[time-nuts] HP 3586A/B/C entirely referenced to 10MHz: Asolution

[John Miles]

I liked this part:

"Initially, the intent was to use the MSBOUT (Most Significant Bit) output
pin as the LO source. This would have been great since the output is
TTL-leveled, exactly what the SLM phase detector is designed to work with.
Unfortunately, this MSBOUT signal is not a clean square wave. There is some
rollover in the DDS engine happening every few milliseconds, stretching the
pulse repeatedly. This caused some modulated noise on the audio. Rejected."

... because I made the same mistake the first time I used an early
commercial DDS part that required an outboard DAC.  ("Why would I need a $50
DAC chip?  Those guys at Qualcomm must be morons.  I'll just hang a low-pass
filter off the MSB...")

-- john, KE5FX


> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of shalimr9 at gmail.com
> Sent: Monday, March 21, 2011 11:32 AM
> To: Time-Nuts
> Subject: Re: [time-nuts] HP 3586A/B/C entirely referenced to 10MHz:
> Asolution
>
>
> Hi Bert,
>
> That is very interesting, thank you for sharing.
>
> Didier KO4BB
>
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: "Bert, VE2ZAZ" <ve2zaz at yahoo.ca>
> Sender: time-nuts-bounces at febo.com
> Date: Mon, 21 Mar 2011 10:11:04
> To: <time-nuts at febo.com>
> Reply-To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] HP 3586A/B/C entirely referenced to 10MHz: A
> 	solution
>
> Hello Everyone,
>
> I have spent the last few weeks modifying the HP 3586 Selective
> Level Meter. The
> intent was to modify the unit and reference the SSB product
> detector stage to
> the internal reference. This would make the entire SLM locked to
> the 10MHz
> reference, whether internal or externally fed.
>
> I have completed the modification with satisfactory results. I
> use a DDS-Based
> Function Generator 16-pin IC and a small 8-pin PIC micro.  For
> more detail,
> visit my website at http://ve2zaz.net/HP3586_AD5962/HP3586_AD5962.htm .
>
> This has been a very good exercise from a DDS perspective and I
> have learned a
> lot on the topic. I would be interested in hearing from those who
> proceed with
> the mod.
>
> Thanks,
>
> Bert, VE2ZAZ
>
>
>
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