[Elecraft] K2 Alignment

[Don Wilhelm]

Tom,

Your limited BFO range will only be a problem when aligning the IF 
filters.  If you find you cannot align the filters properly, then you 
will have to correct that problem, but it may be a case that you have a 
marginal solder connection somewhere in the BFO area and re-flowing the 
soldering will give you a wider range.  Look at the RF Board schematic 
sheet 2 in the lower right corner to identify the components involved 
with the BFO.

Typically the K2 does not drift but a few Hz after being given a bit of 
a warmup period (10 or 15 minutes).
Proper dial calibration and drift are 2 different things.  Drift is the 
frequency change over a short period of time, such as a single operating 
session (usually do to temperature changes).
Dial Calibration can change over time, but typically does not vary much 
because the calibration data is contained in EEPROM and does not depend 
on any realtime reference oscillator for accuracy and consistency.

If your situation is really drift (by my definition above), then I need 
to ask how old is your K2 (serial number please).  If it is SN 3000 or 
below, does it have the A to B upgrades as well as the other Elecraft 
mods installed.  There are 2 mod kits that are important for temperature 
stability - the BFOMDKT and  E850138 (the PLL temperature compensation 
mod - so called "thermistor mod").  Look at the BFO inductor L33 on the 
bottom of the RF board - if it has many turns of fine wire and is held 
in place by a 1/8 watt resistor, then you have the BFOMDKT installed.
Then look on the top of the RF board on the left side near the Control 
Board for RP3 (it may be under the KDSP2 or KAF2 if you have those options).
If you see a small board with resistors on it in the RP3 location, you 
have the "thermistor mod" installed.

Especially since you have the K2/100, if either of those mods are 
missing, I suggest you install them.  In addition, if your K2 is below 
SN 3000, you may want to consider doing the entire set of A to B upgrade 
mods (I recommend it).

Once you have checked those mods, go on with your calibration and 
alignment process.
For the K2 Dial Calibration and filter alignment, I suggest you use 
Spectrogram or another audio spectrum analyzer for the best results.  
See my webpage www.w3fpr.com article on K2 Dial Calibration.

OK, I have given you more information at one time than you may have 
wanted.  However, it is all related to dial calibration and drift 
(again, two different things).  Work through it one step at a time, and 
if you have questions as you go along, please ask.

73,
Don W3FPR



On 7/11/2015 1:48 PM, Tom Field wrote:
> I've been using my K2/100 for a couple of years, and have been very
> satisfied. I have noted some drift in the freq, so decided to go through a
> complete realignment process.
>
> On Page 65 of the manual it describes a measurement of the BFO range as
> being 4-6 kHz. I measure 3.52 kHz. Question one, is this sufficiently out
> to be of concern? and question 2, what are the next steps to correct any
> problem?
>
>