[time-nuts] TADD-1 six channel RF distribution amplifier

John Ackermann N8UR jra at febo.com
Fri Mar 28 15:55:55 EDT 2008


Tom's unit had the bandpass filter installed, and as Bruce noted I've
regretted ever putting the holes on the board for it -- my saying is
that "every resonator is a thermometer"!  The prototype that Tom tested
without a filter had much better tempco, and I suspect that the
filter-less production version would be closer to that performance.

I'm hoping to do my own tempco testing one of these days, but things
beyond my control have gotten me way behind on the project list lately.

John
----

Didier Juges said the following on 03/28/2008 02:09 PM:
> The phase plots on tvb's web site
> http://www.leapsecond.com/pages/tadd-1/3phase2.gif show  that the device's
> temperature was never stabilized. The closest to being stable is at the 29
> minute point on that plot.
> 
> Particularly when the phase value goes up (not sure if it's when temperature
> goes up or down), because the phase was still changing at a pretty high rate
> when the compressor changed state. I think Tom should rerun that test with a
> much slower cycling, to make sure the phase was stable before the compressor
> was turned on (or off). Since the phase excursion was not complete, the
> 150pS/degree is probably underestimated.
> 
> My guess is that the period should be at least doubled.
> 
> Didier KO4BB
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com 
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Jeff Mock
>> Sent: Friday, March 28, 2008 12:29 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] TADD-1 six channel RF distribution amplifier
>>
>>
>> Bruce Griffiths wrote:
>>> Steve wrote:
>>>> I'm thinking about using the TAPR TADD-1 six channel RF 
>> distribution 
>>>> amplifier to distribute the 10MHz output of my Trimble 
>> Thunderbolt to 
>>>> a few pieces of test equipment.
>>>>
>>>> What does the TADD-1 do to the phase noise characteristics of its 
>>>> outputs as compared to the phase noise characteristics of  
>> its input?
>>>> Improve? Degrade? Little or no change?
>>>>
>>>> Thanks.
>>>>
>>>> Steve K8JQ
>>>>
>> I've been using a TADD-1 for about 6-months now and I'm quite 
>> happy with it.  You certainly can't beat the price.  I added 
>> the optional 10MHz BPF and tuned it with a tracking generator 
>> and spectrum analyzer.  The outputs are very clean.
>>
>> I've never tried to measure phase noise, but the op amps and 
>> the rest of the circuit seem to be good choices to me.  tvb 
>> did some analysis of the box you might find interesting:
>>     http://www.leapsecond.com/pages/tadd-1/
>>
>> jeff
>>
>>
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