[time-nuts] Stepping up the output of an OCXO

[Stephan Sandenbergh]

Hi Bruce,

A great many thanks for all the hints and tips you gave me.

Yes, I have actually started working my way through Wenzel's hints & tips
pages after I posted the first message. I remembered that you pointed me
there in a previous conversation we had.

I find the schematic you attached in your last post very interesting - I
happen to have a soft spot for discrete analog solutions that can still beat
their integrated counterparts. 

However, I still tend to lean towards the "mini-circuits" type
attenuator/Gain block idea. The reasons are all the reasons why everyone is
leaning toward integrated solutions. (e.g. the integrated solutions might
cost a bit more, but it uses a lot less board space; if a unit fails you
simply replace it with another one, less components, etc, etc.) 

Nevertheless, I noted you use the word 'must' as in: if you must use the
mini-circuits.... So I suspect there might be a down-side to using this kind
of approach. Or is it just that the discrete solution works somewhat better?
Do you mind elaborating a bit on this?

Regards,

Stephan Sandenbergh

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Dr Bruce Griffiths
> Sent: 02 February 2007 05:46 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Stepping up the output of an OCXO
> 
> Stephan
> 
> Attached GIF file is the schematic for a common base amplifier with
> about 12dB of gain into a 50 ohm load.
> The amplifier will not saturate even if the load is open circuited.
> Q102 temperature compensates Q103 which regulates the dc collector
> current of the common base transistor.
> Other transistor types with equivalent performance may be susbstituted.
> The RF transformers are coupled to the amplifier with series capacitors
> to avoid saturating the cores with dc current.
> 
> Bruce