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[time-freq] Reflock II observations - PROGRESS!!

Peter Horbaczewskyj peter at microwaves.f9.co.uk
Mon Nov 21 14:05:01 UTC 2005


Hi Steve,

As the subject says, I'm making some progress with my setup.
I've taken Bobby's advice and started to use wire links as shorts on the 
board.
Looking at the signals a lot closer with a scope, there actually is a signal 
coming out of the XOR output.
Not a very big one I have to say though. approx 100ns every so often, very 
difficult to see.
Doesn't seem to produce any reaction from the op amp circuitry.

Then I decided to have a go and use the  PD2 UP signal. Finally there is 
some movement
on the frequency meter. Problem now is that there is not enough range on the 
output of the
op amp to reach the magical lock point of 10.0000MHz. Need to change the 
gain so
that I can get 5-6V out as there is no other method of adjustment on my 
oscillator.

Perhaps someone can suggest the best way of achieving this. I assume that 
the
"Offset Voltage Adjustment" pot will limit the range of the op amp output.

73, Peter G4ZXO


----- Original Message ----- 
From: "Peter Horbaczewskyj" <peter at microwaves.f9.co.uk>
To: "TAPR time and frequency projects" <time-freq at lists.tapr.org>
Sent: Monday, November 21, 2005 11:20 AM
Subject: Re: [time-freq] Reflock II observations


> Hi Steve,
>
> The oscillator I am using is something that I had in my junk box. 
> Basically it is an OCXO
> that is controlled by the voltage input from a pot circuit. The frequency 
> range is about
> +/- 50Hz either side of 10MHz for a voltage range of 0 to 7.5V. I am 
> currently using the
> 1pps signal as a reference source and I have tried both the 1pps config 
> files supplied by
> Louis. Neither of them  it would seem appear to give an output on the XOR 
> pin on the
> CPLD. Both the PD2 UP and PD2 DOWN signals are OK. The issue stems from 
> the lack of
> signal to the TLC271CD op amp. Next thing to try is the PD2 UP signal. I'l 
> keep you informed
> of any progress.
>
> The board as it stands is very neatly designed and laid out, but it 
> doesn't lend itself very easily to
> development work or "suck and see" endeavours. Once it works I'm sure that 
> it will be boxed up
> and quietly forgotten about.
>
> 73, Peter G4ZXO
>
> ----- Original Message ----- 
> From: "Steven Bible" <n7hpr at tapr.org>
> To: "TAPR time and frequency projects" <time-freq at lists.tapr.org>
> Sent: Monday, November 21, 2005 3:27 AM
> Subject: RE: [time-freq] Reflock II observations
>
>
>> Hi Peter,
>>
>> You mention 10 Mhz, what is your oscillator and what is your reference?
>>
>> 73,
>>
>> - Steve, N7HPR
>> (n7hpr at tapr.org)
>>
>>
>>
>> -----Original Message-----
>> From: time-freq-bounces at lists.tapr.org
>> [mailto:time-freq-bounces at lists.tapr.org]On Behalf Of Peter Horbaczewskyj
>> Sent: Sunday, November 20, 2005 4:01 PM
>> To: TAPR time and frequency projects
>> Subject: Re: [time-freq] Reflock II observations
>>
>>
>> Hi Bobby,
>>
>> I totally agree with you, I've been trying to get my board working 
>> tonight
>> with not much success at all.
>> You really need to go through all the files with a fine toothcomb and 
>> drag
>> out the information, and hope
>> you've understood it correctly. Currently I am playing with a 10MHz
>> oscillator but don't seem to be getting
>> any signals out on the XOR output of the CPLD, using either of the "pps"
>> files. The other two outputs PD2 UP
>> and PD2 DN appear to be behaving as you would expect. However, moving the
>> little 0 ohm links to select a
>> different output is not the easiest thing to do!! Time to get the scope 
>> out
>> and have a proper look.
>>
>> By the way, I wonder if you realise that Altera provide a standalone 
>> piece
>> of software for programming
>> their chips called "Quartus II Programmer" currently at Ver 5.0. This
>> certainly has the ByteBlaster MV as
>> an option and is pretty simple to use.
>>
>> The circuit that Steve has just published is essentially that one I built
>> for my programmer, using a 74HC244
>> as the interface. This chip will certainly work down to around 2.0V as
>> opposed to the LS types which generally
>> need 5V.
>>
>> Time to go away and ponder what might have gone wrong.
>>
>>
>> Regards and 73, Peter G4ZXO
>
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