[time-nuts] EFRATOM LPRO-101

Jim jim at commo.com
Sat Feb 6 23:11:34 UTC 2010


Thanks Antonio.

I rechecked the circuit.  Indeed R215 is a 100 K (103 marking)resistor 
and mine is reading 230K so I will replace it also.

The resistor immediately next to R215 is marked 2433 and it is reading 
56 pF which indicates to me that it is open. This resistor is slightly 
larger in physical size than R 215.

I will replace both of them.

This repair on SMD is new to me, and I am considering getting a set of 
resistor "Books".  About $40.00 each plus shipping from China.

Thanks for your having me look further.

Jim N0OBG




My LPRO repair records say that  R215 is 100K, size 0805 or 0603. 
So, please check a bit better.

>/Back to the unit, It starts out at over 10, 000,100, climbs a little 
/>/higher, then cycles around 10.0000, 170.  The logic never goes low.
/
It doesn't invert voltage sweeping due to the faulty resistor, and rests on a 
deadlock.
It will work after replacing the resistor.

Antonio I8IOV




Oops!  I had the wrong subject on the last message.

Jim

Thank you all for your support and suggestions.  I did get in touch with 
Bob and he is sending me another one.  I agree, he is great to deal with.

I popped the cover off the unit and in fact found R215 open.   It is a 
1208 283KOhm itsy bitsy tiny dude, and there are even tinier dudes and 
dudettes on the board.  They must be breeding.  What happened to tube 
sockets and wire wrap?

A local Ham friend has a SMD resistor for me to pick up and will do so 
probably tomorrow before the Super Bowl.  It has been an interesting 
learning curve for me with these devices, mainly learning the size.  
Thanks to Scott of TAPR fame he set me on the right track.

Back to the unit, It starts out at over 10, 000,100, climbs a little 
higher, then cycles around 10.0000, 170.  The logic never goes low.

After I replace the resistor I will report back to the group.

Again, thanks for your support.

Jim Conley N0OBG

The heart of the wise inclines to the right, 
     but the heart of the fool to the left. Eccl 10:2 (NIV)




t
> Date: Wed, 3 Feb 2010 12:37:08 -0500
> From: "Bob Camp" <lists at cq.nu>
> Subject: Re: [time-nuts] EFRATOM LPRO-101
> To: "'Discussion of precise time and frequency measurement'"
> 	<time-nuts at febo.com>
> Message-ID: <2E2B89B2FA654D7B86F3A4EC47509423 at vectron.com>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Hi
>
> I would second that as well. 
>
> I got an LPRO in that had a "rattle" when it arrived. After some thought, I
> popped the can and figured out what the issue was. Since it might have been
> gong back, I kept Bob in the loop during the entire process. He was very
> supportive through it all. Definitely a first class guy. 
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Doug Parker
> Sent: Wednesday, February 03, 2010 9:23 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] EFRATOM LPRO-101
>
> Hi,
> ?
> I'd like to confirm that Bob is a very good seller and been great with the
> things I've had off him. 
> ?
> He's also a member of this group
> ?
> Doug
> G4DZU
>
> --- On Wed, 3/2/10, EB4APL <eb4apl at cembreros.jazztel.es> wrote:
>
>
> From: EB4APL <eb4apl at cembreros.jazztel.es>
> Subject: Re: [time-nuts] EFRATOM LPRO-101
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Date: Wednesday, 3 February, 2010, 13:20
>
>
> Hi,
>
> Bob Mokia is a very good seller and you'll not have problems with him.? 
> In? order to avoid paying the return shipping and the delays I would ask 
> him to let you open the unit and try to find an obvious fault such a 
> loose connection.? When I bought my Rb (from another source) I opened it 
> even it was working ok, and I found one of the connector pins touching 
> its PCB pad without any trace of solder on it; nevertheless it worked 
> perfectly but it was just a question of time before the unit will begin 
> to act intermittently so I fixed it.? Thinking about I realized that 
> maybe this unit showed problems and it was retired from active service 
> and maybe it has very low hours on it.
> Do your unit sweeps its frequency above and bellow 10 MHz when warming 
> up the first minutes? it is the normal operation before a lock is 
> obtained and if it is not done it will never lock the oscillator to the 
> Rb frequency.
>
> Good luck,
> Ignacio, EB4APL
>
> -----------------------------------------------------------------------
> Bob Camp wrote:
>   
>> Hi
>>
>> A little more data from a group of recent units:
>>
>> The XTAL pin is looking at the VCXO control voltage, It should move around
>>     
> (sweep) at turn on. It will settle in the vicinity of 6 volts. I have seen
> units anywhere from 5.5 to 7.2 volts on this pin.
>   
>> The BITE is a logic level pin, it's either high or low. 
>>
>> The lamp voltage on "early" units runs around 6 volts. On "later" units
>>     
> it's up around 9 volts. This may be a better bulb, or it just may be a
> different photo detector. Every time I've asked about lamp voltage, the
> answer has been "in range is ok". Trying to predict life from lamp voltage
> apparently is more complex than it might seem.? I would not throw out a 6
> volt unit simply because it's not a 9 volt ....
>   
>> Bob
>>
>>
>> On Feb 3, 2010, at 7:08 AM, Roy Phillips wrote:
>>
>> ???
>>     
>>> Hi Jim
>>> This would appear to be a faulty unit, I also purchased the same unit
>>>       
> from Bob Mokia two weeks ago and its performing very well.? It gives a
> frequency of 10.000,000,005 Mhz.
>   
>>> One very obvious fault is the BITE voltage - - this should initially be
>>>       
> 4.5 volts, which falls to less than 30 mV. within a few minutes. The XTAL
> Control Volts, after a short while falls to 6.145 V., so yours, at 14.67 V,
> would seem to be wrong ! The Lamp volts settle to 6.736 V, and the Ext? C
> Field is 2.426 V. , which checks with your result.
>   
>>> I'm? sure you will get a replacement.
>>> Roy
>>>
>>> --------------------------------------------------
>>> From: "Jim" <jim at commo.com>
>>> Sent: Tuesday, February 02, 2010 9:08 PM
>>> To: <time-nuts at febo.com>
>>> Subject: [time-nuts] EFRATOM LPRO-101
>>>
>>> ? ???
>>>       
>>>> Hello all.
>>>>
>>>> I received an EFRATOM LPRO-101 last week from eBay Fluke 1, and wired it
>>>>         
> up last night. The results are not good.
>   
>>>> Using a HP 5370B counter with calibration less than one year old, the
>>>>         
> frequency reads = 10,000,146,012.9
>   
>>>> Power Applied = 24.9Vdc @ 0.30 amps after warm up
>>>> Lamp Voltage = 5.9 Vdc
>>>> Ext C Field = 2.437
>>>> XTL V Mon = 14.67
>>>> Bite = 4.57
>>>>
>>>> Bite never goes low.
>>>>
>>>> I just sent an email to the outfit I purchased it from, but would like
>>>>         
> to get this working instead of waiting a month or so.
>   
>>>> Is it dead?? Any thing I can do to revive it?
>>>>
>>>> Any suggestions?
>>>>
>>>> Thanks to all.
>>>>
>>>> Jim N0OBG
>>>>
>>>>
>>>> -- 
>>>>
>>>>
>>>>
>>>>         
>
>
>
>
>   
>


More information about the time-nuts mailing list