[UK-CONTEST] K3 working again

[Christopher Plummer]

Chris,
 
I recently built a K3 kit, and had what I thought at the time the same problem.  Symptoms... no RX , no TX, but all the front panel functions seemed to work.  After many hours of frustration I thought it was somethink I had inadvertantly set in one of the menus, so I took the unit with me to Jim G3KAFs QTH to compare with his menus on his K3.  When Jim had built his kit he said he had not had the problem.
 
My thought processes were that I had a problem with the phase locked loops (I had the 2nd RX installed), so started to disassemble to check I had got the leads into the right connections.  That was all OK, so we suspected that both PLLs were not working (unlikely) or the TXCO. Checked that the high stability unit was well plugged in (and the right way round)  Still no joy.  So if in doubt read the instructions (being an engineer this is always the last resort) Eventually found a cryptic and incomplete instructions about PLL CALIBRATION, tucked away at the top mend of one of the set-up menu items. winding the knobs to this and not being told what to do then, I pressed the menu button again to get out of the menu, and Glory Be, the K3 went off and calibrated each band in turn and the RX and TX functions burst into life, turn on the sub RX and do the same again and the lid could be screwwed on finally....It works well.
 
Then it was down to getting a display on the P3, setting the menu level to -70dB seemed to work, but conversations with another K3 owner (or contest group, Tall Trees CG, now have 4 between us) 'Oh just press this button and wind the knob to get the noise floor displayed'  Simple really but also not explicit in the instructions.  So it all works now and I'm discovering what all the controls do.(the last time I had a piece of electronic equipmentthat had triple functions it was a ZX spectrum... yes suffered long before proper PCs came along, but my youngest son could do wonders with it, same as programming the video recorder... get a 7 year old to do it...)
 
I might write to elecraft and suggest a more easily understood operators manual.  The current one seems to have been written by the same guy who did the build manual.. plug this in here etc...
 
Next I have to interface the unit to a laptop with USB ports only to run data modes.... not all USB / Serial converters were created equal...
 
73 de Chris G8APB
 

 

> Date: Wed, 9 Nov 2011 22:49:55 +0000
> From: g3sjj at btinternet.com
> To: uk-contest at contesting.com
> Subject: [UK-CONTEST] K3 working again
> 
> Firstly thanks for all the comments and suggestions. Here is the story for any other K3 owners who experience the problem. Initially I was hesitant to 
> accept that the fault might be a poor contact on a connector pin, however I called in at the local Maplin store and bought a £3.50 can contact 
> cleaner. Spread the ESD mat out and wired myself up to it! Removed both KSYNC3 boards and the KREF3 board, examined the surface mount soldering 
> carefully and then sprayed the pins on the PCB connectors.
> 
> On re-assembly the fault was still there! That is, no rx /tx and PLL1 & 2 display showing either 7.4 or 0.0. By chance I happened to tap the TXCO, 
> which is the metal can component on the KREF3 board, and the fault cleared. The pins were quite sloppy in the DIL carrier so I bent them very slightly 
> to make a more solid fit. I have had the radio on soak test now for several hours now and it is very stable.
> 
> Gary at Elecraft suggested checking the output from the KREF3 board. You should see about 2v pk-pk at 49.380MHz. I checked this on my ageing frequency 
> counter and Tektronix 435 scope. The signal disappeared when the fault occurred confirming the TXCO wasn't oscillating.
> 
> A tip - Instead of trying to get the scope probe down the TMP mini coax sockets, I used a spare patch lead supplied with the 2nd rx kit. Plugged one 
> end into the socket and clipped the probe on to the other end.
> 
> A satisfactory conclusion all round!
> 
> Chris G3SJJ
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