[time-nuts] About HP10544A

Esa Heikkinen scifiscifi at sci.fi
Sun Mar 8 08:23:13 UTC 2009

> 5370A: 1K + 10pF in series connected from 10544A output to input of an
> ECL line receiver cascade.
> 5345A: 1K + 910pF in series connected from 10544A output to input of CC
> CB long tailed pair isolation amplifier.
> 1K from CC base to ground.

What do you think: if I would be able to create perfect buffer for it 
somehow will it still have worse spectrum than tbolt ocxo for example? 
With capasitive coupler test the 2nd anr 3rd harmonic was still high. 
Maybe it's the best what it's possible to get with 10544 anyhow?

So is it even reasonable to try or just get some other ocxo? I would 
like to have as clean 10 MHz as possible with reasonable price. Let's 
say that the spectrum what tbolt ocxo gives could be some kind of 
minimum. But I'll need that ocxo inside thunderbolt in it's original place.

> Since the 10544A phase noise floor is relatively high (~ -145dBc for the
> later variants earlier versions had a significantly higher noise floor
> spec) using 1K in series adds little additional noise.

Is it so that 10544A isn't good for RF lab reference at all? Maybe it's 
designed just for counters etc. where the spurious or harmonics are not 
so big deal?

Unfortunately I'm so rookie with these that clearly I'm seeking wrong 
stuff. At very first I expected to have a good 10 MHz reference with 
just using thundrbolt but then noticed that it's for time, not frequency 
reference. Maybe 10544A is intended for timing applications also, not as 
frequency standard?


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