[time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[EWKehren at aol.com]

Allow me to put all this in  perspective. Three years ago having just 
joined time-nuts I started to be  interested in Dual Mixers. Having CS and Rb my 
main interest was and still is  low noise signal generators and I have all 
the HP equipment for those  measurements. Did my first Shera Rb about 2000 
and a few more since. Time was  not and still is not much of an interest my 
best time instrument is a modified  PICTIC II. 
Starting with the original NBS paper  I came to the conclusion that the 
major cost would be the counter, something I  would have very little use for, 
for other projects since I am well equipped up  to 40 GHz. That is when I 
came up with the idea of what I call a ping pong  counter a counter that counts 
every period, sort of pseudo time stamping. Back  of an envelop calculation 
and I went on the list stating that I think a $  200  D/M system not 
counting OCXO’s  was doable. What was needed was help with the PIC codes. First 
response was  “that is why we call our self Time-nuts”. However Richard Mc 
Cokle did offer his  help and he has been key to the success. The goal of $ 
200 for all material for  a 4 channel counter and D/M is attainable if 10 
boards are ordered.   
The first set of boards where done  in about 5 month. Several people tested 
the D/M but kept on using their counter  and my thanks go out to Corby who 
tested the very first  D/M. 
I was left testing the counter and  logic is my strong suit as Juerg will 
attest my weakness is software even though  at one time I set up and was in 
charge of a software group. Had problems with  the counter PC interface. Now 
thanks to Corby I now know that the problem was  the 56K RS 232 versus 9.6 
K. Tells you how brilliant I am on that subject. Till  recently I thought RS 
232 is RS232. 
I did reach out to the list and  connected with Fred Tijddingen who offered 
to help. I send him a counter and he  asked me to get him some parts that 
where not time related after he agreed to  pay for them. After I shipped 
them, never heard from him again. Be careful, I do  not know if any one else had 
that experience. Many of you know I used to ship  and only asked to be paid 
after you got the parts. Well now I am a lot more  selective. 
A year ago I connected with list  member Juerg Koegel. We share the same 
priorities and complement each other with  our skill sets. On top of that 
Juerg has the equipment that I lack and the know  how to make it talk to PC’s.  
On top  of that Juerg had used a MAX 3000 G/A for a PICTIC counter. Perfect 
match. Juerg  can also write PIC code, not like Richard but what we  need. 
First out the 2 channel and 4  channel counters now with G/A’s and Richards 
PIC;s. The two channel measures  phase and period in the ping pong mode 
allowing you to do the basics of a single  D/M. The 4 channel was intended for 
two D/M’s or with an additional 2 channel  for three corner hat. Can also be 
used for cross correlation.   
How ever the 4 channel in  combination with one D/M allows also very high 
resolution frequency comparison  only limited by the noise floor of the D/M. 
Since the A/V measurements are most  likely not a daily activity using this 
instrument for frequency measurements or  aging tests over long term makes 
it a very useful tool. Juerg does not want me  to talk to much about it, but 
he is right now busy writing PIC code for a 4 line  LCD display that also 
includes a Vinculum VDRIVE2 that allows recording data on  a USB flash drive, 
interfaces with a PC using RS 232, USB and Bluetooth. I call  it the Swiss 
Army Knife, because of all the things the combination D/M, Counter  and Juerg 
LCD can do. 
The D/M is being revisited because  of the counter performance. 1 E-13 is 
easily attainable but the Czech IREE  published a paper and claim 2 E-15. 
Would be nice to get 1 E-14. Tried to get  detailed information, no luck, but 
maybe some list member will be able to. It  was EU funded. 
Working with Juerg has been very  productive 
2 channel counter    done 
4 channel counter    done  
Partridge and TADD-2 Mini like 1 pps  generator using G/A done 
Tbolt  Bluetooth interface  done 
G/A version of Shera using 100 or  200 MHz in testing 
D/M LCD PCB done, in code writing  phase 
Austron circuit using G/A in  testing 
PICTIC II using G/A in board  layout  G/A  done 
At this point I like to make a plug  for the Altera MAX 3000 GA. Easy to 
program (I can do it) low cost and makes all  TTL and HC logic available but 
the best part if something does not work you do  not have to do a new board, 
just reprogram. Using a $ 0.60 socket makes it very  solderable. Made a 
prototype board and I think it is fair to say that our  productivity has gone up 
10 fold. Some one mentioned G/A jitter a day later we  had a test setup 
comparing a Partrige board with our circuit and found out  thanks to Jueg’s 
equipment G/A was as good maybe slightly better.  Software is free and the prog
rammer is $  10. 
What happens next depends on  interest by the list. Juerg and I will not 
get in to the kit business but if  larger interest is there I will find a way 
to accommodate. 
Let  me make it clear, the counter by it self  has only limited usability, 
you also have to have or build a D/M. But the  combination with a PC or 
Display will make it a very useful, flexible,  affordable tool. 
My back of the envelope calculation  still shows $ 200 for the Mixer und 
counter and somewhere between $ 350 and 400  for a full up system using Morion 
MV 89 OCXO for offset, LCD Display with  VDRIVE2, power supplies and 
enclosure. 
I am looking for a volotier to work  with me on the documentation, my 
drafting skills are mnimal and I want Juerg to  focus on display code. Would be a 
distraction.  
Will send a picture of the 2 channel  but have to compress to make it 
through the system. 
Bert Kehren   Miami