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

Greg Broburg semiflex at comcast.net
Tue Mar 22 00:57:34 UTC 2011


Yeah;

But sometimes there is some magic in the design
of the LPF.

Greg

On 3/21/2011 5:51 PM, John Miles wrote:
> 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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