[Elecraft] KX3 Extended VFO temperature compensation procedure

[Phil Wheeler]

I noticed something similar last night when doing 
this. I've not operated since so I don't have any 
experience with the result.

At temp of 45 deg or thereabouts the tone started 
back up. But it didn't rapidly shift or do 
anything bizarre, just increased slowly as the 
temp went to  52 deg.  Then I locked in the 
compensation; have to do RefCal today.

I was surprised that the tone didn't just keep 
going down until temp reached 52 deg.

It would be good to know if this is normal or I 
need to redo the temp comp procedure (hopefully not).

73, Phil w7ox

On 3/18/14, 7:37 AM, Bob wrote:
> Anybody else having issues with non-linear 
> oscillator changes around 40C?  I've done the 
> extended temp calibration 3 times (each time 
> takes about 2 hours), and someplace between 38C 
> and 42C the calibration goes crazy.  Up to that 
> point as the temperature gradually increases the 
> tone shifts lower.  But around that 38-42C spot 
> it start rapidly shifting up in tone and down in 
> tone (frankly all over the place).  When you 
> actually use the KX3 it is obvious that there is 
> something bad happening around there because you 
> can hear signals start to wildly drift around in 
> the receiver as the rig temp moves through that 
> range.  That makes me think that the values 
> obtained by the calibration process are not 
> accurately reflecting true changes in internal 
> oscillator frequency.
>
> I contacted the factory.  Their best advice was 
> to do the calibration again but use an 
> electronic heat source (like a 50 ohm dummy 
> load) under the KX3 with a variable power supply 
> running the dummy load to get a more linear 
> temperature increase.  I haven't done that yet, 
> but my three prior attempts have had a pretty 
> linear temperature increase (one changing the 
> rig temp about 1C per minute from 15C up to 60C).
>
>
> 73, Bob, WB4SON
>