[time-nuts] 35601A as stand-in for 11848A ?

[SAIDJACK at aol.com]

In a message dated 1/4/2008 19:37:32 Pacific Standard Time, jmiles at pop.net  
writes:


>My current thinking is that most people are better off with an  11729B/C, or
>possibly just a homebrew quadrature-PLL implementation if  they don't care
>about microwave downconversion.  The 11729B/C plus  an 8662A (or even an
>8640B) has everything most people will ever need  for PN measurement.

>-- john, KE5FX



Hi guys,
 
does anyone have any experience with "home-brew" quadrature-PLL PN  
measurements? Renting/buying a E5052A or TSC5120A does get to  be expensive.. 
 
I am using different mixers (Mini Circuits ZFM-150 and ZFM-4) and the noise  
floor coming out of these seems much higher than I expected. Any  suggestions 
on mixers anyone? How about the low pass filter and amplifier?
 
I built an LC 8th-order 1.5MHz lowpass, and I wonder if the reflected  energy 
(at 10MHz, 20MHz, etc) is causing noise and  intermodulation in the diodes 
etc.
 
I am using an EL2125CS opamp (<1nv/rtHz noise) for the PLL and the Audio  
amp, with 40 or 60dB gain for the Audio amp.
 
Tried different power into the mixer (0dBm, +10dBm, +13dBm etc), this does  
not seem to affect the noisefloor, which I believe to be at least 25dB too  
high.
 
Thanks for any hints,
bye,
Said
 
 
 
 



**************Start the year off right.  Easy ways to stay in shape.     
http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489