimes that’s all I need.

Occasionally during a QSO though, there is extra information exchanged that adds human interest and elevates it above the level of the quick high-five. Such a contact was the one I had with Gary N2ESE a few days ago. Gary and I first met on 20M a few weeks earlier in early December. I wrote in the log that he was running 5W to a 4 element something. I must have missed the copy on exactly what it was, but I’m forever grateful to guys with beams as they are the reason for quite a few of my QSO’s when band conditions are marginal. I was needing a QSL from NJ for my QRP CW WAS, so sent Gary my QSL, and received this fine-looking card back:

I’m wondering if I made an error copying him, because on the back of the card it says that he runs 75W, so perhaps I missed the 7.  Also from the card, I learned that his 4 ele beam is a Telrex.

Gary’s call rang a bell somewhere in the back of my head, but I couldn’t recall where I’d come across it. Then a little later, while reading John Shannon K3WWP’s online diary, I came across an entry in which he mentions his friend N2ESE. Bingo! I knew that Gary’s call had rung a bell somewhere. I’m a big fan of K3WWP and his ongoing streak of having at least 1 QRP CW QSO a day, which has lasted over 17 years now. He has other streaks, such as a milliwatt streak, but the main one is the oldest – quite impressive.

I haven’t yet had the pleasure of QSO’ing with K3WWP but I hope to one day. In the meantime, a QSO with someone who has had over 100 QSO’s with John, as Gary told me, helped make the QRP world feel a little smaller, would be the best way to describe it, I guess – something to do with that six degrees of separation thing. During our QSO, Gary told me that he has his own QRP streak going, in which he has had at least 2 QRP CW QSO’s a day for over 5 years now.  2 QSO’s a day for 5 years is 1825 QSO’s – not a hard figure to rack up, but the striking thing about Gary’s achievement is the fact that he is on the air every single day without missing a beat. Nice work Gary – thanks for the QSO, and I hope we meet on the bands again soon.

AA0RQ is someone I’ve  QSO’ed with on 14060 in the mornings a few times now.  When it’s not too cloudy, he runs his 3 watt signal from 100% solar power, which leads me to think that he must be running direct from the panel without a battery.  I like the idea that when I talk to him and he says that he is solar, his transmitter is directly powered from the sun – not from a battery that has been charged by the sun. It’s just one little detail that adds interest to our QSO’s.  Bill also runs an experimental QRPp beacon on 10133.57 kHz which is solar powered in the day. More details on his QRZ page.

I’ve also been dabbling in contesting – not for seriously competitive purposes, but more for the fun of making a number of casual contacts with little no conversational commitment – kind of the radio equivalent of sleeping around, I suppose The ARRL 10M contest gave me quite a few states for my QRP CW WAS, and the NAQP this last Saturday got me to within one state of achieving my goal. All I need now is WV, which shouldn’t take too long. The thing I liked most about NAQP was that I got the 2 states I thought would be the hardest – DE and RI.

I’m not a very competitive person and have never previously been interested in awards. However, with my new-found zeal for ham radio and the current preoccupation with CW, I thought that reaching both QRP CW WAS and QRP CW DXCC would at least give me some kind of baseline of achievement. I want to be able to say that I have worked all states and 100 DXCC entities with 5W of CW.  For the QRP version of DXCC, ARRL don’t require that you submit proof – merely to list your QSO’s, so after some thought,  I don’t think I’ll apply for that.  Instead, I’ll apply for the regular DXCC award. I’ll know that it was achieved with just 5W and that’s what matters to me.

I’ve set my own confirmation criteria for WAS, and that is that I won’t claim a QRP QSO for WAS until I have the physical QSL in my hand.  I will most likely collect the physical QSL’s for DXCC too – at least for the first 100, and then possibly for notable entities after that. Mind you, by then, I might be living my dream of living full-time in an RV in which case, I won’t be looking to collect extra stuff. More on that at some point in the future if it ever materializes.

My current QRP CW WAS standing is 42 states confirmed with QSL-in-hand. QSl’s from 7 states are (hopefully) in the mail or will be soon. I just need a QSO with someone in WV. Can anyone help me out? Of the 7 states I am awaiting confirmation, if the QSL’s don’t materialize, I have a few insurance QSO’s to lean on, though I’ll  be looking for insurance QSO’s with a few states, just in case

I’m getting close

I didn’t know what else to call this post.  Unlike many of the other blogs that I eagerly follow, I usually only blog when I’m building something. I’m a big fan of the blogs that report on day to day operating, with information on upcoming events and contests as well as news on new kits and products , like those by Larry W2LJ and John AE5X. That’s not my modus operandi here though, so you’ll have to excuse me if I go for long periods with no updates.

