[time-nuts] Distributiuon Amlifier Altinex DA1804NT

[Vlad]

Tom,

I agree that spikes looks weird. Looking for the raw data, I see its 
fluctuate from 9.999999958E+6 to 1.0000000049E+7
And here how its spread:

#occurr.  / FREQ
    1  +9.999999958E+6
    1  +9.999999980E+6
    1  +9.999999981E+6
    1  +9.999999988E+6
    1  +9.999999989E+6
    1  +9.999999990E+6
    1  +9.999999992E+6
    1  +9.999999996E+6
    1  +9.999999999E+6
    2 +1.0000000001E+7
    1 +1.0000000004E+7
    1 +1.0000000005E+7
    3 +1.0000000006E+7
    2 +1.0000000007E+7
    4 +1.0000000008E+7
    4 +1.0000000010E+7
    4 +1.0000000011E+7
    7 +1.0000000012E+7
    1 +1.0000000013E+7
   17 +1.0000000014E+7
   12 +1.0000000015E+7
   37 +1.0000000016E+7
  394 +1.0000000017E+7
1772 +1.0000000018E+7
1362 +1.0000000019E+7
  550 +1.0000000020E+7
  120 +1.0000000021E+7
   73 +1.0000000022E+7
   34 +1.0000000023E+7
   12 +1.0000000024E+7
    8 +1.0000000025E+7
    6 +1.0000000026E+7
    5 +1.0000000027E+7
    1 +1.0000000028E+7
    3 +1.0000000030E+7
    2 +1.0000000031E+7
    2 +1.0000000032E+7
    1 +1.0000000033E+7
    1 +1.0000000049E+7


I am not sure what to blame. ;-) The setup is pretty simple (on my 
taste). Its Trimble TB, connected to linear power supply. The GPS 
antenna connected via HP GPS Distribution amplifier and mounted 
permanently. The 10 Mhz output from that Trimble TB, connected by coax. 
cable to Ref input of HP 5386A.
The OCXO connected to the input A of counter by very short coax. cable. 
I was using diffrent PSU for all OCXO. Its switching PSU from IBM 
LapTop, its HP laboratory PSU (Linear, 0-24V) and its XL125 switching 
Power Supply. I tried following OCXO: MV89A, its Oscilloquarz 8663-SX 
and its DATUM OCXO (not remember its model. It looks exactly the same as 
one in use inside of Trimble TB). And all of them shows spikes. Today, 
I'll try to use one of those OCXO as Ref signal for counter and try to 
measure another OCXO using that ref. That will give me some clue if 
Trimble TB has an issue.

Regards,
Vlad

On 2015-05-28 03:32, Tom Van Baak wrote:
> Hi Vlad,
> 
> Before we get to your phase noise question...
> 
> Your plots ALTINEX-DA-F.png ALTINEX-DA-T.png look odd and the plot
> ALTINEX-DA.png shows massive amount of glitches. You must make sure
> that the frequency and the phase plots look "nice" before doing an
> ADEV plot. In this case there's probably something wrong with your
> setup. You should NOT be seeing all those jumps, spikes, wiggles, and
> noise in a frequency plot. Hundreds of outlier data points are
> destroying the validity of the ADEV calculations. Something is very
> wrong.
> 
> Check wires, connectors, power supplies, groundings, vibration, air
> flow, mains voltage, etc. Try a 3rd oscillator in case it's a problem
> with one of your two oscillators. But you have to get rid of those
> spikes in the ALTINEX-DA-F.png plot. The way we usually test a
> distribution amp is to use a single oscillator and a splitter; one leg
> goes through the DA and the other does not. The phase difference plot
> then reveals the stability of the DA.
> 
> But regardless of how you measure a DA, the frequency plot should not
> have so many erratic glitches. The kind of plot you should expect is
> the smooth portion between the 8700 second and 11600 second grid
> lines.
> 
> /tvb
> 
> ----- Original Message -----
> From: "Vlad" <time at patoka.org>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Wednesday, May 27, 2015 7:04 PM
> Subject: [time-nuts] Distributiuon Amlifier Altinex DA1804NT
> 
> 
>> 
>> Hello,
>> 
>> Recently, I acquired video distribution amplifier (model Altinex
>> DA1804NT). It says it could handle 350Mhz. I am planing to use it to
>> split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction 
>> site.
>> It has Oscilloquarz model 8663-SX plus some components which give me 4
>> outputs - 2 sines and two squares. After few days of "warm up" I did
>> measurement of ADV from one of the sine outputs and then measurement 
>> of
>> the same sine signal from OCXO, but this time through the Altinex DA.
>> Each test took 8 hours. Attached is the results.
>> 
>> NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. 
>> So,
>> its not DATUM. It is Oscilloquarz 8663-SX
>> I was using Trimble TB as a ref signal  for HP 5386
>> 
>> Since I have no  instruments which measuring phase noise, I am
>> interesting, what will be the quick method to measure the phase noise
>> for that DA ?
>> 
>> 
>> --
>> WBW,
>> 
>> V.P.
> 
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-- 
WBW,

V.P.