[Elecraft] K2 Alignment and Verification of Specifications

[dave]

Don,

Not sure the price for the tests required would be as steep as you 
mention.  I think it would be an expense that some would be willing to 
pay to be assured that the rig they are using is up to speed.  Remember 
we are not looking for 1 dB or even 3 dB here, we expect to find 
elephants.  The calibration of the gear should not be terribly 
critical.  If someone has placed a .047 in where a 47 pf belongs (I have 
found that exact problem) the effects are apt to be noticeable.

The needed test equip could be home brewed.  EMRFD by Hayward, et al, 
has designs for it.  If I understand it all correctly the biggest 
problem is getting oscillators that are strong enough and clean enough 
to do the IMD and other dynamic range tests.  Seems to me a couple of 
crystal controlled oscillators driving clean amps should do the job.   
The Elecraft mini modules are adequate for sensitivity testing.  I don't 
believe it would be necessary to test the K2's full IMD3 dynamic range, 
which IIRC is north of 130 dB.  Remember that we expect to find 
elephants.  Testing to 100 dB or so should be adequate.  And test 
equipment for that range is easier to come by. 

When I suggest doing something similar to the ARRL tests, I'm thinking 
the needed tests, but not to the level of precision that is done there. 

There are other ways to go about it.  One you mention - having someone 
with quite a lot of experience check out the rig to see how it compares 
to others.  An individual with access to 2 or 3 other K2's could do this 
on their own - if they could borrow the rigs long enough for an adequate 
testing period.  No real test equipment required.  With over 5000 K2's 
out there now, this one should be available to almost all builders.  
Whether or not one should trust a comparison to a single K2 is an open 
question.

Someone such as yourself, and a number of others, are quite capable of 
sitting a rig on the bench and running some a/b type tests and knowing 
whether there is a real problem.

Another approach is to do a full audit of each board to be sure each 
component is in the correct location.  This requires nothing except the 
assembly manual and a good magnifier.  But quite a few of the components 
cannot be read once installed.  I've not tried this and it may be easier 
than I think.

The K2 is an excellent design and if the boards are populated and 
soldered correctly, it will work up to spec.  It is simply experience 
that makes me raise a caution flag.  This type of 
testing/verification/comparison is something I'd think buyers of used 
K2's would be interested in.

You mention that factory assembled rigs do not go through the testing I 
mentioned, and this is true.  But they are assembled in a very different 
environment. Most are machine assembled and errors are either zero or 
100%.  Those are easier to find.  Those factories that do hand assembly 
are more likely to have problems, but about all such factories have a 
few "Don's" around who know exactly the expected results from each 
module or subassembly.  Errors are generally spotted quickly and 
corrected.  This is *not* to say that factory assembled rigs come with 
zero defects, but their percentage is lower, much lower, than home 
assembled kits (MFJ excluded).

73 de dave
ab9ca





Don Wilhelm wrote:
> Dave,
>
> Yes, I agree.  Several folks have sent me their K2 just for such a checkout
> and calibration and alignment.  I have the advantage of being familiar with
> the K2 and its normal behavior.  BUT with a little bit of ingenuity, each
> builder can determine if his K2 is performing up to par without sending it
> away (see below).
>
>