Well, the saga continues...
A replacement part (for which a thorough check was specifically asked)
has arrived. It boasts a "Checked OK" written with a marker pen on the
label. Promising...
With high expectations, the necessary connections were made, power
applied, and after warming up it locks at precisely 9.999,817,1 MHz...
bummer.
Sometimes, for (yet) unknown reasons, it unlocks again, and, if the
frequency adjustment trend is upwards, it locks again at ~10.000.000
MHz. The lock signal is active even at higher temperatures - that's
quite better than the first unit, but after a power cycle the story
repeats... mostly the wrong frequency comes out, but, on the brighter
side, it's locked.
On 3/18/2012 10:26 AM, MailLists wrote:
Yes...
Thank you, and the others, for the suggestions for cleaning/reviving the
unit, but I can't recommend to my friend to keep a pile of rust (if
water damage really is the problem) advertised as an used working item.
Regards,
bbg
On 3/17/2012 4:10 PM, Azelio Boriani wrote:
LPFRS from fluke.l? OK, then open it up and clean it, the LPFRS from
fluke.l suffers from high humidity/water immersion and usually are very
rusty inside. I have received one that was very bad but after cleaning
with
tetrachloroethylene (translated with google) it is working properly,
maybe
it will fail soon but now works. I complained with fluke.l and he
refunded
me without asking to ship back the LPFRS.
TIP: handle with extreme care an opened LPFRS, there is a flexible PCB
that
holds the DB9 connector that can tear in the corners.
On Sat, Mar 17, 2012 at 10:59 AM, MailLists<li...@medesign.ro> wrote:
Hello all,
a friend purchased from the bay a<subj.> in the LPRO configuration.
After
some problems encountered during the first power ups, he asked for
help -
I'm passing the questions further...
After about 9 minutes of warm-up from room temperature (22°C) the lock
signal goes low, but after a short time starts to switch low/high with
decreasing low periods, until it remains high with short low pulses,
spaced
at about 2 seconds. After power-down, and sufficient cooling time, the
cycle repeats.
First step was to reapply the thermal interface to the integrated Al
radiator, which helped a bit, the time during which the unit is locked
growing slightly.
Next step was forced cooling, which helped more, so the lock loss
could be
attributed with high probability to elevated operating temperatures. The
temperature of the base plate (integrated Al radiator) at which lock
gets
lost is about 40°C, so for a reasonable operation it should not pass
about
36°C, at which the power consumption raises to about 17W. That also
means
that for a 1°C/W heat sinking - obtainable with a larger passive HS or
active cooling - operation above 30°C ambient gets practically
impossible
(except refrigeration, Peltier, etc.).
Any further help or suggestions are welcome.
Regards,
bbg
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