Hej Ulf,
On 05/08/2014 01:14 AM, Ulf Ralberg wrote:
Bought an LPRS-01 on eBay too. Of course it only locked for a few
seconds. Got some valuable hints from Magnus Danielsson that steered me
in the right direction - the VCXO was probably saturated. After some
inspection, I conluded there were no
Hi Ed,
> When it locks for a few seconds, make a note of the VCXO control
> voltage. Watch it as closely as you can during the lock period. Is it
> very near one end of the sweep range? Does it then drift off the end of
> the range when lock is lost? That behaviour would suggest that the VCXO
Hi Gerd,
When it locks for a few seconds, make a note of the VCXO control
voltage. Watch it as closely as you can during the lock period. Is it
very near one end of the sweep range? Does it then drift off the end of
the range when lock is lost? That behaviour would suggest that the VCXO
h
Hi Ed,
> I don't have an LPFRS, but if I'm reading the manual correctly, the
> fourth column of numbers on the 'M' command (4D, 4C on your screen
> capture) is the VCXO control voltage. Shouldn't this be continuously
> sweeping up and down until it finds lock?
You are right, it sweeps the contro
I don't have an LPFRS, but if I'm reading the manual correctly, the
fourth column of numbers on the 'M' command (4D, 4C on your screen
capture) is the VCXO control voltage. Shouldn't this be continuously
sweeping up and down until it finds lock? Does the output frequency
sweep up and down and
Hi
Check the output frequency of the unit as it sweeps. I'd bet it's not quite
making it to 10 MHz. Look for a trimmer cap near the master crystal. It should
be possible to tweak it so the sweep makes it to either side of 10 MHz.
Bob
On May 26, 2013, at 1:43 PM, "Gerd v. Egidy" wrote:
> Hi,
Hi,
I bought a used Temex LPFRS-01 / LPRO from fluke.l on ebay. Unfortunately the
unit is broken and shows the same defect as was mentioned about a year ago on
this list: after warm-up it locks for a few seconds, but lock is lost again
after a few seconds. The lock output pulls low for a few ve
The disadvantage of the digital adjustment is that it's meant to be
"permanent", the MPU also modifies it's internal EEPROM cell that stores
the new value. Too many adjustments bear the risk of the used EEPROM
cell wearing out, which would be inevitable in a disciplining process,
and an unknown
I'm not using the analog input but the serial port, yes, this doesn't
improve the 1E-11 step but at least I skip the first A/D conversion. The
direct access to the C-field control seems necessary but I like to have my
stuff in the original state. My LPFRS is very rusty so I can drop my "keep
it ori
That would be the tougher part, as, with highest probability, the
external analog adjustment is first AD converted in the MPU (AIN4)
summed with the internally stored fine adjustment value, and then
applied to the C-Field correction, through an external DAC8800.
As both conversions are 8 bit, th
Interesting... have to check my LPFRS now: only tested for the lock
indicator when received and then put aside to complete first the
"discipliner".
On Thu, Apr 12, 2012 at 5:00 PM, MailLists wrote:
> Well, the saga continues...
> A replacement part (for which a thorough check was specifically as
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
After further testing, including a simple lost lock detector (2 555s:
manually resettable bistable + multivibrator and a buzzer), with the
serial port the whole picture looks even grimmer. Most parameters seem
to be in nominal range, relatively stable after warmup, with the notable
exception of
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 flu
Yes, trichloroethylene is banned but not tetrachloroethylene that was used
when the first was banned.
Fluke.l has other LPFRS but beware: they are much worst than the one in the
picture, usually they go on auction so try to stay low should you ever want
to bid on one.
Actually item 29068516928 is o
This is interesting. I have two temex units one which works and one which has
similar issues to yours. The performance of my working one is quite good.
(If you want any specifics let me know and I can provide more details in a few
days, but I recall it is notably better than either of my 5
You must understand the difference between deionized and destillated
water! I think often they sell deionized water of poor quality as
destillated on gas stations etc. Much like "destillated" as a general
synonym for "the best water".
If all fails, simple rain water is very good. Wait for a he
Yes, correct. The problem is that I have no deionized water nor a suitable
oven. The use of the tetrachloroethylene has simplified the procedure for
me (after all I was refunded, should the Rb fail it is not a money loss).
Anyway I'll try to locate a supply for high quality deionized water, the
ove
Hi
If it is water immersion damage, wash it in soap and water. Then rinse it in
hot deionized water (above 10 mega ohms if you can get it). After that bake it
at 80C with good air flow for > 24 hours. It still may rust, but most of the
guck from the water will be gone.
I once spent a lot of qu
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
Hello all,
a friend purchased from the bay a 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 shor
: time-nuts@febo.com
Sent: Mon, March 7, 2011 11:10:13 AM
Subject: Re: [time-nuts] Temex LPFRS-01 analog frequency adjustement
On 03/07/2011 07:45 PM, Mark Spencer wrote:
> Thanks. I recall seeing documentation that more or less said that directly
> connecting these units to an RS232 por
On 03/07/2011 07:45 PM, Mark Spencer wrote:
Thanks. I recall seeing documentation that more or less said that directly
connecting these units to an RS232 port will typically work but is not
guaranteed. If you are able to easily check your unit that would be great but I
will likely try connecti
rch 7, 2011 9:43:47 AM
Subject: Re: [time-nuts] Temex LPFRS-01 analog frequency adjustement
On 03/07/2011 05:52 PM, Mark Spencer wrote:
> Greetings. I'm wondering if any one has any insight (or wishes to speculate)
>as
> to how the external analog frequency adjustment on a Teme
“Greetings. I'm wondering if any one has any insight (or wishes to speculate)
As to how the external analog frequency adjustment on a Temex LPFRS-01
Rubidium standard functions.”
++
The spec sheet says 0-5 volts for analog adjustment. The unit supplies a 5V
hi-stability refer
On 03/07/2011 05:52 PM, Mark Spencer wrote:
Greetings. I'm wondering if any one has any insight (or wishes to speculate) as
to how the external analog frequency adjustment on a Temex LPFRS-01 Rubidium
standard functions.
From experimenting with one over the last few days there seems to be a s
Greetings. I'm wondering if any one has any insight (or wishes to speculate)
as
to how the external analog frequency adjustment on a Temex LPFRS-01 Rubidium
standard functions.
>From experimenting with one over the last few days there seems to be a step
function to the adjustment. I'm w
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