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).
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