Living with the K2 is exactly what I’ve been doing for the last month,  and it’s been grand.  It’s not perfect, but it’s pretty close.  Although it’s not the do-it-all-in-one-small-box that my FT-817 was, it does the things I want it to do, which includes a few things the 817 didn’t do.   No need for details here;  the internet is already full of information about both these rigs.

With the help of the K2,  I’ve taken part in the ARRL 10M contest  – 147 QSO’s including the pleasure of working John AE5X and TJ W0EA, as well as various smaller sprints. I came first in the 6 area division in the last NAQCC sprint although to be fair, it only took 5 QSO’s – we really need more participation from California stations. The guys back east have a lot more competition so I’m not exactly sure why there is less participation here. Perhaps we’re all busy BBQ’ing on the beach or something……..(insert your own partial myth about California life here).

I’ve been on the air quite a lot which is a good thing, as building the K2 satiated my desire for building, at least for a little while; I haven’t felt the urge to build anything else since finishing it. However, there will be a few additions to the K2, so in order to help fund them, I placed my Part 15 AM transmitter on eBay.  As of this morning, the bidding is up to $103.50, which will help to fund the growth of the QRP station at AA7EE

After a QSO the other day with Rick AA4W, we had an e-mail exchange in which he asked me what I thought of my K2.  I’ve said much of this here before, but it does sum up what I think of it so far.  Here’s what I told Rick:

“There are only 2 things that are less than perfect in my estimation, and neither of them are anywhere close to being deal-breakers. They are:

1)    Due to the number of bits in the D/A conversion, as you step through the bandwidth settings of the crystal filter when listening to a signal, the sidetone of the received signal varies very slightly. No matter how carefully you adjust the filter settings, you’d have to be very lucky to be able to eliminate this variation completely. With care and luck, my variation seems to be no more than 10-15Hz between settings. It has to do with the way the DC voltage applied to the BFO varactor is generated by the D/A convertor.  Apparently, they could have used more bits, but this would have increased the cost.

2)    On comparing the sound of the receiver to that in my Norcal 2N2, there is not as much of a peak in the center of the audio passband.  I’m assuming this has to do with the fact that the 2N2 is an exclusively CW rig, while the K2 audio stages had to be designed to pass the wider bandwidth of an SSB signal. From what I’ve read, the KAF2 audio filter, which is a lowpass filter add-on for the K2, is fairly gentle in it’s effect. The DSP option is supposed to work quite well, but nevertheless, there are still some digital artifacts when listening to CW. I am going to try a SCAF – probably the NESCAF, which seems to work well – and has the advantage that it helps a lot in cutting down electrical noise too – and all for just $31.  The only problem is that it is external to the K2, and I really wanted a filter option that was internal.  Incidentally, John K3WWP told me that he loves the DSP in his K2. He said that it is very effective at cutting down the electrical interference that he suffers from at his QTH.

      By the way, if you have the most recent edition of “The Complete DX’er” by W9KNI, he has some very good things to say about his K2.  He likes the relatively unprocessed sound of it, as compared to the more processed sound of the signals as heard on commercial rigs that use multiple conversion in their receivers. You’ll appreciate this too. Someone who comes from a background of only ever having listened on commercially-produced receivers with multiple conversion and much more complex circuitry than the K2 might mistake it’s cleaner sound for lesser performance which of course, it is not.”

The art of delayed self-gratification that I seem to be quite good at has kicked in and I’m waiting a bit longer to see what the first additions to the K2 will be. A KAT2 internal ATU will definitely be one of them.  I would like some audio filtering and I’m trying to decide between an external NEScaf, or the internal KAF2 or KDSP2 modules.

In the meantime, I’m just 4 states away from QRP CW WAS, and quite a lot of countries short of QRP CW DXCC, so there’s plenty to be working on – as long as the A index comes down soon

Although I know my own toroids don’t look as pretty as the pre-wound ones from Mychael AA3WF would have,  I’m getting better at winding them, and they don’t look too bad at all.  There are many examples of attention to detail  in this kit. One of them is that when you pull the toroid leads tight and then solder them, the toroids are actually straight on the board. Often in kits, the holes for toroid leads are placed such that when you pull the leads through and solder them, they are skewed just a little. It’s a small point, but it makes boards look a bit messy. Hats off to Elecraft for helping to line my toroids up in nice neat rows:

A view from above:

Here’s the view from underneath. Note the nuts securing the 2 PA transistors to the case:

The 2 chassis pieces that I received for the back of the transceiver had already had the green masking tape removed. That was a little disappointing, as I wanted to leave the tape in place over the holes that are currently unused.  I’m sure Elecraft would have replaced them for me but it didn’t seem worth contacting them about. I’ll use some regular masking tape:

