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Elecraft K2 Detailed Builder / User
Brian Jones, G0UKB email@example.com
From the uk.radio.amateur discussion group, August 2000
>I have been interested in the Elecraft for some time though have done
>nothing more than download the manual etc. I would be interested in
>your comments regarding build and performance as I am sure would some
Simple - I have a TS850SAT next to me - hasn't been switched on in weeks. The K2 is next to me fired up and chattering away - enuff said! I'm not in the electronics industry and my soldering is self taught - I'd built a few very simple kits before this but nothing anywhere near this complexity so was just a tad daunted..
The basic CW only rig is 3 PCBs and a case. On opening the box the quality of the plated through boards is obvious (once you've got over the 'my God! what a lot of components I'll never get this working shock'). The manual is excellent, folks say reminiscent of the Heathkit style (before my time sadly). There are no surface mount parts anywhere in the kit and most of the part spacings are pretty good although there are a few places where its a bit of a squeeze to get the iron in and I wouldn't recommend soldering after a few pints!
The rig relies extensively on microprocessor technology and the first board to build is the main control board. This is a pretty easy build, and the manual takes this first board very slowly. Then you build the front panel which has all the keys and the LCD. The LCD is scary because there's quite a few close together solder connections but if you can solder AOK then no problem. The main board has lots of components (over 200 capacitors) so is a big build but in stages so not too bad. You have to build a few components on this and then plug in the control and panel boards before you can really get to test them. Its a great relief to see 'Elecraft' on the LCD. There are several toroids to wind but the supplied wire seems to heat-strip the enamel easy enough. There are a few test places in the rig but its a relief when that first audio is heard on 40m!
Easy!!! The rig has built in voltmeter, ammeter, freq counter and power meters! You need a dummy load and I used my bench multimeter and power meter. The built in ammeter and power meters aren't too accurate but more than adequate for alignment and probably enough if you don't care if you're putting out 5W or 5.3W (I use them for every day use).
I haven't aligned the PLL because my external freq counter isn't calibrated but I reckon I'm within at worst 0.2Khz of displayed freq probably less than 0.1 (I must go zero beat a time sig). VCO alignment is just peaking voltages. The IF alignment requires audibly peaking a weak birdie - I, like many others, didn't experience a sharp peak here so peaked in the middle of the broadish range. The bandpass filters require audio aligning but these peak well for every band and are very easy. The rest of the alignment (apart from filters) is done via automatically by the microprocessor. Filters can be adjusted by microprocessor control. I built a nice RF noise generator (from N0SS site) to give me something to align the filters. Using the spectrogram program you can see the audio spectrum on the PC and simply changing the values on the K2 using the tuning knob can adjust and see the peak and skirts of all the filters - very impressive.
Almost none. I started using a very fine solder - too fine and a couple of joints on the control board weren't great so I found ALC wasn't working well (after I'd finished the whole build of course). It was easy to see where to check from the manual and I just resoldered some somewhat ropey joints and all worked fine. In trying to peak the IF filter I wound the slug past the top of the can where it spun freely (the manual does warn not to do this) and thought I'd need to replace but a little extra pressure has brought it back AOK. I think that was all. Its best to be careful because the excellent quality through hole plate PCBs require a little extra effort to desolder.
I bought all the options - SSB board, Noise blanker, Auto ATU, internal battery, 160m/RX ant (and will get 100W amp, RS232 interface and audio filter when available). All worked fine except I have low output on 160m (only about 7-8W) - I'm sure this will be easy to sort when I mail Elecraft support - I just haven't bothered as I don't work topband (I wanted the RX ant more which works FB). The ATU is amazing, it supports 2 antennas and remembers band/band tuning on both so switching antennas is excellent (I use this a lot, I have a windom and a vertical and often get a couple of S-points by switching).
Mods - I replaced the tuning knob with an FT100 knob - the supplied knob is fine but the
rubberised Yaesu knob with dimple is a nice touch. I've added a couple of components to change the slight raspiness of the
sidetone. There was another mod to adjust one of the IFs which tended to skew the SSB audio spectrum slightly. It involved tacking a couple
of components to the bottom of the RF board. Well documented and very simple and improves RX audio quality of SSB (it was fine before but this takes a little bass of 20m voices).
