logarithmic detector amplifier - discrete

[neazoi]

At around the middle of this page http://lea.hamradio.si/~s53mv/spectana/sa.html there is a discrete log detector.
Since it output only up to 100mV max for the full dynamic range, I would like to guild an amplifier for it but using discrete components. Any schematics or ideas are appreciated.

 

[Borber]

Obvious Video amplifier on Fig. 10 is what you want. It's output is 1V/20dB (~4Vmax).
Discrete components does not enable simple realisation with good enough temperature stability.

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Here you have more compact log detector with AD8703 with greater dinamic range:
https://www.qsl.net/n9zia/spec/log_amp.png

 

[chuckey]

I am confused! FiG 9 log detector is discrete. Fig 10 is video amp and is linear and has op amps. Which one are you talking about? I would think their characteristics are matched (Vref if fed between them) so I would use these circuits.
Frank

 

[Borber]

Similar log detector as on Fig. 9 is contained in AD8703. Schematics for that SA were first time published at the end of 1998.

 

[neazoi]

I am confused! FiG 9 log detector is discrete. Fig 10 is video amp and is linear and has op amps. Which one are you talking about? I would think their characteristics are matched (Vref if fed between them) so I would use these circuits.
Frank

As I said, I am looking for a DISCRETE components amplifier.
The log detector in that page outputs a very low voltage and needs an amplifier.
There is a reason why to use a discrete components log amplifier and this is dynamic range, read the article.