What a beaut!  -

Everything about the K2 seems to be working the way it should. Sensitivity and handling of strong signals seem fine.  I plan to measure the minimum discernible signal at some point when I get a calibrated signal source. There are only 2 things that are not quite as perfect as I’d like then (though neither are deal-breakers):

Firstly, due to the way that the transceiver handles the D-A conversion, when stepping through the filters, the BFO is not on precisely the same frequency for each setting of the filter.  My filter settings are (nominally) 1.5K, 1K, 700Hz and 350Hz (though I understand the real bandwidths are narrower in practice). When receiving a signal and stepping through the bandwidths, the signal is at the same pitch except when the 350Hz filter is selected, when it lowers in pitch about 15 – 20 Hz. It’s not a lot, but to someone like me who is sensitive to pitch, it’s a bit annoying.  No matter how hard I try to adjust the BFO frequency, I cannot get it any closer. I understand this is due to the number of bits in the D-A convertor and was one of those compromise decisions that often have to be made during product development.

The other thing is not really an issue. It’s more of an indicator of how used I get to certain receivers and how I often am very picky about how I want my radios to operate. I suspect I’m not the only operator who wants his rig to operate exactly the way he wants it to so that it “fits like a glove”.  On comparing the K2 receiver to the Norcal 2N2 receiver, I notice 2 things. Firstly, the rushing background band noise seems to be pushed to a lower level in the background by the 2N2′s filtering.  It’s difficult to make a direct comparison though, as I don’t know the exact bandwidth of the crystal filters in the 2N2 and the K2  – this would be something worth measuring.  The K2 has more audio output power, so part of it may also be that I simply have the AF gain turned higher on the K2, creating the illusion of more rushing background noise.  On some very weak signals, I find that the 2N2 has a very slight edge.  I don’t think this is a sensitivity issue; I think it has more to do with the audio filtering – the audio on the 2N2 seems to peak more sharply at a fairly specific frequency (I set up all my rigs for a 500Hz sidetone), while the K2 doesn’t have this extra peak. My guess is that the audio circuitry on the 2N2 is tailored more specifically to CW, as it is a CW-only rig. The K2′s audio chain needs to accommodate wider SSB signals so needs to be fairly flat with a passband of a few KHz.  So I think the next step is to figure out some kind of extra audio filtering for the K2 – perhaps a KAF2 or the DSP option?

These 2 small points aside,  I’m happy with my K2 so far. Sure, it’s fun to compare figures and performance characteristics, but there is another very important factor that determines how useful a transceiver will be to the operator, and that is the feature-set and how easily accessible those functions are. No complaints in that regard yet.  Considering the relatively small size of the front panel and the fact that each button controls 2 different functions, Elecraft have made the most often-needed functions the easiest to access. I found it straightforward figuring out how to record and playback the keyer memories, as well as using the Fast-Play function, by which you can playback certain keyer memories with a single button push (great for contest operating).  Use of the dual VFO’s and operating split was intuitive – even for this guy who is fairly new to the world of operating split-frequency on HF.

In the few weeks since having it, I’ve worked T2T, YN7SU, HA3UU, JE4JPQ, JF1RWZ, PA0LEG, CO8WZ, 7N1PRD, BD4FM, CA2LQA, HL2DC, JE2UFF, DK1AX, CO6RD, PV8ADI, ZP6CW, ZP9MCE, GW4EVL, PJ2/W8WTS, C6ATA, JF1SQC, JR3NZ, JA6WFM, ZM1A, UA0ZAM, JF1NSD, JA7FTR, XE1CT, XE2B, JA5FDJ, PW7T, ZS4TX, PV0F, LS1D, C5A, HK1N, LW5EE, XE2AI, HK1R, JR1MQT, LU8YE, LT1F, VK4KW, JA1KGW and PY3ED. Oh – and a bunch of Stateside stations too

I think this rig is a keeper.  I’m already contemplating either the audio filter or DSP filter, the QRP internal tuner, the 160M option and (shock horror) perhaps also the SSB option

At the end of this post, I mentioned how just one part was missing from the kit – a 20-pin connector that connects the front panel board to the main RF board.  It only took a day to arrive so while waiting, I decided to make the best use of my time by pre-winding the toroids.  I had originally planned to buy the pre-wound toroid kit from Mychael AA3WF, reasoning that if I ever wanted to sell my K2, I’d want really great-looking toroids in it. When push came to shove however, budget started becoming very important, so I decided to wind my own and was glad I did. They don’t look quite as nice as Mychael’s, but I think they’re not half-bad. Here are 3 of them.  The one with the yellow core is the VCO coil and is shown with just one winding (I hadn’t wound the secondary at this point).  You can also see the 2.1mm crochet hook I used to pull the windings through the cores.  It’s a method I learned from Jim K8IQY and I find that it helps in keeping the windings fairly close to the core:

This second stage of assembly,  after which you have a working receiver on 40M,  is lengthy. There are a lot of resistors and capacitors to install and as many builders before me have commented, the only way to deal with it is to just get on with it.  For relatively inexperienced builders, this stage could be a bit of a nail-biter, as you have so many parts to install before getting any feedback on whether the circuits you’re building do indeed work. However, if you have a reasonable amount of experience, the manual is so detailed, and entire assembly so well thought-out and described that you just know you’ll either end up with a working rig, or Elecraft will help you correct any mistakes made during assembly.

