AGC problem - ad600/ad8307
 

Hi All

Idea
IF amp. 9MHz - single ad600 working in sequential mode, AGC realized
with AD8307 and opamp (http://www.mydarc.de/dc4ku/S_Meter.pdf -
bild1)
control voltage for AGC realized with TL431 similar to cdg2000.

Problems
1. - find a simplest way to implement a manual IF control. ("manual"
does NOT mean turning off AGC but possibility to change amplification)

How? Change a control voltage? add a manual regulated stage??? How to
realize threshold?

2. How to changing a time constant of AGC

Any directions or ideas? (www?)

73
MAc

AGC problem - ad600/ad8307
 

Hi MAc,

Can you give more examples of what you mean by "manual IF control", I
don't understand what you want to do.

Do you want to:
- Adjust overall dynamic range ?
- Adjust centre frequency ?
- Keep current dynamic range, but apply an offset ?
- etc

Do you have an English translation of your paper ? it looks most
interesting.

Regards,

Mark

On Jun 11, 11:12 pm, MAc wrote:
Hi All

Idea
IF amp. 9MHz - single ad600 working in sequential mode, AGC realized
with AD8307 and opamp (http://www.mydarc.de/dc4ku/S_Meter.pdf-
bild1)
control voltage for AGC realized with TL431 similar to cdg2000.

Problems
1. - find a simplest way to implement a manual IF control. ("manual"
does NOT mean turning off AGC but possibility to change amplification)

How? Change a control voltage? add a manual regulated stage??? How to
realize threshold?

2. How to changing a time constant of AGC

Any directions or ideas? (www?)

73
MAc

AGC problem - ad600/ad8307
 

Hi Mark.
I haven't English translations, only German text

Can you give more examples of what you mean by "manual IF control", I
don't understand what you want to do.

:-) What do I want, hmm
1. Realize and adjust threshold - You see, that it is simple detector
wirhout threshold
2. Adjust time constant of AGC
3. KNOW how to realize IF GAIN (any way) - I dont know what is the best
way - may be offset, may be additional stage, may be czanging the
dynamic range - I am just seeking informations.
What ist the way used in commertial gear? - AGC is stilll working but
amplification can be changed.

Best
MAc

PS I have also an article from FunkAmateur Januar 2005. If you want I
can send you.

AGC problem - ad600/ad8307
 

Hi MAc,

Take a look at the AD8367 variable gain amplifier. Watch out for the
input impedence of 200 ohms. Should be easy to match to 50 ohms using
a 2:1 bifilar tranformer.

Is that the sort of device that you are looking for ?

Regards,

Mark

PS Thanks for the offer of the article, is it in English ?


On Jun 13, 11:18 pm, MAc wrote:
Hi Mark.
I haven't English translations, only German text

Can you give more examples of what you mean by "manual IF control", I
don't understand what you want to do.

:-) What do I want, hmm
1. Realize and adjust threshold - You see, that it is simple detector
wirhout threshold
2. Adjust time constant of AGC
3. KNOW how to realize IF GAIN (any way) - I dont know what is the best
way - may be offset, may be additional stage, may be czanging the
dynamic range - I am just seeking informations.
What ist the way used in commertial gear? - AGC is stilll working but
amplification can be changed.

Best
MAc

PS I have also an article from FunkAmateur Januar 2005. If you want I
can send you.

AGC problem - ad600/ad8307
 

Take a look at the AD8367 variable gain amplifier.

Interesting, thanks

As i wrote i have an IF amplifier based on AD600. Two stages are working
in sequential mode. It is working very good.
An AGC detector with ad8307 is also workink good - but i need change my
current linear characteristic of AGC to charakteristic with threshold.
Now I can only change a slope of LINEAR characteristic - and i need to
change more parameters.

PS Thanks for the offer of the article, is it in English ?


Sorry, It is in German too, but most important informations are in
application note of ad8307 page21 - very interesting 120dB AGC system.
Similar to used by w7zoi.

73
MAc