One last rehash on tuning hash

[john lawrence-3]

In answer to Joe Planisky, here's my rehash on hash.

My K3 which is factory built still has some tuning hash but it's now at a much lower in level, doesn't move the
s-meter (with or without preamp) and is only centered around 28000 +/- 5 KHz.  I can barely hear it now.  I haven't added the h/w mod.  Because this K3 is factory built and never been opened, lets assume it is properly built with cables and fasteners properly positioned and seated.

Eric's comment:
<<The h/w mod does not really impact the noise at all. It is required
though and is there to maintain reliable signaling between the main
processor and the synthesizers when the CPU to Synct serial bus speed is
increased with SPI=2. Its the change to SPI=2 that reduces the noise.>>

I've read some conflicting comments on the need to make the h/w mod.  I gather it's
Eric's position that it's necessary to keep the signals clean between the main MCU and synthesiszers.
Before seeing this latest comment I was left thinking the h/w mod would also further reduce the tuning hash.

With all this in mind I can live with small amount of remaining tuning hash.  And, this K3 has been running in this configuration for almost a month without any signs of problems that could relate to omitting the h/w part of change.

Cheers to the Elecraft team.

John, W1QS

K3 s/n 2274
K2 s/n 4204

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[Eric Swartz - WA6HHQ]

Hi John,

This is not a personal position - Its official current Elecraft company
policy. :-)

To be totally clear, if you enable 'VCO MD, SPI 2 for the VFO noise
reduction, you MUST ultimately make the corresponding h/w mod.

Its OK to test without making the mod to see if 'SPI 2' helps your
situation, but then you ultimately must do the h/w mod. Failure to do
so, when using 'SPI 2', may cause your K3 frequency tuning to be
unreliable at random times, depending upon a wide range of variables,
including band, temperature, supply voltage, type and number of options
installed etc. The display frequency will tune normally, but the actual
Synthesizer frequency, may not always follow correctly.

Of course, if the 'VCO MD, SPI' menu entry is left at the default of
'SPI 1', you do -not- need to make the h/w mod.

(Note: regarding the confusion in this: Ron's original posting where he
thought he had a problem turned out to be a red herring. Upon further
investigation we found he had fast tuning turned -on- for his RIT
control and was not aware of it. He was also seeing the actual freq
display change on his K3, which was the result of bumping the RIT
control in this mode with RIT=OFF. :-)

73, Eric  WA6HHQ
Elecraft
====


John Lawrence wrote:

> In answer to Joe Planisky, here's my rehash on hash.
>
> My K3 which is factory built still has some tuning hash but it's now at a much lower in level, doesn't move the
> s-meter (with or without preamp) and is only centered around 28000 +/- 5 KHz.  I can barely hear it now.  I haven't added the h/w mod.  Because this K3 is factory built and never been opened, lets assume it is properly built with cables and fasteners properly positioned and seated.
>
> Eric's comment:
> <<The h/w mod does not really impact the noise at all. It is required
> though and is there to maintain reliable signaling between the main
> processor and the synthesizers when the CPU to Synct serial bus speed is
> increased with SPI=2. Its the change to SPI=2 that reduces the noise.>>
>
> I've read some conflicting comments on the need to make the h/w mod.  I gather it's
> Eric's position that it's necessary to keep the signals clean between the main MCU and synthesiszers.
> Before seeing this latest comment I was left thinking the h/w mod would also further reduce the tuning hash.
>
> With all this in mind I can live with small amount of remaining tuning hash.  And, this K3 has been running in this configuration for almost a month without any signs of problems that could relate to omitting the h/w part of change.
>
> Cheers to the Elecraft team.
>
> John, W1QS
>  

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