K2 alignment problem at 10/12m
Posted by
Andy Webster on
Jul 05, 2010; 7:03pm
URL: http://elecraft.85.s1.nabble.com/K2-alignment-problem-at-10-12m-tp5257291.html
Hello all,
First up I'd like to say what a superb kit the K2 is, I've really enjoyed the time spent quietly soldering away and the instructions are first class with some great finishing touches (all the resistors in sequence on a custom strip - what will they think of next!). It's a shame it's nearly over...
Anyway, I have a problem on the final part of alignment. All of the lower bands seem fine on both pre-alignment (receive signals peaked for signal strength) and transmitter alignment (filters peaked for ~2W output) except on 12m and 10m bands.
On 12m the receiver is very quiet (although I can hear a broadcast station to try and peak the filter against) and there seems to be little effect when adjusting C44 and C46. On transmit into a dummy load there is consistently only 0.2-0.3W showing.
On 10m the receiver seems OK (receiving some strong CW) and L12 and L13 can be peaked for maximum response but transmit into the dummy load is hit and miss, sometimes approx. 2W, sometime it shows a High Current warning and displays around 10-15W before I quickly deselect Tune.
Obviously these two bands share filters so my attention is drawn there but I thought I'd float the exact symptoms at the collective while I search for my 'scope probe. I've closely inspected the band pass and LPF areas for faults and resoldered all the joints just in case of a dodgy one to no avail. The number of turns on the LPF toroids is correct. Does the different behaviour of the two bands on tune tx indicate a more specific area for attention?
Next step for me is to run a scope along the signal path but appreciate any thoughts as to schoolboy errors I have obviously made...
Many thanks and 73
Andy
G7UHN
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