[time-nuts] FE-5680A Loop Lock Indicator

Robert LaJeunesse rlajeunesse at sbcglobal.net
Sun Sep 22 02:24:19 UTC 2013


Bob,

I would bump that base resistor up a lot higher, to load the FE-5680 less. The PN2222 has enough gain it only needs about 0.3 mA base drive to work as intended. You'd get that with a 10K base resistor.   

Bob LaJeunesse



>________________________________
> From: Bob Stewart <bob at evoria.net>
>To: Time Nuts <time-nuts at febo.com> 
>Sent: Saturday, September 21, 2013 10:02 PM
>Subject: Re: [time-nuts] FE-5680A Loop Lock Indicator
> 
>
>Hi John,
>
>Thanks for the response.  I managed to cobble something up with LTSpiceIV, and get it to work.  And for me, that's saying something!    Here's what I wound up with: "http://www.evoria.net/AE6RV/GPSstd_PLL/LED-driver.png", where V2 is the Loop Lock Indicator.  The PN2222 shorts out the LED until it goes into lock, then the LED comes on.  It does give a short pulse when power is first applied and things are equalizing.  Even with a 1K resistor, the 4.2V from Lock signal is pulled down to 3V.
>
>And here's a pic of my Rb standard on it's temporary home with the LED on a scrap of breadboard:
>"http://www.evoria.net/AE6RV/GPSstd_PLL/Rb.standard.png".
>
>Bob
>
>
>
>
>
>>________________________________
>> From: jmfranke <jmfranke at cox.net>
>>To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>>Sent: Saturday, September 21, 2013 6:58 PM
>>Subject: Re: [time-nuts] FE-5680A Loop Lock Indicator
>> 
>>
>>Yes, but put an isolation resistor between the output and the base of the
>>transistor, something between 3K and 5K should work. The LED will light upon
>>power on and extinguish when lock is achieved.
>>
>>John  WA4WDL
>>
>>
>>--------------------------------------------------
>>From: "Bob Stewart" <bob at evoria.net>
>>Sent: Saturday, September 21, 2013 6:10 PM
>>To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
>>Subject: Re: [time-nuts] FE-5680A Loop Lock Indicator
>>
>>> Hi Bob,
>>> 
>>> I hooked the big voltmeter up to it, and it shows +4.2V out for about a minute, and then goes to 0. Looking on the web, it seems like I can use that to drive a 2N2222 and put the LED and dropping resistor in the collector path with the emitter to ground? Does that sound right?
>>> 
>>> Bob
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> ________________________________
>>>> From: Bob Camp <lists at rtty.us>
>>>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>>>> Sent: Saturday, September 21, 2013 4:12 PM
>>>> Subject: Re: [time-nuts] FE-5680A Loop Lock Indicator
>>>> 
>>>> 
>>>> Hi
>>>> 
>>>> Those readings sound a lot more like a CMOS gate output than some sort of open drain / open collector discrete driver.
>>>> 
>>>> Bob
>>>> 
>>>> 
>>>> On Sep 21, 2013, at 4:43 PM, Bob Stewart <bob at evoria.net> wrote:
>>>> 
>>>>> Hi Bob,
>>>>> 
>>>>> It's rather curious. Using my handheld DVM in the diode scale, I get a reading of 448 in one direction and 458 in the other with it off and cold. In the 2K ohms scale, I get 561 and 562 ohms. Later on, I'll pop the top off again and take a pic so I can expand it and look at it. For what it's worth, my DDS board is 2 revisions earlier than the one Matthias Bopp modifies here "http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%201_0.pdf"
>>>>> 
>>>>> Bob
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>> ________________________________
>>>>>> From: Bob Camp <lists at rtty.us>
>>>>>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>>>>>> Sent: Saturday, September 21, 2013 3:00 PM
>>>>>> Subject: Re: [time-nuts] FE-5680A Loop Lock Indicator
>>>>>> 
>>>>>> 
>>>>>> Hi
>>>>>> 
>>>>>> As far as I know the lock output is a CMOS output that will drive a couple of ma. There are so many variations that yours may indeed be an open collector and good to +15 volts.
>>>>>> 
>>>>>> Bob
>>>>>> 
>>>>>> On Sep 21, 2013, at 10:55 AM, Bob Stewart <bob at evoria.net> wrote:
>>>>>> 
>>>>>>> The instructions I got with this Rb said that you could hook an LED through a 5-10K resistor to the +15 supply and get a lock indication. I'm using a 10K resistor and the LED lights as soon as it's powered up from cold. Is the loop lock indicator circuit broken or is it just another strange option for these things? I saw on one site that if you do it this way it prevents lock, but mine seems to lock OK with or without the voltage.
>>>>>>> 
>>>>>>> 
>>>>>>> Bob - AE6RV
>>>>>>> _______________________________________________
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