----- Original Message -----
From: "mike.dennison" <[email protected]>
To: <[email protected]>
Sent: Sunday, October 20, 2002 9:44 AM
Subject: Re: LF: ICOM 706 Mk2
G3JKV wrote:
> I wouldn't advise using the 706 for this purpose even if you get it down
to
> 136. Its local
> oscillator is rather "wobbly" due to the action of its internal fan and
you
> won't find it stable
> enough for narrow-band QRSS etc. I have one and I installed the
"hi-stab"
> option which
> made it even worse by introducing a second TCXO-induced wobble. Total
> wobble is only
> at 136 is only a few Hz and doesn't normally matter but it does when
you're
> looking for
> 0.01 Hz!
My ancient IC-706 Mk1 works absolutely fine receiving 120s QRSS after a
few
minutes warm up. On the Mk1, the fan is on permanently - perhaps this is
the
fix!
I can confirm this. I have seen the XDV signal on QRS and no wobble
evident.
I also have a 706 late MK1 and have worked various QRS speeds from 1WPM to
60 sec dots and see no wobble or instability. This system was used last year
to work across to the USA and Canada on several occassions on 135.922 khz..
It is well within the tolerance required for the above QRS speeds, however
if you need 0.00000000001 hz accuracy that might be a different story. A
cold outside shed used as a shack during the winter might also blow you off
course.
Most modern rigs are suitable and stable enough for dividing down from HF
freqs, you do not need any special ovens or 200 year old Chinese burnt in
and aged xtals.
73 de Mal/G3KEV
Mike, G3XDV
http://www.lf.thersgb.net
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