[Elecraft] K2 #6050 Arrived

[Don Wilhelm]

Ed,

Ron is quite correct.  I (like the K2 manual) do not recommendation adding
the RF board parts for the K60XV option, even with the rework eliminators.

An even better recommendation - if you have the rework eliminators in hand,
finish the K2 as instructed in the manual, and then when it is tested,
install all the rework eliminators you desire, do all of them at the same
time. - EXCEPT, do not change C71 (for the K60XV) until you have the K60XV
option ready to install.  If you proceed in the manner I have just
suggested, you will have tested the K2 without any confusion because of the
rework eliminators, and after installing the headers and standoffs, etc from
the rework eliminators, you will have a working 'plug and play' K2 with only
the exception that you must change C71 when the K60XV is installed.

I might add that the K2 is a complex kit, but the manual already includes
instructions to test it in a stepwise manner during the construction.  What
I am advocating is that you add one more 'step' to the manual on page 71,
which reads "Install the Rework Eliminators as instructed in the Rework
Eliminator Manual (except do not install the 120 pf capacitor at C71)."

73,
Don W3FPR
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net]On Behalf Of Ron D'Eau Claire
> Sent: Thursday, March 08, 2007 1:07 PM
> To: 'eKotz'; elecraft at mailman.qth.net
> Subject: RE: [Elecraft] K2 #6050 Arrived
>
>
> Ed- AD7GR wrote:
>
> My K2 and options arrived in yesterdays mail just three business days
> after having ordered it... very fast service... my thanks to Elecraft...
> I also ordered and built the Rework Eliminators kit for the K2...
> ordered on Friday, here the following Monday!
>
> ---------------------------
>
> FB Ed! Have fun.
>
> Before you trot out those "rework eliminators" read our resident on-line
> troubleshooting expert Don Wilhelm's comments about them. I can't speak
> about them from personal experience; I never saw any reason to
> install them.
> As Don points out, there's very little savings in time should one want to
> test the K2 with an option removed. But in helping those with
> issues getting
> their K2 working and doing some of the alignment, Don has a lot
> of personal
> experience that shows how they can produce a lot of headaches. Below are
> Don's comments from last November.
>
> Ron AC7AC
>
> IM(not so)HO, Rework eliminators are fine for those options that
> you DO NOT
> intend to install initially (except for the K60XV).  For those
> options that
> you order with your K2, the parts to install these options are
> included with
> the option kits and the K2 manual tells you when to install the
> 'hooks' for
> these options.  Your ability to test the K2 according to the manual
> instructions is compromised with the Rework Eliminators because you must
> coordinate two sets of instructions to get the task accomplished.
>  The easy
> and safe path is to simply follow the K2 manual instructions without
> installing the Rework Eliminators.
>
> The K60XV option is a bit on the 'strange side'.  If you install the parts
> for the K60XV option according to the Rework Eliminator instructions
> (especially the change on C71 and the addition of D19 and D20), the entire
> character of the K2 VFO circuit changes.  The VFO voltages measured at R30
> will change, and since the K2 cannot be tuned to 5300 kHz from
> the 60 meter
> band until the K60XV is actually installed, you end up with a K2
> that cannot
> be fully aligned in a proper manner - and you must re-visit the alignment
> when the K60XV is actually available (so much for the 'plug and
> play' ads).
>
> For problem 'chasing' on options that you have purchased with the
> K2, there
> are easy to implement jumpers that can be placed into the option headers
> with a couple capacitors and a few jumper wires (the Rework Eliminator
> boards are too large IMHO to allow complete access to all probing
> points in
> the K2).  Specifically the KDSP2 can be substituted with 2
> jumpers that take
> the place of the R18 and R19 zero ohm 'resistors'.  The KSB2
> requires 2 wire
> jumpers in place of W2 and W3 and one .001 uF capacitor in place of C167
> stuck into the KSB2 headers.  The KNB2 is the one exception, because a
> proper termination requires a 6 dB pad to be installed at the
> header.  Yes,
> a simple wire jumper in place of W5 will substitute for the 6 dB
> pad in most
> cases, but the termination for the Post-Mixer Amplifier will not be quite
> correct and the receiver IMD will suffer a bit, but for most testing
> purposes, a straight jumper will do the job fine - just do not attempt IMD
> measurements without the proper 6 dB pad.
>
> All in all, I regard the Rework Eliminators as a waste of money and an
> inconvenience for most builders.  As I said, the K60XV rework eliminator
> inclusion can lead to a number of problems and I trust that those problems
> with the K60XV are now identified in the documentation with the Rework
> Eliminator instructions - I have had correspondence with the Rework
> Eliminator folks on this subject, and they did say they would address the
> situation, but I have no information on the outcome of those discussions.
>
> 73,
> Don W3FPR
>
>
>
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