[time-nuts] Re: *** SPAM *** Re: [OT] MB506 pre-scaler module ??

[Bob Camp]

Hi

The “junk back on the input” is not at all uncommon. There are a number of PLL 
IC’s that have the same “feature”. Buffering the input signal is often a good idea. 

Bob

> On May 13, 2023, at 1:21 PM, Gerhard Hoffmann via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Am 2023-05-13 3:00, schrieb ed breya via time-nuts:
> 
>> "The  HMC493LP3  &  HMC493LP3E  are  low  noise
>> Divide-by-4 Static Dividers utilizing InGaP GaAs HBT
> 
> I have built a 1/8 prescaler using the HMC363 to extend the trigger
> bandwidth of my 54750A scope from 2.5 to 12 GHz (or the SR620).
> 
> It was necessary to have a gain block in front of the prescaler
> since the HMC363 pumped some of the divided signal back into its input
> which contaminated the measured channel with some jitter.
> A second gain block at the output makes sure that there is enough
> signal left even after a power divider.
> 
> The home-etched board is still without the preamplifier.
> Oscillation tendency is most easily cured by a small DC offset.
> That costs some sensitivity, another reason for the preamp.
> 
> The design has been published in DUBUS last year. I'll put it
> on my web site when the FTP access works again. Gerbers are available.
> 
> Cheers,  Gerhard   DK4XP<Auswahl_2023051318:57:49.png><Auswahl_2023051319:12:15.png>_______________________________________________
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