[time-nuts] [Bulk] Unified VCXO Carrier Board

J. L. Trantham jltran at att.net
Thu Oct 22 12:30:56 EDT 2015


Gerhard,

Don't know if it would help much in your ultimate plan but the concept has been done before as the 53132-60011 and 53132-60016 Optional Time Base Boards for the 53132A counters.  These boards will accommodate either an Isotemp OCXO33-46 (HP 1813-0931) OCXO for OPT 001, or either of two variants of the 10811 for OPT 010 or 012.  There is a jumper that needs to removed and possibly connected to a power supply for the 10811's.

Might be helpful to take a look at for ideas.

Hope this helps.

Joe

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Gerhard Hoffmann
Sent: Thursday, October 22, 2015 2:41 AM
To: Discussion of precise time and frequency measurement
Subject: [Bulk] [time-nuts] Unified VCXO Carrier Board

I'd like to design a unified VCXO Carrier Board to these requirements:


1. It can host one of the the following VCXOs:

1.1. HP 10811A-6111 (as from 5370A)

1.2 Morion MV89A

1.3 MTI 260

1.4 CV-950

1.5 Timetech

1.6 Axtal

1.7 Pascall


2. It provides unified tuning: 0V = lowest possible frequency, 3V3 or 5V = highest possible frequency, no matter of the VCXO tuning sense and range.

3. provides a 5V tuning voltage reference for those VCXOs that don't have one of their own.

4. Frequency can be adjusted from external Vtune input and from a 10 turn pot.

5.Board has 2 reference frequency inputs with LTC6957 receivers. One of them can interface the onboard VCXO to the CPLD.

6. Board has a 1pps input 3V3 CMOS level

7. It can lock the VCXO to the reference frequency or the 1pps in. 
Provides LED lock indication.

8. It features a Xilinx Coolrunner2 2C64 CPLD, complexity 64 FlipFlops + combin. Logic. Unused Pins are brought out to Testpoints in 100 mil grid. The Coolrunner remembers its configuration and can be reprogrammed using the standard Xilinx USB dongle. It has a 10 pin 2mm header for this purpose. Small circuits can run at 200 MHz. This function exists
already:
<
https://picasaweb.google.com/lh/photo/4Bpcfouj8WH0shNGIyuVUtMTjNZETYmyPJy0liipFm0?feat=directlink
 >

9. The Coolrunner provides a standard 1pps /20us out, maybe 10/100/1000 pps.

10. 2 Monoflops for 1pps LEDs in/out

11. There are 2 output buffers that drive valid 3V3 CMOS into 50 Ohms. 
They can be re-clocked to LTC6957 outputs with 1G74 flipflops.

12. Unbuffered VCXO output is available on SMA connector

13. One additional buffered output (LMH6702/AD8009 or discrete to avoid neg. supply). This is not meant to be a distribution amplifier.

14. Regulators for the voltages needed.

15. Requires soldering skills 0603 / sot23-5 / MSOP. No commercial interest. Could be TAPR or DIY.


I'm open to suggestions & ideas.

regards,
Gerhard, DK4XP


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