[Premium-Rx] Synthesizer Phase Jitter.

[Carcia, Frank A. HS]

Hi John,
I tried the ARRL method on a stock 6830
using a 400 hz. filter. I think the Racal method or my HP141 is funky at
that low frequency or there is some correction factor like IF bw missing in
my numbers.

ARRL RESULTS  

1 KHz.	-90 dB
2		-94
3		-99
5		-102
10		-99
20		-121
30		-132
40		-137
50		-139
100		-142

I then checked a synthesizer module with the HP141 corrected for BW. This
was a modified synthesizer from Racal engineering lab junk box with a number
of 100 pf caps and rerouted coax cables. Gary W. found this in his stash
with a E1 s/n. narrow band spurs lower
than a stock module.

100 Hz	-85
200		-85
500		-85
1 KHz		-90
2		-94
3		-95
5		-102
10		-100
20		-98
30		-105
40		-108
50		-108
100		-115
I think the ARRL method is superior as it is a system test and the spectrum
analyzer performance isn't part of the result. The numbers between us appear
similar. Now I need to run the same test on my hot rod unit with cascaded
filters. Close in I could hear high frequency audio bleeding around the
filters. The ARRL method only requires
a generator and RMS meter. KISS  fc


 
-----Original Message-----
From: John Reed [mailto:jreed at alum.mit.edu]
Sent: Tuesday, April 15, 2003 9:43 AM
To: Carcia, Frank A. HS
Subject: Re: [Premium-Rx] Synthesizer Phase Jitter.



----- Original Message -----
From: "Carcia, Frank A. HS" <francis.carcia at hs.utc.com>
To: "'John Reed'" <jreed at alum.mit.edu>
Sent: Tuesday, April 15, 2003 7:35 AM
Subject: RE: [Premium-Rx] Synthesizer Phase Jitter.

You are probably referring to the close-in phase noise measurements.  That
is correct on the 3 KHz IF filter.  Actually I used a 6 KHz filter.  However
to make phase noise measurements farther out, I used the standard method:
Use a narrow IF filter, first measure MDS, then move the receiver X KHz away
from the generator.  Crank up the generator until the receiver
S/(S+N) is + 3 dB.  Phase noise is given by:  (MDS - generator output at
X) - 10log(filter bandwidth) (in dBc).  This method is outlined in the ARRL
Product Review Test Manual.

73, John

> John,
> I think the procedure said to use 3 KHz filter. I will also look at it
with
> a narrow filter. I'm thinking that will clip off the wide band noise
> though????
> Shouldn't the band pass of the IF be wider than the stuff you want to
> measure in the audio?  fc
>
> -----Original Message-----
> From: John Reed [mailto:jreed at alum.mit.edu]
> Sent: Monday, April 14, 2003 7:30 PM
> To: Carcia, Frank A. HS
> Subject: Re: [Premium-Rx] Synthesizer Phase Jitter.
>
>
>
> ----- Original Message -----
> From: "Carcia, Frank A. HS" <francis.carcia at hs.utc.com>
> To: "'John Reed'" <jreed at alum.mit.edu>
> Sent: Monday, April 14, 2003 7:24 AM
> Subject: RE: [Premium-Rx] Synthesizer Phase Jitter.
>
> Hi Frank,
> Here's what I found for the Harris and Racal phase noise spectra:
>
> Harris RF-590
> 1 KHz  -102 dBc,  2 KHz -102 dBc, 5 KHz -100 dBc, 10 KHz -94 dBc, 15
> KHz -104 dBc,
> 20 KHz -116 dBc, 40 KHz -130 dBc, 100 KHz -148 dBc.
>
> Racal RA6793A
> 1 KHz -90 dBc,   2 KHz -90 dBc,  5 KHz -111dBc,  10 KHz -124 dBc, 15 KHz
not
> taken,
> 20 KHz -130 dBc, 40 KHz -135 dBc, 100 kHz -142 dBc.
>
> As I remembered, the Harris is noisier when you get farther out.  I was
also
> glad to see the 1 KHz numbers on the Harris agreed well with the close in
> data.  However the Racal numbers didn't.  I neglected to record the
spectrum
> analyzer bandwidth I used to get the 1 KHz close in measurement.  If I had
> used 30 Hz as I suspect I did, then they would be within 5 dB.  The above
> numbers are all really dBc, corrected for the 300 Hz CW filters I used in
> making both tests.
>
> 73, John
>