I inventoried all my kits. The only problem I had was that the germanium diode for the RF probe seems to have been missing (I may have dropped it). Nothing else and there are very, very few complaints re missing parts on the K2 forum. Anyway I have an RF probe so didn't need to build this one :-)
Everything fits together. The boards use multipin connectors to snap together to form both electrical and physical stability. The front panel board aligned exactly with the panel so all the buttons, knob etc dropped in place. Quality shows through in little touches such as on the RF board one of the screws holding the board to the case doubles as a leverage point to allow an allan key to lever up the control board which is connected to it. The case consists of flat panels which bolt together using purpose built connectors. A very neat idea and it looks pretty good too.
Used for about 8 weeks but I don't get on air much. Almost exclusively 10W SSB - 117 contacts, 51 DXCC countries, 36 EU IOTA islands. Broke pile-ups into 1A0, 3A, FY (islands - twice), VQ9, HH, 5X, CY9, PY0) - furthers DX LU (over 10000 km) on 2 bands.
Operating is good, audio levels high and good quality, 3 tuning steps 1Kz, 0.1 KHz, 0.01Khz. The microprocessor remembers mode/antenna etc. Memories (10) are easy to use as is split. I have maximum compression turned on but still get good comments on audio and last night EI3GZ said he'd never have known this wasn't a 100w black box rig. No
discernable VFO drift on warming up.
The K2 site gives access to the ARRL review and the RX figures. They are impressive and only the FT1000 does better. I never thought that I could build something with comparable RX to my TS850 but in practice it is better. There is a significant reduction in receiver noise making listening much more pleasurable. For TX I get approx 15W or so on all
bands except 160m , the power knob is right on the front panel and adjusting it displays power on the LCD so I run at 10W on all bands with no problem.
Everything is accessible from the microcontroller menu so lots to configure if you want to play. You can switch the display from freq to volt/current with one switch and use the menu to turn off things like the backlit display etc to get a minimum current draw. With a decent audio signal to listen to my normal RX current is about 0.28A and 10W transmit is about 3A. I haven't played CW much so haven't used the built in keyer but the filters work pretty well (I haven't decoupled my W9GR DSP from my TS850 - no need)
I wish Microchip would get the microcontroller emulators out so the RS232 interface was built - my log relies on that! Something to remind me that I'd forgotten to switch the PSU on and was running on battery would be nice (although I could always switch the internal battery off). The ATU should be tuned at 2W so its a pain having to remember dropping down to 2W from 10 on the (rare) occasions I need to retune. Apparently the next firmware release will do this automatically. Some folks have complained that RIT/XIT doesn't reset to 0 when the tuning knob is turned but I don't find this a problem. A detent would be nice though.
Some of the options require components and links to be desoldered from the RF board. Desoldering worries me as these little through-plated holes tend not to let go. I haven't had any problem removing/changing the half dozen components but it would have been nice not to have to. I suppose, on the plus side, if ever need to service this I have some experience.
The main RF finals are heatsinked to part of the case base. These have to be unscrewed to fit some of the options. No problem but again not something I'd want to keep doing (I must but some extra thermal pads just in case I damage one sometime)
The K2 reflector is active and has a good signal to noise ratio. Lots of ideas about general QRP operating as well as a problem solve by consensus. It seems most folks send problems there rather than going directly to Elecraft service and get good advice feedback. For specific problems the Elecraft folks seem very hot on replying to mail and to notes on the forum. I suggest you go look at a few days worth of reflector - its off the Elecraft site http://www.elecraft.com Current threads suggest some folks have lowish speaker/ headphone audio but mine booms out.
If you can afford it - buy it. If you can't afford it - start saving! Seriously, the kit was a pleasure to build (sure the 200th cap was starting to get tedious but by then the end was clearly in sight). It worked pretty much first time (except for the AGC being a bit dodgy though bad soldering) and is a delight to operate. I live in Southampton, will be going to Wimborne and Telford rallies and travelling to Liverpool and Bradford next month. If you want me to bring it to a rally or Mway service station send me a note and let's see what we can arrange.
I have been using a TS850AT for a few years and managed to acquire an almost new (ex-demo) one at a good price recently. My plan was to keep the other TS850 as a second rig/ one I could take on field days/special events etc. I now use the K2 as my main rig with the new TS850 as my second rig. The other TS850 appears in Radcom for sale next month!
BTW - if you do buy a K2 get a good soldering iron (I use a Weller WTCPT station) and good cutters. Some components are soldered from the other side of the board and if you don't want to pre-cut you'll need cutters whose points cut well if you want to make a really tidy job.
Sorry this is sooo long
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