The ones available from the Microwave Component service were 35 - 40
deg units. These were just about OK. for the normal 20 deg
temperature crystal although a bit close to the turnover as you say.
Taking uWave equipment out portable on a hot day meant sunlight on the
RF box could raise the temp above this, upsetting the stability.
Some heaters Sam, G4DDK, had were 50 - 60 deg units and need a
specially cut crystal, where the perfomance was then excellent. Think
I have some of these decices, but haven't tried them yet as I haven't
any suitable high temp cut xtals in HC18U case.
Didn't know you were a Microwaver Alan ! I always maintained 73kHz
was a microwave band, where experimentation and homebrewing rather
than just operating was the norm. 137k just seems a DX chasing band
these days.
Andy G4JNT
......................................................
You mentioned the Murata heater tabs earlier.....have you any idea
what
temperature these are supposed to stabilise at?? My data book doesn't
quote
this. I have seen problems where the crystal used was not specified
for a
turnover at the 'oven' temperature, leading to worse stability than
without
using the tab. (crystals for use in ovened enclosure are usually cut
at a
slightly different angle I believe) Used correctly they should give a
order
of magnitude improvement for the guys with outside shacks!
Particularly if
the 'tab' 12v supply can be left switched on. It is not a total cure
and for
best performance crystals still need to be protected from direct
draughts
even if only by a cornflake package.
Cheers de Alan G3NYK
[email protected]
-----Original Message-----
From: Talbot Andrew <[email protected]>
To: '[email protected]' <[email protected]>
Date: 27 April, 2000 12:54 PM
Subject: LF: RE: High stability drive sources
>
>> Are more of these becoming available ? A lot have been bought up
by
>> microwave operators recently.
>>
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