[Elecraft] KX3-2M module?

[Stewart Bryant]

On 07/04/2014 17:37, Wayne Burdick wrote:
> "Lance Collister, W7GJ" <w7gj at q.com> wrote:
>
>> Has anybody heard anything regarding the timing of the KX3-2M module for the KX3?  Is it still planned for high enough stability for JT65B mode and a maximum power of 10w?
>
> Hi Lance,
>
> I'm not sure where you got that figure. Our postings on this topic are summarized in an FAQ (http://www.elecraft.com/manual/KX3-2M%20FAQ.htm).
>
> - Max power is 3 W.
>
> - The module is unlikely to support very narrowband modes, because short-term local oscillator excursions at the I.F. (48 MHz) are, in effect, multiplied by about 3. FM and AM modes can be used with normal factory temperature compensation on 2 m. To use CW/SSB, the extended VFO temperature compensation procedure will be required. This level of compensation would also allow the use of narrow-shift RTTY. But JT65 and similar modes on 2 meters would probably require tighter frequency stability.
>
> 73,
> Wayne
> N6KR

I am somewhat curious about the pessimism here.

Surely the important characteristic is the short-term stability over
the one to three minute time frame, and most of that is going to
come from thermal. So if the base oscillator is +/- 1ppm over
0-50 (from the manual and about the TCXO midpoint) this is
150Hz at 2m. A 10Hz drift which is the FAQ number would
require a temperature change of the oscillator module
of about three degrees, or about a degree per minute. That
seem quite a lot to me, particularly if you are applying
s/w correction to help the TCXO.

Stewart/G3YSX