[time-nuts] What's the best way to double 10 MHz to 20 MHz ?

David Kirkby david.kirkby at onetel.net
Fri May 27 14:51:00 UTC 2011


On 27 May 2011 15:21, Bob Camp <lists at rtty.us> wrote:
> Hi
>
> You also may want to avoid an oscillator with much 10 MHz content in it. All sorts of odd things can happen with spurs when you have unplanned stuff on the main reference. Another thing to look closely at is - how much of the radio tracks the reference? On some radios, they don't really lock everything up. You get better performance, but not quite what you would expect.
>
> Bob

Yes, a band-pass filter would seem sensible here.

To the best of my knowledge, everything is locked to this 20 MHz, so
there should be a significant improvement.

However, I must admit as to wondering whether its worth the bother. I
have a Yaesu FT-ONE, which is a pretty poor design, despite it was the
top of the line Yaesu transceiver in its day (~1982) costing $3000. It
has a synthesizer for 100 Hz steps and then uses a varicap diode to
get the 10 Hz steps! This is not very stable, but in practice is
stable enough. There's nothing much one can do about that - perhaps
keeping the temperature constant in the vicinity of the varicap and
other critical components would help. But it also suffers from the use
of more than one reference, so hard to really stabilise.

The Kenwood TS-940SAT should be a lot more stable anyway. The Kenwood
actually seems a lot better technically to me, despite it costs only
$2000 and was released about the same time as the Yause FT-ONE. The
Kenwood TS-940S has a built in ATU (not even an option on the Yaesu
FT-ONE), FM (optional on the Yaesu FT-ONE), TCXO (not even optional on
the Yaesu).


I might however look at using a TCXO o OCXO in the Kenwood.

Dave



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