[time-nuts] LPRO-101 Status

Richard W. Solomon w1ksz at earthlink.net
Tue Jul 28 17:01:08 UTC 2009


My unit's Lamp Voltage does swing up and down until it locks.
It just takes longer than the 3.5 - 4 minutes the manual says.

I checked the Lamp Voltage when Locked and it is 9.4 vdc.

73, Dick, W1KSZ

-----Original Message-----
>From: Don Key <don.key at ntlworld.com>
>Sent: Jul 28, 2009 8:22 AM
>To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>Subject: Re: [time-nuts] LPRO-101 Status
>
>
>----- Original Message ----- 
>From: <iovane at inwind.it>
>To: "time-nuts" <time-nuts at febo.com>
>Sent: Tuesday, July 28, 2009 9:25 AM
>Subject: Re: [time-nuts] LPRO-101 Status
>
>
>On July 25, 2009 don.key at ntlworld.com wrote
>
>>The second one would not lock within 15 minutes, so I returned it (to 
>>China)
>>for a replacement. As I didn\'t have a heatsink, I didn\'t want to leave it
>>any longer. Besides, if it doesn\'t lock within 5 minutes, then I assume it
>>is faulty. Instead of the frequency sweeping up & down, the Xtal volts
>>started at around 6V2, then swept down to 0V & stayed there, leaving the
>>frequency about 180Hz low, as seen on a HP 8591E analyzer.
>
>>Out of interest, did your unit sweep up & down, or was it similar to mine?
>
>I had exactly the same problem with one of my units, but fixed it.
>In LPRO the voltage starts sweeping around 6.2V and goes up and down between
>two preset limits (about 0.5V and 12.5V) until lock occurs.
>Comparator circuits do sense the crossing of voltage limits and
>invert sweeping. Depending on what comparator fails, the unit remains
>in deadlock around 0V or 14.3V.
>I have had both cased with two units.
>In the case of 0V the faulty component was resistor R230 (100K, bottom of 
>pcb).
>It reads onboard about 23K when faulty and about 18K when good. Replaced 
>R230,
>the unit now works.
>In the case of 14.3V the faulty component was R215 (100K, bottom of pcb).
>It reads onboard >1Mohm when faulty. Replaced it, and the unit works.
>
>I have several LPRO, and all of them do lock in about 3.5 mins at ambient
>temperature of 20 °C or so. I use heatsinks.
>
>Bye,
>Antonio I8IOV
>
>
>I was tempted to open up the faulty unit, but thought it was best to return 
>it ASAP for a replacement (even though it cost me £6.51 postage).
>If it happens again, I will know where to look first!
>Cheers
>
>...Jim
>
>
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