[time-nuts] 0MHz distribution...NOT

Bob Bownes bownes at gmail.com
Mon Mar 12 21:43:36 UTC 2012


What, if any, are the phase changes?


On Mon, Mar 12, 2012 at 5:39 PM, Chuck Forsberg WA7KGX N2469R
<caf at omen.com>wrote:

>
>
> On 03/10/2012 04:44 PM, Mark Spencer wrote:
>
>> I've done this as well.
>>
>> I daisy chained several pieces of hp and marconi gear together that all
>> had an approx 1k ohm input impedance for the frequency reference and fed
>> them from a single 10 Mhz source via t connectors with a 50 ohm terminator
>> at the end of the line.   Looking at the signal with either a scope or a
>> time interval counter I have seen noticeable phase shifts when some of the
>> equipment receiving this signal is turned off or on.   That being said so
>> long as the equipment was not turned off or on the adev of the signal was
>> as expected.   Your mileage may vary.
>>
>> Sent from my iPad
>>
>> On 2012-03-10, at 4:24 PM, Michael Blazer<mblazer at satx.rr.com>  wrote:
>>
>>  You may want to take a look at the signal on a scope.  Most instruments
>>> terminate their reference input.  You might actually have 4 50 ohm loads on
>>> the Thunderbolt's output and the input voltage might be marginal.  If your
>>> instruments have both reference input and output, it's better to daisy
>>> chain the units.
>>>
>>>
>>> On 3/10/2012 5:10 PM, Chuck Forsberg WA7KGX N2469R wrote:
>>>
>>>> A month or two ago I had sketched out a simple distribution amp
>>>> for my 10 MHz reference.   In the meantime I became somewhat
>>>> disillusioned about my FE-5680a standards.   So I removed the
>>>> FE-5680a and disconnected its power supply from the box that
>>>> holds the Thunderbolt, power supply, and big line filter.
>>>>
>>>> I decided to try daisy-chaining the Thunderbolt's 10 MHz output.
>>>> I have plenty of hardware left over from the days of 10BaseT networking.
>>>>
>>>> So I have the Thunderbolt going to a BNC T on the back of my FlexRadio
>>>> 1500,
>>>> hence to my Advantest U3641 spectrum analyzer, and finally to the
>>>> external
>>>> reference on my Racal-Dana 1992 nanosecond universal counter.  That end
>>>> has a 50 ohm termination on the other side of its T connector.
>>>>
>>>> All three devices seem happy with the 10 MHz they are receiving.
>>>>
>>>>  I connected my Tek 2712 to the end of the chain.  It reads +10dbm
> +-1db.
>
> Switching units on/off/ext ref causes less than 1db change in the 10 MHz.
>
>
>
> --
> Chuck Forsberg WA7KGX N2469R     caf at omen.com   www.omen.com
> Developer of Industrial ZMODEM(Tm) for Embedded Applications
>  Omen Technology Inc      "The High Reliability Software"
> 10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430
>
>
> ______________________________**_________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/**
> mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> and follow the instructions there.
>


More information about the time-nuts mailing list