[Elecraft] K2 latching relays and filter alignment

[Don Wilhelm]

Albin,

The relay manufacturer has changed since Omron stopped making them.  The 
new relays are made by another manufacturer (Kettering if I recall 
correctly).  Contact Elecraft to find ordering details on the new 
relays, or order from Elecraft.

Since the "filter alignmment" consists of setting the filter width and 
then adjusting the BFO to place it properly with respect to the filter 
center, rather then actual alignment of the filter itself, the best 
tools are an audio spectrum analyzer to observe the audio and a wideband 
noise generator to inject RF into the antenna jack.
The audio spectrum analyzer may be a soundcard program such as 
Specctrogram or SpectrumLab running on the computer.  Take the audio 
output either from the headphone jack or the External Speaker jack.
If a wideband noise source is not available, you can use 'dead band' 
noise from an antenna - make certain there are no actual signals.

A spectrum analyzer and tracking generator will not work well unless you 
can set the analyzer for audio wile the tracking generator is at RF.

73,
Don W3FPR

On 8/24/2020 11:35 AM, Albin Stigö wrote:
> Hi,
> 
> I'm in the process of repairing a K2 I've inherited from Clemed SM6DRH
> who sadly passed away earlier this year at age 90.
> 
> It didn't receive/transmit on 40m and I've identified the problem to
> be a defect ("stuck in the middle") relay K12 (bandpass select relay).
> The relay in question is an Omron G6HU-2 5VDC. These are kind of hard
> to find these days so I was wondering if anyone knows where I can find
> them (preferably in the EU) or a suitable replacement?
> 
> While I'm at it I was thinking about re-aligning all the filters using
> a spectrum analyzer with a tracking generator. I'm wondering if anyone
> has developed a procedure for this, ie where it's good to inject the
> TG signal and where it's good to measure.
>