[time-nuts] TAPR TADD-2 PIC frequency divider

Samuel D. [x86/CPC] sam at canardpc.com
Fri May 22 23:38:39 UTC 2009


Another question about the TADD-2 PIC divider : they said on main page the
source code for the pic will be released in open source. Does anyone know if
the code is available somewhere ?


-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
part de Magnus Danielson
Envoyé : samedi 23 mai 2009 01:33
À : Discussion of precise time and frequency measurement
Objet : [time-nuts] TAPR TADD-2 PIC frequency divider

Fellow Time-nuts,

I acquired myself two TAPR TADD-2 PIC frequency dividers as soon as they 
hit the list as orderable. Tonight I had the pleasure of completing the 
first one.

For a beginner, this kit should be fairly simple. You need to have some 
ability to solder and read resistor and capacitors, even if most 
capacitors comes in separate bags (pretty neat brown bags, but hard to 
open without ripping the lid partly off). The manual could give better 
hints for the beginner, but it is nothing major at all.

Since I fail to fall into the beginner group, I must say that it was 
pretty straight forward to build it. The double-sided, silkscreened and 
plated hole PCB made this as simple as any other modern kit and it is 
easy to make the mounting look good. I was supprised how well my 
resistor-leg bending was still up to speed and accuracy as they all went 
in quickly and smoothly. Everything went very smoothly.

So, at last... everything mounted and time to power up. Without input it 
sits there quitetly. I hooked it up to the time-base output of my SR-620 
and it kicked alive directly. 10 kHz, 1 kHz, 100 Hz, 10 Hz, 1 Hz and PPS 
all just ticked away as expected. I hooked over to a 5 MHz source, the 
OCXO (TOYO oscillator of unknown specs) from an Ericsson AXE-10 station 
that I keep heated at the labbench with a BNC hanging free, and sure 
enought everything was half-rate including the PPS LED (very useful), 
but just unplugging the 5/10MHz jumper fixed that quick enought.

A few items of criticism is in place, from a practical point of view. 
The TADD-2 does not perfectly match the TAPR TADD-series box. I was able 
to sneak out the PPS through the DC input hole, and the ARM and SYNC 
LEDS is way in there, so a similar approach was not possible. The 5/10 
MHz jumper should possibly be made into a toggle-switch. None of those 
fits the casing, but using one of the DB9 holes should fit it nicely. 
The other DB9 hole could be fitted with a suitable DB9 connector for 
power. None of these things is a show-stopper, but of mild details which 
could have been made better and very simple hacks will allow for a more 
versatile setup, for those wishing to use their TADD-2 as a lab-device, 
where as for fixed setups it is of close to no consequence.

I only made a quick attempt to measure jitter, but it is way down there 
around ps or so. It was just an indicator measurement anyway. I will 
make some more propper measurements and analysis.

Regardless, I think it is a nice kit and should allow for easy 
lab-ability for most time-nuts. I particularly like the simultanous 
outputs which is jumperable to suitable outputs and the 5/10 MHz jumper. 
The PPS LED allows for a quick view and the ARM/SYNC should allow for 
synchronisation. It fairly well fills a gap in my set of gear and should 
do that for others too. Doing picket fence exercises becomes trivial 
with one of these.

Good work John, Tom and others that feel involved.

Cheers,
Magnus

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