An advantage to building such a late model K2 is that all the mods, such as the thermistor board to stabilize the VFO further,  the few extra components to shape the keying waveform, and the 2 diodes to improve the handling in the presence of very strong local signals on nearby frequencies, are included. There’s only one little thing that slightly bugged my detail-obsessed mind, and that was that some of the mods look a little messy to me.  It’s probably unrealistic to expect the board layout to be revised for every single mod after the K2 hit the market, but the board is of such high quality and looks so good, that a few components soldered at odd angles on the underside of the board offend my over-developed sensibilities. Luckily, I got over it pretty fast. The components that are either horizontal or vertical are part of the original design while the ones that look patched on afterwards are, well, patched on afterwards.  In the real world, I’m sure that the economics wouldn’t allow having the board layout revised again for these small changes:

In one sign that through-hole components are becoming harder to find, to the left of the above picture in the middle, you can see D36, which is now an SMT part on a small board, modded to fit the main PCB. I feel a little sad at the slow passing of through-hole technology, as not everyone is comfortable with SMT construction and so the building of your own rig will be an experience available to fewer people in the future. Just under D36 is L33 which was originally a choke with axial leads. As I understand it, using a toroidally-wound component for this part and mounting it on the underside of the board gave greater suppression of the opposite sideband in SSB mode. It is wound from fine wire and there’s no need to worry – it comes already wound, though you do have to be very careful with the leads when installing it.

Another view of this part of the underside of the main RF board:

The entire underside of the main board after this second stage of assembly. Near the left side of the board about 2/3 of the way down, you can see the outlines where the 2 PA transistors will be installed in the 3rd and final stage of construction:

At this point, the majority of the circuitry has been built, and that is quite apparent in the following views. The length of mini co-ax connects the built-in frequency counter to one of 3 test points on the board. The K2, as you probably know, has a built-in DVM and frequency counter to assist in building and aligning the radio:

A close-up of the PLL upgrade board that increases the stability of the VFO. It’s the light-brown vertical board just to the left of the crystal:

Here’s the 5 pole variable bandwidth crystal filter. I did a slightly less-neat-than-normal job of soldering the ground leads to the crystal cases. The crystal nearest the front is the messiest-looking. These kind of things really bug me but it’s a perfectly serviceable joint, so I pulled myself together and got over it. In this picture, you can also see the crystals for the second, fixed bandwidth crystal filter and to the left of them (and slightly out of focus), the other SMT part that has been substituted for the original through-hole part. In this case, it’s U12, an MC1350 IC which you can see installed on a small PCB that solders in to the holes for the original DIP part:

This wider shot also shows the 2 BFO crystals. The manual notes that one lead from one of the BFO crystals needs to be folded over and soldered particularly close to the board in order to prevent fouling a rubber bumper that will be placed over it in a subsequent step.  I found that by pre-cutting the lead so that it didn’t quite poke out of the PCB underside and applying solder so that it filled the plated-through hole but didn’t spill over onto the pad, I ended up with a nice flat surface on which to lay the rubber bumper for L33 (the BFO inductor). If you’ve built a K2 before, this will make sense to you. If not – it will become clear when you get to that point in the instructions.

Aww what the heck, here’s another very similar shot. In the background is the control board, and underneath the processor chip, you can see the crystal and associated trimcap that should be adjusted to exactly 4MHz so that the frequency display reads accurately. The manual tells you how to do it – you don’t need any extra test equipment:

This shot shows the VCO inductor. It’s the toroid wound on a yellow core to the right of the picture:

Oh – and the receiver? Well, it seemed to be working well on 40M.  I’ve read blogs from some builders who after a fairly lengthy period of assembly, were having such a blast listening to 40M on their K2′s that they gave themselves a break before continuing. I don’t remember exactly, but I think I had a short break of maybe a day, while entertaining company.  As I had been several months without any capability on the upper HF bands, I wanted to forge on so that I could listen to the higher bands and catch some sunspot action.

In the next post, I’ll show some pictures of the completed basic K2 and share my impressions so far.